Abstract: Patchiness is regarded as a common phenomenon of arid and semi-arid region due to highly heterogeneity. Moss crust, one of the main types of biological soil crusts in desert ecosystems, mainly occurred in the form of patches with different sizes. In order to determine the soil fertility of moss crust patch under the edge effect in Gurbantonggut Desert, soil physical and chemical properties, microbial properties and enzymatic activities were chosen as assessment indicators. Soil samples were collected from three cycles of moss crust patches, center, middle and edge cycles respectively. The data of soil fertility was analyzed quantitatively by grey relational analysis,and ranked by correlation degrees comprehensively. The results showed that: (1) SOM, TN, TK, UE, CAT, SMBC, SMBN and AWCD were significantly influenced by the edge effect, with higher contents in center and middle circle and less in the edge. However, there were no significant difference with the contents of TP, AN, AP, AK, pH, ALP, SC, β-GC among there circles. At the same time, all the soil properties showed no significant difference in the center and the middle circle. (2) The order of soil fertility in three circle with moss crust patch under the edge effect was center circle (0.65) > middle circle (0.59) > edge circle (0.47). We conclude that the soil fertility of moss crust patches present a trend of decrease from the center to edge. It was also proved that the existence of edge effects of moss crust patches could significantly influence soil fertility, which could consequently influence the spatial distribution pattern of vascular plant community, especially for those herbaceous communities.

Key words: moss crust, patch, edge effect, soil fertility, grey relation analysis