不同降雨情景和草场管理方式对内蒙古典型草原土壤呼吸的影响

土壤呼吸是陆地生态系统碳循环的关键过程之一，降水和草场管理方式是影响其季节性、温度敏感性(Q10)和年累计量的重要因素。内蒙古典型草原是我国重要的草地植被类型之一，降水变化是其气候变化的主要特征，而放牧、打草和围封等草场管理方式是其主要的应用背景。但以往对内蒙古典型草原土壤呼吸Q10的研究中未剔除土壤呼吸季节性对Q10估算的干扰效应；而对土壤呼吸年累计量的研究中，既未将降水变化与草场管理方式相结合，也未以实验手段区分环境因素和生物学过程对土壤呼吸年累积量的影响。这些不足制约着我们深入理解内蒙古典型草原的土壤呼吸。本研究以野外降水改变和草场管理方式实验为基础，研究这两个因素对土壤呼吸季节性、剔除季节性干扰的Q10和年累计量的影响。同时采用室内实验和野外实验相结合的手段研究生物学过程对土壤呼吸年累积量的影响。这些研究内容的实施有助于我们准确模拟和预测内蒙古典型草原土壤呼吸对未来气候变化的响应。

Soil respiration (Rs) is a critical component of the terrestrial carbon cycling processes. Precipitation and different pasture management strategies can substantially influence on the seasonality and temperature sensitivity (Q10) of Rs and the annual cumulative Rs. The typical steppe of Inner Mongolia, which is an important component of grassland vegetation of China, has been experiencing a pronounced change in annual precipitation during the last decades. In this area, the most popular pasture management strategies are grazing, mowing and fencing. However, in the typical steppe of Inner Mongolia, former researches on Q10 of Rs ignored the confounding effect of the seasonality of Rs on the estimated Q10 value. In addition, they neither studied the interactions of precipitation changing and different pasture management strategies on annual cumulative Rs, nor used an experimental method to separately investigate the effects of environmental factors and biological processes on the annual cumulative Rs. These disadvantages limited our ability to deeply understand the Rs of this area. In this project, we will use a filed precipitation changing and different pasture management strategies experiment to investigate their effects and interactions on the 1) seasonality of Rs, 2) the estimated Q10 of Rs with excluding the confounding effect of the seasonality of Rs and 3) the annual cumulative Rs. Furthermore, an experimental method combining a cultivation experiment with the filed experiment will be used to determine the effects of biological processes on the annual cumulative Rs. This project will be helpful to reduce uncertainties in predicting responses of Rs to the on-going climate change in typical steppe of Inner Mongolia.