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Wildlife corridors can help maintain landscape connectivity but novel methods must be developed to assess regional structural connectivity quickly and cheaply so as to determine where expensive and time-consuming surveys of functional connectivity should occur. We use least-cost methods, the most accurate and up-to-date land conversion dataset for East Africa, and interview data on wildlife corridors, to develop a single, consistent methodology to systematically assess wildlife corridors at a national scale using Tanzania as a case study. Our research aimed to answer the following questions; (i) which corridors may still remain open (i.e. structurally connected) at a national scale, (ii) which have been potentially severed by anthropogenic land conversion (e.g., agriculture and settlements), (iii) where are other remaining potential wildlife corridors located, and (iv) which protected areas with lower forms of protection (e.g., Forest Reserves and Wildlife Management Areas) may act as stepping-stones linking more than one National Park and/or Game Reserve. We identify a total of 52 structural connections between protected areas that are potentially open to wildlife movement, and in so doing add 23 to those initially identified by other methods in Tanzanian Government reports. We find that the vast majority of corridors noted in earlier reports as \"likely to be severed\" have actually not been cut structurally (21 of 24). Nonetheless, nearly a sixth of all the wildlife corridors identified in Tanzania in 2009 have potentially been separated by land conversion, and a third now pass across lands likely to be converted to human use in the near future. Our study uncovers two reserves with lower forms of protection (Uvinza Forest Reserve in the west and Wami-Mbiki Wildlife Management Area in the east) that act as apparently crucial stepping-stones between National Parks and/or Game Reserves and therefore require far more serious conservation support. Methods used in this study are readily applicable to other nations lacking detailed data on wildlife movements and plagued by inaccurate land cover datasets. Our results are the first step in identifying wildlife corridors at a regional scale and provide a springboard for ground-based follow-up conservation.

Wildlife corridors are typically designed for single species, yet holistic conservation approaches require corridors suitable for multiple species. Modelling habitat linkages for wildlife is based on several modelling steps (each involving multiple choices), and in the case of multi-species corridors, an approach to optimize single species corridors to few or a single functional corridor for multiple species. To model robust corridors for multiple species and simultaneously evaluate the impact of methodological choices, we develop a multi-method approach to delineate corridors that effectively capture movement of multiple wildlife species, while limiting the area required. Using wildlife presence data collected along ground-based line transects between Lake Manyara and Tarangire National Parks, Tanzania, we assessed species-habitat association in both ensemble and stacked species distribution frameworks and used these to estimate linearly and non-linearly scaled landscape resistances for seven ungulate species. We evaluated habitat suitability and least-cost and circuit theory-based connectivity models for each species individually and generated a multi-species corridor. Our results revealed that species-habitat relationships and subsequent corridors differed across species, but the pattern of predicted landscape connectivity across the study area was similar for all seven species regardless of method (circuit theory or least-cost) and scaling of the habitat suitability-based cost surface (linear or non-linear). Stacked species distribution models were highly correlated with the seven species for all model outputs (r = 0.79 to 0.97), while having the greatest overlap with the individual species least-cost corridors (linear model: 61.6%; non-linear model: 60.2%). Zebra was the best single-species proxy for landscape connectivity. Overall, we show that multi-species corridors based on stacked species distribution models achieve relatively low cumulative costs for savanna ungulates as compared to their respective single-species corridors. Given the challenges and costs involved in acquiring data and parameterizing corridor models for multiple species, zebra may act as a suitable proxy species for ungulate corridor conservation in this system.

Habitat loss and fragmentation due to human activities is the leading cause of the loss of biodiversity and ecosystem services. Protected areas are the primary response to this challenge and are the cornerstone of biodiversity conservation efforts. Roughly 15% of land is currently protected although there is momentum to dramatically raise protected area targets towards 50%. But, how much land remains in a natural state? We answer this critical question by using open-access, frequently updated data sets on terrestrial human impacts to create a new categorical map of global human influence (‘Low Impact Areas’) at a 1 km 2 resolution. We found that 56% of the terrestrial surface, minus permanent ice and snow, currently has low human impact. This suggests that increased protected area targets could be met in areas minimally impacted by people, although there is substantial variation across ecoregions and biomes. While habitat loss is well documented, habitat fragmentation and differences in fragmentation rates between biomes has received little attention. Low Impact Areas uniquely enabled us to calculate global fragmentation rates across biomes, and we compared these to an idealized globe with no human-caused fragmentation. The land in Low Impact Areas is heavily fragmented, compromised by reduced patch size and core area, and exposed to edge effects. Tropical dry forests and temperate grasslands are the world’s most impacted biomes. We demonstrate that when habitat fragmentation is considered in addition to habitat loss, the world’s species, ecosystems and associated services are in worse condition than previously reported.

We define African savannahs as being those areas that receive between 300 and 1,500 mm of rain annually. This broad definition encompasses a variety of habitats. Thus defined, savannahs comprise 13.5 million km 2 and encompass most of the present range of the African lion ( Panthera leo ). Dense human populations and extensive conversion of land to human use preclude use by lions. Using high-resolution satellite imagery and human population density data we define lion areas, places that likely have resident lion populations. In 1960, 11.9 million km 2 of these savannahs had fewer than 25 people per km 2 . The comparable area shrank to 9.7 million km 2 by 2000. Areas of savannah Africa with few people have shrunk considerably in the last 50 years and human population projections suggest they will likely shrink significantly in the next 40. The current extent of free-ranging lion populations is 3.4 million km 2 or about 25 % of savannah area. Habitats across this area are fragmented; all available data indicate that between 32,000 and 35,000 free-ranging lions live in 67 lion areas. Although these numbers are similar to previous estimates, they are geographically more comprehensive. There is abundant evidence of widespread declines and local extinctions. Under the criteria we outline, ten lion areas qualify as lion strongholds: four in East Africa and six in Southern Africa. Approximately 24,000 lions are in strongholds, with an additional 4,000 in potential ones. However, over 6,000 lions are in populations of doubtful long-term viability. Lion populations in West and Central Africa are acutely threatened with many recent, local extinctions even in nominally protected areas.

• Parenchyma cells in the xylem store nonstructural carbohydrates (NSC), providing reserves of energy that fuel woody perennials through periods of stress and/or limitations to photosynthesis. If the capacity for storage is subject to selection, then the fraction of wood occupied by living parenchyma should increase towards stressful environments. • Ray parenchyma fraction (RPF) and seasonal NSC dynamics were quantified for 12 conifers and three oaks along a transect spanning warm dry foothills (500 m above sea level) to cold wet treeline (3250 m asl) in California’s central Sierra Nevada. • Mean RPF was lower for both conifer and oak species with warmer dryer ranges. RPF variability increased with elevation or in relation to associated climatic variables in conifers – tree-line-dominant Pinus albicaulis had the lowest mean RPF measured (c. 3.7%), but the highest environmentally standardized variability index. Conifer RPF variability was explained by environment, increasing predominantly towards cooler wetter range edges. In oaks, NSC was explained by environment – values increasing for evergreen and decreasing for deciduous oaks with elevation. Lastly, all species surveyed appear to prioritize filling available RPF with sugar to achieve molarities that balance reasonable tensions over starch to maximize stored carbon. • RPF responds to environment but is unlikely to spatially constrain NSC storage.

Lions are one of the world’s most iconic species but are threatened with extinction. Developing effective range-wide conservation plans are crucial but hampered by the relative lack of knowledge on specific threats facing each population and the socio-political context for conservation. Here, we present a range-wide examination of the relative fragility of lion populations, examining socio-political factors alongside ecological ones. We found Ethiopia’s Maze National Park had the most ecologically fragile geographic population while Kavango-Zambezi was the least. At a country level, lion populations had highest ecological fragility in Cameroon and Malawi. When we examined socio-political fragility, Somalia was the most fragile lion range country, followed by South Sudan. When socio-political and ecological fragility were combined, lion populations in Maze National Park and Bush-Bush (Somalia) and more broadly, Somalian and Malawian lion populations were the most fragile. These insights should help inform more nuanced and appropriately targeted lion conservation plans.

This dissertation assesses aspects of biodiversity conservation in East Africa from three angles: 1) protected area representation and effectiveness, 2) wildlife corridors, and 3) large mammal sensitivity to humans in savanna ecosystems. I first consider protected area representation and effectiveness across East Africa. Protected areas are the cornerstone of in situ conservation and their effective management is critical for maintaining biodiversity in the long term. East Africa contains a network of 1,776 protected areas (including 186 protected areas with IUCN management categories I through IV) covering more than 27% of its terrestrial area. However, many of these protected areas were established before the advent of modern conservation biology, and several are now threatened by land conversion fueled by rapid human population growth. Here I document the extent to which East African protected areas encompass ecoregions and endemic terrestrial vertebrate taxa and, using new land conversion data derived from high spatial resolution satellite images, I assess how they have been encroached upon by agriculture and other land use. I find that East African protected areas cover most ecoregions well (>10% threshold of ecoregion representativeness set by the Convention on Biological Diversity’s Aichi Target 11), some very well (>90% - Rwenzori-Virunga montane moorlands and East African montane moorlands), but Masai xeric grasslands and shrublands, Somali Acacia-Commiphora bushlands and thickets, and Southern Swahili coastal forests and woodlands are poorly represented. While protected areas cover the geographic distribution of most East African endemic and near-endemic terrestrial vertebrate species, they cover less than 10% of the distribution of 47 endemic species (16% of the 303 endemic species). Encouragingly, East African protected areas are largely unconverted to human use, with only 6.8% of their total area experiencing land conversion (1.6% for strict protected areas). I then aim to assess the current state of wildlife corridors across Tanzania using Wami-Mbiki Wildlife Management Area as a test case. Wildlife corridors can help maintain landscape connectivity but novel methods must be developed to assess regional structural connectivity quickly and cheaply so as to determine where expensive and time-consuming surveys of functional connectivity should occur. I use least-cost methods, the most accurate and up-to-date land conversion dataset for East Africa, and interview data on wildlife corridors, to develop a single, consistent methodology to systematically assess wildlife corridors at a national scale using Tanzania as a case study. My research aims to answer the following questions; (i) which corridors may still remain open (i.e. structurally connected) at a national scale, (ii) which have been potentially severed by anthropogenic land conversion (e.g., agriculture and settlements), (iii) where are other remaining potential wildlife corridors located, and (iv) which protected areas with lower forms of protection may act as stepping-stones linking more than one National Park and/or Game Reserve. I identify a total of 52 structural connections between protected areas that are potentially open to wildlife movement, and in so doing add 23 to those initially identified by other methods in Tanzanian Government reports. I find that the vast majority of corridors noted in earlier reports as “likely to be severed” have actually not been cut structurally (21 of 24). Nonetheless, nearly a sixth of all the wildlife corridors identified in Tanzania in 2009 have potentially been separated by land conversion, and a third now pass across lands likely to be converted to human use in the near future. My study uncovers two reserves with lower forms of protection that act as apparently crucial stepping-stones between National Parks and/or Game Reserves and therefore require far more serious conservation support. Methods used in this study are readily applicable to other nations lacking detailed data on wildlife movements and plagued by inaccurate land cover datasets. My results are the first step in identifying wildlife corridors at a regional scale and provide a springboard for ground-based follow-up conservation. Finally, I evaluate the sensitivity of the larger mammals of savanna Africa to humans. Habitat loss and overexploitation are driving differential declines in vertebrate taxa but variation in responses means it is often difficult to determine where to place conservation effort. Here I present an easy-to-use method to rank the relative sensitivities of the larger mammals of savanna Africa to human activities in order to prioritize conservation activities. I first make coarse predictions about susceptibility based on species’ intrinsic ecological traits. Next I determine actual presence of these species using transect surveys within the heavily impacted Wami-Mbiki Wildlife Management Area in Tanzania, by conducting interviews outside this protected area, and monitoring changes in populations within both of these zones. (Abstract shortened by ProQuest.)