School of Natural Resources and Environmental Studies
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Item Fine-scale variation in soil and topography influences herbaceous vegetation and the distribution of large mammalian herbivores(John Wiley & Sons Ltd., 2023-09) Ang'ila, Robert O.; Kimuyu, Duncan M.; Wambugu, Geoffrey M.; Kenfack, David; Musili, Paul M.; Kartzinel, Tyler R.Current understanding of the distribution of vegetation and large mammalian herbivores (LMH) is based on a combination of biogeographic studies and highly controlled field experiments, but a more complete understanding of these patterns requires study of their natural co-occurrence patterns at intermediate spatial scales. The study was conducted in the 120-ha Mpala Forest Global Earth Observatory (ForestGEO) plot, Kenya. We examined differences in herbaceous plant communities and habitat use by LMH among three topographic habitats with distinct soil types, namely steep slopes, valley and plateau. Each pair of habitats differed in plant and animal com-position. The steep slopes and plateau respectively had ≥1-fold higher percentage herbaceous cover than the valley, whereas the steep slopes and valley had >1.5-foldgreater grass species richness and diversity than the plateau. The activity of LMH was≥1.7-fold higher in the valley than the steep slopes and plateau, reflecting a positive relationship between LMH activity index and richness and diversity of grass species. Results indicate that fine-scale variation in topography and soil are associated with both the distribution of herbaceous vegetation and LMH, suggesting a need to ac-count for local habitat characteristics when examining the distributions of plants, animals, and plant-herbivore interactions in natural systems.Item Fine‐scale variation in soil and topography influences herbaceous vegetation and the distribution of large mammalian herbivores(Wiley, 2023-04) Ang'ila, Robert O.; Kimuyu, Duncan M.; Wambugu, Geoffrey M.; Kenfack, David; Musil, Paul M.; Kartzinel, Tyler R.Current understanding of the distribution of vegetation and large mammalian herbivores (LMH) is based on a combination of biogeographic studies and highly controlled field experiments, but a more complete understanding of these patterns requires study of their natural co-occurrence patterns at intermediate spatial scales. The study was conducted in the 120-ha Mpala Forest Global Earth Observatory (ForestGEO) plot, Kenya. We examined differences in herbaceous plant communities and habitat use by LMH among three topographic habitats with distinct soil types, namely steep slopes, valley and plateau. Each pair of habitats differed in plant and animal com position. The steep slopes and plateau respectively had ≥1-fold higher percentage herbaceous cover than the valley, whereas the steep slopes and valley had >1.5-fold greater grass species richness and diversity than the plateau. The activity of LMH was ≥1.7-fold higher in the valley than the steep slopes and plateau, reflecting a positive relationship between LMH activity index and richness and diversity of grass species. Results indicate that fine-scale variation in topography and soil are associated with both the distribution of herbaceous vegetation and LMH, suggesting a need to account for local habitat characteristics when examining the distributions of plants, animals, and plant-herbivore interactions in natural systemsItem Fine-scale habitat heterogeneity influences browsing damage by elephant and giraffe(Wiley Publishers, 2020-06) Kimuyu, Duncan M; Kenfack, David; Musili, Paul M.; Ang’ila, Robert O.Effects of large mammalian herbivores on woody vegetation tend to be heterogeneous in space and time, but the factors that drive such heterogeneity are poorly understood. We examined the influence of fine-scale habitat heterogeneity on the distribution and browsing effects of two of the largest African terrestrial mammals, the elephant and giraffe. We conducted this study within a 120-ha (500 x 2,400 m) ForestGEO long-term vegetation monitoring plot located at Mpala Research Center, Kenya. The plot traverses three distinct topographic habitats (“plateau,” “steep slopes,” and “valley”) with contrasting elevation, slope, soil properties, and vegetation composition. To quantify browsing damage, we focused on Acacia mellifera, a palatable tree species that occurs across the three habitat categories. Overall tree density, species richness, and diversity were highest on the steep slopes and lowest on the plateau. Acacia mellifera trees were tallest and had the lowest number of stems per tree on the steep slopes. Both elephant and giraffe avoided the steep slopes, and their activity was higher during the wet season than during the dry season. Browsing damage on Acacia mellifera was lowest on the steep slopes. Elephant browsing damage was highest in the valley, whereas giraffe browsing damage was highest on the plateau. Our findings suggest that fine-scale habitat heterogeneity is an important factor in predicting the distribution of large herbivores and their effects on vegetation and may interact with other drivers such as edaphic variations to influence local variation in vegetation structure and composition.