Interactions between soil, rainfall, and wildlife drive surface water quality across a savanna ecosystem

Authors


Correspondence to: A. M. Strauch, Department of Natural Resources and Environmental Management, University of Hawaii Manoa, 1910 East-West Road, Sherman 101, Honolulu, HI 96822, USA. E-mail: astrauch@hawaii.edu

ABSTRACT

Surface water resources play an important role in the transportation of nutrients within and between regions. Water quality varies spatially across landscapes, but the extent of this variability and the interaction between water quality and wildlife are not well-known. In some savannas, heterogeneous climatic and geologic patterns result in gradients of precipitation and soil nutrients, leading to temporal and regional differences in soil and vegetation quality. Wildlife utilise these seasonal patterns, influencing soil nutrient dynamics and vegetation. However, the impact of seasonally abundant wildlife, climate, and soils on surface water quality is unknown in savannas. Fluctuations in surface water quality were measured across the Serengeti ecosystem at 6-month intervals, and the influence of rainfall, watershed, and seasonal wildlife migration were then modelled. The results suggest that although soil composition in watersheds influences the concentration of soil-derived nutrients in rivers, rainfall and wildlife have a significant effect on the seasonal concentrations of most nutrients. The role of migratory wildlife in surface water quality in some watersheds is likely dampened by the large influence of resident species across seasons and habitats. The alteration of rainfall patterns by climate change is expected to influence nutrient transport into savanna rivers. Copyright © 2012 John Wiley & Sons, Ltd.

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