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- Creators: Reed, Kaye E
- Creators: School of Life Sciences
Aboveground nitrogen content showed a maximum in 2011, decreasing until 2015, increasing again until 2017, and dropping in 2018; belowground nitrogen content showed the opposite temporal trend. Because foliar nitrogen content was assumed to be relatively constant over time, my data suggested that belowground nitrogen content increased between 2011 and 2015 and decreased between 2015 and 2017. Aboveground nitrogen content underwent fluctuations due to fluctuations in aboveground biomass. This occurred due to ‘thatching’, or events of widespread toppling of large macrophyte stands. The ratio of aboveground to belowground biomass can vary widely in the same CTW. My findings suggested that managing senesced aboveground plant material in CTWs may optimize the CTW’s ability to sequester nitrogen. Further research is needed to determine the best management strategies, as well as its possible implications.
Jaguar population decline is largely attributed to habitat loss and retaliatory hunting. Maintaining a viable prey base in the wild can help to mitigate this issue and decrease human-wildlife conflicts. This study aims to assess the presence of prey species in jaguar habitat in order to inform conservation efforts to maintain and improve the health and relative abundance of the wildlife community. We analyzed nearly 40,000 photographs from 85 camera traps to assess the presence of prey species at sites where jaguars are known to occur. Jaguar-prey site overlap was calculated based on the percent of jaguar sites where each prey species was present. Medium-sized mammal prey species (e.g. Central American agouti) were present across the majority (up to 87%) of sites, while large mammal prey species were present in 16%-42% of sites, varying by species. These results suggest that conservation management of jaguars would benefit from improved monitoring and maintenance of a stable prey community.
One method that has shown promise in approximating dietary diversity is dental microwear analyses. Dental microwear variance has been used to infer dietary variation in fossil species, but a strong link between variation in microwear and variation in diet is lacking. This dissertation presents data testing the hypotheses that species with greater variation in dental microwear textures have greater annual, seasonal, or monthly dietary diversity.
Dental microwear texture scans were collected from Phase II facets of first and second molars from 309 museum specimens of eight species of extant African Old World monkeys (Cercopithecidae; n = 9 to 74) with differing dietary diversity. Dietary diversity was calculated based on food category consumption frequency at study sites of wild populations. Variation in the individual microwear variables complexity (Asfc) and scale of maximum complexity (Smc) distinguished groups that were consistent with differences in annual dietary diversity, but other variables did not distinguish such groups. The overall variance in microwear variables for each species in this sample was also significantly correlated with the species’s annual dietary diversity. However, the overall variance in microwear variables was more strongly correlated with annual frequencies of fruit and foliage consumption. Although some variation due to seasonal and geographic differences among individuals was present, this variation was small in comparison to the variation among species. Finally, no association was found between short-term monthly dietary variation and variation in microwear textures.
These results suggest that greater variation in microwear textures is correlated with greater annual dietary diversity in Cercopithecidae, but that variation may be more closely related to the frequencies of fruit and foliage in the diet.