A central challenge in ecology is establishing the processes driving the spatio-temporal dynamics of diverse species assemblages in the face of global change. Such processes may include environmental variability, climatic perturbations, biotic interactions, spatial distribution and space utilization by particular species. Large mammalian herbivores in savannas are a wonderful example of all these interacting factors determining together community dynamics. A spatially explicit representation of the temporal dynamics of herbivores may enable a more realistic understanding of the relative importance of the processes and factors underlying the dynamics and their emergent properties, such as diversity hotspots in spatially heterogeneous systems. Dynamical spatially-explicit models have been used extensively to reveal novel theoretical insights into self-organisation, and predator-prey dynamics, but relatively few studies have thus far applied this modeling approach to test specific predictions using empirical animal abundance data, partly because of the high data requirements for fitting even modest spatially explicit models. Here we used a coupled map lattice (CML) model with 44 aerial surveys of wildlife conducted in the Mara region of Kenya from 1977 to 2002 at a spatial resolution of 5×5 km² grid cells (n =289 cells) to evaluate the relative significance of several biotic processes underpinning the dynamics of a large mammalian herbivore assemblage inhabiting the Mara-Serengeti ecosystem of Kenya and Tanzania.
Results/Conclusions
Our data support the classification of the large herbivore community into different functional guilds with full biological interpretation. Our results indicate that the distribution of large herbivores density varied with body size, feeding style and seasons. The migratory eland, wildebeest and zebra concentrated in the reserve in the dry season but moved into the adjacent pastoral ranches in the wet season. Thus, protection of the Reserve alone is insufficient to sustain the current populations of these ungulates in the long-term without concurrent protection of the adjoining pastoral ranches.
