干旱区生态环境知识资源中心

In an attempt to understand the factors affecting the distribution of the desert isopod Hemilepistus reaumuri among patches with different soil moisture, we studied its density and distribution in two patch types in relation to soil moisture. One patch type received natural rainfall, while the other was enriched by additional irrigation. We hypothesized that isopod densities in the two patch types would conform to the "ideal free distribution" model. Our results show that (1) the number of settlers are higher in the irrigated patches; (2) isopods demonstrate ideal free distributions only in low rainfall years; and (3) the overall effect of water-enriched patches is a decrease in population fluctuations. These results allow us to regard isopods as patch selectors at the scale of the experimental patchiness. The implication of this study is that in fragmented areas, e.g., due to human disturbance, water enrichment of the landscape in patches can create high quality patches with high abundance of isopods. These patches may stabilize population size.