Abstract: In the arid desert ecosystems, natural precipitation may have an important impact on the distribution pattern of desert microarthropods. However, our knowledge on the influence of precipitation changes on the distribution, composition and diversity of desert microarthropod community remains limited. We investigated the affected by natural precipitation changes in the activity density and taxa richness of microarthropods beneath Reaumuria songarica shrubs and Nitraria sphaerocarpa shrubs in an arid desert ecosystem. The results of this study showed that precipitation events strongly impacted on microarthropod, mite and springtail community in wet season (July and August), while a similar pattern was not found in dry season (May and June). For example, the abundance and taxa richness of mites, springtails and microarthropods after the precipitation event in July and August (July-24.8 mm and August-6.8 mm) were significant higher than in May and June (May-4.0 mm, June-14.8 mm and June-6.6 mm). Then, the response to microarthropod community beneath R. songarica shrubs to precipitation events were similar to N. sphaerocarpa shrubs, and varied from the season. For example, the peak of the microarthropod community beneath two shrubs response to precipitation events was observed in the second in June-14.8 and the third on June 6.6, while a decreased at first and then increased trend was found beneath R. songarica shrubs on July-24.8 mm and August-6.8 mm and beneath N. sphaerocarpa shrubs on July-24.8 mm. In addition, we found that the abundance and taxa richness of mite community beneath N. sphaerocarpa shrubs were significant higher than that beneath R. songarica, and no similar pattern was obtained on springtail community, which might structure the pattern of short-term responses of microarthropods to natural precipitation change in wet seasons.

Key words: arid desert, precipitation events, shrubs, microarthropods, principal response curves (PRC)