84,503 research outputs found
NATURAL HISTORY AND BIOGEOGRAPHY OF THE AMPHIBIANS AND REPTILES OF KIBALE NATIONAL PARK, UGANDA
This study lists the amphibian and reptile species of Kibale National Park, Uganda, and discusses the natural history and biogeography of this unique herpetofauna. This herpetofaunal inventory was compiled based upon literature records and collections made during 17 mo fieldwork between 1995 and 1997, and includes 28 anuran, 15 lizard, and 32 snake species. Faunal comparisons with seven other tropical African forests show a high degree similarity between the Kibale herpetofauna and those of central and West Africa
HOME RANGE AND MICROHABITAT ASSOCIATIONS OF THE SOUTHERN RED-BACKED VOLE (MYODES GAPPERI) IN NEW HAMPSHIRE FORESTS
Resources, such as food and shelter, are unevenly distributed across the landscape at both macro and micro scales. Home range is one measure of space use that reflects an individualâs resource requirements (e.g., microhabitat characteristics) and competition for those resources (e.g., density dependence). This study focuses on the home range of the southern red-backed vole (Myodes gapperi), comparing field methods for estimating home range and modeling the microhabitat characteristics that define the core area of the home range. Southern red-backed voles (Myodes gapperi) are common to boreal forests, most often found in coniferous or mixed deciduous stands, and in the northeast, have an affinity for eastern hemlock (Tsuga canadensis). With eastern hemlock populations in decline due to the invasive eastern hemlock woolly adelgid (Adelges tsugae), it is unknown how M. gapperi space use will be affected.
From 2014-2017, southern red-backed voles were censused across 12 (~1 ha) grids using mark-recapture methods and for a subset of individuals radiotelemetry. Individual home range size, core area size, and core area overlap were calculated for adults using kernel density estimators from both mark recapture live trapping and radiotelemetry data. At each capture point, forest structure, ground cover, and geographic features were measured to assess influence of microhabitat on home range and core area. Density was calculated on each grid for each year of the study using the POPAN parameterization of the Jolly-Seber model.
In this thesis, Chapter One presents the effects of M. gapperi density on individual home range and core area. Differences in size and overlap are examined within and between sexes, and estimates compared between the two field techniques, mark-recapture and radiotelemetry, often used to delineate home range and core area. Density did not affect space use and female voles shared area more often with males than other females. The home range size of males was larger than that of females, however, core area was consistently about 30% of total home range. Area estimates generated under mark-recapture and radiotelemetry were similar for females, but differed for males with larger home ranges calculated using radiotelemetry. Mark-recapture methods may have underestimated male home range as a consequence of the trapping grid being smaller than male home range.
Chapter Two identifies habitat characteristics at the macro and micro scale that influence M. gapperi space use. Macrohabitat differences were evaluated between trap stations that were visited and were not visited by M. gapperi and microhabitat characteristics were modeling within female M. gapperi core areas. Myodes gapperi are found in areas with higher eastern hemlock basal area and more coarse woody debris. Within these stands, female M. gapperi select for core areas closer to water, with greater red maple basal area, deeper leaf litter, and a greater density of hemlock stems
A new land cover map for the Mekong: Southeast Asiaâs largest transboundary river basin
The transboundary Mekong basin, including territorial parts of China, Myanmar, Laos, Thailand, Cambodia, and Vietnam, is endowed with a rich natural resource base. The rapid socio-economic development of the region, however, substantially increases pressure on its natural resources that are increasingly subject of over-exploitation and environmental degradation. Some of the main environmental problems facing the region are common or transboundary issues that only can be addressed by transboundary approaches based on consistent and regional comparable information on the state of the environment at basin scale. In this context, a regional specific land cover map, the MEKONG LC2010 product, was produced for the entire Mekong Basin, utilising information from the MODIS sensor aboard the platforms Aqua and Terra
Mitochondrial DNA signature for range-wide populations of Bicyclus anynana suggests a rapid expansion from recent refugia
This study investigates the genetic diversity, population structure and demographic history of the afrotropical butterfly Bicyclus anynana using mitochondrial DNA (mtDNA). Samples from six wild populations covering most of the species range from Uganda to South Africa were compared for the cytochrome c oxidase subunit gene (COI). Molecular diversity indices show overall high mtDNA diversity for the populations, but low nucleotide divergence between haplotypes. Our results indicate relatively little geographic population structure among the southern populations, especially given the extensive distributional range and an expectation of limited gene flow between populations. We implemented neutrality tests to assess signatures of recent historical demographic events. Tajima's D test and Fu's FS test both suggested recent population growth for the populations. The results were only significant for the southernmost populations when applying Tajima's D, but Fu's FS indicated significant deviations from neutrality for all populations except the one closest to the equator. Based on our own findings and those from pollen and vegetation studies, we hypothesize that the species range of B. anynana was reduced to equatorial refugia during the last glacial period, and that the species expanded southwards during the past 10.000 years. These results provide crucial background information for studies of phenotypic and molecular adaptation in wild populations of B. anynan
Recommended from our members
Diazotrophs Show Signs of Restoration in Amazon Rain Forest Soils with Ecosystem Rehabilitation.
Biological nitrogen fixation can be an important source of nitrogen in tropical forests that serve as a major CO2 sink. Extensive deforestation of the Amazon is known to influence microbial communities and the biogeochemical cycles they mediate. However, it is unknown how diazotrophs (nitrogen-fixing microorganisms) respond to deforestation and subsequent ecosystem conversion to agriculture, as well as whether they can recover in secondary forests that are established after agriculture is abandoned. To address these knowledge gaps, we combined a spatially explicit sampling approach with high-throughput sequencing of nifH genes. The main objectives were to assess the functional distance decay relationship of the diazotrophic bacterial community in a tropical forest ecosystem and to quantify the roles of various factors that drive the observed changes in the diazotrophic community structure. We observed an increase in local diazotrophic diversity (ι-diversity) with a decrease in community turnover (β-diversity), associated with a shift in diazotrophic community structure as a result of the forest-to-pasture conversion. Both diazotrophic community turnover and structure showed signs of recovery in secondary forests. Changes in the diazotrophic community were primarily driven by the change in land use rather than differences in geochemical characteristics or geographic distances. The diazotroph communities in secondary forests resembled those in primary forests, suggesting that at least partial recovery of diazotrophs is possible following agricultural abandonment.IMPORTANCE The Amazon region is a major tropical forest region that is being deforested at an alarming rate to create space for cattle ranching and agriculture. Diazotrophs (nitrogen-fixing microorganisms) play an important role in supplying soil N for plant growth in tropical forests. It is unknown how diazotrophs respond to deforestation and whether they can recover in secondary forests that establish after agriculture is abandoned. Using high-throughput sequencing of nifH genes, we characterized the response of diazotrophs' β-diversity and identified major drivers of changes in diazotrophs from forest-to-pasture and pasture-to-secondary-forest conversions. Studying the impact of land use change on diazotrophs is important for a better understanding of the impact of deforestation on tropical forest ecosystem functioning, and our results on the potential recovery of diazotrophs in secondary forests imply the possible restoration of ecosystem functions in secondary forests
Insights on the role of forest cover and on the changes in forest cover on thirty-five endangered mammal species distributions
The changes in forest cover can determine the survival of terrestrial endangered mammal species in the wild. This study assessed the impacts of forest cover changes on endangered mammal species distribution at global scale aiming to understand how the changes in forest cover may have impacted the distributions of 35 endangered small and large-body terrestrial mammals. There were used forest data obtained from time-series analyses of Landsat images between 2000 and 2014, species occurrence records collected by observations between 2000 and 2015 of Global Biodiversity Information Facility and species range data of International Union for Nature Conservation (IUCN) of the year 2015, to test the ânatural and resource conditionsâ hypothesis. Hypothesis on ânatural and resource conditionsâ produced models with high prediction accuracy of above 70 percent for 88 percent of 35 species models. The changes in forest cover explained species occurrences in 10 percent of all species models. In average, 59 percent of species occurrence records overlapped with species range data. The 51 percent of all species had no occurrence records between 2000 and 2015. Species and forest data collection as well as transnational cooperation for conservation of species roaming in the wild in upland forested areas and in cross-border areas may be critical for endangered mammal species conservation
- âŚ