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1
Britton, Andrea Jane. "Modelling invasions on heathlands." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284563.
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Nolan, Abigail. "Modelling change in the lowland heathlands of Dorset." Thesis, University of Southampton, 1999. https://eprints.soton.ac.uk/388232/.
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Tripp, Edward James. "Nitrogen deposition and the sustainability of lowland heathlands in Britain." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13027/.
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Despite widespread conservation efforts, global heathland area has substantially decreased in recent decades. Heathland habitats require low nitrogen availability in order to persist. Over the past 150 years, however, nitrogen deposition has increased markedly. Early observational studies and research using artificial N applications have identified N deposition as the primary driver of heathland succession into grassland or woodland, and N enrichment is considered a threat to heathland sustainability. This study investigated soil fertility and vegetation composition at 25 lowland heathland sites in low rainfall regions of mainland Britain within a modelled wet N deposition range of 1.85 to 10.90 kg N ha-1 y-1. A bioassay approach was used to quantify relationships between soil fertility and N deposition, heathland patch size and the management regimes. This study discovered significant positive relationships between N enrichment and C. vulgaris shoot mass, N and P concentrations. No relationship between N enrichment and N : P mass ratio was found suggesting no N induced shift to P limitation. It was determined that soil phosphomonoesterase activity was not up-regulated in response to N enrichment. This suggests that the soil P reserves are sufficient to satisfy demand under current N deposition loads. Heathland patch size was negatively related to C .vulgaris shoot dry-mass which was used as a proxy for soil fertility. Measured atmospheric ammonia concentrations were not related to C. vulgaris growth and shoot chemistry. No relationships were found between any variable tested and heathland vegetation composition suggesting that local factors, such as management intervention, may be substantial determinants of vegetation composition. This study presents relationships between temperature at origin and C. vulgaris growth from populations located along a latitudinal gradient in Western Europe. The findings of this thesis have implications for current heathland management, and for future management under a climate change scenario.
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Uren, Sally Clare. "The effects of wet and dry deposited ammonia on Calluna vulgaris." Thesis, Imperial College London, 1992. http://hdl.handle.net/10044/1/8895.
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Martin, Kirsten. "Disturbance-Based Management and Plant Species Change in Massachusetts Sandplain Heathlands over the Past Two Decades." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5813.
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Massachusetts sandplain heathlands are habitats of conservation concern, harboring many rare plant species and providing habitat for animals that depend on openlands. These heathlands are threatened by human development, shrub encroachment in the absence of disturbance, and potentially increasing soil nutrient levels. Sandplain heathlands are managed with prescribed fire, in order to maintain their open structure and maintain species diversity. In order to assess how past management was correlated with species change, I used a data set that spanned twenty years from three different heathlands in Massachusetts. I looked for correlations between management and species change. Correlations between species change and prescribed burning were very site, or microsite, specific, indicating that variables such as vegetation type and edaphic characteristics need to be taken into account before management is applied. Prescribed fire was also associated with an increase in ruderal species in one of the sites studied, indicating that there may be undesirable effects of prescribed fire in this system. Species diversity was negatively associated with shrub encroachment, reinforcing the importance of preventing shrubs from encroaching into these heathlands. I also found evidence that burning has not been a successful technique in preventing shrub encroachment in these sites. Lastly, the nitrophilic species Carex pensylvanica increased in all three sites, indicating that future studies should investigate the possibility that sandplain heathlands are currently experiencing nitrogen deposition beyond their critical loads.M.S.
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Biology
Sciences
Biology
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Collier, Fay Alexandra. "The mycorrhizal fungi involved in the tree invasion of lowland heathlands." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/5294.
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In England, the loss of lowland heathland, a habitat of high conservation importance, is primarily due to the invasion of birch and pine. This secondary succession has been researched in depth from a plant perspective but little is known about the role of mycorrhizal fungi, even though both trees and heather are mycorrhizal. In fact, tree encroachment onto lowland heathland can be regarded as the replacement of a resident ericoid mycorrhizal community by an invading ectomycorrhizal community. I determined the identity and distribution of the ectomycorrhizal fungi associated with birch and pine encroachment onto lowland heathlands. I established whether there are mycorrhizal fungi that mediate the invasion by a) comparing the mycorrhizal inoculum potential of soil and ectomycorrhizal fungal diversity at three levels of invasion (uninvaded heathland, invaded heathland and woodland), b) comparing the fungi forming mycorrhizas on tree seedlings and trees across diverse sites, c) determining the effect of proximity to trees on mycorrhization and seedling biomass, and d) identifying fungal dispersal methods. I established that in lowland heathlands i) seedlings have limited access to ectomycorrhizal fungi even within sapling rooting zones, ii) ectomycorrhizal inoculum potential increases as the level of tree invasion increases, iii) mycorrhizal seedlings accumulate more biomass than non-mycorrhizal seedlings, iv) there are five keystone ectomycorrhizal fungi that participate in tree invasion - Rhizopogon luteolus, Suillus bovinus, S. variegatus (pine symbionts), Laccaria proxima and Thelephora terrestris (primarily birch symbionts), v) some ectomycorrhizal fungi cannot colonise seedlings via spores, and vi) ectomycorrhizal communities differ between lowland heathland sites. This study is the first to identify the mycorrhizal fungi that associate with tree seedlings on lowland heathlands and it is one of the first biome-level mycorrhizal studies of secondary plant succession. The data presented provide the stepping-stones required for future ecologically-relevant modelling and experimentation aimed at understanding mycorrhizal invasions.
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Daniel, Rosalie, and mikewood@deakin edu au. "Aspects of the interaction between Xanthorrhoea australis and Phytophthora cinnamomi in south-western Victoria, Australia." Deakin University. School of Biological and Chemical Sciences, 2002. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20051201.144848.
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Diseases in natural ecosystems are often assumed to be less severe than those observed in domestic cropping systems due to the extensive biodiversity exhibited in wild vegetation communities. In Australia, it is this natural biodiversity that is now under threat from Phytophthora cinnamomi. The soilborne Oomycete causes severe decline of native vegetation communities in south-western Victoria, Australia, disrupting the ecological balance of native forest and heathland communities.
While the effect of disease caused by P. cinnamomi on native vegetation communities in Victoria has been extensively investigated, little work has focused on the Anglesea healthlands in south-western Victoria. Nothing is known about the population structure of P. cinnamomi at Anglesea. This project was divided into two main components to investigate fundamental issues affecting the management of P. cinnamomi in the Anglesea heathlands. The first component examined the phenotypic characteristics of P. cinnamomi isolates sampled from the population at Anglesea, and compared these with isolates from other regions in Victoria, and also from Western Australia. The second component of the project investigated the effect of the fungicide phosphonate on the host response following infection by P. cinnamomi.
Following soil sampling in the Anglesea heathlands, a collection of P, cinnamomi isolates was established. Morphological and physiological traits of each isolate were examined. All isolates were found to be of the A2 mating type. Variation was demonstrated among isolates in the following characteristics: radial growth rate on various nutrient media, sporangial production, and sporangial dimensions. Oogonial dimensions did not differ significantly between isolates. Morphological and physiological variation was rarely dependant on isolate origin.
To examine the genetic diversity among isolates and to determine whether phenotypic variation observed was genetically based, Random Amplified Polymorphic DNA (RAPD) analyses were conducted. No significant variation was observed among isolates based on an analysis of molecular variance (AMQVA). The results are discussed in relation to population biology, and the effect of genetic variation on population structure and population dynamics.
X australis, an arborescent monocotyledon indigenous to Australia, is highly susceptible to infection by P. cinnamomi. It forms an important component of the heathland vegetation community, providing habitat for native flora and fauna, A cell suspension culture system was developed to investigate the effect of the fungicide phosphonate on the host-pathogen interaction between X. australis and P. cinnamomi. This allowed the interaction between the host and the pathogen to be examined at a cellular level.
Subsequently, histological studies using X. australis seedlings were undertaken to support the cellular study. Observations in the cell culture system correlated well with those in the plant. The anatomical structure of X australis roots was examined to assist in the interpretation of results of histopathological studies. The infection of single cells and roots of X. australis, and the effect of phosphonate on the interaction are described. Phosphonate application prior to inoculation with P. cinnamomi reduced the infection of cells in culture and of cells in planta. In particular, phosphonate was found to stimulate the production of phenolic material in roots of X australis seedlings and in cells in suspension cultures. In phosphonate-treated roots of X australis seedlings, the deposition of electron dense material, possibly lignin or cellulose, was observed following infection with P. cinnamomi. It is proposed that this is a significant consequence of the stimulation of plant defence pathways by the fungicide.
Results of the study are discussed in terms of the implications of the findings on management of the Anglesea heathlands in Victoria, taking into account variation in pathogen morphology, pathogenicity and genotype. The mode of action of phosphonate in the plant is discussed in relation to plant physiology and biochemistry.
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Davis, Charles D. "Impact of Fuel Management Strategies on Potential Fire Behavior in the Heathlands and Moorlands of North-West Europe." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu161893613230021.
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Schirmel, Jens [Verfasser]. "Arthropods in a changing environment : a multi-level and -species approach to diversity and ecology in coastal heathlands / Jens Schirmel." Greifswald : Universitätsbibliothek Greifswald, 2011. http://d-nb.info/1013465237/34.
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Graham, Tristian. "The impact of Phytophthora dieback and the aerial application of phosphite on terrestrial invertebrate communities of south coast heathlands, Western Australia." Thesis, Graham, Tristian (2003) The impact of Phytophthora dieback and the aerial application of phosphite on terrestrial invertebrate communities of south coast heathlands, Western Australia. Honours thesis, Murdoch University, 2003. https://researchrepository.murdoch.edu.au/id/eprint/32628/.
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Terrestrial invertebrates were surveyed from south coast heathland environments, Gull Rock and Waychinicup National Park. These study sites chosen from within these two regions consist of both healthy and Phytophthora cinnamomi infected vegetation. Phosphite was being aerially applied to parts of these sites as a preventative treatment for the further spread of Phytophthora dieback disease into healthy areas. The experiment aimed to sample terrestrial invertebrate communities using pitfall traps and a foliage beating technique in Phytophthora dieback affected areas and healthy areas and also before and after phosphite application to assess any potential non-target impacts. Invertebrates were identified and analaysed at ordinal level classification and Coleoptera (beetles) were sorted to morphospecies to assess impacts at a finer taxonomic level. Shannon-Wiener Index of Diversity, Sorenses Index of Similarity, Multi-dimesional Scaling, Multi-variate ANOVA and Univariate ANOV A were all used to decide whether there were any impacts of Phytophthora dieback and Phosphite Application of the invertebrates collected. Analysis revealed strong seasonal effects within data but no trends eluding to impact of Phytophthora dieback or Phosphite application.
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Laidlaw, William Scott, and mikewood@deakin edu au. "The Effects of Phytophthora Cinnamomi on heathland flora and fauna of the Eastern Otway Ranges." Deakin University. School of Biological and Chemical Sciences, 1997. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20051111.121612.
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The plant pathogen, Phytophthora dnnamomi, is a cause of dieback disease observed in sclerophyll vegetation in Australia, The effects of P. dnnamomi on flora and fauna were studied at two locations in heathland vegetation near the coastal town of Anglesea, Victoria. The pathogen was isolated from soils beneath diseased heathland plants. The extent of diseased vegetation was assessed by the presence and absence of highly sensitive indicator species, Xanthorrhoea australis and hopogon ceratophyllus. The characteristics of heathland vegetation exhibiting dieback disease associated with the presence of P. dnnamomi were investigated.
Plant species richness was similar between diseased and non-diseased areas however diseased areas were characterised by significant declines in the cover and frequency of susceptible species, increases in resistant species and increases in percent cover of open ground. Compared to non-diseased areas, diseased areas exhibited fewer shrub species and decreased shrub cover. The percentage cover and number of species of sedges, lilies and grasses were higher in diseased areas. Structural differences were significant between 0-0.6 m with decreased cover of vegetation in diseased areas. Differences in structure between diseased and non-diseased areas were not as great as expected due to increases in the cover of resistant species. A number of regenerating X australis were observed in post-disease areas. Cluster analysis of floristic data could clearly separate diseased and non-diseased trap stations.
The population dynamics and habitat use of eight small mammal species present were compared in diseased and non-diseased areas using trapping and radio-tracking techniques. The number of small mammal species captured in post-disease areas was significantly lower than non-diseased areas. Mean captures of Antechinus stuartii and Rattus fiisdpes were significantly lower in diseased areas on Grid B. Mean captures of Rattus lutreolus were significantly lower in diseased areas on both study grids. Significant differences were not observed in every season over the two year study period. Radio tracking revealed more observations of Sminthopsis leucopus in non-diseased vegetation than in diseased. Cercartetus nanus was frequently observed to utilise the disease susceptible X. australis for nesting.
At one location, the recovery of vegetation and small mammal communities in non-diseased and diseased vegetation after fuel reduction burning was monitored for three years post-fire. Return of plant species after fire in both disease classes were similar, reaching 75% of pre-fire richness after three years. Vegetation cover was slower to return after fire in diseased areas. Of the seven small mammal species captured pre-fire, five were regularly captured in the three years after fire. General linear model analysis revealed a significant influence of disease on capture rates for total small mammals before fire and a significant influence of fire on capture rates for total small mammals after fire. After three years, the influence of fire on capture rates was reduced no significant difference was detected between disease classes. Measurements of microclimate indicate that diseased, burnt heathland was likely to experience greater extremes of temperature and wind speed. Seeding of diseased heathland with X. australis resulted in the establishment of seedlings of this sensitive species.
The reported distributions of the mamma] species in Victoria were analysed to determine which species were associated with the reported distribution of dieback disease. Twenty-two species have more than 20% of their known distribution in diseased areas. Five of these species, Pseudomys novaehollandiae, Pseudomys fumeust Pseudomys shortridgei, Potorous longipes and Petrogale pencillata are rare or endangered in Victoria. Four of the twenty-two species, Sminthopsis leucopus, Isoodon obesulus, Cercartetus nanus and Rottus lutreolus am observed in Victorian heathlands.
Phytophthora cinnamomi changes both the structure and floristics of heathland vegetation in the eastern Qtway Ranges. Small mammals respond to these changes through decreased utilisation of diseased heathland. The pathogen threatens the diversity of species present and future research efforts should be directed towards limiting its spread and rehabilitating diseased areas.
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Plucinski, Matthew Paul Mathematics & Statistics Australian Defence Force Academy UNSW. "The investigation of factors governing ignition and development of fires in heathland vegetation." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Mathematics and Statistics, 2003. http://handle.unsw.edu.au/1959.4/38702.
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Heathlands typically experience regimes consisting of frequent and intense fires. These fire regimes play important roles in the lifecycles and population dynamics of all species in these communities. Prescribed fire is commonly applied to heathlands to minimise the risk of wildfires as well as to promote biodiversity. Ignitions in heathlands tend to either be unsustainable, or quickly develop into rapidly spreading intense fires. This presents a major problem for the application of prescribed fire and is the primary focus of this thesis. Heathland ignition has been investigated in three sections; litter ignition; vertical development of fire into the shrub layer; and horizontal spread through the shrub layer. These were studied in laboratory experiments using miniature versions of field fuels. Ignition success in litter layers was related to the dead fuel moisture content. Litter type, ignition source, and presence of wind were found to affect the range of ignitable fuel moisture contents of a litter bed. The effect of litter type was best explained by density. Dense litter beds required drier conditions for ignition than low density litter beds. The vertical development of fire into shrubs was mostly dependent on live fuel moisture content, but crown base height, presence of wind, ignition source, shrub height and the percentage of dead elevated fuel were also important. Horizontal spread of fires through shrub layers was most affected by the presence of a litter layer, with nearly all ignitions successful when there was an underlying litter fire. Fire spread would only occur in shrubs without a litter layer when the shrub layer was dense and dry, or had a substantial dead fuel component. Spread was more likely to be sustained when there was wind. Models predicting the moisture content of dead fuels were tested in heathlands, and as would be expected those that can be calibrated for different fuel types were found to have the best performance. Fuel moisture content and fuel load models were reviewed for heathlands, and a number of recommendations for future research were made.
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Wills, Timothy Jarrod 1974. "Succession in sand heathland at Loch Sport, Victoria : changes in vegetation, soil seed banks and species traits." Monash University, Dept. of Biological Sciences, 2002. http://arrow.monash.edu.au/hdl/1959.1/7742.
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Griffiths, Megan Elizabeth. "Salt spray effects on rare New England coastal sandplain heathland plant communities /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2003.
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Thesis (Ph.D.)--Tufts University, 2003.Adviser: Colin M. Orians. Submitted to the Dept. of Biology. Includes bibliographical references (leaves 181-200). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Meeteren, Maartje Johanna Maria van. "Heathland ecosystem functioning under climate change." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2005. http://dare.uva.nl/document/78861.
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Crabtree, Lora. "Nitrogen source preferences in heathland plants." Thesis, University of Aberdeen, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419654.
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Plant growth is limited by N availability in high latitude and altitude ecosystems where soil N is held in organic matter due to slow rates of soil processes. Adaptations to stress tolerance in these ecosystems include mechanisms for increased N capture, including from organic sources. N uptake up heathland plants was examined, specifically with respect to; source effects, species differences, short-term uptake and ecological relevance. N capture was measured with 15N-labelled sources, including ammonium, glycine, leucine, fungal cell wall and powdered worm, over treatment durations between 2 and 168h. No consistent or predictable source preferences were found for Calluna vulgaris, mixed grasses, including Agrostis capilaris, Deschampsia flexuosa and Festuca ovina, and sedges (Carex spp.) between ammonium and glycine with only slightly less leucine-N captured. There was measurable uptake from the complex organic sources 2 and 6 hours after source addition. Calluna generally acquired more source-N but comprised a much greater proportion of combined biomass, consequently graminoids species captured more N per unit biomass. Over shorter treatment durations grasses were able to acquire more N in total than Calluna despite smaller biomass. Glycine-N turnover was measurable after 2 h with 6.5% in the ammonium pool. Subtle differences in mechanisms of plant stress tolerance in high latitude and altitude systems are suggested, with graminoids species able to rapidly capture N despite the non-mycorrhizal cluster root of Carex and the arbuscular mycorrhizal grass roots. In contrast the woody shrub Calluna is adapted to require less N.
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Angold, Penelope Gaynor. "The role of buffer zones in the conservation of semi-natural habitats." Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314943.
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Williams, Christina Mary. "Heath creation through the establishment of Calluna vulgaris (L.) Hull on ex-arable land in north-east Scotland." Thesis, University of Aberdeen, 1996. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU089791.
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The declining area of heathland in north-west Europe is causing widespread concern amongst conservationists. The aim of the experiments described in this thesis was to investigate methods of heath creation by establishing the dwarf shrub, Calluna vulgaris (L.) Hull, on the ex-arable land. Arable land, surplus to requirement and available through set-aside schemes, could be used to expand or join together small pockets of remnant heath. Field experiments were designed to test various methods of introducing Calluna, but, in all cases, it failed to persist and spread after introduction. The most promising method of introduction was to transplant young plants. The conditions at the field site, in arable production immediately prior to the experiments being set up, were such that Calluna was unable to establish dominance. High residual soil fertility combined with a large weed seed bank produced a dense cover of vegetation in which Calluna did not persist. Pot experiments were carried out to determine whether soil amendments might make the creation of heath more feasible on ex-arable sites. Most amendments reduced the dry matter production of the weed species tested compared to the control treatment (un-amended field soil). One treatment, elemental sulphur, significantly reduced the growth of a major weed species (Trifolium repens) at very low application rates, whilst Calluna grew well on the amended soil. Elemental sulphur lowers soil pH and therefore reduces the availability of most plant nutrients and increases the solubility of some metals. When tested in the field, high rates of sulphur significantly increased the survival of Calluna transplants. The author suggests that soil modification with an acidifying agent is the key to heath creation on agriculturally-improved soils. Vegetation management, such as the use of herbicides may also have a part to play, although once soil conditions are suitable this management would be reduced very much to a secondary role.
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Allchin, Elizabeth Ann. "Vegetation dynamics following management burning of lowland heathland." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284333.
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Management of the southern lowland heaths is usually for conservation, and aims to create structural diversity, prevent succession to scrub and maintain the low nutrient status of the system. The main aim of this study was to investigate the effects of burning, fire temperature and intensity on seed banks, nutrients, vegetative regeneration and seedling demography. In the first experiment (1994), vegetation fuel loads were manipulated in stands representing two different growth phases of vegetation (mature and degenerate) at two sites (Arne in Dorset and Aylesbeare in Devon) to test the hypothesis that frre temperature and intensity depend chiefly on fuel load rather than other factors associated with the pre-burn age of the stand. There were two burning treatments of low and high fuel loads. Fire temperatures were measured with temperature-sensitive paints on tiles ('pyrometers'). Intensity (the heat released per unit area) was highly correlated with fuel load. Fire temperatures were higher in the high fuel load treatments than in the low fuel load treatments at all stands except the Aylesbeare degenerate stand. where temperatures were low in both treatments. In the second experiment (1995). paraffin was added to treatment plots at the mature stand at Aylesbeare in an attempt to produce higher temperatures. but this aim was not achieved. Thermocouples and pyrometers were used to measure temperatures and indicated that these fires were hotter than the fires at the same stand in the first experiment. There was no effect of burning or of temperature on the size of the seed banks in the soil and litter in the frrst experiment. The litter seed bank of Erica tetralix was depleted by a similar quantity in both treatments in the second experiment. There was no effect of burning on the nutrients (P. Ca. K) in the humic soil in either of the experiments. The concentration of nutrients was higher in the ash than in the litter of control plots after burning (except at the Aylesbeare degenerate stand). There were significant but inconsistent effects of temperature on the quantities of nutrients. Vegetative regeneration after burning depended chiefly on the pre-bum age of the stand and possibly on grazing. but fire temperature had no effect. There was rapid resprouting at both the mature stands, but regeneration at the degenerate stands was sparse. Calluna rapidly regained dominance at the Arne mature stand but was relatively less abundant at the Aylesbeare mature stand after burning than it was before. Agrostis curtisii. Ulex gallii and Erica tetralix were co-dominant in the regrowth at this stand. However. there was a decline in the relative abundances of U. gallii and A. curtisii by the third growing season after burning. At the mature stands. seedlings affected by resprouting vegetation were sheltered from microclimatic extremes and experienced higher survivorship than seedlings in areas of bare ground. However. seedling density under resprouts decreased over time as continued growth of resprouts prevented seedling germination and establishment. Seedling populations on bare ground at both types of stand oscillated widely, and there was a rapid turnover. Although bare ground persisted at the degenerate stands, there was no invasion of non-heathland species. A canopy of ericaceous species should eventually develop via gradual accumulation of seedling density and vegetative spread from the few stem bases that were able to resprout. The range of temperatures generated by the fuel loads tested did not have significant effects on regeneration from seed or from stem bases. However. the removal of vegetation by burning had a large impact on vegetation dynamics by enabling seedling emergence and resprouting from stem bases. The balance between regcneration from seed and from stcm bases depended on the pre-bum age of the stand.
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Pardiwala, Rashneh N. "Effects of atmospheric nitrogen deposition on heathland ecosystems." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/12762.
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This study examined the degree to which enhanced nitrogen inputs in a Calluna-dominated ecosystem can alter plant physiological responses, affect the response of soil respiration to environmental parameters by disturbing acclimatised soil microbial populations, influence the relationship between soil carbon fluxes and soil microbial populations, and change soil mineral nitrogen availability to the plants. A pilot study investigated the response of nitrogen deposition on Calluna vulgaris plants maintained in open-top chambers. Heathland monoliths were exposed to acid mist treatments of ammonium nitrate spanning across extreme values. Growth response to increasing fertiliser additions was detectable and high nitrogen fertiliser inputs significantly stimulated shoot growth. Fertiliser inputs were reflected in soil and tissue nitrogen concentrations with an increase in total nitrogen content within actively growing tissues while shoot phenolic concentration decreased in response to nitrogen additions in agreement with the carbon-nutrient hypothesis. A field study was conducted in experimental plots set up in a dense stand of mature heather at Castlelaw Hill, near to Edinburgh. A new, simple methodology is developed and operated to accurately measure soil respiration under controlled laboratory conditions using small soil microcosm with a gas analysis unit. Annual seasonal pattern of soil carbon dioxide effluxes and environmental parameters of soil temperature, moisture, pH, organic matter, microbial biomass and plant growth were measured. Soil temperature, pH, organic matter and microbial biomass were found to be important determinants of carbon dioxide fluxes from soil. In all the soil horizons, carbon dioxide efflux in response to temperature followed the expotential first order equation with an increase with increasing temperature but soil carbon dioxide fluxes decreased with depth. Nitrogen inputs significantly increased soil respiration and the results suggest that long-term effects of atmospheric N deposition, with accelerated mineralisation at higher temperatures, could disrupt the carbon balance of nutrient-poor ecosystems, as noted for heathlands.
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Cawley, Leigh Eric. "Pollutant nitrogen and drought tolerance in heathland plants." Thesis, Manchester Metropolitan University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341054.
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It has been suggested that pollutant nitrogen inputs adversely influence the response of heathland plants to certain climatic and biotic stresses. One specific hypothesis being that elevated nitrogen deposition may reduce drought tolerance in heathland vegetation. However, there is little evidence from field studies that this is the case. The aims of this research project have been firstly to establish the effects of increased nitrogen inputs upon plant water relations in certain dwarf heathland shrubs under winter and summer drought conditions. Secondly, to contribute to the understanding of how changes in plant water relations caused by increased inputs of nitrogen affects the growth, physiological perfonnance and consequent long tenn survival of heath land plant communities. Experimental field work was carried out at an existing upland site in Clwyd, North Wales near Ruabon from July 1995 to April 1999. Experimental work with potted plants was carried out in the glasshouse at Crewe, Octoberl995 to June 1997. A lowland field site at Budworth Common in Cheshire, consisting of twenty, 2 x 1 metre plots in a replicated random block layout was established by the author during March 1996, remaining a site of investigation until December 1998. At both the upland and lowland field sites the vegetation was dominated by Calluna vulgaris (L.) Hull. At Ruabon a twelve month study of shoot relative water contents in relation to soil moisture deficits was carried out on a monthly basis. Visible frost injury was surveyed and recorded each spring (April 1996 to April 1999). At Budworth Common (summer 1997), following 12 months of nitrogen applications (0, 20, 60 and 120 kg N ha-1yr-1 (NH4N03» a protracted period of drought was imposed on field plots by the use of drought shelters, these covered the whole of each plot.Comparisons were drawn between watered and droughted plants in the field. This was carried out by applying the equivalent summer rainfall for Budworth Common to one half (1m2) of every treatment plot and droughting the other half (1m2). Nitrogen treatments were continued at fortnightly intervals throughout. Budworth Common was used to study the impacts of elevated nitrogen and drought for a five month period from May to September 1997. Intensive experimental field work over the drought period recorded: weekly measurements of soil moisture deficits, shoot water potentials and shoot extension growth. Measurements of shoot relative water contents and infra red gas analysis were taken, the flowering period was recorded. During the post drought year (summer 1998) a spontaneous outbreak of Lochmaea suturalis (heather beetle) in the field plots showed the beetles to have a preference for high N treated Calluna. An increase in the competitive grass species Deschampsia jlexuosa was seen in droughted plots during summer 1998, particularly the high N treatments. As a result of experimental work carried out both in the field and laboratory this study has shown that elevated nitrogen does have detrimental impacts on the drought tolerance of certain heathland plants. Field work results compared positively with those obtained from the pot experiment. A higher incidence of visible frost and drought damage was recorded in high nitrogen plots. Lower soil moistures were recorded in high nitrogen plots. Measurements of shoot water potentials revealed that high nitrogen treatments under drought conditions exhibited more negative values than did low nitrogen plants. High nitrogen increased the number of early opening flowers under conditions of full water but in plants receiving high nitrogen and drought flowering was delayed. This study increases the understanding of the impacts of elevated nitrogen inputs on the water relations of heathland plants.
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Scandrett, Eurig. "Gap formation and cyclical change in heathland vegetation." Thesis, University of Aberdeen, 1987. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU010080.
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The phasic, cyclical model of Calluna-dominated vegetation dynamics, proposed by A.S. Watt, is evaluated by investigation of the gap in the degenerate plant. Succession in the gap is analysed by Markov models and found to be non-Markovian, with a number of processes occurring simultaneously. Vegetation changes are better interpreted in terms of certain ecological attributes of the species concerned. The inter-relationships between three important moss species are investigated further. Regeneration of Calluna is very variable. Seedling establishment requires a safe site and sufficient moisture, and depends on wet summers. Vegetative layering occurs more frequently but varies between parent plants and substrate types. The presence of soil micro-organisms appears necessary for adequate adventitious root production. An outbreak of heather beetle was monitored and contrasted with outbreaks in the Netherlands. The population was reduced by a parasitoid which acted density independently. At these low densities, a mosaic of gaps is formed in the vegetation by spatial heterogeneity of heather beetle attacks. These gaps behave in a similar fashion to degenerate gaps, and most Calluna regeneration occurs by layering. The value and limitation of Watt's model is discussed, especially by reference to forest gap-dynamics theory.
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Preece, Catherine. "Impacts of icing events on sub-arctic heathland vegetation." Thesis, University of Sheffield, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.574535.
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The Arctic is experiencing large climatic changes, particularly during winter, including warming, rain-on-snow events and increased frequency of freeze-thaw cycles. These changes are predicted to lead to an increase in the frequency of icing events. During these events vegetation can become encased in ice which may damage plants through freezing, hypoxia or high C02 (created within impermeable ice layers) and mechanical injury. To date however, ice encasement impacts on arctic vegetation remain largely unknown. In the study area in sub-arctic Sweden, snow pack surveys verified the occurrence of impermeable ice layers within open and forest dwarf shrub heathland (the dominant vegetation types of the region). Field manipulation experiments were established in these two habitats with icing events simulated in January and March of2008, 2009 and 2010. Impacts of ice encasement on the growth, reproduction, phenology and abundance of four widely distributed dwarf shrub species were determined in the following growing seasons. Additionally, a suite of physiological indicators of damage were monitored including foliar electrolyte leakage, chlorophyll fluorescence and ethanol accumulation. Overall, plants demonstrated an intermediate to high level of tolerance to icing with responses being species-specific. To investigate the relationship between ice encasement and hypoxia and CO2 build-up within ice, a novel field chamber experiment was established, simulating winter-time hypoxic and high CO2 conditions. In this study also, the species showed high tolerance to hypoxia and whilst high CO2 did have some negative impacts, overall effects were rare. This tolerance may therefore provide one explanation for the general tolerance of icing seen in the ice simulation studies. In conclusion, whilst icing events have been shown to have some impacts on sub- arctic dwarf shrubs, community impacts may take many years of repeated icing events to become apparent given the intermediate to high level of tolerance of the plants.
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Phoenix, Gareth Kevin. "Effects of ultraviolet radiation on Sub-Arctic heathland vegetation." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322936.
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Pywell, Richard Francis. "The restoration of heathland on farmland in southern Britain." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385161.
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Hughes, Marion Geraldine Brierley. "Experimental management of heathland in the Lizard District, Cornwall." Thesis, University of Bristol, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292568.
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Staley, Jeremy Ross. "Aspects of the population dynamics of Lochmaea suturalis Thompson (Coleoptera: Chrysomelidae; sub-family: Galerucinae), the heather beetle : a combined laboratory and modelling approach." Thesis, University of Newcastle Upon Tyne, 2000. http://hdl.handle.net/10443/956.
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This thesis describes a series of laboratory and field experiments that quantify the population dynamics of the heather beetle (Lochmaea suturalis Thomson), in relation to temperature and its host plant heather (Calluna vulgaris (L. ) Hull). The sex ratio, fecundity, egg laying threshold temperature, emergence threshold temperature, life stage development periods, and life stage mortalities were investigated. It was shown that the life stages were significantly dependent on temperature, whilst it was shown that there was no significant relationship between larval growth and Calluna vulgaris plants sourced from the study sites. The results of the population dynamics experiments were incorporated into a temperature driven, cohort based, and daily looped, stochastic population dynamics computer model. The temperature component of the model was derived from temperature data collected from nine moorland sites, at different altitudes, where there was shown to be a significant relationship between temperature and altitude. The population dynamics model was run for a fifty year period with a population of I million beetles at seven temperature regimes and five different altitudes. The model predicted that as daily mean temperatures rose, so there was a greater chance of increasing populations and that as altitude increases, so the chance of increasing populations decreases. At a predicted daily mean temperature rise of 2-3'C there was evidence of considerable population increases at lower altitudes, and with a daily mean temperature rise of 4-6'C the beetle population exhibited persistent, large, fluctuating populations in the region of three to sixty fold increases at all modelled altitudes over a number of years. An uncertainty and sensitivity analysis of the model was undertaken utilising a Latin Hypercube Swnpling regime, where it was shown that fecundity, egg mortality and pupal mortality were the most important life history variables in i contributing to the model output imprecision. The thesis discussesth eser esults in the light of predicted climate change and their use as an aid to moorland and heathland managers.
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Hyvärinen, Marko. "Modified element distributions in Cladonia portentosa as indices of acid and nitrogen deposition in the British Isles." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363928.
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Greshon, Stephanie. "A study of the plant community structure of a valley mire complex at Thursley Common National Nature Reserve, Surrey." Thesis, University of Westminster, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237281.
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Flagmeier, Maren. "Scottish liverwort heath : response to a changing environment and prospects for the future." Thesis, University of Aberdeen, 2013. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=201893.
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Upland plant communities are vulnerable to environmental change, especially if the component species have limited dispersal abilities and consist of fragmented populations. Oceanic-montane liverwort-rich heath is a rare upland vegetation type found in the oceanic areas of the British Isles and Norway. This thesis contributes both fundamental knowledge about the liverworts’ biology and an understanding of how this can be applied in conservation management, taking into account the compositional changes that have already occurred within liverwort heath. These issues were explored by i.) a re-survey of 50- and 20-year old liverwort heath plots, ii.) assessment of the genotypic diversity of one liverwort using microsatellite markers, iii.) ex-situ and in-situ experimental studies on growth and reproduction and, iv.) transplantation of one liverwort to unoccupied sites to assess habitatlimitation and the potential of translocation as a conservation management tool. The re-survey revealed that the liverwort heath has undergone compositional changes. Liverworts and dwarf shrubs decreased while graminoids increased. This was linked to grazing pressure, eutrophication and warmer and drier conditions. High genotypic diversity was demonstrated in a liverwort unknown to reproduce sexually in the British Isles (Anastrophyllum alpinum), suggesting that sexual reproduction must have occurred in the past. The data also indicated clonal growth at the local level, but no dispersal of vegetative fragments between populations. Thus, dispersal limitation is likely to have implications for the species under future environmental change. Ex situ and in situ cultivation of whole liverworts and fragments revealed that most of the species can grow from both fragments and whole shoots. Therefore, in the absence of sexual reproduction, the species can persist locally by growth and vegetative spread. Also, there is potential for ex situ conservation of these species, in situ enhancement of existing populations, and creation of new ones. Translocation of Herbertus hutchinsiae suggested that the species is dispersal limited. Transplants grew at all sites, exhibiting best growth within range. Therefore, translocation is a management option for this species to enhance or increase extant populations, to restore populations that have declined over the last half century and to reach future suitable climate space. These results have large implications for nature conservation management, to safeguard the unique liverwort heath.
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Genney, David R. "Below-ground ecology of Calluna vulgaris and Nardus stricta." Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325227.
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Papanikolaou, Niki D. "Response of alpine heathland soils to environmental change and land management." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2008. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=25204.
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Barker, Christopher Graham. "The impact of management on heathland response to increased nitrogen deposition." Thesis, Imperial College London, 2001. http://hdl.handle.net/10044/1/11439.
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Ray, Nicholas David. "Long term impacts of nitrogen deposition and management on heathland soils and vegetation." Thesis, Manchester Metropolitan University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440236.
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Owen, Kathleen Mary. "The creation of heathland and acid grassland on former arable land at Minsmere." Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263899.
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Gunnlaugsdóttir, Elín. "Composition and dynamical status of heathland communities in Iceland in relation to recovery measures." Doctoral thesis, Uppsala universitet, Matematisk-naturvetenskapliga fakulteten, 1985. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-184363.
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Pippen, Brendan Gerard Physical Environmental & Mathematical Sciences Australian Defence Force Academy UNSW. "Fuel moisture and fuel dynamics in woodland and heathland vegetation of the Sydney Basin." Awarded by:University of New South Wales - Australian Defence Force Academy. School of Physical, Environmental and Mathematical Sciences, 2008. http://handle.unsw.edu.au/1959.4/38697.
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The vegetation of the Sydney Basin, Australia, is highly flammable and subject to a wide range of fire regimes. Sclerophyllous shrubs and sedges are common and in some vegetation types up to 70 % of fuel consumed during a fire can be live. Research into fire behaviour and fuel dynamics has been minimal. To address this issue this thesis investigated the principal factor affecting the ease of ignition and rate of combustion of individual fuel particles and fuel beds in bushfires: dead fine fuel moisture (FFM). Two common Sydney Basin vegetation types, eucalypt woodland and heathland, each with a history of problematic fire management, were measured in the field for diurnal fluctuations in FFM following rain, under conditions similar to when prescribed burns are conducted. The FFM components of current operational fire behaviour models were found to be inadequate for predictions of FFM and fire behaviour under these conditions. The equilibrium moisture content (EMC) of five fuel types from the field site was investigated in a laboratory study. An existing function describing EMC as a function of temperature and relative humidity was evaluated and found to be very accurate for these fuels. Two FFM predictive models incorporating this function were evaluated on the field data and the laboratory results were shown to be applicable to the estimation of FFM in the field. One model gave very accurate predictions of FFM below fibre saturation point, but its accuracy was reduced when screen level conditions were used instead of those measured at fuel level. A recent process-based model that accounts for rainfall showed promise for predicting when fuel is < 25 % FFM. Systematic problems with the radiation budget of this model reduced the accuracy of predictions and further refinement is required. Live fine fuel moisture content (LFMC) of common heathland shrubs and sedge was investigated over two years and found to be both seasonal and influenced by phenology. LFMC minima occurred in late winter and spring (August to October), and maxima were in summer (December to February) when new growth was recorded. The dominant near-surface fuel in mature heath was sedge. It was found to have little seasonal variation in its??? percentage dead but the percentage dead maxima occured at the same time as the LFMC minima of shrubs and sedge in both years. Simple instantaneous models for duff moisture content in woodland and heathland and LFMC and the percentage dead sedge in heathland were developed. The information gained by this study will form the basis for future development of fuel moisture models for prescribed burning guidelines and fire spread models specific to the vegetation communities of the Sydney Basin.
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Clarke, Christopher Trolle. "Improving the success of heathland reconstruction schemes with particular emphasis on participation and location." Thesis, University of East Anglia, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320081.
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Jones, Alan Glyn. "Heathland responses to nitrogen deposition : exploring the role of habitat management and soil biochemistry." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/5696.
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Elevated levels of nitrogen deposition are altering the normal functioning of seminatural ecosystems around the world. Of concern in Europe are the nitrogen driven changes occurring to (semi)-natural ecosystems such as obrotrophic bogs, upland moors and lowland heathland. Lowland heathland is a particularly vulnerable oligotrophic habitat, with a narrow climatic optimum that restricts the remaining fragmented patches to a small corner of highly populated northwestern Europe. Increased nitrogen availability reduces the competitiveness of characteristic heathland plants, such as Calluna vulgaris, that are adapted to situations where nitrogen is the limiting nutrient. Resulting changes such as accelerated productivity, increased herbivore and frost damage, and changes in the nutrient limitation status of heathlands can lead to invasion by nitrophilous graminoid species, but this process may be dependent on (1) the intensity and duration of elevated nitrogen inputs, (2) the relative availability of other nutrients and (3) conservation management intended to reduce overall nutrient levels. The present study investigated the effects of nitrogen deposition in N and P limited vegetation, and in heathlands around the UK that are experiencing anthropogenically enhanced background levels of nitrogen deposition. Physical and biochemical parameters of vegetation, litter and soil were used as indicators. A long-term fieldscale manipulation study at Thursley Common, Surrey was used to quantify the effect of nitrogen inputs to an N limited system and, in particular, determine how these effects were modified by a gradient of management intensity, and an unplanned wildfire. The process of vegetation recovery, following a cessation of nitrogen inputs was also investigated. The effects of nitrogen deposition to P limited heathland were investigated using heathland mesocosms. Two nationwide heathland surveys investigated how the effect of nitrogen deposition within a gradient of background deposition in England was modified by environmental factors, such as geology or soil type. The first survey examined the effect of stand age (and management) on responses to nitrogen deposition. The second survey focused on the physical and biochemical responses to nitrogen deposition in Calluna, litter, bryophytes and soil to quantify its impact on heathlands across England. The Thursley nitrogen manipulation investigation showed clear ongoing responses in rates of canopy development and shoot growth to nitrogen deposition, which were reduced by increasing levels of management intensity. Historical nitrogen inputs in the recovery experiment continued to significantly increase rates of Calluna canopy development 9 years after inputs had ceased. These effects were re-invigorated by the unplanned wildfire. The mesocosm experiment indicated that P limited heathlands are susceptible to the detrimental effects of nitrogen deposition, particularly, altering shoot phenology and increasing drought stress. Both the nationwide surveys indicated that, at a national scale, heathland vegetation and soil biochemical indices are responsive to background nitrogen deposition levels within (and exceeding) the critical load range, despite environmental influences, such as geology and soil type which were also found to have significant effects on these parameters.
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White, Helen Marie. "Biotic and Abiotic Factors of Picea rubens (Red Spruce) Seedling Regeneration in Disturbed Heathland Barrens of the Central Appalachians." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/101088.
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During the late 19th and early 20th centuries, extensive logging reduced the forests of red spruce (Picea rubens) by nearly 99% through portions of West Virginia. In the wake of this disturbance, red spruce has begun regenerating on the ridge and mountaintop areas of Canaan Valley, West Virginia, where heath and grassland communities have both persisted in natural barrens and expanded into formerly forested areas. To understand abiotic and biotic conditions guiding the advance of the red spruce stand, I conducted a broad-scale assessment of thirty-one demographics plots spread across two sites (north Cabin Mountain and Bear Rocks/Dolly Sods), and a more focused assessment of red spruce species associations within thirty-two paired plots at Cabin Mountain. At the 15m x 15m demographics plots, I conducted a count of all P. rubens present, measured specimen height, DBH or diameter at ground level (DGL) for specimens < 1.37m tall, and assessed the relative percent cover of rock, shrub, herbaceous, and tree cover. These data, along with additional abiotic components derived from a DEM, formed the basis of my assessment using a generalized linear mixed model (GLMM) to identify the most significant biophysical variables related to P. rubens count. In the paired plots, I used the relative interactions index (RII) to compare the total cover of each present non-graminoid vascular species and the grouped cover types Rock, Graminoid, Lichen, Litter, and Moss in one 45cm-radius plot with a < 1.37m P. rubens specimen, and one paired 45cm-radius plot in open heath. The significance of differences in total cover were assessed with the Wilcoxon test and Tukey HSD. The GLMM identified percent rock cover and distance from the nearest P. rubens stand to be important correlates of P. rubens count at the demographic plots. Graminoid cover was found to be higher in P. rubens 45cm-radius plots than in paired heath plots, and Vaccinium angustifolium cover was found to be concentrated in 45cm radius plots beyond the first 15cm from the P. rubens stem. These findings reinforce a complex interplay between both the biotic and abiotic characteristics of a microsite and the successful germination and regeneration of a red spruce seedling in the heathland.Master of Science
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Lawson, Clare Suzanne. "The establishment of grassland and heathland vegetation on former arable land in North East Scotland." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265763.
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Gregory, Jon. "Marginal Environments and the Idea of Improvement : Transforming Heathland and Moorland Landscapes c.1650 - 1850." Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.514256.
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Sharps, Katrina. "The conservation ecology of the European nightjar (Caprimulgus europaeus) in a complex heathland-plantation landscape." Thesis, University of East Anglia, 2013. https://ueaeprints.uea.ac.uk/47930/.
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The conservation ecology of the European nightjar (Caprimulgus europaeus) was investigated in a complex heathland-plantation landscape in eastern England. Using radio telemetry, 31 nightjars were tracked in 2009 and 2010. The breeding behaviour of males was found to have potential implications for nightjar survey methods. While surveyors should be aware of the possibility of song territory overlap between male birds, results suggest that the occurrence of roaming unpaired males would not lead to an over-estimate in population. Home range 95% kernels for females, paired and unpaired males were an order of magnitude larger than song territories, highlighting the importance of foraging habitat in the broader landscape. Compositional analysis showed that foraging nightjars selected open canopy plantation forest (aged 5-10 years) and newly planted coupes (aged 0-4 years), with grazed grass-heath also used when available within 2km of the territory centre. Open ungrazed and un-planted habitat within the forest was avoided by birds, relative to availability. Moth trapping indicated that birds may choose foraging habitat based on the ease of prey capture rather than prey abundance. Dissection of nightjar faecal pellets demonstrated that moths and beetles were key components of the diet and that variation in diet during the breeding season may be due to changes in resource abundance and varying chick requirements. Comparison of the diets of birds nesting or roosting at varying distances from grass-heath suggested that forest and heathland habitats provide similar foraging resources for the nightjar. Behavioural data from nest camera footage indicated that the factors influencing the duration and frequency of adult non-attendance at the nest were incubation stage, temperature and chick requirements. This thesis combines investigations of nightjar breeding behaviour, home range, habitat use and diet, which can be used as an evidence base to inform conservation management.
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Friedrich, Uta [Verfasser], and Werner [Akademischer Betreuer] Härdtle. "Impact of nitrogen deposition on the functioning of heathland ecosystems / Uta Friedrich. Betreuer: Werner Härdtle." Lüneburg : Universitätsbibliothek der Leuphana Universität Lüneburg, 2012. http://d-nb.info/1034194895/34.
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Al, Fassi Fahad Abdulrahman. "The microbial ecology of heathland soil with special reference to factors affecting microbial biomass and activity." Thesis, University of Sheffield, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318137.
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Bishop, Craig Douglas. "The Nature and Stability of Frost Flat Heathland/ Forest Ecotones in the Central North Island, New Zealand." Thesis, University of Auckland, 2005. http://hdl.handle.net/2292/797.
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This thesis examines the nature and stability of the ecotone between frost flat heathland (FFH) vegetation, and surrounding forest, in the Central North Island of New Zealand. FFH vegetation is found throughout the Central North Island, in locations where surrounding topography causes cold air to pool on clear, still nights. This increases frost severity and -due to the low frost tolerance of most woody New Zealand plant species - frosts are severe enough to prevent the establishment of most plant species which are common in the surrounding forest vegetation. The majority of work was carried out at four study sites. Rangitaiki is a large (c.2600 ha) remnant of FFH vegetation on a flat, pumice filled, basin. The other three study sites (Tahau, Waione and Pouakani) are much smaller (c.56 ha, c.35 ha, and c.61 ha respectively) basins where cold air is dammed by downstream river gorges. Vegetation change was examined along permanent transects established perpendicular to the FFH/ forest ecotone. Vegetation changed (over l0 - 20m) from a monoculture of Dracophyllum subulatum heathland (= FFH) to more diverse forest or scrub vegetation (= forest). A DCA ordination of the transect data showed that vegetation associations on either side of the ecotone diverged over time. That is, there was a more rapid change in the species composition of vegetation across the FFH/ forest ecotone in older sites. While seed rain density is low in FFH vegetation, it is sufficient, particularly around emergent focal trees, to allow forest to invade FFH. Frost severity increased dramatically across the ecotone in all seasons, at all sites, and the extreme ground frost minimums recorded suggest that it is low temperatures which exclude most forest species from FFH vegetation. Microclimate variation was high at all study sites, and locations with favourable microclimates in FFH vegetation were more likely to support (ephemeral) populations of forest tree seedlings. The most important determinants of variation in microclimate were overhead cover of vegetation and microtopography. The survivorship of 2,270 planted Leptospermum scoparium seedlings - a frost tolerant pioneer species which is important in forest vegetation at all study sites - was examined on transects perpendicular to the ecotone at three study sites. The most important determinant of seedling survivorship was distance from the ecotone, although the distance at which seedling survivorship dropped to zero was site and transect specific. Changes in seedling weight and height growth rate over the study period showed that many seedlings which survived the study period, would not have survived in the long term. There were no significant changes in soil profiles dug along transects perpendicular to the ecotone at all study sites. This suggests that edaphic factors are not the cause of the current ecotone position. The size-age structure of L. scoparium and D. subulatum stems in FFH and forest vegetation was examined using basal disks (n=627) collected on tansects perpendicular to the ecotone. These data suggest that the current ecotone position was set soon after the large scale disturbances which initiated vegetation associations at the four study sites. A short section of the site perimeter at the Waione study site has not been disturbed as recently as the other sites, and age structure data suggests that the ecotone at this location has been stable for at least 100 years. Transect position has no influence on the diameter growth rates of L. scoparium stems, which suggests that it is frost mortality, rather than a growth rate limitation due to lower temperatures, which is preventing this species colonising FFH vegetation. Stem age data also suggested that the scattered L. scoparium shrubs which manage to colonise FFH vegetation are killed by severe irregular climatic events, the most recent of which occurred in the summer of 1972/73. The same events probably also affected the species composition in forests surrounding the FFH study sites. Historical meteorological data suggests the most likely cause of the 1972/73 climatic disturbance was a severe summer drought, combined with a series of moderately severe summer frosts. A severe winter frost in 1978 had no observable effect on indigenous vegetation at the four study sites. The restricted distribution of two key cold tolerant indigenous woody species - due to increased fire frequency - has almost certainly resulted in a longer term dominance of some sites by FFH vegetation. Phyllocladus alpinus (not present at any of the study sites) and Halocarpus bidwilli (very restricted distribution at one study site only) have cold tolerances and life history characteristics that allow them to invade FFH. The preceeding results suggest that the composition and structure of both FFH, and surrounding forest vegetation, is a direct result of the unique abiotic environment and vegetation history of each site. Protecting vegetation covering the widest possible range of variation in edaphic and environmental conditions should therefore ensure greatest variation in different plant communities, and genotypes of different plant species, is conserved. The ecotone transitions studied in this thesis are clearly identifiable, and appear to represent the true distributional limits of most indigenous woody forest species. FFH/ forest ecotones may therefore be useful as sites for monitoring the future effects of climate change on plant communities. The varied responses of vegetation at the four study sites to the 1972/73 climatic event suggests that monitoring transects should be established at as many different sites as possible, and at different locations within each study site.
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Schmidt, Johannes Matthias [Verfasser], and S. [Akademischer Betreuer] Schmidtlein. "Remote sensing in support of conservation and management of heathland vegetation / Johannes Matthias Schmidt ; Betreuer: S. Schmidtlein." Karlsruhe : KIT-Bibliothek, 2017. http://d-nb.info/1144367670/34.
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Warnock, James. "Heathland productivity and the determination of stocking densities in the Eastern Mournes Area of Special Scientific Interest." Thesis, Queen's University Belfast, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325968.
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Henning, Katrin [Verfasser], and Goddert von [Akademischer Betreuer] Oheimb. "Restoration and management of abandoned, dry continental heathland and sandy grassland communities / Katrin Henning ; Betreuer: Goddert von Oheimb." Lüneburg : Universitätsbibliothek der Leuphana Universität Lüneburg, 2019. http://d-nb.info/1177360837/34.
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Henning, Katrin Verfasser], and Goddert von [Akademischer Betreuer] [Oheimb. "Restoration and management of abandoned, dry continental heathland and sandy grassland communities / Katrin Henning ; Betreuer: Goddert von Oheimb." Lüneburg : Universitätsbibliothek der Leuphana Universität Lüneburg, 2019. http://nbn-resolving.de/urn:nbn:de:gbv:luen4-opus-145274.
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