Browsing by Subject "habitat fragmentation"

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    Low-intensity logging and hunting have long-term effects on seed dispersal but not fecundity in Afrotropical forests.
    (AoB PLANTS, 2019-02) Nuñez, Chase L; Clark, James S; Clark, Connie J; Poulsen, John R
    Hunting and logging, ubiquitous human disturbances in tropical forests, have the potential to alter the ecological processes that govern population recruitment and community composition. Hunting-induced declines in populations of seed-dispersing animals are expected to reduce dispersal of the tree species that rely on them, resulting in potentially greater distance- and density-dependent mortality. At the same time, selective logging may alter competitive interactions among tree species, releasing remaining trees from light, nutrient or space limitations. Taken together, these disturbances may alter the community composition of tropical forests, with implications for carbon storage, biodiversity conservation and ecosystem function. To evaluate the effects of hunting and logging on tree fecundity and seed dispersal, we use 3 years of seed rain data from a large-scale observational experiment in previously logged, hunted and protected forests in northern Republic of Congo (Brazzaville). We find that low-intensity logging had a meaningful long-term effect on species-specific seed dispersal distances, though the direction and magnitude varied and was not congruent within dispersal vector. Tree fecundity increased with tree diameter, but did not differ appreciably across disturbance regimes. The species-specific dispersal responses to logging in this study point towards the long-lasting toll of disturbance on ecological function and highlight the necessity of conserving intact forest.
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    Viability and improvement of constructive wildlife corridors in tropical forests, proposing a new method for evaluating corridors geospatially using MaxEnt
    (2022-12-14) Markus, Caitlin
    Habitat corridor ecology remains a new and developing field in wildlife and forest management. Little is known about how corridors statistically work or how they should be established and monitored. Stuart Pimm and his non-profit Saving Nature build constructive habitat corridors in tropical forests, and he now hopes that the data collected from these corridors can contribute to the growing knowledge in this field. In this study, I analyzed camera trap data from Saving Nature’s corridors in Colombia, Ecuador, and Brazil. Occupancy models were run to determine general corridor efficiency based on the species detected in the camera traps and species that were expected to appear based on environmental variables. I also attempted to propose maximum entropy models as an alternative way to achieve the same goal. Finally, least cost path corridor models were run to identify the areas animals are most likely to be found in, so that cameras can be repositioned to collect more data. Overall, all corridors were determined to be working adequately, but with room for improvement. MaxEntmodels show some potential as a method to evaluate corridor projects, but model refining and further research and development are required.