published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

The density, diversity, and nest-site selection of riparian breeding birds were studied from 1982 to 1985 in mesquite (Prosopis glandulosa) and tamarisk (Tamarix chinensis) communites along the Colorado River in northern Arizona. Avian density in tamarisk communities was significantly greater (P=0.052 and 0.024 in 1984 and 1985, respectively) than avian density in native mesquite communities with similar vegetative cover and height attributes. Avian diversity was similar in both communities. Breeding bird densities in tamarisk were higher than those reported from other geographic areas. Vegetation structure and shrub species composition were measured at nest sites of eleven species of riparian birds in a tamarisk community to examine avian habitat relationships. Riparian birds exhibited differences in their choice of nesting habitat. Discriminant analysis indicated that Bell's Vireo (Vireo bellii), Yellow Warbler (Dendroica petechia) and Yellow-breasted Chat (Icteria virens) were relative generalists in nest site selection, while Common Yellowthroat (Geothlypis trichas) and Northern Oriole (Icterus galbula) were relative habitat specialists. Bell's Vireo and American Coot (Fulica americana) nested in habitats that were the most different. Willow Flycatcher (Empidonax traillii) and Yellow Warbler nested in habitats that were the most similar. Willow Flycatcher and Yellow Warbler consistently used habitat most similar to that used by all other species. Nest placement preferences of six riparian passerines were examined in the tamarisk community to test the null hypothesis that nest placement in any given species of shrub was random. Ninety-five of 105 nests sampled were located in tamarisk. Five of the six species of passerines exhibited a significant preference for tamarisk for nest placement. A highly significant preference for tamarisk was shown by the four species with the smallest median frequency of tamarisk in their nesting habitat. The usefulness of tamarisk for nest placement was higher than that reported from other areas.

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.

Submitted by Mariana Dornelles Vargas (marianadv) on 2015-05-18T12:06:00Z No. of bitstreams: 1 padroes_estruturais.pdf: 1608201 bytes, checksum: 202eac1edefaff08f88aa686d56f9c59 (MD5) / Made available in DSpace on 2015-05-18T12:06:00Z (GMT). No. of bitstreams: 1 padroes_estruturais.pdf: 1608201 bytes, checksum: 202eac1edefaff08f88aa686d56f9c59 (MD5) Previous issue date: 2011 / Nenhuma / Fatores topográficos afetam as comunidades vegetais em diferentes escalas espaciais agindo como filtros para a distribuição e abundância das espécies. Essa influência é proeminente em ecossistemas montanos. No sul do Brasil as encostas íngremes dos rios da bacia hidrográfica do rio Pelotas abrigam importantes remanescentes florestais montanos, apesar da pressão antrópica histórica exercida pela extração madeireira, agropecuária, silvicultura e nas últimas décadas, principalmente pela exploração hidrelétrica. O represamento de rios é um dos mais proeminentes impactos aos ecossistemas de água doce, com reflexos sobre a vegetação ripária. A construção de reservatórios hidrelétricos em rios montanos com vales estreitos como aqueles da bacia hidrográfica do rio Pelotas causa a elevação artificial do nível e do lençol freático podendo afetar a vegetação ripária situada acima do novo nível dos rios. Portanto são esperadas diferenças estruturais entre florestas de encosta que margeiam reservatórios hidrelétricos e áreas controle. Este estudo foi desenvolvido em florestas de encosta de três tributários do rio Pelotas, em Campo Belo do Sul, SC. Foram instaladas 90 unidades amostrais (0,9 ha) em encostas que margeiam o reservatório da UHE Barra Grande e em encostas controle. Foram amostradas todas as árvores e arbustos vivos com DAP ≥ 5 cm. O desenho amostral permitiu comparar a heterogeneidade topográfica, a estrutura florestal e a composição de espécies (separadamente) entre rios, e em cada um deles o tratamento efeito da barragem através de análises de variância uni e multivariadas. Também foi utilizada uma análise de espécies indicadoras para determinar as espécies mais afins a cada encosta. A riqueza de espécies foi comparada por meio de curvas de rarefação baseadas na amostra. Neste trabalho foi utilizado o conceito de número efetivo de espécies (diversidade verdadeira) para calcular a diversidade de árvores. Foram amostradas 1233 árvores de 87 espécies e 40 famílias. As análises estatísticas revelaram heterogeneidade topográfica entre as encostas, que se refletiu na estrutura florestal e na composição de espécies. Essas diferenças também foram observadas em cada um dos rios para o tratamento efeito da barragem. Riqueza e diversidade de espécies se mostraram relativamente homogêneas. Os resultados corroboram o papel da heterogeneidade ambiental na estruturação das comunidades. As diferenças estruturais e em composição de espécies observadas para o tratamento efeito da barragem sugerem efeitos sobre a vegetação. Por outro lado, múltiplos fatores podem ter relações causais com essas diferenças, e, portanto, são necessários estudos complementares. / Plant communities are affected by topography in different spatial scales, acting as an environmental filter to species distribution and abundance. This influence is prominent in montane ecosystems. In southern Brazil, steep slopes of the Pelotas river watershed has important montane forest remnants, despite the pressure exerted by anthropic historical logging, agriculture, forestry, and in recent decades, hydroelectric exploitation. The damming of rivers is one of the most prominent impacts on freshwater ecosystems, with impacts on the riparian vegetation. The hydroelectric reservoir construction in a montane river with narrow valleys like those of the Pelotas river watershed causes the artificial increase of river water level and the groundwater affecting the riparian vegetation located above the new level of rivers. So, are expected structural differences between slope forest bordering Barra Grande hydroelectric reservoir and control areas. This study was carried out in slope forests of the three tributaries of Pelotas river in Campo Belo do Sul, SC. Were installed 90 sample plots (0.9 ha) on slope forests bordering the reservoir and control areas. We sampled all trees and shrubs alive with DBH ≥ 5 cm. The sample design allowed us to compare topography, forest structure and species composition (separately) between rivers, and the effect of the dam treatment through univariate and multivariate analysis of variance. It was also used an indicator species analysis to determine indicator species to each slope. Species richness was compared using rarefaction curves based on the sample. In this study we used the concept of effective number of species (true diversity) to calculate trees diversity. We sampled 1233 trees of 87 species and 40 families. Statistical analysis revealed topographic heterogeneity among the slopes, which was reflected in forest structure and species composition. These differences were also observed in each of the rivers for the effect of the dam treatment. Richness and true diversity proved relatively homogeneous. Our results support the role of environmental heterogeneity on forest communities. The forest structure and species composition differences observed for the effect of the dam treatment suggest effects on vegetation. On the other hand, multiple factors may have causal relationships with these differences, and therefore further studies are needed.

Graduation date: 2002

Livestock grazing in riparian habitats alters the vegetation structure, which has a detrimental effect on wildlife. This study examined the effect of cattle grazing in riparian habitats on winter bird biodiversity, small mammal biodiversity, and microclimate. Study sites were ungrazed, moderately grazed, and heavily grazed riparian habitats along the Oldman River, Alberta during winter 2005 and 2006. Bird species richness, individual abundance, and diversity indices were higher in ungrazed habitats than in grazed habitats. Deer mouse population sizes were not different except during spring 2006, when populations were larger in ungrazed sites. Microclimate data were collected in riparian sites and upland sites in winter 2006. Temperatures were higher and wind speeds were slower in riparian sites than in upland sites. Wind speeds were faster in heavily grazed riparian sites than in lightly grazed sites. Faster winds in heavily grazed sites may account for the decreased winter biodiversity in these habitats. / x, 118 leaves ; 29 cm

Freshwater and terrestrial ecosystems are connected through biomass exchanges such as the flow of predators, prey, nutrients and detritus between them. Emerging aquatic insects provide an alternate food source to riparian consumers often termed an allochthonous subsidy. Stable isotope analyses of naturally occurring carbon and nitrogen is effective for tracing energetic food sources to consumers. This thesis evaluated whether stable isotope analysis would be effective in the Oldman River Basin, Alberta. Aquatic and riparian primary consumers are distinct in their isotopic signatures and valid for to use in stable isotope analysis. Stable isotope modelling was then used to evaluate the proportional contribution of aquatic insects to riparian spider and beetle diets. Carbon analysis showed an overall aquatic insect contribution of 25 % and 18 % for spiders and beetles, respectively; while nitrogen analysis showed an overall contribution of 36 % and 20 %, respectively. The spatial extent of the aquatic insect contribution upland from the river was shown to decrease from 50 - 55 % at 1 m to 0 % at 30 m for both consumers using carbon, and from 35 - 40 % at 1 m to 0 % at 40 m using nitrogen. Finally, regression modelling of the size of a river and the spatial scale of an aquatic insect dietary contribution showed a significant relationship, indicating larger water bodies support higher production of aquatic insects. A meta-analysis of published literature applied to this model also indicated a significant relationship between the size of the river and the extent of an aquatic insect contribution. / xii, 126 leaves m ; 29 cm

South Africa has a long history of problems with invasive alien species. In an assessment of alien invading plants and water resources in South Africa Versveld et al. (1998) estimated that Invasive Alien Plants (IAPs) in South Africa covered an area equivalent to the size of KwaZulu-Natal. However this area of invasion was primarily concentrated along the river courses of South Africa as alien invasions are arguably a riparian problem (Versveld et al., 1998). In a 1998 assessment of the distribution of IAPs in South Africa Versveld et al. (1998) found a total invasion extent of 8% for South Africa (including Lesotho), while KwaZulu-Natal had a higher total extent of invasion at 9.75%. However the authors noted the limitations of the IAP mapping assessment and stated that from personal observations and observers’ comments the area invaded by IAPs may be as much as 2-3 times greater than the 9.75% value obtained for KwaZulu-Natal. South Africa’s most widespread invasive alien tree (Dye and Jarmain, 2004), Acacia mearnsii (black wattle), is ubiquitous throughout KwaZulu-Natal, and invades most severely where water is plentiful, such as along watercourses and road verges. However following dispersal along rivers, A. mearnsii spreads into adjacent terrestrial habitats (Richardson and Kluge, 2008) including indigenous grassland and forest. A. mearnsii was introduced to South Africa in the middle 19th century to provide tanbark, woodchips, construction poles and firewood, and its introduction spread rapidly across KwaZulu-Natal through farmers and foresters (Henderson, 2001; WESSA, 2008). River and riparian zone rehabilitation is becoming accepted as having an essential role to play in the long term solution of water resource quality and supply problems and environmental health as a whole. As a result the impact of IAP invasions on water resources, ecological habitats and the delivery of ecosystem goods and services has undergone much scientific investigation (van Wilgen et al., 2008). Numerous studies have shown that, under most circumstances, removal of IAPs results in a general increase in streamflow and returns a stream to a more natural seasonal flow regime. However, scientific studies on the influences of woody IAPs on the hydrogeomorphology of riparian areas, and the resultant effects on stream hydrology and ecology, have undergone little scientific investigation in the South African context. Hydrogeomorphology studies the linkages of surface and subsurface water, and hydrological processes with landforms and geomorphic processes in temporal and spatial dimensions. As a result the discipline is well applied to the study of the interaction of, and interdisciplinary impacts of IAPs on riparian areas. Macdonald (2004:22) stated that there is a need to “investigate the interaction of IAPs with other aspects of water quality, for example soil erosion rates, including river channel and bank erosion.” In the early 1990s, after a study assessing the potential impact of IAPs on the geomorphology of river channels in South Africa, Rowntree (1991) stressed that further research on the influence of IAPs on stream geomorphology is required to guide truly effective riparian zone management. Since this study, little scientific work has been undertaken on this topic in the South African context. The literature review portion of this dissertation reviews the findings of various researchers as to how IAPs physically influence riparian habitats, specifically with reference to the role of IAPs in degrading riparian and streambank landscapes to an extent that streambank stability and stream channel form is adversely affected. This topic is introduced by illustrating the many functions that riparian zones can perform and some of the possible consequences of a loss of riparian habitat integrity. Worldwide awareness of the functions and values of riparian systems has led many countries to perform inventories of threatened and valuable riparian areas. A database of stream habitat integrity is useful for environmental impact assessments, development planning and resource inventories. Thus a multitude of stream survey and aquatic health sampling techniques and methodologies have been developed, some of which could be applied to assessing the influence of IAPs on riparian zones. 1.1 Research Aims and Objectives This dissertation forms a research study based on field research centred around field methods and tools developed after a review of relevant literature. The key aims of this research study are to; · refine an international river habitat survey method for application within South Africa, and · develop a test case to implement the developed method in analysing the impacts of IAPs on stream hydrogeomorphology in small headwater streams of KwaZulu-Natal, South Africa. These aims are achieved through the following objectives; · investigate the current body of knowledge covering the impact of woody IAP invasions on streambank stability and channel form, · review available stream survey methods and develop a stream survey methodology which can be applied to investigate the relationships between woody IAP invasions and streambank stability and form within headwater streams of KwaZulu-Natal, · investigate the relationships illustrated by the data after applying the developed stream survey tools and fieldwork methodology, and · discuss any shortfalls of the developed tools and methods, and suggest future needs. The hypothesis of the study contends that, within the focus of this study, invasion of headwater streams by woody IAPs can result in; · increased channel incision and bank steepening, and · an increase in streambank instability. 1.2 Document Structure Chapters 2 to 4 form a review of current literature to establish a base of understanding of the implications, processes and components involved in the invasion of riparian zones by Invasive Alien Plants. In Chapter 5 the approaches to stream surveying are assessed and selected methods of stream survey seen as applicable to this study are reviewed. Based on these findings, a method of stream survey for application in this study is developed and described in Chapter 6 following a description of the fieldwork sites and methodology. Chapter 7 provides an extensive analysis and exploration of the results of the various components of the fieldwork, which are then discussed in Chapter 8. Chapter 9 outlines final conclusions, analysis of the applicability of the findings, and suggestions with regards to future research needs. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Two riparian habitats in southeastern Arizona provide the setting for a study of 127 plants useful to human foragers. A view of plant part availability is based on annual phenological profiles, and on historic and prehistoric records of plant use. Food choice is limited in March and April, but high August through November. Riparian plants also offer numerous non-food resources. Trees and shrubs serve more needs in relation to number of available species than do perennial herbs (including grasses) and annuals. Southwestern ethnographic literature hints that certain native taxa (Panicum, Physalis, Populus, Salix, Typha and Vitis) might receive special care. Inherent qualities of parts, coupled with ethnographic records of preparation and use, provide a basis for speculation on which parts might survive in an ancient record. Most are expected to disintegrate in open sites. Parts sought for different needs can enter a dwelling via diverse routes that produce confusingly similar archaeological debris. Modern experiments to wash pollen from 14 separate harvests permit evaluation of plant fruit and leaves as pollen traps, to help interpret pollen recovered from ancient dwellings. High amounts of Berberis, Rumex and Ribes pollen, sometimes in clumps or as tetrads, travel on harvested fruit. Arctostaphylos, Monarda, Oxalis, Rhus, Rhamnus, Vitis and Juniperus parts carry lower amounts. Quercus and Gramineae pollen grains travel on parts of other taxa, as well as on their own fruit. The phenological profiles offer insight into group life-form activities in response to local temperature and precipitation trends. Rising and maximum temperatures coincide with intense vegetative and reproductive activity for trees, shrubs, herbaceous perennials, and annuals. Increased levels of precipitation coincide with maximum flowering and fruiting of herbaceous perennials and fall annuals. Limited data on six taxa from Utah generally agrees with observations in this study, suggesting strong genetic control in the phenology of some riparian taxa.

No description available.