Livestock, soil compaction and water infiltration rate : Evaluating a potential desertification recovery mechanism

Castellano, M J
Valone, T J
Journal of Arid Environments
Publication Year: 
Models predict that desertification, the loss of perennial grasses in arid and semiarid environments, will be difficult to reverse due to the positive feedback between plant cover and water infiltration; reductions in plant cover concurrently reduce water infiltration to a level that is insufficient for grass growth and recruitment. Thus, a desertified state becomes stable. However, these models cannot account for recently reported perennial grass recovery in desertified habitats. Here, we suggest a novel mechanism to explain these observations: the natural increase in water infiltration rate associated with recovery from livestock-induced soil compaction. We empirically evaluate this mechanism by comparing vegetation, water infiltration rates and soil compaction at three nearby, desertified livestock exclosures that differ in time since livestock removal and perennial grass recovery; the oldest exclosure (54 years) has experienced a significant increase in perennial grasses, while there has been no such increase at the two younger exclosures (25 and 10 years). Across sites, relative differences (inside compared to outside) in water infiltration rate and soil compaction increased across each grazing fence with time since livestock removal. The relative difference in soil compaction and relative difference in water infiltration rate were significantly greatest at the sole exclosure in which perennial grasses have recovered. These data support a key aspect of desertification models: the importance of water infiltration rate for resilience of vegetation in desertified systems. Although water infiltration rate plays a critical role in understanding the stability of desertified systems, theoretical models of desertification have only incorporated plant cover as the key mechanism affecting infiltration rate. Our work suggests soil compaction may also be an important mechanism.
Name of Journal: 
Journal of Arid Environments
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Journal Issue/Article
Grassland Society of Southern Africa

The Grassland Society of Southern Africa (GSSA) is involved and concerned with the science and practice of range and pasture management. This broad field involves primarily the use and conservation of natural resources. It encompasses applied fields such as livestock production, wildlife management, nature conservation, water catchment management and range and mine-dump rehabilitation. The disciplines include, amongst others, ecology, botany zoology, range and pasture science, animal science, soil science and genetics. This collection includes journal articles from the African Journal of Range and Forage Science as well as related articles and reports from throughout the Southern African region.