模拟降水变化对荒漠草原优势植物叶片氮回收特征的影响

未来降水量的变化会改变草地对水资源的利用情况，影响植物内部养分循环。为了理解植物叶片氮回收特征对降水量变化的响应规律，本研究以5种内蒙古荒漠草原优势植物为研究对象，通过模拟降水试验(减水50%、自然降水、增水50%和增水100%)，分析了降水量变化对土壤水分含量、土壤有效氮(Nitrogen，N)含量、植物叶片N浓度、N回收效率(Nitrogen resorption efficiency，NRE)的影响。结果表明：与自然降水相比，增水100%显著增加了土壤水分含量、地上生物量和植物的NRE，显著降低了土壤有效N浓度、绿叶和枯叶中N浓度；而减水50%显著降低了土壤水分含量，增加了土壤有效N，降低了地上生物量，对绿叶和枯叶N浓度没有显著影响，降低了短花针茅(Stipa breviflora)的NRE；植物NRE与枯片中的N浓度呈显著负相关关系。综上，增水通过影响土壤水分含量以及叶片N浓度间接降低了荒漠草原优势植物叶片的NRE。

Effects of Simulated Precipitation on Leaf Nitrogen Resorption Characteristics of Dominant Plants in Desert Steppe

The precipitation in the future will change the utilization of water resources and affect the nutrient cycle in plants in the desert steppe. To better understand the response of plant leaves nitrogen (N) resorption characteristics to precipitation changes,in this study,five dominant plants in the desert steppe of Inner Mongolia were used as the research objects,and the effects of precipitation changes on soil moisture and soil available nitrogen were analyzed through simulated precipitation experiments (decrease water by 50%,natural water,increase water by 50%,increase water by 100%) the effect of N concentration in plant leaves,and N resorption efficiency (NRE). The results showed that compared with natural water,increasing water by 100% significantly increased soil moisture and significantly reduced soil available N. The aboveground biomass increased significantly under the increased water treatment,and the N concentration in mature green leaves and senescent dead leaves decreased significantly under the increased water treatment. The increase in water treatment significantly reduced the NRE of plants. A decrease of water by 50% significantly reduced soil moisture,increased soil available N,and decreased aboveground biomass,reduced NRE of Stipa breviflora but had no significant effect on N concentration in mature green leaves and senescent leaves. There was a significant negative correlation between plant nitrogen resorption efficiency and N concentration in senescent withered slices. By increasing aboveground biomass,increasing water diluted the N concentration of plant leaves,resulting in the decrease of NRE. To sum up,increasing water indirectly reduced the NRE of dominant plants in desert steppe by affecting soil moisture and leaf N concentration.