ECOSYSTEM MANAGEMENT OF DESERTIFIED SHRUBLANDS IN ISRAEL

The objectives of this study were to understand the ecological process es and possible management strategies in desertified shrublands. We hy pothesized that biological production and diversity in desertified shr ublands in the Negev in Israel are low due to water, soil, and nutrien t leakage from the ecosystem. We designed a series of field experiment s in order to examine (a) whether source-sink relationships exist betw een the crusted soil and the shrub patches, (b) whether resources (wat er, soil, and nutrients) leak from the system, and (c) whether managem ent, which changes the landscape mosaic by introducing new sink patche s that reduce leakage of resources, may increase productivity and dive rsity. The results indicate that the low number of shrub patches, whic h serve as sinks for resources, leads to water, soil, and nutrient lea kage from the ecosystem. This leakage reduces ecosystem production and diversity. We found that artificially created pits, which act as sink s for resources, decrease leakage and increase biomass production and annual plant species diversity. Based on the experimental results, we developed conceptual models for shrubland desertification and ecosyste m management. The models are based on a source-sink relationship betwe en two patch types characteristic of shrublands. The models relate lan dscape productivity to the number of sink patches and suggest that, in cases where there are too few sinks, artificially created sink patche s should be added. Management methods were developed to reduce resourc e leakage in the desertified shrubland of the Negev. Methods included construction of man-made pits in the landscape that add resource-enric hed patches to the landscape. These patches are used to create parks c onsisting of clusters of trees integrated into a matrix of shrubs and herbaceous vegetation. The managed parks are used for recreational pur poses and for rangeland.