Aerin L. Jacob

Variability in ecosystem service measurement: a pollination service case study

Research quantifying ecosystem services (ES) - collectively, the benefits that society obtains from ecosystems -is rapidly increasing. Despite the seemingly straightforward definition, a wide varie ...

Going, Going, Gone: A 15-Year History of the Decline of Primates in Forest Fragments near Kibale National Park, Uganda

Given accelerating trends of deforestation and human population growth, immediate and innovative solutions to conserve biodiversity are sorely needed. Between 1995 and 2010, we regularly monitored the population size and structure of colobus monkey populations in the forest fragments outside of Kibale National Park, Uganda. Through this monitoring we assessed the monkeys’ gastrointestinal parasites and fecal cortisol levels. Over 15 years, we documented a rapid decline in the number of fragments that supported primates, largely as a result of tree removal. Fecal cortisol levels of primates found in the fragments were consistently higher than in populations found in the continuous forest of the national park. The fragment populations also harbored gastrointestinal parasites rarely found in the main forest and exchanged bacteria with nearby people and livestock at high rates, suggesting that fragmentation facilitates disease transmission. Fragments supported the fuelwood needs of an average of 32 people living immediately adjacent to the fragment, and partially supported families up to three farms away (~400 m, representing 576 people). Intensive fuelwood harvesting occurred when neighboring households engaged in brewing beer (an average of 9.6 % of the households), distilling gin (8.8 %), or producing charcoal (14.5 %). Our data suggest that the future of small and unprotected forest fragments is bleak; a scenario that is unfortunately typical outside protected areas in many tropical regions.

Integrating Landscapes that have Experienced Rural Depopulation and Ecological Homogenization into Tropical Conservation Planning

If current trends of declining fertility rates and increasing abandonment of rural land as a result of urbanization continue, this will signal a globally significant transformation with important consequences for policy makers interested in conservation planning. This transformation is presently evident in a number of countries and projections suggest it may occur in the future in many developing countries. We use rates of population growth and urbanization to project population trends in rural areas for 25 example countries. Our projections indicate a general decline in population density that has either occurred already (e.g., Mexico) or may occur in the future if current trends continue (e.g., Uganda). Using both temperate and tropical examples we present evidence that this process will lead to ecological homogenization as a dominant habitat (e.g., forest replaces a mosaic of human-maintained landscapes), resulting in declines in biodiversity at the local scale. Building on this information, we consider research programs that need to be conducted so that policy makers are prepared to effectively manage depopulated rural areas.

What is the predictive power of the colobine protein-to-fiber model and its conservation value?

Predicting variation in animal abundance across time and space has proven very difficult; however, a model exists to predict the biomass of small folivorous primates that has considerable correlative support. This model suggests that the protein-to-fiber ratio of leaves in a habitat can predict folivore biomass. Here we present an experimental test of this protein-to-fiber model to assess if the number of infant monkeys per female and group size can be predicted based on the leaf chemistry of a habitat. We expected regenerating forest in Kibale National Park, Uganda to have leaves with higher concentrations of crude protein and lower concentrations of fiber than old-growth forest trees, and consequently, we expected a greater number of infants per female in the folivorous red colobus (Procolobus rufomitratus) with access to this area. As predicted, regenerating forests did have trees with leaves with high concentrations of protein and low concentrations of fiber, but there was no corresponding change in the demographic structure of red colobus groups. We also tested whether energy was a potential determinant of these parameters, but found no evidence for its importance. Our findings support recent studies that are critical of the protein-to-fiber model, which lead us to question the models generality, particularly for conservation and management.