Rozprawy doktorskie na temat „Vegetation removal”

Thesis advisor: Noah P. Snyder
Dam removal is typically used to restore fish passage, natural flow regimes, and sediment transport in streams. However, dam removal also impacts the riparian vegetation, a change that can have wider effects throughout the ecosystem. Quantifying vegetation change requires a multi-year record to document pre-removal communities and both the immediate and delayed responses. In this study, vegetation change was assessed at the Merrimack Village Dam on the Souhegan River in Merrimack, NH, which was removed in August 2008. The removal caused a ~3 meter drop in water level and rapid erosion of impounded sediment, with ~50% removed in the first three months. The vegetation was sampled using plots at specific intervals along 7 monumented transects that were perpendicular to the channel or adjacent wetland. Tree, shrub, and herbaceous communities were assessed using species percent areal coverage techniques in July 2007, 2009, 2014 and 2015. Change over time was quantified using Analysis of Similarity (ANOSIM) on the Bray-Curtis dissimilarity matrix. As expected, vegetation communities in control plots upstream of the impoundment did not show significant change during the study period. Tree and shrub communities adjacent to the impoundment also did not show significant change. All herbaceous communities adjacent to the impoundment changed significantly (p < 0.05). The herbaceous plots closest to the channel changed to bare sand in 2009 due to erosion in the former impoundment, but by 2014 the riparian fringe community seen in 2007 had re-established and expanded in this area, but at a lower elevation. Between 2007 and 2014, the wetland herbaceous community changed from aquatic species to a stable terrestrial community that persisted without significant change in 2015. From 2007 to 2014, the vegetation community on a mid-channel island of impoundment sand changed from a community with ~50% invasive reed canary grass to a ~98% community of invasive black swallowwort, a species not recorded at the site pre-removal. The vegetation response was greatest in areas with largest geomorphic and hydrologic change, such as along the channel margin where erosion and bank slumping created an unstable scarp or on the mid-channel island and off-channel wetland strongly impacted by the lowered water table. However, large unvegetated areas never persisted nor did the areal coverage of invasive species expand: two common concerns of dam removals
Thesis (BS) — Boston College, 2016
Submitted to: Boston College. College of Arts and Sciences
Discipline: Scholar of the College
Discipline: Earth and Environmental Sciences

2 pp.
Persistent woody plants can sometimes conflict with gardening and landscape goals. In many cases, plant removal becomes necessary. This may be accomplished through manual stump removal or the use of herbicides. With some knowledge of the life history of the target plant, cut stumps can be safely and effectively treated with herbicides to prevent regrowth. Species lists, safety tips, examples, photos, and non-herbicide alternatives are provided to ensure optimum stump killing success.

Woody vegetation encroachment has become a major threat to tallgrass prairie streams mainly because of fire suppression. This process converts prairie streams from open to closed canopy systems. The effects of these riparian changes are poorly understood, but the relative importance of basal resources presumably shifts from primarily autochthonous to allochthonous with increasing canopy cover, potentially altering macroinvertebrate functional structure and production. To assess the effects of woody vegetation encroachment on stream ecosystem structure and function, riparian trees were removed from two headwater stream reaches on the Konza Prairie Biological Station (KPBS) in eastern Kansas. Experimental stream reaches were compared to streams with naturally open and closed canopies before and after the manipulation. Benthic organic matter and macroinvertebrates were collected monthly from each reach for one year before and one year after woody vegetation removal. Total community production in canopy removal reaches ranged from 8.9-10.2 g AFDM m-2 y-1 before riparian removal, and this increased significantly to 13.4-14.5 g AFDM m-2 y-1 after riparian removal. Scraper production in canopy removal reaches was 2.8-3.9 g AFDM m-2 y-1 before riparian removal, and increased significantly to 6.0-8.7 g AFDM m-2 y-1 after riparian removal, presumably due to enhanced food availability. Total community production in naturally open reaches ranged from 7.6-12.6 g AFDM m-2 y-1 before riparian removal and decreased to 6.5-9.8 g AFDM m-2 y-1 after riparian removal. Riparian forest removal altered macroinvertebrate production and functional structure, but higher macroinvertebrate production in canopy removal reaches compared to naturally open reaches suggested natural conditions were not restored one year after riparian removal. However, macroinvertebrate communities in naturally open and canopy removal reaches became more similar after riparian removal. Functional structure, based on production, in naturally open and canopy removal reaches after riparian removal was dominated by scrapers (45-60% of total production), with similar proportions of collector-gatherers (12-26%) and predators (15-25%). Collector-filterers and shredders contributed < 9% of total production in naturally open and canopy removal reaches after riparian removal. Results demonstrate that woody vegetation encroachment and riparian forest removal significantly influence tallgrass prairie stream structure and function. Information from this study can help inform and guide management, restoration, and conservation of remaining tallgrass prairie streams.

Dam removals are becoming increasingly common as dams reach their life expectancy and face costly upgrades associated with relicensing. Though removal is often viewed as a success in terms of ecological restoration, it also represents a major disturbance to an area. Previous research has shown that native species do not survive as well at these disturbed sites, and invasive species often dominate. This study examines the vegetation response in the drained reservoir area after the removal of Hemlock Dam on Trout Creek, a tributary to the Wind River in southern Washington. Transects were established and quadrats were sampled to determine the plant classifications and cover of vegetation and to examine possible correlations between environmental variables and the spatial distribution of plant classification groups. Sampling took place in the third and fourth years following dam removal, and the data was analyzed to determine significant changes and relationships. The results of this study showed that the site was dominated by a volunteer native forb Lotus purshianus (Spanish clover) and a planted native tree Alnus rubra (red alder). Most of the other species found were native volunteer forbs and grasses characteristic of early succession in this region. Both invasive species and planted species, with the exception of Alnus rubra, had low canopy covers. There was a significant increase in native plant canopy cover, as well as total canopy cover, from 2012 to 2013. There were also significant relationships between plant classification groups and environmental variables, including soil infiltration, elevation, and distance from stream. This study will help inform resource managers about the kinds of plants that will volunteer after dam removals and the possible success of re-vegetation projects.

This study investigates the effect of ecosystem age on the nitrate removal efficiency, nitrate removal rate and first-order area-based removal rate coefficients (both with and without temperature adjustment) of created wetlands. Data was collected from the first to eleventh year after wetland creation in an experimental wetland facility in south-west Sweden. The 18 small (22-29 m2) free water surface wetlands were divided into three groups based on initial planting: EVW (emergent vegetation wetlands), SVW (submerged vegetation wetlands) and CW (unplanted control wetlands). Summer and winter values from the 11 studied years were analysed separately in the repeated measures ANOVA. Over these 11 years the mean nitrate removal efficiency was 12 % and the mean nitrate removal rate was 0.17 g m-2 d-1. Mean removal rate coefficient (K) was 0.020 g d-1 and mean temperature adjusted removal rate coefficient (Ka) was 0.042 g d-1. The best performing wetlands were those initially planted with, and after four years almost completely covered by, emergent vegetation (EVW). This study indicates a positive correlation between wetland age and nitrate removal potential. It further indicates aging may be hastened by initial planting of wetland vegetation.

The goal of this study was to assess effects of sediment removal on vegetation communities in Prairie Pothole wetlands in North Dakota to determine if this management technique is providing desired results to create conditions for ideal vegetation communities in wetlands that will benefit wildlife. This project consists of vegetation surveys from seasonal wetlands located in Benson, Eddy. Towner. and Wells counties in North Dakota. Three types of wetlands were surveyed: natural (reference), excavated (treatment), and converted cropland. Vegetation surveys were completed in the shallow marsh and wet meadow zones of seasonal wetlands. Sites were sampled using a modified Daubenmire method. Aerial photos were assessed to determine the occurrence of drawdown cycles in wetland sites. Plant communities were analyzed using non-metric multidimensional scaling and multi-response permutation procedure was used to make comparisons between sites. The wet meadow zones and shallow marsh zones of the three types of wetlands were all significantly different (p<0.016) from one another. In general, restored wetlands show vegetation trends that liken natural wetlands while those that have been allowed to recover without restoration tend to be cattail choked. When examining hybrid cattail specifically visual obstruction scores were approximately four times greater in converted cropland sites versus treatment or reference sites. Vegetation composition indicates hydrologic conditions (fresh to brackish conditions) of specific sites and regional distribution are likely influential factors in wetland plant establishment.
North Dakota State University
U.S. Fish and Wildlife Service
Ducks Unlimited

The purpose of this research was to assess the ability of subsurface flow wetlands, with aeration and vegetation, to remove nitrogen in cold weather climates. Aeration was shown to enhance the wetland cell's ability to remove not only nitrogen but also CBOD, COD, and phosphorus (retention) more effectively. There was a significant difference (p< 0.05) in both total nitrogen and ammonia effluent concentrations comparing aerated to unaerated wetland cells, while no significance was found comparing planted and unplanted wetland cells. The effluent ammonia concentrations from the aerated wetland cells ranged from 2.7 to 5.7 mg N/L, while for unaerated cells effluent concentration ranged from 22 to 23 mg N/L. The effluent total nitrogen concentrations from the aerated wetland cells ranged from 9.0 to 12 mg N/L, while those from unaerated cells ranged from 23 to 24 mg N/L. The effluent concentrations showed no significant difference (p < 0.05) when comparing results of three temperature ranges. There is a correlation when comparing ammonia mass removal rates to mass loading rates. Ammonia removal in the aerated wetland cells ranged from 82 to 95%, while unaerated cells ranged from 39 to 45%. The hydraulic retention times ranged from 3.13 to 4.33 days and the tanks-in-series ranged from 1.46 to 2.84. Using this information the wetland cells were modeled using both the TIS and the PkC* models. The k values (PkC* model) of the aerated wetlands for ammonia ranged from 131 to 221 m/d, while the unaerated wetland cells had values ranging from 20.4 to 36.7 m/d. The models appear to show a good prediction of the effluent ammonia concentration for the unaerated cells but the aerated cells show the model does not effectively capture the effects of aeration.

Thesis (M.S.) University of Missouri-Columbia, 2006.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 27, 2007) Includes bibliographical references.

Dam removal is increasing as dams age, yet little is understood about the pedogenic response to dam removal. This study reports on the edaphic changes of reservoir sediments and vegetation cover one year following removal of a small earthen dam in Northern California. In August 2012, I sampled surface sediments from the former Dream Lake reservoir in Lassen Volcanic National Park, and compared their physical and chemical properties with soil samples from two reference sites. I also estimated percent cover of vegetation in the former reservoir and reference sites. My results show that the reservoir was under reduced conditions, as determined by gleyed soil color and a higher pH when compared to reference samples. In contrast to reservoirs on larger river systems which tend to be sinks for organic matter, Dream Lake showed a reduction in organic matter when compared to reference locations. My results suggest reservoirs created by dams cannot be considered to have similar sediment properties, namely increases in organic material. Unlike other studies that found former impoundments invaded by non-native species, the former Dream Lake site has been colonized by native grasses, sedges, and rushes. This study documents the edaphic properties and vegetation response of a small reservoir one year after dam removal, and suggests a more thorough investigation of those properties prior to undertaking costly restoration of these highly dynamic systems.

An important aspect of restoration ecology is the removal of non-native invasive plants. While restorations in urban areas involve similar challenges to restorations in rural areas, urban efforts also contend with unique issues such as increased fragmentation and decreased seed sources for native species. This study examined efforts to eradicate Ligustrum sinense and allow native vegetation to occupy the landscape. The herbaceous layer was inventoried at study plots in riparian bottomlands of four Atlanta, Georgia, natural areas two years after start of treatment to remove L. sinense. Plant taxa were described and compared to a similar study conducted in a rural area of northeastern Georgia. Significant abundance of L. sinense was recurring at urban sites while recurrence at rural sites was low. Other non-native invasive species, frequently used in urban landscaping, were also occurring at urban sites and not at rural sites.

This study was made as a part of a feasibility study on a polishing wetland at Rimbo wastewater plant (wwp) in Norrtälje municipality. The wwp had to decrease the nitrogen discharge to reach the limit 15 mg tot-N/l. The nitrogen in the outlet was mainly in the form of nitrate, hence the wetland mainly ought to support denitrification. The proposed area for the wetland was situated right next to the wwp and was already in the municipalitys posession. One aim of this study was to examine what spieces of plants needed to achieve highest possible denitrification. Some different plant spieces for providing a good and interesting environment for birds and people were also proposed. Furthermore a massbalance model was developed for studying the important exchange processes in a wetland, to study the impact of an uneven streambed on the hyporheic water exchange and for trying to predict the wetlands nitrogen removal capacity. Proposed plants to support denitrification was different reeds such as Common reed (Phragmites australis), Bulrush (Typha), Reed Sweet-grass (Glyceria maxima) och Reed Canry-grass (Phalaris Arundinacea). Common reed is a durable species who can survive in deeper water up to 2 metres while the others need a shallower water about 0,5 m of depth. For the good of the birdlife, different spieces of Sedges (Carex) were chosen due to their ability to produce large amounts of nutrient rich seeds. Measurment in sediment cores from Ekeby wetland in Eskilstuna gave a potential denitrification capacity of 3,31 mg NO3-N m^-3 _sed s^-1. The denitrification capacity was then used in a massbalance model were the theory of advective pumping in an uneven bedsurface also was implemented. Evaluation of the model results showed that an uneven bedsurface did not contribute to an increased nitrogen removal from the wetland, possibly due to a far too low advection and flow of the water. This was also a reason to why the distribution between denitrification from the water- and plant community vs the sediment was unbalanced. The model results showed that less than 1 % of the reduced nitrogen came from the sediment part, in contrast to current knowledge that says about 50%. The model and the participating exchange processes need to be further evaluated before the models prediction of nitrogen removal can be used in design of a wetland. Calculations and comparisons with other wetlands showed that with a well estimated, grown up and maintained wetland, there should be no problems in achieving the goal of nitrogen removal in Rimbo wetland. Such a wetland should also provide a good habitat for birds and animals and also be a good recreationarea for people to visit, properties that were appreciated as important effects in other wetlands studied in this work.

Detta arbete gjordes som en del av en förstudie för anläggande av en efterpolerande våtmark till reningsverket i Rimbo, Norrtälje kommun. Reningsverket behövde sänka sitt utsläpp av kväve till riktvärdet 15 mg tot-N/l. Huvuddelen av kvävet i utloppsvattnet förelåg i nitratform, varför denitrifikationen borde förstärkas genom att anlägga en våtmark. Det tilltänkta området för våtmarken ligger i anslutning till reningsverket och ägs idag av kommunen. I detta arbete undersöktes vilken växtlighet i våtmarken som var lämpligast för syftet att få en så bra denitrifikation som möjligt. Även olika växtarter för att ge en intressant miljö för fåglar och människor togs fram. Dessutom utvecklades en massbalansmodell som användes för att studera de utbytesprocesser som är viktiga i en våtmark, frågan hur en ojämn bottenmorfometri påverkar det hyporheiska vattenutbytet samt om det går att förutsäga reningskapaciteten i Rimbo våtmark. Lämpliga växter för denitrifikationen ansågs vara vassbildande växter, och då främst främst bladvass (Phragmites australis), men även kaveldun (Typha), jättegröe (Glyceria maxima) och rörflen (Phalaris Arundinacea). Bladvass är en mycket tålig växt som klarar stort vattendjup, medan de andra vassorterna behöver en grundare våtmark på ca 0,5 m. För fågellivets bästa ansågs starrväxter (Carex) vara viktiga arter då de producerar stora mängder frön. Mätning av denitrifikationspotentialen i sediment från Ekeby våtmark gav en hastighet för denitrifikationen i sedimentet på 3,31 mg NO3-N m^-3 _sed s^-1. Denitrifikationen från sediment användes sedan i en massbalansmodell där även även teorin om advektivt pumputbyte vid ojämn bottenform implementerades. En utvärdering av modellresultaten kunde avgöra att en ojämn eller vågig bottenmorfometri inte skulle förbättra reningen i våtmarken. Detta beroende på bland annat för låg advektionshastighet och flöde. Detta låga flöde ned i sedimentet bidrog även till att fördelningen av kväveborttag från sediment respektive vatten- och växtdelen blev snedfördelad. Enligt modellen var det mindre än 1% av kvävet som togs bort från sedimentet medan all vetenskap tyder på närmare 50%. Modellen och de ingående utbytesprocesserna bör utvärderas och utvecklas ytterligare innan den kan användas som verktyg för att beräkna kvävereningen från en våtmark. Beräkningar och jämförelser med andra våtmarker visade dock att en väl beväxt, utförd och beskickad våtmark inte skulle ha några problem att sänka nitrathalten till riktvärdet. En våtmark skulle även utgöra en bra uppehållsmiljö för fåglar, djur och människor vilket anses som viktiga mervärden i våtmarker på andra platser i Sverige.

Thesis (MSc)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: The present global biodiversity crisis is characterized mostly by loss of species due to habitat destruction but there other major threats – notably invasive alien species. The term “biodiversity hotspot” has been coined to emphasize areas for conservation prioritization – areas that have high biodiversity under threat from habitat destruction, invasive species, etc. The Cape Floristic Region (CFR) in the Western Cape (WC) Province of South Africa has the highest biodiversity of all Mediterranean-type climate regions globally and is classified among global biodiversity hotspots. The CFR, a Mediterranean-type climate heathland with a naturally high fire frequency, faces threat from transformation by development, disturbed (increased) fire frequencies and intensities, and invasive organisms, most notably invasive trees. Such threats disturb keystone species and keystone processes including insect pollinator assemblages and associated insect flower visitation webs and frequencies. Invasive pines are a serious threat to insect flower visitation as pine trees (Pinus spp.) shade out much indigenous vegetation in the CFR. Little is known of their long-term effects on insect flower visitors and vegetation recovery in post-pine restoration and recovery areas after such trees are removed. I investigated the recovery of vegetation and the most important insect pollinator, bees, after the removal of pines by fire and passive recovery in a CFR valley in the Western Cape. In 1999, a wildfire burned much of the WC Limietberg Nature Reserve along with an adjacent pine tree forestry stand - which was then left to recover, providing an ideal opportunity to investigate the enduring effects of pine afforestation in the CFR. In two data chapters, I compared the post-fire passive recovery of vegetation (Chapter 2) and bee diversity (Chapter 4) in areas which had previously been planted with pines vs. those which had contained natural fynbos. To improve on sampling methodology, I conducted an experiment that demonstrated the Observer Effect in bee sampling with a sweep net (Chapter 3), and I developed a novel sampling device (Chapter 5) for insect flower visitors. Sampling of vegetation and bee diversity was conducted in a paired sampling design, where fynbos (Natural) sub-sites were paired with sub-sites which had previously been afforested with pines (Post-Pine Recovery; PPR) and the two sub-sites were separated by a distinct, linear boundary (Natural/PPR boundary). Sampling was conducted along transects parallel to the boundary and extending in both directions from the boundary into the Natural and in the opposite direction into PPR sub-sites. Five transects were positioned at 3, 10, 20, 30, and 40 m from the boundary (Ecotone) and three were positioned at 60, 80, and 100 m from the boundary (Deep). In Chapter 2, I found that natural sub-sites consistently had higher total plant species abundance and species richness than PPR sub-sites. Approximately two thirds of plant species were more abundant in Natural sub-sites than in PPR sub-sites. There was no significant correlation in species richness or abundance with distance from the Natural/PPR boundary. Some genera are cautiously indicated as having lower success in recovery after pine afforestation: Erica spp., Restio spp., Hypodiscus spp. while Helichrysum spp. is also tentatively indicated to recover well in PPR sub-sites. Soil disturbance and concomitant disruption of normal ecosystem functions, including pollination, is indicated as a probable reason for disruption of plant recovery. In Chapter 3, sweep netting methodology was tested for the Observer Effect. A noticeable increase in bee visitation frequency to a common generalist plant species in bloom, Metalasia densa, was correlated with longer waiting periods after I stopped moving indicating the presence of an Observer Effect. This suggests that sweep netting for bees should only be commenced after a waiting period of five minutes during which the sweep netter is motionless. In Chapter 4, using a flight-intercept modified pan trap, I compared bee species richness and bee species abundance across different seasons and in both mass-flowering and sparser flower patches. There was no significant difference in bee species richness between Natural and PPR sub-sites. All bee species, except one complex, were more abundant in Natural sub-sites. Nearly two thirds of all bee species (n=37 of 56) caught with sweep netting and the modified pan trap are undescribed species. Similar to the vegetation, the effects of soil disturbance as a result of decades of pine forest shading and pine forest litterfall followed by an unusually hot pine forest fire are indicated as the most likely reasons for lower bee abundance in PPR sub-sites. This is due to the difficulty associated with viable nest establishment and suitable pollen and nectar forage availability in disturbed areas. In Chapter 5, the newly developed Pan and Flight Intercept Combination (PAFIC) trap’s design, pilot testing, and comparison with the traditional pan trap is discussed. A preliminary test suggests that the PAFIC trap is more efficient (with higher abundance) than the traditional pan trap. In Chapter 6, I discuss the implications of the disturbance of pine forestry and unusual pine fire to plant species and bee species assemblages. Bee-pollination webs in PPR sub-sites are indicated as being substantially simpler than those in Natural areas as well as compositionally different. The recovery of pollination as a keystone process in post pine-afforestation areas faces a substantial challenge given the disturbance to soil that decades of pine afforestation followed by pine forest fire can cause. Some suggestions are made for the restoration of fynbos areas recovering from pine afforestation including a discussion of augmenting re-vegetation measures (fynbos seed dispersal and seedling planting) with methods of restoring of healthy pedogenesis, epigaeic arthropod communities, and fynbos seedbanks.
AFRIKAANSE OPSOMMING: Die huidige globale biodiversiteit krisis is gekenmerk meestal deur die verlies van spesies as gevolg van die vernietiging van habitat. Maar daar is ook ander groot bedreigings – veral merkbaar indringerspesies. Die term “biodiversiteit brandpunt” is geskep om gebiede vir bewaring prioritisering te beklemtoon - gebiede wat 'n hoë biodiversiteit bevat wat bedreig word deur die vernietiging van habitat, indringerspesies, ens. Die Kaap Floristiese Streek (KFS) in die Wes-Kaap (WK) Provinsie van Suid-Afrika het die hoogste biodiversiteit van alle Mediterreense tipe klimaat streke wêreldwyd, en is onder die globale biodiversiteit brandpunte geklassifiseer. Die KFS, 'n Mediterreense-tipe klimaat heideveld met 'n natuurlike hoë brand frekwensie, word bedreig as gevolg van transformasie deur ontwikkeling, versteurde (verhoogde) vuur regimes, en indringer organismes, veral indringerbome. Sulke bedreigings versteur hoeksteen spesies en die hoeksteen prosesse, insluitende insek bestuiwer samestelling en verwante insek blom besoekings webbe en frekwensies. Indringer dennebome (Pinus spp.) is 'n ernstige bedreiging vir insek blom besoeking want dennebome verskaf skaduwee aan baie inheemse plantegroei in die KFS. Min is bekend oor die langtermyn effekte op insek blom besoekers en plantegroei restorasie na denneboom verwydering en restorasie gebiede na sodanige bome verwyder word. Ek ondersoek die restorasie van plantegroei en die belangrikste insek bestuiwer, bye, na die vernietiging van dennebome deur vuur en passiewe herstel in 'n KFS vallei in die Wes-Kaap. In 1999 het'n veldbrand baie van die WK Limietberg Natuurreservaat saam met 'n aangrensende denneboom bosbouplantasie gebrand - wat toe gelaat is om te herstel via intermediêre suksessie na inheemse fynbos plantegroei. Dit bied 'n ideale geleentheid om die blywende gevolge van denneboom aanplanting in die KFS te ondersoek. In twee data hoofstukke, vergelyk ek die passiewe herstel van plantegroei na ‘n brand (Hoofstuk 2) en by diversiteit (Hoofstuk 4) in gebiede wat voorheen geplant is met dennebome teenoor diegene wat natuurlike fynbos vervat het. Om te verbeter op steekproefmetodiek, het ek 'n eksperiment onderneem wat demonstreer hoe die Waarnemer Effek by monsterneming met 'n vee-net beïnvloed (Hoofstuk 3), en het ek 'n nuwe monsterneming toestel ontwerp (Hoofstuk 5) vir insek blom besoekers. Monsterneming van plantegroei en by diversiteit is uitgevoer in 'n gegroepeerde steekproef ontwerp, waar fynbos (Natuurlik) sub-terreine gegroepeer is met sub-terreine wat voorheen aangeplant was met dennebome (Na Denneboom Verwydering Herstel; NDVH) en die twee sub-terreine is geskei deur 'n duidelike, lineêre grens (Natuurlik / NDVH grens). Steekproefneming is gedoen langs transekte parallel tot die grens en versprei in albei rigtings van die grens tot binne die natuurlike fynbos en in die teenoorgestelde rigting tot binne NDVH sub-terreine. Vyf transekte is geposisioneer binne 50 m van die grens (Oorgang sone) en drie is ver geplaas van die grens (Diep). In Hoofstuk 2 het ek gevind dat natuurlike sub-terreine konsekwent hoër totale getal plant individue en spesierykheid as NDVH sub-terreine gehad het. Ongeveer twee derdes van plantspesies was meer volop in natuurlike sub-terreine as in NDVH sub-terreine. Daar was geen beduidende korrelasie in spesierykheid of totale hoeveelheid plant individue met betrekking tot afstand van die Natuurlike /NDVH grens. Sommige genera word versigtig aangedui as met laer sukses in die restorasie terreine na denneboom aanplanting: Erica spp., Restio spp., Hypodiscus spp. terwyl Helichrysum spp. voorlopig aangedui is as goed herstel in NDVH sub-terreine. Grondversteuring en gepaardgaande ontwrigting van normale funksionering van die ekosisteem, insluitend bestuiwing, word aangedui as 'n waarskynlike rede vir die ontwrigting van die herstel van plantegroei. In Hoofstuk 3 is vee-net metodologie getoets vir die Waarnemer Effek. 'N merkbare toename in by besoeking frekwensie van 'n algemene plantspesie in blomtyd, Metalasia densa, is gekorreleer met langer wagtydperke nadat ek gestop het om te beweeg, en dui dus op die teenwoordigheid van 'n Waarnemer Effek. Dit dui daarop dat die vee-net vir bye eers gebruik moet word na 'n wagtydperk waartydens die waarnemer bewegingloos verkeer. In Hoofstuk 4, met behulp van 'n vlug-onderskep gewysigde pan lokval, het ek by spesierykheid en totale by hoeveelheid vergelyk oor verskillende seisoene en in beide massa-beblomde en yler blom kolle. Daar was geen beduidende verskil in by spesierykheid tussen natuurlike en NDVH sub-terreine. Alle by spesies, behalwe een spesie kompleks, was meer volop in natuurlike sub-terreine. Byna twee derdes van alle by spesies (n = 37 van 56) gevang met vee-nette en die van die gewysigde pan lokvalle is onbeskryfde spesies. Soortgelyk aan die plantegroei, is die gevolge van grondversteuring as gevolg van dekades van denneboom bos skadu en denneboom bos blaar afval gevolg deur 'n buitengewoon warm denneboom bos brand as die mees waarskynlike redes vir laer by hoeveelheid in NDVH sub-terreine aangedui. Dit is as gevolg van die probleme wat verband hou met lewensvatbare nes vestiging en geskikte stuifmeel en nektar voer beskikbaarheid in versteurde gebiede. In Hoofstuk 5 is die nuut ontwikkelde Pan en Vlug Onderskep Kombinasie (PEVOK) lokval ontwerp, aanvanklike toetsing, en vergelyking met die tradisionele pan lokval bespreek. 'N Voorlopige toets dui daarop dat die PEVOK lokval meer doeltreffend (met 'n hoër oorvloed) is as die tradisionele pan lokval. In Hoofstuk 6 bespreek ek die implikasies van die versteuring van denneboom bosbou en ongewone denneboom vuur met betrekking tot plant spesies en by spesies samestelling. By-bestuiwing webbe in NDVH sub-terreine word aangedui as wesenlik eenvoudiger as dié in natuurlike areas asook verskillend in samestelling. Die herstel van bestuiwing as 'n hoeksteen in na denneboom-aangeplante gebiede staar 'n aansienlike uitdaging in die gesig, gegee die versteuring van grond wat dekades van denneboom aanplanting gevolg deur denneboom bos brand kan veroorsaak. Sommige voorstelle is gemaak vir die herstel van fynbos gebiede wat herstel van denneboom aanplanting, insluitend 'n bespreking van die aanvulling van plantegroei hervestiging maatreëls (fynbos saadverspreiding en saailinge plant) met die metodes van die herstel van 'n gesonde pedogenese, bogrondse geleedpotige gemeenskappe, en fynbos saadbanke.

Biomasseplantagen und Aufforstung zur terrestrischen Kohlenstoffdioxid-Entfernung werden derzeit als Möglichkeit diskutiert um dem anthropogenen Treibhauseffekt entgegenzuwirken. Für die Bewertung solcher Maßnahmen ist ein umfassendes Verständnis ihrer Nachhaltigkeit und möglichen Konsequenzen erforderlich. In dieser Arbeit werden biogeochemische und hydrologische Auswirkungen von Biomasseplantagen und Aufforstung quantitativ und im Kontext der Planetarischen Grenzen (PG) analysiert. Simulationen mit einem globalen Vegetationsmodell zeigen, dass die Auswirkungen von Biomasseplantagen auf die Biosphäre nicht zu vernachlässigen sind und die der historischen landwirtschaftlichen Bodennutzung noch überschreiten können. Außerdem werden Szenarien zur räumlichen Verteilung von Biomasseplantagen unter Berücksichtigung von regionalen und globalen PG für biogeochemische Flüsse, Intaktheit der Biosphäre, Landnutzungswandel und Süßwassernutzung evaluiert. Unter Einhaltung regionaler PG können nur marginale Potentiale erzielt werden. Unter kompletter Ausnutzung des Risikobereichs könnten 1.4-6.9 GtC/a entzogen werden, abhängig von Biomasseverwertungs- und Kohlenstoffspeicherungseffizienzen. Die Relevanz von koevolutionärer Dynamik zwischen dem Kohlenstoffkreislauf und gesellschaftlichem Eingreifen wird mit einem konzeptionellen Modellierungsansatz im Kontext der PG aufgezeigt. Eine Fokussierung auf das Klimaproblem ohne die ganzheitliche Berücksichtigung von erdsystemischen Interaktionen kann ungewollte Überschreitung anderer PG zur Folge haben. Die Kombination von Bevölkerungswachstum und Nahrungsmittelbedarf mit der Minimierung von Kohlenstoff- und Biodiversitätsverlusten zeigt Möglichkeiten und Grenzen für terrestrische Kohlenstoffspeicherung auf. Räumliche Umverteilung in hochproduktive Regionen sowie substantielle landwirtschaftliche Produktivitätssteigerungen ermöglichen die Ernährung von 9 Milliarden Menschen sowie ein Kohlenstoffspeicherungspotential von bis zu 98 GtC.
Terrestrial carbon dioxide removal (tCDR) via afforestation or biomass plantations are discussed as options to counteract anthropogenic global warming. Therefore, it is important to understand sustainability limits and implications of tCDR in the context of Earth system dynamics. This thesis provides a model based assessment of biogeochemical and hydrological side-effects of biomass plantations and afforestation in the context of planetary boundaries (PBs), delimiting a safe operating space for humanity. Simulations with a global vegetation model indicate considerable biogeochemical and hydrological consequences of biomass plantations which are even larger than those of historical agricultural land use. Further, land use scenarios of biomass plantations are developed with a multi-objective optimisation model considering the PBs for biogeochemical flows, biosphere integrity, land system change and freshwater use. Respecting PBs yields almost zero tCDR potential. The transgression of PBs into a zone of increasing risk of feedbacks at the planetary scale can provide considerable tCDR potentials of 1.4-6.9 GtC/a, depending on efficiency of biomass conversion and carbon capture and storage. The importance of co-evolutionary dynamics of the Earth''s carbon cycle and societal interventions through tCDR is demonstrated with a conceptual modelling approach in the context of carbon-related PBs. A focus on climate change without an integrated trade-off assessment may lead to navigating the Earth system out of the safe operating space due to collateral transgression of other PBs. Integrating population growth and food demand while minimising carbon and biodiversity loss demonstrates opportunities and limitations for tCDR. Substantial improvements of crop and livestock productivities and the displacement of agricultural production into regions of high productivity yield sustainable terrestrial carbon sequestration potentials of up to 98 GtC while feeding 9 billion people.

Este trabalho teve como objetivo principal analisar, em condições de campo, o efeito de lâminas de irrigação e de doses de nitrogênio sobre o comportamento espectral da cultura do feijão, a partir de medidas de reflectância hiperespectral, na faixa de 350 a 1150 nm, e da correlação entre os parâmetros biofísicos e as variáveis agronômicas da cultura, nessas condições. O experimento foi conduzido na área experimental de Agricultura Irrigada da Fazenda Areão, sob a responsabilidade do Departamento de Engenharia Rural da Escola Superior de Agricultura Luiz de Queiroz DER/ESALQ/USP, localizada no município de Piracicaba, SP, de setembro a dezembro de 2007. O delineamento experimental foi em blocos casualizados com parcelas subdivididas, alocando-se, nas parcelas, os tratamentos relacionados aos níveis de irrigação ((179,5; 256,5; 357,5 e 406,2 mm) e nas subparcelas os tratamentos relativos às doses de nitrogênio (0; 80 e 160 kg ha-1), totalizando doze tratamentos em cada bloco. Como os tratamentos foram dispostos em quatro blocos (repetições), o total de parcelas experimentais foi de 48. As medidas radiométricas de campo foram adquiridas por meio do espectrorradiômetro SPECTRON SE-590, em sete datas, durante o ciclo da cultura. Foram coletados, ainda, a altura das plantas, o índice de área foliar, a produtividade de grãos, o número de grãos por vagem e o número de vagens por planta. Os índices espectrais calculados foram o NDVI e o NB_NDVI. Foi aplicada a remoção do contínuo nos espectros de reflectância para analisar a profundidade da banda e a área da banda de absorção, centrada em 665 nm. O fator água influenciou as variáveis biofísicas (IAF, altura da planta, produtividade, número de vagens por planta e número de grãos por vagem), sendo maiores os valores encontrados nas plantas que receberam maiores quantidades de água. O aumento da dose de nitrogênio não influenciou as variações das variáveis biofísicas, devido, possivelmente, ao processo de lixiviação desse nutriente para as camadas abaixo do sistema radicular da cultura. As análises dos índices de vegetação e dos parâmetros da remoção do contínuo (área e profundidade da banda de absorção) mostraram que as lâminas de irrigação afetaram o comportamento espectral do feijão no comprimento de onda de 665 nm, e que esses parâmetros não foram influenciados pelas doses de N. Os índices de vegetação (NDVI e NB_NDVI) e os parâmetros da remoção do contínuo (a profundidade da banda e a área da banda de absorção) foram eficientes na estimativa do IAF, da altura de plantas e da produtividade de grãos. Durante todo o desenvolvimento da cultura, as melhores correlações entre as variáveis biofísicas e as variáveis espectrais foram observadas nos estádios V4 e R6 de acordo com a variável analisada, sendo, portanto, estes os melhores estádios para monitorar espectralmente a cultura. Diante das metodologias utilizadas, as variáveis biofísicas foram mais bem estimadas pelo índice NB_NDVI, nos estádios V4 e R6, quando comparado ao índice NDVI e aos parâmetros da remoção do contínuo (profundidade e área da banda de absorção).
The objective of this research was to analyze the effect of irrigation levels and nitrogen fertilization on the spectral behavior, in the wavelength range of 350 to 1150 nm, of bean crop and the correlation between biophysical parameters and agronomical variables. The experiment was carried on at the Fazenda Areão, located at the University of São Paulo (ESALQ/USP) campus, Piracicaba, São Paulo, Brazil, from September to December, 2007. The experimental design was the randomized blocks, with split plots, with 12 treatments, 4 irrigation levels (179,5; 256,5; 357,5 e 406,2 mm) and 3 nitrogen rates (0; 80 e 160 kg ha-1), and four blocks. The field radiometric data were acquired with the SPECTRON-SE 590 spectroradiometer for seven dates during the crop growing season. Plant height, leaf area index (LAI), grain yield, the pod number per plant and the grain number per pod were also acquired. The spectral indices used were NDVI and NB_NDVI. The continuum removal was applied for the reflectance spectrum, on visible region centered on 665 nm, to analyze the band area and band depth. The irrigation also influenced the biophysical variables, so the largest medium values were observed in the treatments that used the largest irrigation levels. The nitrogen fertilization did not interfere on the biophysical variables, probably due to the leaching process. The vegetation indices and continuum removal analysis showed that irrigation levels affected the spectral behavior of bean crop on 665 nm and this parameters had not been influenced by nitrogen levels. The vegetation indices (NDVI and NB_NDVI) and the continuum removal parameters (band area and band depth) were efficient in the estimate of IAF, plant height and grain yield. During all the crop development, the best correlations between biophysical variables and spectral variables were observed on V4 and R6 stages, according to the variable analized. In face of the methodologies used, the biophysical variables were better estimated by NB_NDVI, on V4 and R6 stages, when compared with NDVI and the continuum removal parameters.

There is a regulatory tension within wastewater treatment, between the requirement to meet tightening consents and the need to reduce the carbon footprint of treatment processes. With 75% of wastewater treatment works serving populations of less than 2,000, low-energy tertiary treatment options suitable to small rural works need to be developed. One option that lends itself particularly well to small works is land-based wastewater treatment (LBWWT). The aim of this research was to evaluate the role of LBWWT in the UK water industry and investigate the impact ridge-and-furrow enhanced microtopography (MT) may have upon a particular type of LBWWT - slow-rate (SR) infiltration. This was achieved through meeting three objectives. Firstly, the use of LBWWT was reviewed and assessed. Secondly, the impact of ridge-and-furrow enhanced MT upon the vegetation diversity and nutrient removal of a SR- LBWWT was established by means of a three year field trial. Finally, the cost- effectiveness of SR-LBWWT and the impact of ridging and furrow irrigation upon cost-effectiveness were evaluated using Cost-Effectiveness Analysis (CEA). The first objective comprised of a review of the historical and current use of LBWWT, a review of the relevant changing legislation to identify what may be required of LBWWT and an assessment of LBWWT’s potential to meet these requirements. The result of the evaluation found that, based upon the literature, SR-LBWWT is ‘fit-for-purpose’ as tertiary treatment for small treatment works. To meet the second objective, a SR-LBWWT system trial was established at a small wastewater treatment works in Knowle, Hampshire. The trial consisted of three clay-loam grass plots irrigated with secondary treated effluent. There were two configurations of trial plot - flat and ridge-and-furrowed. Effluent (sub- surface soil water) nutrient concentrations were monitored as was vegetation diversity. In addition a number of physical, hydrological and biogeochemical parameters were monitored and hydrological modelling carried out. Mean nutrient removal performances of 90% for ammonia, 72% for nitrate, and 91% for phosphate were observed with the ridge-and-furrowed plot. Ridging and furrow irrigation was found to not have a significantly detrimental effect upon the trial plots’ removal performance for ammonia, nitrate or phosphate. Extrapolation modelling suggested, however, that this would not be the case for LBWWT systems on predominantly clay or sand soils. Ridging and furrow irrigation was found to have a statistically significant positive effect upon the vegetation diversity of the LBWWT trial plots; with mean final year Shannon-Wiener values of 0.96 and 0.69, for the ridge-and-furrowed and non-ridged plots, respectively. For the final objective, analysis found that SR-LBWWT are cost-effective when compared to horizontal sub-surface flow constructed wetlands (HSSFCW), an established low-energy treatment option. Mean cost-effectiveness ratio values of £208.5 and £262.7 per % effectiveness were observed for LBWWT and HSSFCW, respectively. Following the field trial CEA was extended to include ridge-and-furrowed SR-LBWWT systems. This found that ridging and furrow irrigation improves the cost-effectiveness of SR-LBWWT serving small populations, reducing the mid cost-effectiveness ratio to £193 per % effectiveness. This is a result of the cost-reducing effect of ridge-and-furrowing over laser-level grading; and based upon the findings of the trial that ridging and furrow irrigation can be achieved (in clay-loam soil slow-rate systems) without significant detriment to the water treatment effectiveness of LBWWT. The main conclusions of this thesis are: that SR-LBWWT has a role to play in the UK water industry, as tertiary treatment for small wastewater treatment works. That SR-LBWWT is cost-effective in relation to HSSFCW. That ridging and furrow irrigation increases that cost-effectiveness by reducing the construction and operational costs. That ridging and furrow irrigation can be employed without significant detriment to a SR-LBWWT system’s water treatment performance. And finally, that ridging and furrow irrigation can have a positive impact upon the establishment vegetation diversity of a SR-LBWWT system.

Ecossistemas campestres encontram-se fortemente impactados por conversão de hábitat e por espécies exóticas invasoras. É necessário restaurar os ecossistemas campestres ao redor do globo. Entretanto, para os ecossistemas campestres brasileiros há poucas experiências de restauração e precisamos testar a viabilidade de técnicas normalmente empregadas em outros lugares. O objetivo deste estudo foi testar diferentes combinações de técnicas para restauração de campos invadidos por Urochloa decumbens nos Campos Sulinos, sul do Brasil. Combinaram-se duas técnicas de controle da espécie invasora (aplicação de herbicida e remoção superficial de solo) e duas técnicas de introdução de espécies nativas (transposição de feno e semeadura direta). Foram estabelecidos oito blocos em um experimento bifatorial no Morro Santana, Porto Alegre, combinando dois fatores e cada um com três tratamentos (duas técnicas mais o controle). A cobertura de vários grupos de espécies, riqueza de espécies e composição de espécies foram avaliadas por análises de variância, e então também por análise de coordenadas principais. Adicionalmente, a relação entre a cobertura da invasora e das espécies nativas foi investigada. As técnicas de controle da invasora mostraram-se eficientes tanto na redução da cobertura da espécie, como em permitir a entrada de espécies nativas na comunidade. Comparando as duas técnicas, aplicação de herbicida pareceu ser melhor do que a remoção superficial de solo, pois parcelas que tiveram a aplicação tiveram menor cobertura da invasora e maior riqueza de espécies. Já as técnicas de introdução de espécies mostraram-se insuficientes para adicionar espécies nativas na comunidade para competir com U. decumbens. Padrões de composição de espécies diferiram entre os tratamentos. Técnicas de controle do invasor diferiram grandemente do seu controle, que foi dominado por U. decumbens. Uma clara relação existe entre a cobertura da invasora e a presença e cobertura de espécies nativas. Então o controle da espécie invasora é fundamental para uma maior recuperação da vegetação. Entretanto, os resultados aqui apresentados correspondem a apenas oito meses após a finalização da implementação do experimento, e ações futuras de manejo na área deverão combinar novamente o controle da invasora com introdução de espécies nativas.
Grasslands ecosystems are strongly impacted by land use and invasive species. It is necessary restore these ecosystems around the world. However, there are few experiences with ecological restoration for the Brazilian grasslands and we need to test the viability of techniques normally used in others grasslands ecosystems. The aim of this study was to test different combinations of techniques to the ecological restoration of grasslands invaded by Urochloa decumbens in Campos, Southern Brazil. We combine two techniques to control the invasive species (herbicide application and topsoil removal) and two techniques to introduce native species (hay transfer and direct sowing). We established nine blocks in a bi-factorial experiment on Morro Santana, Porto Alegre, Rio Grande do Sul, combining two factors and each one with three treatments (two techniques plus the control). The coverage of various groups of species, species richness, and species composition were evaluated by variance analyses, and the later also by a principal ordination analysis. Additionally, the relation between invader coverage and native species was investigated. Both techniques to control invasive species have shown to be efficient to reduce the coverage of the invasive species, as well as to allow the arrival of native species. Specifically comparing them, the herbicide application seems to be a better treatment than the topsoil removal, once plots with herbicide had lower invasive species coverage and higher species richness. However, the species introduction techniques failed efficiently to add native species to the community composition and to compete with U. decumbens. Species composition patterns differed among the treatments. The invader control techniques greatly differed from their control, which was dominated by U. decumbens. A clear relationship exists between the invader coverage and the presence and coverage of native species. Thus, the control of the invasive species is fundamental to further vegetation recovery. Nevertheless, results here presented correspond to just eight months from the experiment implantation and future monitoring and management actions on the area should combine once more the control of the invasive species and the introduction of native species.

Degradation of water resources has become one of the most pressing global concerns currently facing mankind. Constructed Wetlands (CWs) represent a concept to combat deterioration of water resources by acting as buffers between wastewater and receiving water bodies. Still, constructing wetlands for the sole purpose of wastewater treatment is a challenging task. To contribute to this research area, the fundamental question raised in this doctorate thesis was: how do factors such as vegetation and residing water movements (hydraulics) influence wastewater treatment in CWs? Also, effects of different data analysis methods for results of CW hydraulics and wastewater treatment were investigated. Research was focused on  phosphorus (P), ammonium-nitrogen (NH4+-N) and solids (TSS) in wastewater and o n P in macrophyte biomass. Studies were performed in pilot-scale free water surface (FWS) CW systems in Kenya (Chemelil) and Sweden (Halmstad) and as computer simulations. Results from the Chemelil CWs demonstrated that meeting effluent concentration standards simultaneously for all water quality parameters in one CW was difficult. Vegetation harvest, and thus nutrient uptake by young growing macrophytes, was important for maintaining low effluents of NH4+-N and P, especially during dry seasons. On the other hand, mature and dense vegetation growing for at least 4 months secured meeting TSS standards. Phosphorus in above-ground green biomass accounted for almost 1/3 of the total P mass removal, demonstrating high potential for P removal through macrophyte harvest in CWs. Also, results suggested that harvest should be species-specific to achieve high P removal by macrophytes and overall acceptable wastewater treatment in CWs. Still, different methods to estimate evapotranspiration (ET) from the Chemelil CWs showed that water balance calculations greatly impacted estimations of wastewater treatment results. Hydraulic tracer studies performed in the Chemelil and Halmstad CWs showed that mature and dense emergent vegetation in CWs could reduce effective treatment volumes (e-values), which emphasized the importance of regulating this type of vegetation. Also, it was shown that hydraulic tracer studies with lithium chloride performed in CWs with dense emergent vegetation had problems with low tracer recoveries. This problem could be reduced by promoting the distribution of incoming tracer solution into the CW using a barrier near the CW inlet pipe. Computer simulation results showed that the choice of tracer data analysis method greatly influenced quantifications of CW hydraulics and pollutant removal. The e-value could be 50% higher and the pollutant removal 13% higher depending upon used method. Moreover, unrealistic evalues (above 100%) in published literature could to some extent be explained by tracer data analysis method. Hence, to obtain more reliable hydraulic data and wastewater treatment results from CWs, more attention should be paid to the choice of tracer data analysis method.
Konstruerade våtmarker representerar ett koncept för möjligheten att nå en hållbar vattenresurshantering genom att agera som ”filter” mellan föroreningskälla och viktiga vattenresurser såsom sjöar och hav. Mycket kunskap saknas däremot om hur man konstruerar våtmarker med en optimal och pålitlig vattenreningskapacitet. Den här avhandlingen undersöker därför hur vegetation och vattnets väg genom våtmarken (hydrauliken) påverkar avloppsvattenrening i våtmarker. Dessutom undersöktes hur valet av dataanalysmetod av insamlad data påverkar resultaten. Studier genomfördes i Kenya och Sverige i experimentvåtmarker (ca. 40-60 m2) och inkluderadedatainsamling av vattenkvalité, hydraulik (spårämnesexperiment) samt biomassa och fosfor i biomassan av två olika våtmarksväxter. Dessutom genomfördes datorsimuleringar. Resultaten från Kenya visade att växtskörd och efterföljande näringsupptag av nyskördade växter var viktig för att uppnå låga utgående koncentrationer av fosfor och ammonium i en tropisk våtmark, speciellt under torrsäsongen. Däremot var en välutvecklad och tät vegetation viktig för reningen av partiklar. Fosfor i grön växtbiomassa representerade cirka 1/3 av våtmarkernas totala fosforrening, vilket påvisade potentialen i att genom skörd ta bort fosfor från avloppsvatten m.h.a. konstruerade våtmarker. Resultaten pekade också på att skörden bör vara art-specifik för att uppnå en hög fosforrening och generellt bra vattenreningsresultat. Dock visade olika beräkningsmetoder att vattenbalansen i en tropisk våtmark markant kan påverka vattenreningsresultaten. Resultaten från spårämnesexperimenten demonstrerade att den effektiva våtmarksvolymen för vattenrening blev mindre vid hög täthet av övervattensväxter. Detta pekade på att regelbunden växtskörd var viktig för att uppnå god vattenrening i våtmarker. Experiment med spårämnet litium visade att man kan få felaktiga resultat p.g.a. att en del spårämne fasthålls på botten i våtmarken om denna har mycket övervattensväxter. Därför bör spridningen av spårämnet i sådana våtmarker underlättas m.h.a. en spridningsbarriär nära inloppsröret. Simuleringar visade också att valet av dataanalysmetod av spårämnesdata starkt kan påverka resultaten och därmed också vår tolkning av en våtmarks hydraulik och reningskapacitet. Den effektiva volymen kunde vara 50% högre och reningseffekten 13% högre beroende på vilken metod som användes. Likaså kan valet av dataanalysmetod ha bidragit till överskattade och orealistiska effektiva volymer (över 100%) i artiklar publicerade de senaste 25 åren. Genom att fokusera mer på valet av dataanalysmetod och t.ex. jämföra resultaten från två olika metoder kan man minimera risken för bristfälliga resultat och därmed felaktiga slutsatser om en våtmarks vattenreningskapacitet.

Abstract Climate change and its warming effects on vegetation and soils are a widely recognized phenomenon. In addition to warming, the understorey vegetation in northern environments has been subjected to several environmental changes, such as increasing nitrogen (N) and other disturbances. This thesis examines the effects of N-fertilization and disturbances on the vegetation biomass and abundance, plant community composition and plant, soil and microbial N and C pools. Seedling establishment of the most common dwarf shrubs (deciduous Vaccinium myrtillus, evergreens V. vitis-idaea and Empetrum nigrum ssp. hermaphroditum) was investigated after artificial disturbance treatments (vegetation and soil removal). These studies were conducted in the boreal and subarctic ecosystems and in the forest-tundra ecotone in northern Finland. N-fertilization and disturbances enhanced the amount of graminoids in plant communities, and the recovery ability of graminoids was enhanced after N-fertilization, which homogenized the vegetation and resulted in a new stable state in the plant community. The recovery ability of evergreen dwarf shrubs was low after disturbances. Disturbances created habitats for seed germination, but the seedling establishment of dwarf shrubs studied was still limited by seed availability. N-fertilization had no effect on microbial biomass. Instead, microbial biomass decreased with disturbance treatment in the boreal forest. However, the concentration of N increased in above-ground vegetation, both after N-fertilization and disturbance without any indication of N immobilization, suggesting that plant species captured the available N effectively for their recovery. The study shows that the likely outcome of N enrichment, when combined with disturbances, is the enhanced growth of graminoids. The seedling establishment does not compensate for the reduction of the vegetative recovery of evergreen dwarf shrubs, which makes evergreen dwarf shrubs sensitive to environmental changes. As the understorey is more resilient to perturbations in the boreal forest than in the subarctic ecosystem, these results emphasize the sensitivity of the vegetation to simultaneous environmental changes in the northernmost ecosystems. Moreover, microbial properties are more resilient to environmental changes than is above-ground vegetation
Tiivistelmä Ilmaston muutos ja siitä aiheutuvan lämpenemisen vaikutus kasvillisuuteen ja maaperään on laajasti tunnustettu ilmiö. Lämpenemisen lisäksi pohjoisten alueiden aluskasvillisuuteen kohdistuu useita muutospaineita, kuten lisääntynyt typpipitoisuuden nousu ja kasvillisuutta muokkaavat häiriöt. Tässä tutkimuksessa mitattiin lisääntyneen typpipitoisuuden ja häiriöiden vaikutus kasvillisuuden biomassaan ja runsauteen sekä yhteisörakenteeseen, sekä kasvilajeihin, maaperään ja mikrobibiomassaan sitoutuneen typen ja hiilen määrään. Lisäksi tutkittiin yleisimpien varpukasvien (lehtensä pudottava mustikka, ikivihreät puolukka ja variksenmarja) siemenellistä lisääntymistä kokeellisen häiriön (kasvillisuuden tai maaperän poisto) jälkeen. Tutkimukset tehtiin boreaalisessa ja subarctisessa ekosysteemeissä sekä metsänrajaympäristössä Pohjois-Suomessa. Typpilannoitus ja häiriöt lisäsivät heinien määrää kasviyhteisöissä. Lisäksi typpilannoitus edisti heinien kasvullista palautumiskykyä häiriön jälkeen, joka johti kasvillisuuden homogenisoitumiseen ja kasviyhteisön uuteen tasapainotilaan. Häiriöt heikensivät ikivihreiden varpujen kasvullista palautumista häiriön jälkeen. Häiriö loi sopivia elinympäristöjä siementen itämiselle, mutta tutkittujen lajien siementen määrä rajoitti siemenellistä lisääntymistä. Typpilannoitus ei vaikuttanut mikrobibiomassaan, mutta häiriö vähensi mikrobibiomassaa boreaalisessa ekosysteemissä. Kuitenkin kasvien typen pitoisuudet lisääntyivät sekä lannoituksen että häiriön jälkeen ilman viitteitä typen sitoutumisesta mikrobibiomassaan. Tämä viittaa siihen, että kasvit käyttävät maaperän typen tehokkaasti häiriön jälkeiseen palautumiseen. Väitöskirjan mukaan typen lisääntyminen häiriöiden yhteydessä edistää heinien esiintymistä. Koska ikivihreiden varpujen siemenellinen lisääntyminen ei kompensoi häiriöstä kasvulliselle palautumiselle aiheutuvaa haittaa, ovat ikivihreät varvut erityisen herkkiä häiriöille. Aluskasvillisuus on vastustuskykyisempi ympäristön muutoksille boreaalisessa kuin subarktisessa ekosysteemissä, mikä korostaa pohjoisimpien alueiden herkkyyttä yhtäaikaisille ympäristön muutoksille. Maaperän olosuhteet ovat kasvillisuutta kestävämpiä ympäristön muutoksille

Thesis (MSc)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: Invasive alien trees, especially Acacia species, are a great threat to biodiversity in South African rivers. The national Working for Water Programme is addressing the alien problem by removing alien trees from river margins. The concern is that this may be creating even further disturbance by affecting water quality and habitats. In particular, how is this affecting rare and endemic species? Benthic macro invertebrates and aerial odonates were assessed along five Western Cape rivers in alien-invaded, cleared and natural sites between December and March. The aim was to assess the effect of both alien invasion and alien clearing on aquatic invertebrates. Odonata, being easily sampled, were also assessed as they are severely affected by the lack of understorey plants in shaded, alien-invaded sites. Odonata and benthic macroinvertebrates were treated as two separate studies and no attempt was made to correlate the results obtained from both studies. SASS5, a qualitative, rapid bioassessment technique, based on the sensitivity of the families present, was used as a measure of river health and, indirectly, of water quality. SASS indicated a decline in water quality conditions after alien clearing, a likely response to the greater insolation as well as erosion of cleared banks, resulting in elevated temperatures and suspended solids and lowered oxygen levels. Community responses to alien disturbance and other environmental factors were analysed using PRIMER and CANOCO software. Assemblages of Odonata were found to provide a rapid, cost-effective means of assessment and monitoring. Potential indicator and detector species were also identified using the lndicator Value method. Assemblage patterns of aquatic invertebrates, however, were dominated by between-river and seasonal effects. Therefore, while SASS detected overall changes in river health, without identifying the cause, potential aquatic detector taxa were identified that may be useful for linking general disturbance to alien invasion or clearing. All indicator and detector taxa identified in both studies can be used for long-term monitoring and for identifying biodiverse areas for clearing or protection. In both studies, sensitive, endemic taxa were lost after clearing, being replaced by more tolerant, widespread taxa. Recovery of the biota appears to follow the recovery succession of the vegetation, with most sensitive or endemic taxa only appearing after the recovery of indigenous plants. A number of recommendations are made regarding the restoration of both water quality (particularly with respect to shade and soil erosion) and biotope availability (particularly in terms of the recultivation of indigenous plants) in order to achieve biodiversity objectives. The role of catchment management, prioritisation procedures and long-term monitoring are also discussed.
AFRIKAANSE OPSOMMING: Uitheemse, indringerbome, veral Acacia spesies, is 'n groot bedreiging vir biodiversiteit in Suid- Afrikaanse riviere. Die nasionale Werk vir Water-projek spreek hierdie probleem aan deur uitheemse bome van rivieroewers te verwyder. Die kommer is dat water kwaliteit en habitatte sodoende verder versteur kan word. Byvoorbeeld, hoe word endemiese en bedreigde spesies geraak? Akwatiese makroinvertebrate en volwasse Odonata in vyf Wes-Kaapse riviere is tussen Desember en Maart bestudeer en gemonster in natuurlike gebiede, in gebiede waar indringerbome teenwoordig is, en in gebiede waar hulle verwyder is. Die doel was om die effek van indringerverwante impakte op akwatiese invertebrate vas te stel. Odonata is ook bestudeer omdat hulle maklik gemonster kan word en omdat hulle ernstig geraak word deur indringers. Die uitheemse plantegroei oorskadu die oewers en verhoed die groei van inheemse oewerplante. Die bentiese makro-invertebrate en Odonata is as twee aparte studies behandel en geen poging is gemaak om die resultate van die twee te vergelyk nie. SASSS, 'n kwalitatiewe, bioasseseringsmetode wat op die sensitiwiteit van die aanwesige families baseer word, is gebruik om waterkwaliteit op 'n indirekte manier te bepaal. SASS het aangedui dat daar 'n afname in waterkwaliteit is nadat indringerplante verwyder is. Dit is moontlik as 'n gevolg van groter blootstelling aan sonskyn en erosie van rivieroewers wat veroorsaak dat temperature en die hoeveelheid gesuspendeerde materiaal verhoog word, en dat suurstof konsentrasies verminder word. Die gevolge van indringerplante en ander omgewingsfaktore op akwatiese gemeenskappe is met PRlMER en CANOCO sagteware ontleed. Groepering van Odonata kan gebruik word om op 'n maklike en koste-effektiewe manier om die impak van indringerplante en hul verwydering te bepaal en te monitor. Aanwyserspesies is ook deur middel van die 'Indicator Value' metode geïdentifiseer. Die verspreidingspatrone van invertebraatspesies word deur geografiese en seisoenale effekte oorheers. Dus, terwyl SASS veranderinge in waterkwaliteit kan aantoon, sonder om die oorsaak daarvan te identifiseer, kan aanwyserspesies gebruik word om meer spesifieke impakte deur indringerplantegroei, of indringerverwydering, te bepaal en te monitor. Hulle kan ook gebruik word om gebiede met hoë biodiversiteit vir bewaring of indringerverwydering te identifiseer. Beide studies dui aan dat sensitiewe en endemiese taksa na indringerverwydering verlore gaan, en vervang word met meer geharde, wydverspreide taksa. Herstel van die biota volg op die herstel van die plant gemeenskappe, en die mees sensitiewe of endemiese taksa herstel eers nadat die inheemse plantegroei herstel het. 'n Aantal aanbevelings in verband met die restorasie van waterkwaliteit (veral in terme van die hoeveelheid skaduwee en erosie) en die beskikbaarheid van biotope (veral in terme van inheemse plante) om biodiversiteitsdoelwitte te bereik word gemaak. Die rol van opvanggebied bestuur, voorrang prosedures en lang termyn monitering word ook bespreek.

The main objective of this study was to examine the abundance and diversity of ants in suburban sites following vegetation removal or modification for development. This research examines the capacity of suburban sites to support ant diversity, which is dependent on the site characteristics and their surrounding environment. The study focused on 29 suburban garden and 3 suburban reserve sites on the Gold Coast, Queensland, Australia. This region, through continuing land development, undergoes ongoing habitat disturbance and modification. Ground-dwelling ants were collected by pitfall trapping in study sites over three summers between 1997 and 1999. In total, 28,512 ants from 60 species in 31 genera were collected. Garden sites that maintain vegetation structural diversity were found to be most similar to reserve sites in terms of ant community composition. These sites were highest in ant richness and diversity and contained particularly high proportions of specialized ant species. Sites in close proximity to remnants of native vegetation contained higher species diversity and a greater proportion of specialized ant species. The introduced tramp ant, Pheidole megacephala was found in 28 of the 32 sites and was found to significantly reduce ant species richness and diversity and displace the dominant ant Iridomyrmex sp. 1 in suburban environments. This ant poses a serious threat to the recovery of a diverse ant fauna to suburban environments. Ant community composition was shown to vary significantly among suburban sites. The ant functional groups commonly found in disturbed sites were abundant in open sites with little canopy cover in this study. Sites that provided vegetation structural diversity and areas of closed canopy supported similar functional groups to natural vegetation remnants. These results indicate that ant communities in suburban environments respond to disturbance in a similar manner to ant communities in tropical forests and rainforests. The dominance by functional groups and presence of specialized species may therefore be used as an indicator of disturbance and the restoration of suitable habitat in suburban sites. The presence of specialized species of ants in suburban garden sites and their clear preference for particular site characteristics indicate that these species utilize resources available in the suburban matrix. These results indicate that residential suburban sites are of value in the enhancement of ant diversity in fragmented landscapes and that they may provide supportive habitat to, and act as corridors between, vegetation fragments. In order to preserve biodiversity within suburban environments, landowners should be advised to retain as much existing vegetation within a site as possible. Clearing should be limited to that necessary to allow construction of dwellings and for safety. In addition, landowners should be encouraged to establish or maintain structurally diverse vegetation layers within sites in order to provide diverse microenvironments for fauna habitat.

The euthropthication of the Baltic Sea is a threat that is beginning to be taken seriously by the governments concerned. In Sweden, regulations concerning the allowed nitrogen (N) concentration in the effluent water from wastewater treatment plants are being tightened up. The Rimbo wastewater treatment plant has been imposed to reduce the annual mean concentration of total N in the effluent water to levels below 15 mg l-1. A more and more common way to reduce the nitrogen level in wastewater is to let the water pass through a wetland. This study investigates the possibility to build this kind of wetland at the outlet of the Rimbo wastewater treatment plant.

A prestudy of the topography, soil characteristics and groundwater flow indicates that the land area in question is well suited for the construction of a wetland. A proposal for the design has been made by using a physically based computer model developed in the PRIMROSE project (PRocess based Integrated Management of constructed and Riverine wetlands for Optimal control of wastewater at catchment ScalE), which is financed by the EU. Analysis of the residence time distribution (RTD) is a tool for understanding wetland design characteristics and can be used for wetland engineering such as optimizing design for best possibleefficiency in nitrogen removal. In order to characterize the performance of a wetland, it is useful to translate the RTD to a key figure representing the treatment efficiency. In this work, two types of such key figures have been used. Key figure 1 gives the hydraulic efficiency and Key figure 2 gives an estimation of the nitrogen retention by an integration of hydraulic characteristics and the chemical transformation of nitrogen.

The results of this study show that constructing a wetland in Rimbo probably would be an efficient way to reduce the nitrogen level at the effluent of the wastewater plant below the limits of the regulations. In addition, a wetland would form a nice place of recreation for the people in Rimbo and also make a good habitat for birds.

Övergödningen i Östersjön är ett problem som uppmärksammas alltmer. Ett led i att minska kvävebelastningen på Östersjön är ökade krav på rening i de svenska kommunala reningsverken. Rimbo avloppsreningsanläggning har blivit ålagd ett riktvärde för totalkväve på 15 mg l-1 i utgående vatten, vilket motsvarar en reningsgrad som inte uppnås idag. Ett alltmer vanligt sätt att minska föroreningshalterna är att anlägga våtmarker i anslutning till reningsverken för att efterpolera spillvattnet. Det här arbetet är en del av en förstudie till en sådan våtmark i Rimbo.

En förundersökning av topografi, jordart och grundvattenflöden indikerar att det område som föreslagits i anslutning till reningsverket i Rimbo lämpar sig väl för ett våtmarksbygge. Förslag till utformning har tagits fram med hjälp av en fysikaliskt baserad modell över vattenströmning, utvecklad inom det EU-finansierade projektet PRIMROSE (PRocess based Integrated Management of constructed and Riverine wetlands for Optimal control of wastewater at catchment ScalE). Analys av vattnets uppehållstidsfördelning ger förståelse för våtmarkens egenskaper och kan därför användas vid t ex optimering av våtmarksdesign med avseende på kväverening. För att på ett enkelt sätt kunna jämföra olika våtmarkers effektivitet är det praktiskt att översätta uppehållstidsfördelningen till ett nyckeltal för reningseffekten. I det här arbetet har två olika sådana nyckeltal beräknats. Det första ger den hydrauliska effektiviteten och det andra bygger på en metod där våtmarkens interna hydraulik integreras med den kemiska omvandlingen av kväve. Nyckeltal 1 ger ett mått på hur stor del av volymen i våtmarken som används för kväverening, medan Nyckeltal 2 ger ett mått på den procentuella kväveavskiljningen.

Den här förstudien visar att en våtmark sannolikt skulle vara ett utmärkt sätt att klara riktvärdet för kvävehalten vid reningsverket i Rimbo. Därutöver skulle en våtmark kunna utgöra ett positivt inslag i landskapet och öka den biologiska mångfalden, inte minst vad gäller fågelliv.

Previous field demonstration projects in metro-Atlanta have shown that seep berms, which are elongated sedimentation basins at the outlet of a disturbed land area, can provide high suspended sediment trap efficiencies with respect to coarse sediments on construction sites having drainage areas greater than five acres. Previous literature has shown that vegetative filter strips are efficient traps for fine suspended sediment in stormwater runoff. A combination of a seep berm and vegetative filter in series was studied in this thesis as an erosion control measure with quantification of its flow resistance and sediment removal efficiency. First, a field demonstration project was implemented to evaluate seep berms as a viable erosion control measure through a side-by-side comparison with the more commonly-used silt fences on construction sites with drainage areas less than five acres in metro Atlanta. High suspended sediment trap efficiencies were recorded for the seep berm on two separate sites, and the seep berm was shown to be superior to silt fences with respect to sediment control in the site runoff. Then a vegetative filter was studied in the laboratory in a specially-built flume for that purpose. The relationship between vegetative drag coefficient and various parameters reflecting flow conditions and vegetation density in steady, uniform open channel flow was studied in the flume. Both rigid, emergent vegetation and submerged, flexible vegetation were studied at two different plant densities. The application of porous media flow concepts to open channel flow through vegetation resulted in a collapse of data for vegetative drag coefficient for the various vegetation types and densities into a single relationship when plotted against vegetative stem Reynolds number. Point velocity and turbulence intensity profiles at different locations in the vegetative filter were recorded with an acoustic Doppler velocimeter to observe the turbulence structure of the flow and its effects on vegetative drag and settling of sediment. A sediment slurry consisting of a suspension of fine sand was fed into the flume, and an automated sampler was used to measure suspended sediment concentrations along the vegetative filter length for a series of discharges from which sediment flux and trap efficiency could be determined. Experimental data for trap efficiency were plotted against a dimensionless settling efficiency for each type of vegetation and density. These relationships, along with the one developed for the coefficient of drag, were applied in a numerical design technique that allows designers to determine the flow depth, velocity and trap efficiency of a vegetative filter of known dimensions for a given flow rate, sediment grain size distribution, slope, and vegetation density. In a typical design example, the combined trap efficiency proved that a seep berm followed by a vegetative filter can be a very effective erosion control measure.

Mestrado em Engenharia Agronómica - Instituto Superior de Agronomia
This work consists in a study of a useful technology applied in precision agriculture: remote sensing. Remote sensing in forest management has nowadays, an important role, enabling to prevent and fight forest fires, to study the plant sanitary state, to inventory, and, more importantly, to estimate forest production. Forest production is the topic of this study, applying this technology to cork forest management. In this thesis we collected data in the field, essential to the forest inventory. We analyzed the data and correlated with remote sensing data (through the calculation of several vegetation and geometric indices) captured by a ultra-high resolution camera attached to an airplane. The images constituted a efficient and cheap way to get information able to be compared with the field data through adjusted models, in order to explain the spatial variability of the productivity and quality of cork. Using the visible and infrared bands, it was possible to calculate the vegetation indices like NDVI, PCD and IPVI that were able to find strong relations with the field data. The adjusted models were able to explain 58% of the spatial variability of the cork productivity from the cork oak forest we studied and they even able to explain 50% of the spatial variability of cork's quality. With the results obtained of this study, in the future we will be able to predict and get accurate and reliable conclusions related to the productivity and quality of cork, just through the use of remote sensing

Mestrado em Geomateriais e Recursos Geológicos
Remote Sensing has been used for decades, and more and more applications are added to its repertoire. With this study we aim to show the use of Remote Sensing in the field of vegetation recovery monitoring in burned areas and the added value of data with a high spatial resolution. This was done by analysing both Landsat 7 and 8 scenes, after the forest fire of summer 2012 in the parish of Calde, in the central region of Portugal, as well as an orthophoto produced with images acquired by an unmanned aerial vehicle.
A Deteção Remota tem sido utilizada durante décadas com novas aplicações a surgirem constantemente. Com este estudo pretende-se demonstrar o uso da Deteção Remota no campo da monotorização da recuperação de vegetação em áreas ardidas e o valor acrescentado da elevada resolução espacial dos dados utilizados. Para o efeito, foi feita a análise de áreas ardidas na freguesia de Calde, região central de Portugal, depois do incêndio florestal no verão de 2012, usando imagens Landsat 7 e 8 assim como uma ortofoto produzida com imagens adquiridas por um veículo aéreo não tripulado.

Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia
Riparian forests are responsible for many functions considered essential to the preservation of the ecological condition of fluvial corridors. The aim of this thesis is to characterize the structural and compositional patterns of the riparian vegetation in relation to its ecological quality using remote detection and geographic information systems. Separability analyses allowed to characterize and distinguish the spectral patterns and divergent optical behavior between the main riparian forests of Portugal. Spectroradiometry analyses enable the identification of the optimal bands for the remote detection of the alien invasive species Arundo donax, giant reed, from the surrounding vegetation, taking into account its seasonal spectral variability. The Geostatistical techniques combined with the application of landscape metrics, in high spatial resolution images, allowed the remote identification of the structural patterns for riparian forests and for the riparian areas invaded by the giant reed. It was obtained a relation between the observed degradation patterns and a gradient of human disturbance in the surrounding areas of fluvial corridors. The combination of the spectral and geometric attributes allowed to increasing giant reed mapping accuracy in riparian habitats, using a semi-automatic technique.

Mestrado Vinifera Euromaster - Instituto Superior de Agronomia - UL
The trial wants to study the characteristics of c.v. Nero d’Avola in the Eastern part of Sicily after early leaf removal. Axiom to create high quality wine is to have high quality grapes. This can be possible only with right management of vineyard. The objective is to understand how the early leaf removal can change the productive and vegetative balance of vine and micro-climate of the cluster region. Specifically this research wants to highlight the process that some variables can cause during the leaf out process of the cv Nero d’Avola in the area of Hyblaean Mountains (Monti Iblei). This study show like early leaf removal at fruit set stimulates the increase of the length of lateral shoots. The early defoliation influenced the fruit-set processes, in terms of lower berry number and a higher percentage of chicken berries. The sugar content was positively influenced by early defoliation .Probably related to the greater leaf area per gram of grapes at harvest , younger canopy in the last stage of ripening and also for greater exposure of luster to light. The percentage of light interception is higher in the defoliated treatments ,especially, in the south-east side of canopy. About anthocyanin accumulation we can confirm that early defoliation lead to a more rapid build-up, thanks to the exposure to light, which stimulates the metabolites synthesis. Defoliation remains a very effective way to diversify agronomic management and the types of grapes obtainable from a same variety in the same environment. In conclusion we can say ,the defoliation at different times and different intensity, depending on the climate and the environment, can control the yield, especially in high-yielding varieties, and can improve the sugar accumulation, and increase the concentration of polyphenols in the short term. The early defoliation in hot climate is a agronomic practice in developing ,but is important to understand which are the most limits and advantages

Mediante a utilização de tecnologias de deteção remota, integram-se diferentes fontes de dados da atmosfera e das culturas (imagens da superfície cultivada obtidas por satélite ou por plataforma aérea não tripulada), com os quais se monitorizam, com elevada resolução espacial e temporal, as necessidades hídricas das culturas, calculando a evapotranspiração cultural (ETc), indicadores biofísicos e índices de stress hídrico da vegetação (NDVI, Kc*, Kcb*, CWSI), que indicam a oportunidade e a dotação da rega, facilitando uma eficiente gestão da água, num regadio sustentável. A análise aplicou-se na área regional do Perímetro de Rega do Divor, tendo utilizado 7 parcelas experimentais, que são áreas regadas por rampas rotativas com a cultura do milho, cuja condução agrícola foi da responsabilidade dos respetivos agricultores. A tecnologia baseada nas imagens obtidas por satélite parece conjugar-se bem com a utilização de sensores (ou câmaras fotográficas), em plataformas voadoras a baixa altitude, resolvendo estas os problemas, inerentes à informação de satélite, nomeadamente à elevada periodicidade e à dependência da nebulosidade. Toda esta informação é georreferenciada, podendo servir de suporte à elaboração em SIG de mapas da situação hídrica e da oportunidade de rega das culturas, que poderão servir de base a um sistema de avisos de rega aos agricultores e gestão da rega no perímetro ou grande região de regadio; ABSTRACT:Through the use of remote sense technologies, data from different sources of the atmosphere and crops are integrated (images of the cultivated surface obtained by satellite or by flying unmanned platform), with which crop water requirements are monitored with high spatial and temporal resolution, by calculating evapotranspiration (ETc), biophysical indicators and indices of water stress of vegetation (NDVI, Kc, Kcb, CWSI), indicating the opportunity and the allocation of irrigation, facilitating an efficient water management for a sustainable irrigated agriculture. The analysis applied to Irrigated District of Divor, having used 7 experimental plots, which are areas watered by center-pivot systems, cultivated to corn, the agricultural driving having been the responsibility of the respective farmers. The technology based on satellite images seems to combine well with the use of sensors (or cameras), located on low altitude flying platforms, by solving some problems inherent to satellite information, in particular to the low frequency and the dependence of cloud cover. All this information is referenced, and can support the preparation of maps with GIS technology, describing water situation and opportunity of watering crops, which could serve as a basis for a farmers irrigation advice system and the region or the large perimeter irrigation management.

O objetivo deste trabalho foi a análise da variabilidade dos povoamentos florestais no Alto Alentejo, com dados derivados de imagens de satélite, nomeadamente do Sentinel-2. Para a análise da variabilidade dos povoamentos florestais, foi produzido um mapa de uso/ocupação do solo e calculadas métricas de diversidade, ao nível da classe e da paisagem. O mapa de uso/ocupação do solo foi obtido para 5 classes florestais e 1 não florestal, utilizando o algoritmo de classificação Random Forest, com as bandas, os índices de vegetação e os de texturas como variáveis independentes. Neste mapa obteve-se uma precisão global de 89% e um kappa de 86%. A heterogeneidade da paisagem foi avaliada com 11 métricas para o Alto Alentejo e para 4 sub-regiões. A composição e a configuração da paisagem da área estudo é bastante heterogénea. A variabilidade das métricas no Alto Alentejo e entre as regiões evidencia a diversidade dos povoamentos florestais; Analysis of forests stands variability with satellite images ABSTRACT: The objective this study is the analysis of the forest stands variability in Alto Alentejo with data derived from satellite images, namely of Sentinel-2. For the forest stands variability analysis, a soil land use and land cover map was produced and calculated the diversity metrics, at the class and landscape levels. The map was obtained through the classification of the satellite image, with 5 forest classes and 1 non forest class, using the classification algorithm Random Forest, with the bands, the vegetation and the texture indices as independent variables. The soil land use and cover map had global precision of 89% and a Kappa of 86%. The landscape heterogeneity was evaluated with 11 metrics for Alto Alentejo e for 4 sub-regions. The study area composition and configuration is rather heterogeneous. The metrics’ variability in Alto Alentejo and between the sub-regions highlights the diversity of the forest stands.

Detta examensarbete är utfört på plats i Lajaedo, Brasilien och i anslutning till Sanitário de Lajeado – RS, Brasilien, mellan januari till maj 2010. I samband med denna rapport utfördes två andra examensarbeten inom samma områden. Det är menat att denna rapport skall ligga till grund för framtida projekt och beslut om utökad lakvattenrening.Lajeado ligger i södra Brasilien ca 100 km från atlantkusten. 10 km utanför Lajeado ligger en ung avfallsdeponi på ca 15 000 m2 till ytan med tillhörande lakvattenrening med ett utjämningsmagasin, en syrsättningsbassäng samt sedimentering. Deponin tar emot 42 ton fast kommunalt avfall per dag och har ett lakvattenflöde på genomsnitt 0,5 – 1,0 m3/h.Syftet med denna rapport är att undersöka vilken inverkan vegetation har på reningen av lakvatten inom parametrarna TKN, BOD5 och COD, i småskaliga våtmarker av typen rotzonsanläggning. Då den befintliga reningen på plats har svårt att uppfylla vissa uppsatta lagkrav.Sammansättningen på och mängden av lakvatten beror främst på faktorerna, nederbörd, Temperatur och nedbrytningen i deponin.Vegetationens har många olika betydelser i en rotzonsanläggning. Plantan transporter ner syre till dess rotsystem där syremolekyler diffunderar ut. Vegetation fungerar även som en extern kolkälla vid denitrifikationsteget. Det är viktigt att vegetationen trivs och rotsystemet är välutvecklat, för att få en maximal reduktion av föroreningar i våtmarken.Åtta småskaliga våtmarker byggdes upp i anslutning till lakvattenreningen, i avkapade plasttunnor. Alla våtmarker byggdes upp med unika förutsättningar för att kunna jämföra resultatet. Två olika substrat användes och jämfördes, i fyra kar planterades vegetation och fyra utan, fyra hade kontinuerligt flöde som jämfördes med fyra kar med batch flow.Resultaten visar att växterna inte har någon större inverkan på reningsgraden av BOD5, COD och TKN. Men såg tydliga tecken på högre vattenavdunstning i våtmarkerna med biomassa och generellt högre halter av BOD5, COD och TKN i jämförelse med våtmarkerna utan biomassa. Vegetationen hann inte acklimatisera sig till miljön i våtmarkerna, men det var på god väg. För att få ett bättre resultat och en mer signifikant skillnad mellan våtmarkerna skulle försöken ha pågått under en längre tid. Det behövs mer forskning och projekt under en längre period.Detta examensarbete är utfört på plats i Lajaedo, Brasilien och i anslutning till Sanitário de Lajeado – RS, Brasilien, mellan januari till maj 2010. I samband med denna rapport utfördes två andra examensarbeten inom samma områden. Det är menat att denna rapport skall ligga till grund för framtida projekt och beslut om utökad lakvattenrening.Lajeado ligger i södra Brasilien ca 100 km från atlantkusten. 10 km utanför Lajeado ligger en ung avfallsdeponi på ca 15 000 m2 till ytan med tillhörande lakvattenrening med ett utjämningsmagasin, en syrsättningsbassäng samt sedimentering. Deponin tar emot 42 ton fast kommunalt avfall per dag och har ett lakvattenflöde på genomsnitt 0,5 – 1,0 m3/h.Syftet med denna rapport är att undersöka vilken inverkan vegetation har på reningen av lakvatten inom parametrarna TKN, BOD5 och COD, i småskaliga våtmarker av typen rotzonsanläggning. Då den befintliga reningen på plats har svårt att uppfylla vissa uppsatta lagkrav.Sammansättningen på och mängden av lakvatten beror främst på faktorerna, nederbörd, Temperatur och nedbrytningen i deponin.Vegetationens har många olika betydelser i en rotzonsanläggning. Plantan transporter ner syre till dess rotsystem där syremolekyler diffunderar ut. Vegetation fungerar även som en extern kolkälla vid denitrifikationsteget. Det är viktigt att vegetationen trivs och rotsystemet är välutvecklat, för att få en maximal reduktion av föroreningar i våtmarken.Åtta småskaliga våtmarker byggdes upp i anslutning till lakvattenreningen, i avkapade plasttunnor. Alla våtmarker byggdes upp med unika förutsättningar för att kunna jämföra resultatet. Två olika substrat användes och jämfördes, i fyra kar planterades vegetation och fyra utan, fyra hade kontinuerligt flöde som jämfördes med fyra kar med batch flow.Resultaten visar att växterna inte har någon större inverkan på reningsgraden av BOD5, COD och TKN. Men såg tydliga tecken på högre vattenavdunstning i våtmarkerna med biomassa och generellt högre halter av BOD5, COD och TKN i jämförelse med våtmarkerna utan biomassa. Vegetationen hann inte acklimatisera sig till miljön i våtmarkerna, men det var på god väg. För att få ett bättre resultat och en mer signifikant skillnad mellan våtmarkerna skulle försöken ha pågått under en längre tid. Det behövs mer forskning och projekt under en längre period.

The ability for a subsurface flow constructed wetland system to treat landfill leachate was evaluated in Lajeado, Rio Grande do Sul, Brazil. Eight 0.95 m x 0.6 m experimental (SSF) units with a depth 0.4 m were used. Each wetland had unique conditions. Four units were planted with Typha angustifolia L. and four units were unplanted. Two different substrate dimension were used, four units with sand and four with gravel. Four wetlands operated in batch mode and four units with continuous flow. Batch flow systems were drained and filled up each week. To review vegetations impact on BOD5, COD and nitrogen compounds reduced in a wetland. This project lasted between January until May 2010 and samples were analyzed in April to May in four weeks.The result from this project show higher evapotranspiration water loss in units with planted vegetation and higher effluents concentration of BOD5, COD and nitrogen compounds, than in unplanted units.The ability for a subsurface flow constructed wetland system to treat landfill leachate was evaluated in Lajeado, Rio Grande do Sul, Brazil. Eight 0.95 m x 0.6 m experimental (SSF) units with a depth 0.4 m were used. Each wetland had unique conditions. Four units were planted with Typha angustifolia L. and four units were unplanted. Two different substrate dimension were used, four units with sand and four with gravel. Four wetlands operated in batch mode and four units with continuous flow. Batch flow systems were drained and filled up each week. To review vegetations impact on BOD5, COD and nitrogen compounds reduced in a wetland. This project lasted between January until May 2010 and samples were analyzed in April to May in four weeks.The result from this project show higher evapotranspiration water loss in units with planted vegetation and higher effluents concentration of BOD5, COD and nitrogen compounds, than in unplanted units.

Thesis (M.S.)--University of Wisconsin--Madison, 2000.
Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 134-139).

Ecosystem changes from grassland to shrubland in the Rio Grande Plains are thought to have negative effects on the hydrology of the region. The increase in woody plants, known as woody encroachment, may alter the amount of water moving beyond the root zone of plants. Water moving beyond the root zone is referred to as deep drainage, and has potential to become aquifer recharge. A vegetation manipulation project was designed to understand the effects of woody vegetation removal on soil water dynamics in the recharge zone of the Carrizo-Wilcox aquifer of south Texas. The primary objective of the project was to determine the potential to increase groundwater recharge through woody vegetation removal. To understand the effects of vegetation removal on various soil textures we studied changes in soil water, rooting depth, and the role of water redistribution by woody vegetation. Woody vegetation was removed using common methods of cut-stump and roller chop across three soil types. Soil water contents and changes were measured using neutron moisture meter to a depth of 180 cm. Average rooting depth was determined across three soil types. Soil and stem water stable isotopes were used to understand soil water movement. Rooting depth was determined to between 140 and 160 cm for all soil textures. Soil water content and changes were analyzed at three depth increments: 0-60, 60-120 and 120-180 cm. ANOVA analysis showed that there was no treatment response in average soil profile water in the sandy or sandy loam soils. There was a significant decrease in soil profile water for clay loam soil in response to roller chopping. Changes in soil profile water were the greatest in the sandy roller chopped soils. Below 120 cm, three months had significant differences in change in soil water in the sandy roller chop plot. During dry conditions, Honey mesquite shifts water use to deeper in the soil profile. In clay loam soils under dry conditions there is evidence of water being moved up from below 2 m soil depth to drier shallow soils. Roller chopping in sandy soils is the vegetation removal treatment and soil type most likely to result in water moving beyond the root zone. Although treatments had significant effects on soil moisture dynamics that interacted with soil type, we did not find support for deep drainage effects over the Carrizo-Wilcox aquifer from woody vegetation removal.

This thesis aims to contribute for the study of critical factors that influence the removal of organic matter and nitrogen in constructed wetlands with horizontal subsurface flow. It was realized that plants contribute for increasing the removal of organic matter and nitrogen, because they provide oxygen to the rhizosphere and the gowth of roots increases the surface area for biofilm development and uptake nitrogen through the roots. The Phragmites australis releases more oxygen during the daytime, and the oxygen transfer capacity was noted to change between 0.03 and 1.53 gO2.m-2.d-1. There was a positive linear relationship (p<0.05) between the organic removal rate and the influent organic load for the lower load. The removal of the ammonia mass load was not affected (p>0.05) by the respective applied load. The performance evaluation of three full-scale beds showed large fluctuations in organic and solid loads and low nitrogen load. The average removal efficiency (RE) of BOD5 was 88% and for nitrogen was low (<27% NT <30.8% for N-Org. <7% NH4+-N and <18% of NOX-N), although the plants were well developed and the hydraulic retention time was suitable for promoting nitrification. The COD removal ranged between 59% and 76%. There was a significant linear relationship (p<0.05) between the applied load of NT and SST and the respective concentration in the effluent. The effect of seasonal variation in the performance of other full-scale bed has shown that the RE of TSS and BOD5 are not affected (p>0.05) by seasonal periods, while nitrogen and phosphorus are significantly influenced (p<0.05) by the year season. The RE of TSS, COD and BOD5 was not significantly (p>0.05) affected by the income of high hydraulic loads, which shows good resilience of these systems.

Masters Research - Master of Science
The wide range of ecological influences exerted across landscapes causes a mosaic-like physiognomy which influences localised biodiversity. Dense infestations of Lantana camara contribute to these ecological influences and it has been established through various research projects that some species are favoured by Lantana infestations while others are disadvantaged. This research project examines whether small-scale infestations have any discernible impact upon floristic diversity and leaf-litter invertebrate diversity in the Lower Hunter region of New South Wales. It helps to clarify questions relating to establishing priorities for land management strategies. The study established that small patches of Lantana reduce floristic diversity and that this should be incorporated into the establishment of priorities for Lantana management strategies. Significant floristic differences between the paired Lantana plots and the non-infested plots were established for all of the study sites. Furthermore, the reduced floristic diversity was amongst the indigenous species. No difference in the diversity of weed species was found between the Lantana plots and the non-infested plots. There was no discernible difference in leaf-litter invertebrate diversity or population between the Lantana plots and the non-infested plots. This indicates that the commonplace tick-infestation of bushland regenerators when removing Lantana may have more to do with the removal methods than with an increase in the occurrence of ticks.

A thesis submitted to the Faculty of Science University of the Witwatersrand, Johannesburg for the Degree or Doctor or Philosophy October 1987
A t h r e e - y e a r study was un dertaken in the semi-arid (500mm p a . ) n o rth -eastern lowland area of South Afric a. All the woody plants were removed from one -hectare savanna plots on three d i f f e r e n t soil types , and key hydrological and biological changes were monitored relative to adjacent controls. Runoff increased initially, but decreased once the grass cover increased. Deep drainage and lateral subsurface flow increased on the sandiest site. Evaporation from the soil surface increased on the heavier t e x t u r e d soils. The duration of plant - available water in the soil increased on all cleared p l o t s . & The p re - c l e a r in g woody plant abo veground biomass was in the range of of which 0 . 6 6 to 0 . 8 0 t ha was 5.6 to 11.2 t ha -1 leaf biomass. The annual herbaceous production was stron gly rainfal' dep endent, averaging 1 to 1.5 t ha -1 , and increased by 0 . 4 - 0 6 t .ha -1 except on the most f erti le site ( 0 . 6 - 2 0 t ha ) . Total available forage increased with c l e a ring, but so did its variability The observed changes in herbaceous layer palatability could not be a t trib u t e d to clearing. Woody plants and grasses wore shown to have w a te r- u s e niche separation in both rooting depth and time of water use. Simulation over forty years of wetting patterns indicated 75 to 85 % niche overlap, w t h separation on the depth axis more important in sandy sites, and on the time axis in clayey sites. Competition between woody plants and grasses was strongly asymmetrical in favour of woody plants. w >

This thesis presents results from a large-scale dynamic restoration program implemented by Parks Canada Agency (PCA) to remove invasive marram grasses (Ammophila spp.) from a foredune-transgressive dune complex in Pacific Rim National Park, British Columbia, Canada. The program goal is to restore habitat for endangered Pink sandverbena (Abronia umbellate var breviflora) as required by the Canadian Species at Risk Act (SARA). Three sites were restored by PCA via mechanical removal of invasive marram grasses (Ammophila spp.) in September 2009. This study documents geomorphic and sediment mass exchange responses at one of these sites as derived from detailed Digital Elevation Model (DEM) surveys of a 10 320 m2 study area that spans three discrete geomorphic units (beach, foredune, and transgressive dune complex). Subsequent approximately bi-monthly total station surveys for the first year post-restoration are compared to a pre-restoration baseline Light Detection and Ranging (LiDAR) survey (August 2009) to quantify and describe morphodynamic responses and volumetric changes. Two different methodologies were utilized for post processing of volumetric change DEMs in order to filter out non-statistically significant change. The first filter used software developed for fluvial geomorphology and was tested using the student’s t distribution. This approach, while novel in the field of coastal geomorphology, was less complex than the second which was based on spatial statistical procedures popular in the ecological sciences. This filter was based on local Moran’s Ii, which was used to generate 1.5m and 5m distance thresholds of statistically significant geomorphic change. These thresholds were specified to simulate the outer limit of saltating grains and the dimensions of landform development, respectively. Results show that the beach receives appreciable sediment supply via bar welding and berm development in the winter, much of which is transported to the foredune and transgressive dune complex units in the spring. This promotes rapid redevelopment of incipient dunes in the backshore, rebuilding of the seaward slope of the foredune following wave scarping, and localized extension of depositional lobes in the transgressive dune complex fed by sediment from the beach and foredune stoss (only shown in local Moran’s Ii results). The results of this study suggest that the foredune-transgressive dune complex at Wickaninnish Dunes has experienced enhanced aeolian activity and positive sediment volume changes over the first year following mechanical restoration. In addition, comparison of the two methodologies show that spatial statistics were found to provide both more realistic calculated volumes at a smaller threshold distance (e.g., – 0.012m3 m-2 in the foredune after devegetation; only +0.015m3 m-2 in the transgressive dune complex in the year following restoration) and better highlighting of important spatial processes at a larger threshold distance (e.g., foredune stoss erosion; feature highlighting) than the volumetric change calculations based on a simpler statistical threshold.
Graduate

Pine plantations have been established on secondary grassland on the dune systems of the Eastern Shores of Lake St Lucia, KwaZulu-Natal, South Africa for the past 40 years. These plantations have been progressively felled for the past six years, and will continue to be felled until the year 2011, by which time they will be eliminated. Space-for-time substitution was used to determine the direction of both woody and herbaceous vegetation succession and to predict possible future management implications for the Eastern Shores. Soil samples were taken from undisturbed grassland, grassland with trees, dune forest, pine plantations, and clearfelled areas at various successional stages. To determine the effects of the pine plantations on the soils of the area, soils were subjected to particle size analysis, and determination of pH, organic carbon, phosphorus, exchangeable bases, iron and aluminium. Minimal modification of the sandy soils by the pine plantations was found to have occurred. That which did occur was shown to be short-term, and to be ameliorated by the establishment of an indigenous woody understorey, resembling pioneer dune forest. Soil under plantations was shown to have a lower pH and cation exchange capacity than under opposite indigenous vegetation but no other direct effects were observed. The direction of succession was determined by the nature of the indigenous vegetation adjacent to the plantation. Pine plantations were shown to facilitate succession towards dune forest by the exclusion of fire, provision of perches and refugia for forest-dwelling animals, and creation of a forest environment for the establishment of trees. However, the extent of re-establishment of indigenous dune forest under pine plantations was shown to be directly related to the nature of the adjacent indigenous vegetation, be it grassland, grassland with trees or dune forest.
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.

Tese de doutoramento em Ciências Geofísicas e da Geoinformação (Detecção Remota), apresentada à Universidade de Lisboa através da Faculdade de Ciências, 2008
The study aims at investigating the relationship between climate variability and vegetation dynamics by combining meteorological and remote-sensed information. The vegetation response to both precipitation and temperature in two contrasting areas (Northeastern Europe and the Iberian Peninsula) of the European continent is analysed and special attention is devoted to the impact of the North Atlantic Oscillation (NAO) on the vegetative cycle in the two regions which is assessed taking into account the different land cover types and the respective responses to climate variability. An analysis is performed of the impact of climate variability on wheat yield in Portugal and. the role of NAO and of relevant meteorological variables (net solar radiation, temperature and precipitation) is investigated. Using spring NDVI and NAO in June as predictors, a simple regression model of wheat yield is built up that shows a general good agreement between observed and modelled wheat yield values. The severity of a given drought episode in Portugal is assessed by evaluating the cumulative impact over time of negative anomalies of NDVI. Special attention is devoted to the drought episodes of 1999, 2002 and 2005. While in the case of the drought episode of 1999 the scarcity of water in the soil persisted until spring, the deficit in greenness in 2005 was already apparent at the end of summer. Although the impact of dry periods on vegetation is clearly noticeable in both arable land and forest, the latter vegetation type shows a higher sensitivity to drought conditions. Persistence of negative anomalies of NDVI was also used to develop a procedure aiming to identify burned scars in Portugal and then assess vegetation recovery over areas stricken by large wildfires. The vulnerability of land cover to wildfire is assessed and a marked contrast is found between forest and shrubland vs. arable land and crops. Vegetation recovery reveals to strongly depend on meteorological conditions of the year following the fire event, being especially affected in case of a drought event.
Fundação para a Ciência e Tecnologia (FCT), (SFRH/BD/32829/2006)