Changes in large-scale vegetation structure triggered by processes such as deforestation, wildfires, and tree die-off alter surface structure, energy balance, and associated albedo-all critical for land surface models. Characterizing these properties usually requires long-term data, precluding characterization of rapid vegetation changes such as those increasingly occurring in the Anthropocene. Consequently, the characterization of rapid events is limited and only possible in a few specific areas. We use a campaign approach to characterize surface properties associated with vegetation structure. In our approach, a profiling LiDAR and hemispherical image analyses quantify vegetation structure and a portable mast instrumented with a net radiometer, wind-humidity-temperature stations in a vertical profile, and soil temperature-heat flux characterize surface properties. We illustrate the application of our approach in two forest types (boreal and semiarid) with disturbance-induced tree loss. Our prototype characterizes major structural changes associated with tree loss, changes in vertical wind profiles, surface roughness energy balance partitioning, a proxy for NDVI (Normalized Differential Vegetation Index), and albedo. Multi-day albedo estimates, which differed between control and disturbed areas, were similar to tower-based multiyear characterizations, highlighting the utility and potential of the campaign approach. Our prototype provides general characterization of surface and boundary-layer properties relevant for land surface models, strategically enabling preliminary characterization of rapid vegetation disturbance events.

There has been a critical decline in grassland bird populations due to habitat fragmentation and deterioration, and suppression of natural fires. Alteration of the disturbance cycle may lead to changes in vegetation structure and thus habitat suitability for breeding grassland birds. Management practices at the Mississippi Sandhill Crane National Wildlife Refuge, including the use of prescribed fire, are in need of evaluation. My study asked what frequency of prescribed burns is necessary to support breeding grassland birds and whether vegetation structure varies among burn units. In this study, bird abundance and species richness did not differ significantly among burn units and vegetation cover-type was not a strong predictor of these factors either. There was evidence of site utilization by breeding grassland birds immediately following a burn, which suggests that the bird community is able to recovery quickly post-fire and these units may serve as viable habitat for breeding grassland birds.

Northern bobwhites (Colinus virginianus) are a culturally and economically significant game bird characteristic of grassland landscapes throughout their range. Despite the variety of research conducted on this species for nearly a century, populations continue to steadily decline, raising concern for future populations and highlighting the need for region-specific research. My research was conducted at Burning Star State Fish and Wildlife Area in northeastern Jackson County, Illinois from 2020-2022. My research addressed the following two objectives to provide insight on the population ecology of bobwhites at this site: (1) investigate the impact of multiple woody cover types within the home ranges of wintering bobwhites, how that cover may interact with winter severity, and their impacts on pre-breeding season survival, and (2) investigate the density of over-wintering diurnal raptor species between landscape types and discuss how this may be influencing predation risk. For objective 1, I radio-marked 141 individuals of which 102 had ≥ 15 relocations for estimating home-range size, and 127 individuals had ≥ 5 relocations and were used in survival analyses. I used an extended cox proportional hazards global model with continuous variables at the home-range scale. Variables considered included interspersion and juxtaposition index of blackberry, aggregation index of blackberry, and total area of blackberry, early successional forest, trees, and autumn olive. In addition, I used year, winter severity index (a time-dependent covariate), and an interaction term for year and winter severity index. The global model including all variables was retained as the most parsimonious model. Increases in the aggregation index of blackberry, area of autumn olive, and area of early successional forest were associated with increased hazard while increases in the interspersion and juxtaposition index of blackberry, area of blackberry, and area of trees were associated with a reduced hazard (α<0.05). For objective 2, I conducted 34 point-count surveys of predatory raptors throughout 6 landcover types every two weeks from October 2021 – January 2022. Bald eagles and barred owls were removed from analyses as I either did not credit them as significant predators of bobwhites or were nocturnal species, respectively. Observations from the 6 landcover types were split into two detection models based on whether the landcover type was classified as “open area cover” with a 125 m buffer distance or as “closed canopy cover” with a 75 m buffer distance. A uniform detection function was identified as the most parsimonious model for both the open area cover and closed canopy cover type models. Open area cover had a higher but not statistically significant difference in raptor density. My study demonstrates that woody cover types within the home-ranges of over-wintering bobwhites have strong relationships with the survival of those individuals and that diurnal raptors do not appear to be heavily concentrated in woody landscapes as predicted.

Over the last millennium peatlands have accumulated significant carbon stores. Drainage for agricultural use has been widespread and has altered the functioning of these mires: shifting them towards carbon release. Recently, in recognition of the range of ecosystem services derived from these landscapes peatland restoration projects have been initiated. Carbon storage is often cited amongst the aims of these projects, especially since the inclusion of rewetting wetlands in the Kyoto Protocol. However, little is known about the effects of ditch blocking on CO2 fluxes, particularly in Molinia caerulea dominated peatlands, a species common on degraded peatlands which tolerates a range of water table depths. This thesis aims firstly to quantify CO2 fluxes from a drained Molinia caerulea dominated blanket bog and to improve understanding of the temporal and spatial controls on these fluxes and secondly, to quantify the immediate effects of ditch blocking. Closed chamber measurements of net ecosystem exchange and partitioned below-ground respiration from control-restored paired sites were collected over the growing seasons immediately pre- (2012) and post-restoration (2013/2014). These flux data were coupled with remotely sensed data quantifying vegetation phenology and structure with a fine resolution (daily/cm) over large extents (annual/catchment). Although temporal variation in water table depth was not related to CO2 fluxes, the seasonal average related to vegetation composition suggesting raising water tables may promote a change in vegetation composition within these species-poor ecosystems. The distribution of water table depths, vegetation composition and CO2 fluxes did not vary with proximity to drainage ditches despite their prominence. An empirical model suggests in a drained state these peatlands are CO2 sources, indicating carbon previously accumulated is gradually being lost. Data suggest restoration does not always significantly affect water tables and consequently CO2 fluxes in the short-term. Where shallower water tables were maintained during dry conditions photosynthesis decreased and heterotrophic respiration increased: enhancing carbon release. Research undertaken during atypical weather has been unable to determine if restoration will be able to raise water tables sufficiently to protect the existing peat store and promote the vegetation change required to reinstate CO2 sequestration in the longer-term.

The objective of this study is to determine whether changes in arthropod community structure in restored longleaf pine savannas corresponds to differences in vegetation structure often associated with burn frequency. Longleaf pine savannas are fire-maintained ecosystems characteristic of the southeastern United States and have experienced severe declines (around 97%) since European settlement. Changes in fire regime have been instrumental in the declines. Restoration of these ecosystems has involved reinstitution of periodic burnings to promote and maintain vegetative characteristics of the savannas. This study investigates trends in arthropod communities from areas heavily invaded by hardwood shrubs against those dominated by longleaf pines and associated vegetation. These data suggest that herb-dominated sites have higher overall diversity. While overall abundance differences were not found, significant differences have been detected at the order and family level, indicating that vegetation structure and periodic burning are important factors in maintaining arthropod communities characteristic of these savannas.

Orientador: Marco Aurélio Pizo Ferreira / Banca: Alexsander Zamorano Antunes / Banca: Augusto João Piratelli / Banca: José Ragusa Netto / Banca: Mauro Galetti Rodrigues / Resumo: A expansão de plantações florestais tem sido intensificada nos últimos anos, ultrapassando 70.000.000 ha nos trópicos. Eucalyptus é o principal gênero plantado, ocupando 50% das áreas silviculturais. Monoculturas arbóreas e fragmentos de vegetação secundária figurarão entre os principais elementos das paisagens tropicais futuras. Logo, compreender como diversas espécies se comportam diante dessa situação é fundamental quando se objetiva a conservação da biodiversidade. Este trabalho estudou a avifauna em um mosaico composto por talhões de Eucalyptus spp. e alguns de vegetação nativa na Floresta Estadual Edmundo Navarro de Andrade (Rio Claro, SP). Esses talhões possuíam diferentes idades (plantados de 1934 a 1990), extensões (~1-51 ha) e graus de regeneração de vegetação nativa. Os principais objetivos foram caracterizar a avifauna encontrada nesses talhões quanto à riqueza, abundância e composição e compará-las, verificando possíveis associações com a estrutura da vegetação (riqueza, altura, área basal, densidade de plantas, densidade de plantas mortas, cobertura do dossel e densidade vertical nos estratos de 0,0 a 1,0, de 1,1 a 2,0 e de 2,1 a 5,0 m). Para a amostragem de aves foi empregado o método de pontos. No primeiro capítulo, foram amostrados 14 talhões de E. citriodora. Foram registradas 103 espécies de aves, variando de 23 a 55 por talhão. Myiodynastes maculatus, Cyclarhis gujanensis, Amazilia lactea e Megarynchus pitangua mostraram maior plasticidade ambiental, não revelando fortes associações com as variáveis da vegetação. A abundância total foi maior em talhões que apresentavam vegetação mais desenvolvida. Talhões com maior complexidade da vegetação apresentaram maior riqueza e abundância de espécies insetívoras e de dependentes de florestas. A distância entre os talhões de E. citriodora e de vegetação nativa... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The expansion of planted forests is surprisingly fast in the last years, exceeding 70.000.000 ha in the tropics, 50% of which are composed of Eucalyptus spp.. Planted and secondary forests are likely to be dominant features of tropical forest landscapes in the future. Therefore, to understand the use of different species in this situation in basic to the biological conservation. This work investigated the avifauna at a mosaic of Eucalyptus spp. patches in the State Forest Edmundo Navarro de Andrade (Rio Claro, Sâo Paulo, Brazil). These patches (~1-51 ha) were created in different years (1994-1990), presenting different levels of regeneration of the native vegetation. The principal aims were to evaluate the richness, abundance and composition of the bird community associating these parameters to the structure of the vegetation (richness, height, basal area, plant density, dead plant density, canopy cover and vertical density from 0,0 to 1,0, from 1,1 to 2,0 and form 2,1 to 5,0 m). The avifauna was sampled with point counts. In the first chapter, 14 patches of E. citrioddora were studied. It was recorded 103 species, from 23 to 55 per patch. Myiodynastes maculatus, Cyclarhis gujanensis, Amazilia lactea and Megarynchus pitangua were the most habitat generalist species. These species were not associated to any vegetation parameter. The abundance was greater in patches with more developed vegetation. Patches with high vegetation complexity had greater richness and abundance of insectivorous and forest dependent species. The distance between E. citriodora and native vegetation patches influenced negatively the richness and abundance of forest dependent species. In chapter 2, in addition to the 14 E. citriodora patches, four E. microcorys and three native vegetation patches were included in the analyses. It was recorded 115 species. On average, there were 47, 35 and 24 species in the patches... (Complete abstract click electronic access below) / Doutor

The greater sage-grouse (Centrocercus urophasianus; sage-grouse) is the largest grouse species in North America and an indicator species for the condition of sagebrush (Artemisia spp.) ecosystems. The Box Elder Sage-Grouse Management Area (SGMA) in northwestern Utah encompasses one of the state’s largest sage-grouse populations. To fill knowledge gaps regarding the population inhabiting the Raft River subunit of the Box Elder SGMA, I captured, radio-marked, and monitored 123 (68 female, 55 male) sage-grouse from January 2012 through December 2013. My purpose was to describe how the seasonal movements, survival, and reproductive rates of this sage-grouse population are effected by small-scale habitat use and breeding season foraging patterns. Sage-grouse in the Raft River subunit have distinct winter and summer ranges, and some travelled long distances annually. Survival rates were similar to other Utah populations and range-wide averages. Nest and brood success rates were above range-wide averages and those reported in the adjacent Grouse Creek subunit of the same SGMA. Sage-grouse in the study area selected habitats with specific vegetation characteristics to fit their seasonal needs. Sage-grouse use sites differed from random sites with greater forb height, grass height, and shrub height and cover. Nest success rates were directly related to selected vegetation, as successful nests were located more often under sagebrush and within greater forb height and cover and grass and shrub height than unsuccessful nests. Brood sites were also greater in forb, grass, and shrub height than other use sites. In March and April of 2013, I located radio-marked sage-grouse at flock browse sites to observe their sagebrush diet selection patterns. Lab analyses showed no differences in nutritional quality or chemical composition between browsed sagebrush plants and non-browsed and random plants. However, browsed black sagebrush (A. nova) was lower in protein and higher in chemical content than browsed Wyoming big sagebrush (A. tridentata wyomingensis). Radio-marked females were frequently observed at sites where black sagebrush was browsed, and one individual chemical was considerably more concentrated in browsed plants associated with females that nested successfully. My research provides useful information regarding the seasonal habitat use patterns and vegetation preferences of sage-grouse in the Box Elder SGMA. To conserve the sage-grouse population in northwestern Utah, management actions must protect the seasonal habitats and vegetation that the species depends on for its productivity and survival.

I examined the effects of nest site vegetation structure and cattle grazing on songbird nesting success in native mixed-grass prairie in Grasslands National Park of Canada and Mankota Community Pastures in southwestern Saskatchewan. This is the first study to compare songbird nesting success in season-long grazed and ungrazed native mixed-grass prairie. Sprague’s pipit, Baird’s sparrow, vesper sparrow, lark bunting, and chestnut-collared longspur all selected for denser vegetation at the nest than was generally available. Sprague’s pipit daily nest survival declined with increased vegetation density and litter depth at the nest site. Vegetative cover did not influence daily nest survival of the other species. Environmental conditions during the study may have resulted in an increased risk of predation for Sprague’s pipits nesting in greater cover. Grazing did not influence daily nest survival of any of the 5 species. Low-moderate intensity cattle grazing appears compatible with management for prairie songbirds in native mixed-grass prairie.

The Southern Ground Hornbill (SGH) (Bucorvus leadbeateri) has recently been listed globally by the IUCN Red list as Endangered or Critically Endangered. In South Africa, the declining population of the SGH has led it to be listed nationally as Vulnerable and falls under the “Protected Species” legislation. Research into the habitat preferences and identification of suitable reintroduction areas have been few since the initiation of reintroduction attempts, therefore resulting in mixed outcomes of previously-reintroduced SGH. The aim of this study was to identify and verify optimal reintroduction sites for the SGH, in the Musina area in the Limpopo Province. Five main objectives were determined, namely: to identify optimal reintroduction areas; to develop a habitat profile of the designated area; to determine the availability of prey items; to determine the availability of large trees needed for nesting and roosting; to evaluate pre-release sites by involving a number of stakeholders. Three study sites were selected on the farm Greyghost Safaris (Ludwigslust), each made up of a different plant community. Sampling was carried out a total of four times during the year: one sampling bout in each season. A niche-based modelling technique was used to describe the suitability of a particular habitat (“ecological space”) then used to project it onto another geographical space. Floristic and faunal surveys were conducted to determine the species composition of prey items and composition and frequency of the herbaceous and woody layer. High-resolution, natural-colour aerial imagery was used in order to determine the availability of trees for nesting and roosting. Pre-release site evaluations and stakeholder engagements were conducted by means of interviews with landowners on and around the study sites. The Limpopo River Valley and across to the KNP on the eastern border of the Limpopo Province, is suitable re-introduction sites for the SGH. This study site provided a good opportunity to explore what an optimal site for reintroduction should resemble. / Thesis (MSc (Zoology))--North-West University, Potchefstroom Campus, 2012.

The Southern Ground Hornbill (SGH) (Bucorvus leadbeateri) has recently been listed globally by the IUCN Red list as Endangered or Critically Endangered. In South Africa, the declining population of the SGH has led it to be listed nationally as Vulnerable and falls under the “Protected Species” legislation. Research into the habitat preferences and identification of suitable reintroduction areas have been few since the initiation of reintroduction attempts, therefore resulting in mixed outcomes of previously-reintroduced SGH. The aim of this study was to identify and verify optimal reintroduction sites for the SGH, in the Musina area in the Limpopo Province. Five main objectives were determined, namely: to identify optimal reintroduction areas; to develop a habitat profile of the designated area; to determine the availability of prey items; to determine the availability of large trees needed for nesting and roosting; to evaluate pre-release sites by involving a number of stakeholders. Three study sites were selected on the farm Greyghost Safaris (Ludwigslust), each made up of a different plant community. Sampling was carried out a total of four times during the year: one sampling bout in each season. A niche-based modelling technique was used to describe the suitability of a particular habitat (“ecological space”) then used to project it onto another geographical space. Floristic and faunal surveys were conducted to determine the species composition of prey items and composition and frequency of the herbaceous and woody layer. High-resolution, natural-colour aerial imagery was used in order to determine the availability of trees for nesting and roosting. Pre-release site evaluations and stakeholder engagements were conducted by means of interviews with landowners on and around the study sites. The Limpopo River Valley and across to the KNP on the eastern border of the Limpopo Province, is suitable re-introduction sites for the SGH. This study site provided a good opportunity to explore what an optimal site for reintroduction should resemble. / Thesis (MSc (Zoology))--North-West University, Potchefstroom Campus, 2012.