内蒙古温带草原典型草地生态系统生产力对水分在不同时间尺度上的响应

doi:10.7522/j.issn.1000-694X.2015.00065

摘要/Abstract

摘要：

水分是干旱、半干旱区草地生态系统生产力的主要限制因素,但水分如何影响生产力的季节内变异,以往研究相对不足。本研究以内蒙古温带典型草原为研究对象,基于多通道自动原位监测箱系统获得的生态系统日尺度总初级生产力(GPP)及遥感植被归一化指数估算年尺度的地上净初级生产力数据,在不同时间尺度上研究了水分对生产力的影响。结果表明:年降水量对该典型草原草地生态系统地上净初级生产力年际变异无显著影响,但土壤水分显著影响GPP的季节变异,土壤水分解释了GPP季节变异的22%;其他环境因子对生产力的季节变异也有一定影响;温度是生态系统处于干旱时GPP的主要限制因素,GPP随温度的升高而降低;而辐射是生态系统处于湿润时GPP的主要限制因素,GPP随辐射的升高而升高。本研究结果将有利于提升未来降水格局改变对草地生态系统生产力影响的认识。

关键词: 温带草原, 生产力, 降水

Abstract:

Water is a main driver to the productivity of grassland in arid and semi-arid area, however, we have quite limit knowledge about how water availability impacts the intra-annual variations of productivity. In this study, we quantified the effects of water availability on productivity at different temporal scales based on daily gross primary productivity (GPP) measured by a multichannel automated chamber system and annual aboveground net primary productivity (ANPP) evaluated by normalized difference vegetation index. Our results showed that there were no significant effects of annual precipitation on the inter-annual variations of ANPP. However, we found a similar seasonal dynamics of GPP with the soil water content, and soil water content remarkably affected GPP. Soil water content contributed to the 22% intra-annual variations of GPP. Our results also demonstrated that besides soil water, there were other environmental factors that affected the intra-annual variations of GPP. Air temperature determined the intra-annual variations of GPP when the soil water condition was relatively dry, and GPP decreased with increasing air temperature. Radiation was the dominant factor to affect the intra-annual variations of GPP when the soil water condition was relatively wet, and GPP increased with increasing radiation. The effects of other environmental factors on GPP may explain the weaker explanation power of annual precipitation to the inter-annual variations of productivity. Our results may help to thoroughly understand the effects of altering precipitation regimes on grassland productivity in the future.

Key words: temperate steppe, productivity, precipitation

中图分类号:

Q948.11

郭群, 李胜功, 胡中民, 赵玮, 王敏. 内蒙古温带草原典型草地生态系统生产力对水分在不同时间尺度上的响应[J]. 中国沙漠, 2015, 35(3): 616-623.

Guo Qun, Li Shenggong, Hu Zhongmin, Zhao Wei, Wang Min. Response of Gross Primary Productivity to Water Availability at Different Temporal Scales in a Typical Steppe in Inner Mongolia Temperate Steppe[J]. JOURNAL OF DESERT RESEARCH, 2015, 35(3): 616-623.

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