Dissertations / Theses on the topic 'Riparian management'

Thesis (M.S.)--University of Nevada, Reno, 2008.
"May, 2008." CD-ROM contains Adobe Acrobat copy of thesis, power-point presentation entitled: Effectiveness and reliability of photo-pair interpretation, and photographs taken during the study. Includes bibliographical references. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2009]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

This study illustrates a utilization-focused program evaluation approach newly applied to resource management. The Alberta Riparian Habitat Management (Cows and Fish) Program provides awareness programming to cattle producers to facilitate community-based action on riparian issues. The rationale is to develop producers' ecological literacy by increasing riparian knowledge and use of sustainable grazing management strategies by sharing appropriate ecological and management information. Attitude change is presumed to underlie the new behaviour(s). Programming contributed to ecological literacy when it was community-based, producer-positive and partnership-oriented, and when opportunities existed for personal interaction among peers. Effectiveness declined when resources were insufficient and when programming seemed unrelated to local landscape or operational features. The attitude-behaviour relationship was weakly associated with ecological literacy; its complexity and relevance to ecological behaviours merits further investigation. Program evaluation is of utility in resource management. Its potential will be fully realized by ensuring that research designs appropriately parallel programming rationale and evaluation requirements.
ix, 316 leaves : ill. ; 28 cm.

The Kentucky Division of Water indicates that agriculture is responsible for 55% of the Commonwealth’s assessed streams not supporting their designated uses. Riparian buffers reduce nonpoint source pollution in agroecosystems by storing and cycling nutrients, stabilizing streambanks, increasing infiltration, and storing water. Specific information regarding riparian buffer management is needed for land managers to maximize buffer effectiveness at reducing agricultural contaminants impairing water quality. Baseline soil properties (texture, pH, C and nutrients) of the riparian buffer surrounding a tributary of Cane Run Creek in Fayette County, KY were characterized prior to imposing three mowing regimes (intense, moderate, and no mow treatments) and one native grass regime. Measurements were made along parallel transects located 2-m and 8-m distances from the stream. Root biomass, aggregate distribution, and saturated hydraulic conductivity were measured along the 2-m transect in two consecutive years following treatment establishment. The 2-m transect soils had the highest C, pH, Ca, Zn, and sand content. The 8-m transect had the highest P, K, Mg, and clay content. Semivariogram analysis of C content indicated slight to moderate spatial dependency along the 2m transect and moderate to strong spatial dependency along the 8m transect. Root biomass increased with decreased mowing frequency at the surface depth after one year; the native grass treatment had significantly less root biomass in both years compared to mowing treatments. There was no significant treatment effect on aggregate size distribution at the surface depth in either year. Mean weight diameter and large macroaggregates decreased from 2011 to 2012. Vegetation treatment had no statistically significant effect on water stable aggregates or saturated hydraulic conductivity. Experimental semivariograms provided evidence of spatial structure at multiple scales in root biomass, aggregates, and soil C. Spatial variability occurred over a shorter lag distance in 2012 than 2011, suggesting an effect of imposed treatments slowly developing over time. This study provides important insights on riparian buffer soil properties, soil sampling strategies to detect spatial variability in riparian buffers, and length of time needed to assess effects of vegetation management regimes on riparian root biomass, soil aggregates, and hydraulic conductivity.

Riparian ecosystems are valued for ecosystem services which have impacts on the well-being of humans and the environment. Anthropogenic disturbances along rivers in arid and semiarid regions have altered historical flow regimes and compromised their integrity. Many rivers are hydroecologically deteriorated, have diminished native riparian forests, and are pressured for their water supplies. My first study is founded on the premise that river restoration has increased exponentially with little documentation on effectiveness. We designed a conference to discuss lessons learned from past restoration activities to benefit future efforts. Participants, including scientists, managers, and practitioners, agreed that creating measureable objectives with subsequent monitoring is essential for quantifying success and employing adaptive management. Attendees stated that current projects are local and have limited funding and time, whereas future efforts must have longer funding cycles, larger timeframes, should contribute to regional goals, and address factors responsible for ecological decline. Bridging gaps among science, management, and policy in the 21st century is a key component to success. My second study focused on the benefits of long-term monitoring of local riparian restoration. Many efforts include revegetation components to re-establish native cottonwood-willow communities, but do not address how high-density establishment impacts vegetation dynamics and sustainability. Over five years, we documented significantly higher growth rates, lower mortality, and higher cover in cottonwood compared to non-native tamarisk. Cottonwood height, diameter at breast height, growth rates, and foliar volumes were reduced at higher densities. Herbaceous species decreased every year but native shrubs volunteered after two years resulting in a reduction of overall plant diversity from 2007-2009 with a slight increase from 2009-2011.My third study focused on improving basin-scale evapotranspiration (ET), a large component of the water budget, to better inform water resource allocation. My research suggests that multiple models are required for basin-scale ET estimates due to vegetation variability across water-limitation gradients. We created two empirical models using remote sensing, a multiplicative riparian ET model (r²=0.92) using MODIS nighttime land surface temperature (LST(n)) and enhanced vegetation index, and an upland ET model (r²=0.77) using multiple linear regression replacing LST(n) with a precipitation input.

Buffer strips alongside watercourses are now a widely accepted method of reducing nutrient and sediment run-off from agricultural land thereby improving water quality and meeting policy goals. However, this change in land use may have consequences for riparian biodiversity which have yet to be fully understood. This study investigated the impact of buffering on various aspects of biodiversity by comparing three types of margins in three river catchments in north east Scotland. Margins were categorised as unbuffered (open and unfenced), buffered (fenced-off vegetated) and wooded (long established woody vegetation - fenced and unfenced). Components of biodiversity studied included vegetation patterns, and the abundance, diversity, movement and assemblage composition of ground-dwelling arthropods focussing primarily, though not exclusively, on ground beetles (Coleoptera, Carabidae). This study further considered management options which may improve or enhance biodiversity. Evidenced changes in vegetation were associated with soil parameters (including decreasing pH), channel morphology, decreasing light availability and tree canopy cover, and bryophyte abundance along a successional gradient from unbuffered-buffered-wooded sites. Buffered and wooded sites showed lower activity density and species richness of ground beetles, but while one measure of functional diversity was high for wooded sites, buffered sites were found to have significantly lower values. Both species and trait assemblage structure of ground beetles were influenced by soil and vegetation, but also by features of buffer strip design such as width, length and age. Active management of sites through grazing or cutting increased ground beetle abundance, particularly hygrophilous species, but did not affect diversity. Radiotracking showed increased movement of ground beetles was correlated with intensity of grazing. Few truly riparian plant or arthropod species were identified indicating the process of buffering essentially 'terrestrialises' the riparian margins. The presence of a tree canopy layer appears to be the key instigator of change in soil conditions with vegetation and arthropods responding accordingly. Therefore planting and maintaining trees in buffer strips could be crucial to ensuring that functional diversity and associated ecosystem services are maintained. Active management through grazing or cutting could help in this regard. The results from this study suggest that rather than buffering all riparian margins within catchments, it is fundamentally important for biodiversity to maintain a mosaic of different successional stages and a diversity of habitats.

The physical parameters of past experimental riparian buffer studies were used to develop a riparian buffer classification framework (RBCF) that uses high resolution remotely sensed data to identify the physical parameters of a riparian buffer and assign an estimate of total suspended solids (TSS) removal efficiency. Topographic data with a contour interval of 2 feet, color digital orthophotography with 1-foot resolution, and hydrography data covering a 1.8 square mile study area located within the city limits of Raleigh, North Carolina were utilized to test the RBCF. A cartographic model was developed to prepare each data layer for analysis. Applying the RBCF within the framework of the cartographic model produced highly detailed maps of existing riparian areas, and also provided an estimate of a riparian buffer?s efficiency in removing TSS from stormwater runoff. In this study, riparian buffers are identified through remote sensing at spatial scales of sufficient detail to determine regulated widths and also to examine the separate management zones within a buffer. Automated processing techniques for remotely sensed data, used in combination with specific resource classification schemes such as the RBCF will enable the assessment and analysis of site-specific conditions at county-wide scales.

Ecological research involving habitat studies was conducted on the Elm Fork of the Trinity River in Denton County, Texas, from spring 1985 to spring 1986. Habitat Evaluation Procedures and Habitat Suitability Index Models developed by the United States Fish and Wildlife Service were applied to a 1419 hectares study area to determine the quality of habitat for four species: beaver, Castor canadensis, wood duck, Aix sponsa, pileated woodpecker, Dryocopus pileatus, and white crappie, Poxomis annularis. Population estimates were generated. A wildlife management plan was developed for the study area. Habitat Suitability Index Models were found to be overly conservative, underestimating the quality of habitat in areas of ecological transition.

The focus of this research is on re-design of degraded riparian systems in a desert climate and urban context. Specifically, it explores a landscape approach for rehabilitating the Tucson’s Arroyo Chico Wash. Analyses were performed to assess the site condition within its context to determine an appropriate treatment that addresses social and ecological functions. In particular, a greenway plan that implements water management infrastructure was designed on the site, creating social and ecological benefits for surrounding communities. Ultimately, it is the author’s intent to establish a framework and principles for similar riparian projects in urban environments.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007.
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 November 27, 2007) Vita. Includes bibliographical references.

In New Zealand, there are many published guidelines about the management of riparian areas. The question needs to be asked, are these guides useful? This research thesis investigates the extent to which riparian management guides meet the needs of the users. This research also considers the importance of riparian management (with regards to the appropriateness of educational guides) in assisting practitioners and the interested public in the management of riparian areas. The main way of investigating this topic was with the help of discussion groups. Discussion groups were held with interested organisations. These groups fell into three categories; Urban groups, Rural groups and Interest groups. The groups were asked to define what would make a guide most useful and desirable to them under three major categories: 1) what the guide looked like, 2) what information was contained, and 3) how was the information accessed. An opportunity was also provided for any further comments. This information was used to create a list of the most popular criteria that existing guides and further publications could be examined against. Eleven criteria were identified as follows: Information should be available online; Have pictures; Include diagrams; Is simple and easy to understand; Contains how to and appropriate methods; Has a plant list; Considers maintenance issues; Identifies where to locate further information; How to contact experts; Is available in libraries; Is in booklet form. The availability of existing information was investigated and its suitability assessed against the criteria. A list of all regional, territorial and unitary councils as well as 'other organisations' that were regarded as sources of environmental knowledge were investigated to see how many had produced information on riparian and wetland management issues. In terms of sources of information, 'other organisations' produce the greatest rate of riparian management information, followed by regional/unitary authorities. Two guides from Canterbury best meet the criteria identified by the interested parties, for the Canterbury region. Each scored 10/11 and failed on different criteria. This led to the conclusion that riparian management guides in Canterbury, while obviously still having room for improvement, are very close to meeting what interested parties feel is most important. Finally, a prototype (model) based on the research is provided for anyone who might be considering preparing a riparian management guide.

The extents of riparian ecosystems are in decline in the American Southwest largely due to land development practices. Unfortunately, there is a paucity of scientific research regarding the direct and indirect impacts of urbanization on riparian ecosystems. To date, research has focused on specific ecological functions and propagation of declining species without regard to the effects of urbanization on the riparian resource. A long -term ecological monitoring project was initiated along Rincon Creek in Tucson, Arizona with the objective of monitoring targeted parameters to see how they are affected by urbanization. To support research and scientific effort toward that end, a relational database and data management system were created to facilitate input, storage, manipulation, and documentation of raw data collected along Rincon Creek. The raw data tables were normalized to at least third normal form to enhance flexibility and reduce inconsistent and redundant data. Standardized graphs, queries, and reports were also developed to facilitate derivation and dissemination of information. Finally, the relational design provides a template for other agencies or organizations collecting similar monitoring data that wish to incorporate comparable data management systems.

Land use practices over the last 200 years have dramatically altered the distribution and amount of riparian vegetation throughout many catchments in Australia. This has lead to a number of negative impacts including a decrease in water quality, an increase in sediment transport and a decrease in the quality of terrestrial and aquatic habitats. The task of restoring the functions of riparian zones is an enormous one and requires spatial and temporal prioritisation. An analysis of the existing and historical functions of riparian zones and their spatial distribution is a major aid to this process and will enable efficient use of remediation resources. The approach developed in this thesis combines remote sensing, field measurement and terrain analysis to describe the distribution of five riparian zone functions: sediment trapping, bank stabilization, denitrification, stream shading and large woody debris production throughout a large semi-arid catchment in central Queensland.

Riparian buffers in agricultural landscapes are designed to trap pollutants in overland flow by slowing, filtering, and infiltrating surface runoff entering the buffer via sheet flow. However, observational evidence suggests that concentrated flow is prevalent from agricultural fields. Also, over time sediment can accumulate in riparian buffers forming berms that restrict sheet flow from moving into the buffers; these berms ultimately back up surface runoff, resulting in an eventual breakthrough which concentrates runoff. Breakthrough by concentrated flow can lead to gully formation that may reduce the filtering capacities of buffer systems by providing direct conduits to stream channels. This study explores the frequency of concentrated flow paths in riparian buffers at both the field and watershed scale. At the field scale, intensive topographic surveys were conducted at 10 field sites in southern Illinois to characterize concentrated flow paths, accumulated berm sediments, and field area drained by concentrated flow. Detailed digital elevation models (DEMs) were created for each site and riparian buffer and agriculture field characteristics were analyzed to assess the development and occurrence of concentrated flow paths. At each site, soil samples were analyzed to characterize sediment deposition patterns within the buffer. To assess the prevalence of concentrated flow paths at the watershed scale, three watersheds in southern Illinois were selected for walking stream surveys. Five stream segments, approximately 1000 m long, were randomly selected within each watershed and surveyed for the occurrence and size of concentrated flow paths. These data were analyzed with respect to riparian buffer vegetation, buffer width, and surrounding land cover data. Concentrated flow paths were identified in all topographic surveys and all walking stream surveys indicating a common occurrence in agricultural watersheds of southern Illinois. Among field scale sites, concentrated flow accounted for 82.5-100% of the drainage areas contributing to riparian buffers. Results from the watershed scale analysis suggest that concentrated flow paths are significantly more abundant in agricultural land cover, than forested land. Current riparian buffer design principles are based on the assumption that sheet flow is the primary form of surface runoff entering buffers. Furthermore, buffers are installed and not maintained which can lead to berm accumulation and buffer failure. Results from this study indicate that concentrated flow was the prevalent form of runoff at field scale sites. Managers need to consider the occurrence of concentrated flow paths when designing riparian buffers to protect stream water quality.

Lowland riparian ecosystems constitute a tiny fraction of total land area in the southwestern United States and northern Mexico, yet they are extremely important to human livelihoods and biotic communities. Facing ongoing projected climate change toward hotter and drier conditions, riparian ecosystems are both vulnerable to changes in climate and increasingly critical to the well-being of humans and wildlife. Due to the dynamic nature of these ecosystems and their abundance of resources, riparian areas have been modified in various ways and to a large extent through human endeavor. These alterations often interfere with multiple and complex ecological processes, making riparian areas more vulnerable to disturbance and change. Few naturally functioning riparian areas remain, and those that do are imperiled by climate change, groundwater pumping, land use, and other factors. A small but growing body of literature suggests that wildfires may be increasing in frequency and severity in southwestern riparian zones. This literature review summarizes and synthesizes the state of the knowledge of wildfire and prescribed fire effects on abiotic processes and vegetation, and post-fire rehabilitation. Results suggest that in lowland riparian ecosystems, fire regimes and fire effects are influenced primarily by streamflow and groundwater regimes. Thus, increasing fire frequency and severity may be attributed to drought, land use, water use, and their subsequent effects on the spread of non-native plant species, as well as a history of fire suppression and increasing anthropogenic ignitions in areas with a growing human presence. Changing fire regimes are likely to have drastic and potentially irreversible effects on regional biodiversity and ecosystem function. However, there are options for managing riparian ecosystems that will be more resilient to fire and climate change, such as implementing environmental flows, prescribed fire, fuel reduction treatments, floodplain restoration, and promoting gene flow. This study is intended to inform management decisions, and identify gaps in systematically reviewed literature.

Riparian ecosystems of the southwestern United States are highly valuable to both the ecological and human communities which surround them. Over the past century, they have been subject to shifting management practices to maximize human use, control, ecosystem service, and conservation. This creates a complex relationship between water policy, management, and the natural ecosystem necessitating research on spatial and temporal dynamics of riparian vegetation. The San Acacia Reach of the Middle Rio Grande, a 60 mile stretch from the San Acacia Diversion Dam to San Marcial, has experienced multiple management and river flow fluctuations over the past 80 years, resulting in threats to riparian and aquatic ecosystems. This research was completed through the use and analysis of multi-source remote sensing data, GIS, and a review of the on-the-ground management decisions to better understand how the location and composition of the riparian vegetation has been affected by these shifting practices. This research focused on four phases, each highlighting different management practices and river flow patterns during the last 80-years. Each of these periods provides a unique opportunity to observe a direct relationship between river management and riparian land cover response and change. Overall, management practices reduced surface river flows and limited overbank flooding and resulted in changes in the composition, density, and spatial patterns of the vegetation, including increased non-native vegetation growth. Restoration efforts over the past few decades have begun to reduce the presence of non-native species. Despite these changes, this ecosystem was shown to be extremely resilient in maintaining its function/service throughout the entire study time frame.

The dissertation presented in this manuscript contributes to river science by providing a detailed overview on the state of the art on the interaction between riparian vegetation and hydrogeomorphological processes, by devising a novel model encompassing most of such processes and by proposing a field methodology aimed at providing means for improving the modelling of such interactions. The state of the art is summarized in an extensive review describing riparian vegetation and hydrogeomorphological processes mutual feedbacks. Such review did not simply seek to describe these feedbacks but, compiling from a large array of results from field, laboratory and modelling studies, provides a set of physical thresholds that trigger system changes. Therefore, processes are not only described terms but also explained with a quantitative approach. Processes description provided the conceptual foundation for the development of the novel simulation model while model parameterization was based on the quantitative information collected in the review. Such novel model, encompasses the main relationships entwining riparian woody vegetation and hydrogeomorphological processes and is able of replicating long term riparian landscape dynamics considering disturbance events, environmental stressor and riparian woody vegetation establishment from seeds and large wood. The manuscript presents the model structure and its conceptual validation by means of hydrological scenarios aimed at testing the coherence of the simulation results with expected system behaviour. Examples of such coherences are vegetation growth rate in response to hydrological regime, entrainment and establishment of large wood in an unconfined river system and vegetation effect on erosion and deposition patterns. Analysis of sedimentation patterns from the modelled results suggested that vegetation flow resistance should be modelled with greater detail. These conclusions pointed the dissertation research towards the testing of a novel class of vegetation flow resistance equations, proposed by different authors, able of describing woody vegetation flow resistance on a physical basis. These equations have the advantage of considering flow stage, plants foliation level and species-specific flexibility. However, the use of such equations is limited by the difficulty of measuring the vegetation properties required as equation-inputs. In order to test if these equations could effectively improve sediment dynamics predictions, a field method was formulated and tested. The field method allows to sample vegetation properties that can be used with these novel class of flow resistance equations. In the manuscript, such method is applied and the resulting vegetation properties used in several modelling scenarios. Such scenario proved that hydraulic variables modelled with these novel flow resistance approaches are more realistic and thus that the model developed during the dissertation could benefit from inclusion of such flow resistance equations in its source code.

Forest management, including timber harvesting, is the primary land use activity in most of Sweden.  However, clear cutting forests (i.e., final felling) can create a number of environmental problems in aquatic ecosystems and their communities. To combat these affects, intact riparian ‘buffer zones’ are typically left along streams and lakes in the Swedish landscape. There are many ideas on how wide a buffer zone has to be, to maintain an optimal ecological and hydrological state of a stream. Not only is the width of buffer zones debated, but also their overall design, including whether un-buffered stream segments could be beneficial. This study aims to test the effects of riparian buffers on macroinvertebrate biodiversity and community composition in streams draining catchments with clear cutting.  To do this, I estimated the family richness and a variety of additional metrics from nine streams from southern Sweden in the Jönköping area. Three of the streams had intact buffers (<5 meter), three had no buffers, and three were unharvested (i.e., forested) catchments that served as controls. This study used data and benthic invertebrate samples collected as part of a bigger study, which were picked and manually sorted by the author. Richness ranged from 3 families at one site to as many as 13 at another one. Total abundance ranged between sites from 19820/m2to 27920/m2individuals. Overall, the results showed no significant difference in any of the invertebrate metrics across the three stream types. However, family richness increased among sites as a function of water temperature. The lack of buffer effects reported here may reflect the extremely warm summer of 2018, which caused a massive drought and was the warmest one ever recorded in the parts of Sweden where the invertebrates were collected.

Black Hawk Creek was included in the Iowa Department of Natural Resources (DNR) 303(d) list of impaired waters in 1998 due to non-point sources of fecal coliform bacteria. Water quality degradation in the stream network is also impacted by excess nutrients in surface runoff from cropped fields and pastures, sedimentation erosion of streambanks from the high volume of water flow following storm events, and the pulse of enriched groundwater drained into the streams from the subsurface tile network. Rotational grazing will replace the current continuous grazing management system. Implementation includes controlling both sides of Black Hawk Creek in the permanent pastures with electric fencing, installing reinforced controlled stream crossing sites, establishing a permanent clean water distribution system and enhancing the Kentucky bluegrass dominated pastures with three cool season naturalized grass and three legume species adapted to the north central Iowa loess landscape. Multi-species ripariain buffers based on the Leopold Center for Sustainable Agriculture's model and other models based on simulating the functionality of presettlement ecosystem savannah grassland will be created between monocultures of corn and soybean fields and the stream network. Follow on studies will monitor the effectiveness of a managed forage sward, riparian buffers, and natural healing of streambanks to mitigate excess nutrient movement into the streams.
Master of Natural Resources

Sap flow, leaf gas exchange, and micrometeorological parameters were evaluated during 1997 in riparian forest at perennial and ephemeral stream sites on the San Pedro River in southeastern Arizona, USA. At the perennial stream site, measurements of sapwood area based transpiration and sapwood area/canopy area of clusters of Populus fremontii and Salix goodingii were used to estimate transpiration across the stand. Stand structural heterogeneity resulted in as much as 30% variation in mean transpiration across the stand. Transpiration of cottonwood was more dependent upon vapor pressure deficit at the ephemeral stream site which had an open, less dense canopy compared to that at the perennial stream site. This may be due to differences in advection properties and canopy feedback processes between sites. Conversely, transpiration in willow was less dependent upon vapor pressure at the ephemeral stream site than that at the perennial stream site. This may be due to water stress associated with deeper depth to groundwater.

Forest management practices usually preserves riparian buffers along watercourses in order to protect stream water from physical, chemical and ecological changes caused by clear-cutting. The purpose of this thesis was to investigate whether there is a relationship between the size of the riparian buffer zone along small streams, i.e., headwaters, and a number of physical and chemical attributes of these streams. Twelve headwaters in the Västerbotten county and twelve in Jönköpings county were investigated. These headwaters had a range of buffer widths from “No buffer” (no trees left), Thin buffer” (< 5 m wide), to “Moderate buffer” (>5 m wide) and “Reference” (no harvest) streams were also included. Tested physical and chemical conditions were light in the riparian zone, air and water temperature, stream bed cover and water chemistry. Buffer width had a significant effect on reducing light levels and temperature in the riparian zone; a buffer width over 13 m on each side of the stream was needed to maintain light and air temperature as in reference conditions. Regarding water temperature, increasing sedimentation and water quality, no significant reducing effect of increasing riparian buffer width was found.

Approximately 75% of the avian species in Utah use riparian habitats at some time during their life cycles and at least 80% of this habitat in Utah has been lost or altered since settlement; currently 0.6% of land cover in Utah is considered riparian. In 1992, with the support of Utah Partner's in Flight, the Utah Division of Wildlife Resources began a statewide neotropical migratory bird (NTMB) and habitat monitoring program to assess the status of bird populations at 31 sites. Additional sites (up to 52) were added in later years; bird and habitat assessments at 37 riparian sites have been continuously monitored since 1998. Using this long-term dataset, my primary study goals were to: 1) estimate abundance and densities of 38 focal avian species, 2) document and describe changes in riparian vegetation over time, and 3) investigate how these two processes are related by creating bird-habitat association models. Recent results from population trend analyses suggest that the patterns of annual variation and regional synchrony seen in riparian-dependent species groupings may be driven by landscape-wide effects on habitat. I developed riparian-bird habitat association models to better understand these large-scale effects using important variables specific to nine species of interest. I constructed classification and regression trees for three distinct foraging guilds to assess species-specific and community level habitat associations. Variables identified as important predictors of species density varied according to the species of interset. However, the variables selected by the classification models were consistent with each species life history strategies. Model results are intended to provide the framework for the development of management guidelines that will inform terrestrial riparian restoration and conservation efforts in Utah.

Russian olive is an exotic actinorhizal tree intentionally introduced to the U.S. in the early 1900’s. It has become a dominant component of riparian ecosystems throughout the western U.S. Unlike most other riparian trees in the semi-arid west, Russian olive germinates and grows both in the open and in the understory of mature cottonwood stands. As an actinorhizal species, it forms an endosymbiosis with soil actinobacteria in the genus Frankia that allows for atmospheric N₂-fixation. This leads to higher soil N concentrations and mineralization rates underneath the tree’s canopy than outside. Russian olive’s high abundance and impact on soil N suggest it may alter plant communities, but these impacts have not been previously demonstrated. I investigated the impacts of Russian olive on shading, soil N availability, and plant communities and documented how those impacts varied across a semi-arid riparian ecosystem along the South Fork of the Republican River in eastern Colorado. Of the suite of environmental variables I measured, presence or absence of cottonwood canopy had the largest effect on Russian olive impacts. Russian olive increased shading, soil N availability, and proportion exotic plant and forb cover more in the open than underneath a cottonwood overstory.

Actinorhizal endosymbioses provides an important N source in terrestrial ecosystems, but N₂-fixation rates decrease due to high exogenous N and low photosynthetically active radiation (PAR). The amount that these environmental variables reduce N₂-fixation in host-Frankia symbiosis types dictates the strength and duration of those symbioses’ impacts on ecosystems. To understand how the two main types of endosymbioses (Alnus- and Elaeagnus-Frankia) differ in their response to environmental variability, I conducted a greenhouse experiment comparing growth and nodulation between two genera of actinorhizal species, Elaeagnus and Alnus, across exogenous N and PAR levels. Overall, Elaeagnus species had higher nodulation rates and tissue % N than Alnus species. Nodulation rate and growth response to nodulation were both lower at low PAR than high PAR for both genera. The reduction in the growth response to nodulation at high exogenous N was lower in Elaeagnus-Frankia symbiosis than Alnus-Frankia symbiosis. These results suggest that Elaeagnus species are more likely to cause a greater and longer-lasting increase in soil N than Alnus species.

A main objective of exotic species management is to increase native plant cover. However, few studies monitor plant community response to exotic species management, and the few that have suggest secondary invasion is likely, particularly when effects of the target invasive persists and management efforts cause disturbance. To measure the role of these two factors in plant community response to Russian olive removal, I monitored soil N availability and plant communities along the South Fork of the Republican River two years before and three years after the tree’s removal. Russian olive’s impact on soil N availability persisted, with levels staying high around removed Russian olive stems three years after removal. The plant community around removed Russian olive also had no increase in native plant cover but a dramatic increase in kochia ( Bassia scoparia) cover following removal. My research demonstrates that Russian olive increases exotic plant cover in areas it invades and simply removing the tree does not promote native species recovery.

Thesis (M.S.) University of Missouri-Columbia, 2004.
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 (June 29, 2006) Vita. Includes bibliographical references.

The goal of the Aquatic Indicators of Land Condition (AILC) project is to develop analytical tools that integrate land condition information with stream condition for improved watershed management within the United States Bureau of Land Management (BLM). Based on the goal of the AILC, two objectives for this study were: to determine the effect of four GIS-derived distance measurements on potential relationships between common BLM landscape stressors (mining and grazing) and changes in benthic macroinvertebrate community structure; and to assess the effectiveness of individual questions on a commonly-used Bureau-wide qualitative stream assessment protocol, the proper functioning condition (PFC) assessment. The four GIS distance measurements assessed for biotic relevance included: straight-line distance, slope distance, flow length, and travel time. No significant relationships were found between the measured distance to stressor and macroinvertebrate community structure. However, the hydrological relevance of flow length and travel time are logically superior to straight-line and slope distance and should be researched further. Several individual questions in the PFC assessment had statistically significant relationships with the final reach ratings and with field-measured characteristics. Two of the checklist questions were significantly related to the number of cow droppings. This may indicate a useful and efficient measure of stream degradation due to grazing. The handling and use of the PFC assessment within the BLM needs further documentation and examination for scientific viability, and the addition of quantitative measurements to the PFC in determining restoration potential would be desirable.
Master of Science

The physical and biological characteristics of a stream are strongly influenced by its surrounding catchment. The riparian zone acts as a buffer between land and water ecosystems and can play an essential role to retain contaminants (e.g. sediment) from entering and affecting the receiving waterway. When the riparian zone is not managed, the consequence can be high amounts of sediment entering the waterway that negatively affects in-stream communities with a decline in native invertebrate and fish populations. I investigated three aspects of riparian management in the Canterbury region, South Island, New Zealand, by investigating the public perception using a questionnaire to determine what the public knows about riparian management and what practices are being done in the farming community. Results showed that riparian management varied across farm types, and there was some confusion about the roles of riparian management. Crop farmers were the least likely to do riparian management, in contrast to dairy farmers who were the most likely to do riparian management. A main concern is that the majority of respondents highlighted that filtering nutrients was the main goal for riparian management, and only 5% thought it was due to sediment, and 10% to decrease erosion. I then conducted a field survey to investigate riparian zone sediment retention in different land-uses (dairy farming, production forestry and urbanisation) compared to native forest. Surprisingly, dairy farms produced the least amount of sediment, and urban areas produced the most, and there was a marginal effect of season. However, generally there was no difference between the amounts of sediment passing through the riparian zone. Therefore, I was unable to distinguish if there were any vegetation effects occurring within the riparian zone. To complement the field survey, I tested sediment overflow by conducting multiple experiments using a rain simulator. The simulator controlled the intensity and amount of rainfall over differing percentages of riparian groundcover. My results were consistent with other studies showing that as groundcover increases, sediment runoff decreases. However, there was no relationship between rainfall intensity and the amount of sediment in runoff. My thesis indicated that riparian planting to reduce sediment flow into streams needs to focus on high amounts of groundcover (such as rank grass).

Riparian ecosystems are valuable to the ecological and human communities that depend on them. Over the past century, they have been subject to shifting management practices to maximize human use and ecosystem services, creating a complex relationship between water policy, management, and the natural ecosystem. This has necessitated research on the spatial and temporal dynamics of riparian vegetation change. The San Acacia Reach of the Middle Rio Grande has experienced multiple management and river flow fluctuations, resulting in threats to its riparian and aquatic ecosystems. This research uses remote sensing data, GIS, a review of management decisions, and an assessment of climate to both quantify how riparian vegetation has been altered over time and provide interpretations of the relationships between riparian change and shifting climate and management objectives. This research focused on four management phases from 1935 to 2014, each highlighting different management practices and climate-driven river patterns, providing unique opportunities to observe a direct relationship between river management, climate, and riparian response. Overall, we believe that management practices coupled with reduced surface river-flows with limited overbank flooding influenced the compositional and spatial patterns of vegetation, including possibly increasing non-native vegetation coverage. However, recent restoration efforts have begun to reduce non-native vegetation coverage.

Riparian zones lie at the interface between aquatic and terrestrial ecosystems and usually have fertile soils, which play a crucial role in maintaining ecosystem productivity and biodiversity. Riparian zones are currently subject to vegetation loss and degradation due to human activities, intensification of agricultural practices, weed invasion, and global climate change. Therefore, there is an urgent need to revegetate and/or maintain the current vegetation of riparian zones. Soil nitrogen (N) is one of the most important growth-limiting nutrients and plays a crucial role in plant growth and productivity. Various management practices such as revegetation establishment, weed control methods, fertiliser applications, and/or organic amendments are practiced to sustain vegetation in riparian zones. However, management practices can alter soil N cycling. It is essential to understand the effect of different land management practices on soil N transformations, to maintain the long-term functional stability of riparian zones ecosystems. Revegetation of degraded riparian zones is considered one of the most effective measures in riparian management, which may influence soil N cycling. To date, no systematic literature review (meta-analysis) exists to assess the effects of different vegetation types and age on soil N pools regarding the revegetation of riparian zones (Chapter 2). Vegetation types along the riparian zones can be both native tree species and/or horticultural trees. The success of riparian revegetation projects with tree species currently depends on weed control to reduce the non-target vegetation competing over nutrients. I, hence, investigated the effects of chemical weed control on N cycling using glyphosate (commonly used herbicide) and organic-based herbicides including the registered products BioWeedTM, Pelargonic acid (Slasher®), and horticultural vinegar (acetic acid) compared with mulching. Additionally, there is a lack of information on how different herbicides could affect soil N dynamics and microbial community structure even after the application was ceased for at least one year (Chapter 3). Horticultural crops established within riparian zones are also one of the major land-use practices requiring large quantities of fertiliser, particularly N, and herbicide inputs. Glyphosate is commonly applied in horticultural lands and glyphosate interactions with organic amendments (e.g., biochar) remain uncertain. I explored the long-term interactions between biochar-amended soil and repeated application of glyphosate even after the application has ceased for over two years on soil microbial communities and soil N transformations are not well understood (Chapter 4). Glyphosate application is likely to be resumed even after stopping for a period of time and usually, very short-term N pools in response to glyphosate application in the presence of soil organic amendments like biochar are overlooked. Short-term N pools may have implications for long-term N management and hence it is important to understand short-term N pools with respect to treatments (Chapter 5). Therefore, my thesis specifically aimed to: (1) Examine the influence of riparian zone revegetation with different revegetation types and age on soil N pools by conducting a quantitative literature review (meta-analysis) (Chapter 2). (2) Assess and compare the effects of different organic-based herbicides (BioWeedTM, Slasher®, and acetic acid) and the commonly used herbicide glyphosate with mulch, on soil N dynamics and microbial community structure at two riparian revegetation sites up to two years repeated application of herbicides followed by one year after stopping herbicides applications (in total three years since the revegetation establishment) (Chapter 3). (3) Investigate the impacts of long-term repeated application of glyphosate (12 years) interacted with biochar (for three years) on soil N cycling, more specifically abundance of nitrifying populations such as the ammonia-oxidizing bacteria and archaea (AOB and AOA) as well as the overall soil microbial diversity and community structure (both fungi and bacteria) after two years following the cessation of herbicide applications (Chapter 4). (4) Explore how the interaction of biochar and glyphosate would immediately affect soil N transformations in short-term (in a 5-day laboratory incubation) using the 15N pool dilution techniques (Chapter 5) In Chapter 2: A meta-analysis was undertaken using a categorical mixed effect model to synthesise the results from 52 published articles. This study aimed to explore how different revegetation types (woodland, shrubland, and grassland) and revegetation age (< 3 years, 3-10 years, 10-20 years, 20-40 years, or > 40 years) would affect soil N pools. This meta-analysis revealed that revegetation of riparian zones significantly increased soil total nitrogen (TN) particularly in woodlands, which was associated with the presence of N fixing species and high litter inputs. Soil TN increased in revegetation ages between 10 and 40 years following revegetation, which might be associated with the increased soil organic carbon (SOC) inputs within those ages following establishment. Of the revegetation types considered in this study, NO3--N concentration in soil followed the order of grassland < shrubland < woodland, suggesting that woodland might be more efficient in soil NO3--N retention than grassland. However, revegetation significantly decreased soil moisture by 7.6% compared with the corresponding control, which might be associated with the selection of exotic species as dominant vegetation in riparian zone revegetation. This study provides insight into the influence of different revegetation types and age on soil N pools and soil moisture. This study also highlights the importance of revegetating riparian zones to increase soil TN, particularly in woodlands. Therefore, in Chapter 3, I used two newly established revegetation sites at (Kandanga and Pinbarren sites), planted with native wood species to investigate how different weed control methods including organic-based herbicides (BioWeedTM, Slasher®, and acetic acid) and the commonly used herbicide, glyphosate with mulch would affect soil N dynamics and microbial community structure over three years following revegetation establishment(two years repeated application of herbicides followed by one year after stopping herbicides applications). Soil samples were collected three times following revegetation establishment at months 2, 14, and 26 at the Kandanga site and at months 10, 22, and 34 at the Pinbarren site. The last sampling at the Pinbarren site (at month 34) occurred one year after the last herbicide was applied. In this study, I found that soil microbial biomass carbon (MBC) was significantly higher in response to mulch compared with glyphosate and organic-based herbicide treatments at months 26 at the Kandanga site and months 10 at the Pinbarren site following the revegetation establishment. However, soil MBC at month 34 at the Pinbarren site was only significantly higher in the mulch treatment than glyphosate and BioWeedTM. The level of MBC in glyphosate and BioWeedTM was also lower than the acceptable threshold at month 34 at the Pinbarren site. I also found that soil nitrate (NO3--N) was significantly higher in the soil treated with mulch than only glyphosate treatment at months 22 and 34 after revegetation at the Pinbarren site. Higher soil NO3--N in mulch compared with that of glyphosate could be partly explained by decreased denitrifying bacteria (Candidatus solibacter and Candidatus koribacter). However, there were no significant differences in soil NO3--N between mulch and other organic-based herbicides despite the fact that C. solibacter and C. koribacter were still lower under mulch than those of other herbicides. My study suggested that the application of mulch in the riparian revegetation projects would be beneficial for soil microbial functionality, particularly soil MBC as compared with [glyphosate and other organic-based herbicides. Additionally, this study suggested that some herbicides like glyphosate and BioWeedTM may have long-lasting effects on soil 125 microbial biomass even if they do not necessarily change microbial diversity. Hence, the long-term use of glyphosate and BioWeedTM needs to be considered with caution. Some woodlands within riparian zones are also horticultural sites where intensive weed control management practices are applied (Chapter 4). Therefore, an established horticultural site (Macadamia orchard) located in a riparian zone, with a history of repeated application of glyphosate (up to four times per annum for 12 years) was chosen to understand the impacts of repeated application of glyphosate interacted with biochar on soil N cycling. Wood-based biochar was first applied at this site in 2012 (64 months before my sampling time) at two different rates of 10 dry t ha-1 (B10) and 30 dry t ha-1 (B30) and the glyphosate had not been applied for two years before my sampling. Therefore, biochar and glyphosate applications coincided for three years before glyphosate was ceased. The results showed that soil TN was significantly higher in the glyphosate applied areas compared with those of no glyphosate, which may suggest that glyphosate may have stimulated N transformations in this study through increasing soil carbon (C) substrate resulting from the degradation of glyphosate and dieback of weeds. Similarly, no effect of glyphosate on soil microbial diversity and community structure was observed two years after glyphosate application had been ceased. However, glyphosate-treated soil had significantly higher AOB abundance than no glyphosate areas, which might be potentially associated with increased total carbon (TC). Conversely, biochar did not affect soil TN in this study, potentially due to the low TN content of the biochar used in this study (wood-based biochar), but had also significantly higher AOB abundance than those of no biochar plots, potentially through stimulated N cycling. In summary, neither glyphosate nor biochar impacted soil microbial diversity or community structure, but both increased AOB abundance with possible long-term implications on soil N cycling even after two years since the last glyphosate was applied. In Chapter 5, I then investigated the short-term N pools in response to the immediate interaction of glyphosate in an amended soil with biochar. I conducted an incubation study (5-day) to understand the short-term and immediate effects of glyphosate interacted with biochar on soil N transformations (ammonification, nitrification, and N mineralisation) using the 15N pool dilution techniques. Soil samples were collected from the same horticultural site used in Chapter 4. My 5-day incubation study showed that δ15N of NO3--N was not affected by any of the factors assessed including glyphosate, biochar, nd moisture content, nor were their interactions significant. However, this study showed that both nitrification and N mineralisation were stimulated by biochar. My results also showed that application of glyphosate significantly decreased δ15N of NH4+-N in soil following 3- and 5-day incubation, indicating that N mineralisation occurred, which could be related to stimulation of soil microbes due to the addition of C as a source for soil microbes resulting from the decomposition of glyphosate. In summary, my work highlighted the importance of revegetating riparian zones to increase soil N retention particularly using woodland species and showed that glyphosate and organic-based herbicides may not necessarily alter soil microbial diversity but there were long-lasting effects on soil microbial biomass observed about one year after the application being terminated. In the horticultural site, there was also an indication of both glyphosate and biochar having affected soil microbial abundance. This long-lasting effect of herbicides on soil N cycling may have implications for the long-term sustainability of riparian zones. Therefore, my work suggested that the application of mulch should be an alternative for chemical weed control when possible.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text

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 (February 23, 2006) Includes bibliographical references.