黄土高原典型草原植被及土壤化学计量对降水变化的响应

研究植被和土壤生态化学计量及其耦合关系，是解析气候变化背景下草地植被养分动态平衡和能量流动的重要途径。本研究以宁夏固原云雾山典型草原为研究对象，采用控雨-滴灌装置模拟3个降水梯度(自然降水的50%，100%和150%)，分析了植物叶片、根系、凋落物及土壤的碳(Carbon，C)、氮(Nitrogen，N)、磷(Phosphorus，P)化学计量特征随降水变化的响应规律，结果表明：叶片C，N，P含量和凋落物C，N，C∶N，C∶P和N∶P值在50%降水处理下较高，根系C，P，N∶P在150%降水处理下较高；土壤全氮含量在150%降水处理显著低于50%和100%降水处理。降水变化下，叶片、根系、凋落物与土壤之间的碳氮磷化学计量均有显著相关关系。本研究表明：黄土高原草地植物叶片、凋落物、根系及土壤之间元素耦合关系较强；植物生长易受N，P元素限制，降水量不足P元素限制作用加强。

Response of Vegetation and Soil Stoichiometry to Precipitation Gradients of Typical Steppe in the Loess Plateau

Studying the ecological stoichiometry of vegetation and soil and their coupling relationship is an important way to analyze the dynamic balance and energy flow of grassland vegetation under the background of climate change. This study takes the typical grassland of Yunwu Mountain in Guyuan,Ningxia as the research object,a rain control-drip irrigation device was used to simulate three precipitation gradients (50%,100%,and 150% of natural precipitation). The response and interrelationship of stoichiometric characteristics of carbon (C),nitrogen (N),and phosphorus (P) in leaves,roots,litter,and soil of plant community with precipitation gradient were analyzed. Results showed that:leaf C,N,P content and litter C,N,C∶N,C∶P and N∶P values were high under 50% precipitation treatment,root C,P,N∶P were high under 150% precipitation treatment;The content of soil total nitrogen (TN) in 150% precipitation was significantly lower than that in 50% and 100% precipitation treatments. Under precipitation gradients,there was a significant correlation between the carbon,nitrogen,and phosphorus stoichiometry of leaves,roots,litter,and soil,The results showed that there was a strong element coupling relationship among plant leaves,litter,root system,and soil in the grassland of the Loess Plateau. The plants in the study area were restricted by N and P elements,and the P element restriction was strengthened by insufficient precipitation.