Pedosphere 19(2): 217--229, 2009
ISSN 1002-0160/CN 32-1315/P
©2009 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Ecogeomorphic feedbacks in semiarid rangelands: A review |
I. STAVI 1, H. LAVEE1, E. D. UNGAR2 and P. SARAH1 |
1 Laboratory of Soil and Geomorphology, Department of Geography and Environment, Bar Ilan University, Ramat Gan 52900 (Israel). E-mail:istavi@yahoo.com;
2 Department of Agronomy and Natural Resources, Institute of Plant Sciences, Agricultural Research Organization, the Volcani Center, Bet Dagan 50250 (Israel) |
| ABSTRACT |
| The ecogeomorphic processes occurring on semiarid rangelands are reviewed, with emphasis on the source-sink relations and positive feedback loops that existed between shrub patches and intershrub areas, and the way livestock presence affected these interactions. Compared with intershrub areas, the shrub patches had a higher soil porosity, infiltration capacity, water-holding capacity, hydraulic conductivity, structural stability, and organic matter content, and lower bulk density. These differences derived from a host of processes whose intensity was less in the shrub patches, including raindrop impact, mechanical crust formation, overland water flow, soil erosion, evaporative moisture loss, and flock trampling. There was also greater shading of the soil surface;soil and litter deposition;water accumulation; microbial, fungal, and mesofaunal activities in the shrub patches. The overland flow of water carried soil and litter from the intershrub areas to the shrub patches and resulted in microtopographic modifications that tended to strengthen these source-sink relations. Grazing had an impact on these processes, not only at the shrub-intershrub scale but also within the intershrub areas, through the creation of highly compacted trampling routes. The combined role of the above ecogeomorphic processes was to maintain the rangeland's functionality. Without these inter-relationships, water loss, soil erosion, and nutrient depletion would occur at the hillside scale, causing degradation of the landscape. |
| Key Words: intershrub areas, shrubs, soil resources, trampling routes |
| Citation: Stavi, I., Lavee, H., Ungar, E. D. and Sarah, P. 2009. Ecogeomorphic feedbacks in semiarid rangelands: A review. Pedosphere. 19(2): 217-229. |
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