Abstract: To explore the typical scrub/shrub litters response to the precipitation change in arid desert region,the litters of Reaumuria soongarica and Salsola passerina that are constructive species in the Hexi corridor were used as the research object,and the dynamic variation of decomposition rate and nutrient content of two litters under different precipitation conditions was studied using decomposition bag method. The results showed that:(1) After 15 months of decomposition,the mass loss rate and decomposition rate of the two shrubs litters showed the order of precipitation increase > natural precipitation > precipitation decrease,and the litters of R. soongarica were more sensitive to precipitation increase in non-growing season. (2) The C and N contents of the two litters showed a release-enrichment-release pattern under different precipitation treatments,while the P content showed an enrichment-release pattern. (3) The decrease of precipitation inhibited the release of C element,especially in the growing season. However,the increase of precipitation in non-growing season promoted the release of P element. (4) For different litters under the same precipitation condition,the decomposition rate of S. passerina litters was higher than that of R. soongarica. The C and N residue rates of R. soongarica litters were higher than those of S. passerina,while the P residue rate was lower than that of S. passerina. In general,the increase of precipitation accelerated the decomposition of the litters of the two typical shrubs,and the decomposition rate of S. passerina was higher than that of R. soongarica under the same precipitation conditions;The effect of R. soongarica was more obvious in non-growing season precipitation increasing. Under the change of precipitation pattern in the future,the increase of precipitation may contribute to the C and N return of desert shrub litters,then improving the available nutrients of soil,and thus having a beneficial effect on the growth of desert vegetation.

Key words: Rainfall change, Desert plants, Litter, Mass loss rate, Nutrient dynamic

摘要： 为探究干旱荒漠区典型灌丛凋落物对降水变化的响应，本研究以河西走廊干旱荒漠区2种建群植物灌木红砂(Reaumuria soongarica)和珍珠猪毛菜(Salsola passerina)凋落物为研究对象，采用分解袋法，对不同降水条件下凋落物分解速率及养分含量动态变化进行研究。结果表明：凋落物质量损失率和分解速率表现为：降水增加＞自然降水＞降水减少，其中红砂对非生长季(11月—次年3月)的降水增加表现更敏感。C、N含量均呈释放-富集-释放的状态，P含量呈富集-释放模式；降水减少抑制了C的释放，其中生长季(4—10月)降水减少对其抑制作用更明显，非生长季降水增加促进了P的释放。同一降水条件下珍珠猪毛菜的分解速率高于红砂，红砂的C和N残留率大于珍珠猪毛菜，而P小于珍珠猪毛菜。在未来降水格局变化下，降水增加可能会有助于荒漠灌木凋落物C和N归还，从而提高土壤的有效养分。

关键词: 降水变化, 荒漠植物, 凋落物, 质量损失率, 养分动态