不同刈割强度对晋北赖草草地生态系统CO_(2)交换的影响

Effects of Different Mowing Intensities on Ecosystem CO_(2) Exchange of Leymus secalinus Grassland in Jinbei

刈割是草地的主要利用方式,合理的刈割强度对维持草地生态系统碳平衡具有重要意义。本研究以山西省右玉县赖草(Leymus secalinus)草地生态系统为研究对象,动态监测2021年生长季不刈割、轻度刈割、中度刈割和重度刈割对草地生态系统净碳交换(Net ecosystem carbon exchange,NEE)、生态系统呼吸(Ecosystem respiration,ER)和生态系统总初级生产力(Gross ecosystem productivity,GEP)的影响,探究草地生态系统CO_(2)交换对不同刈割强度的响应。实验结果显示,刈割显著影响GEP,主要是由于GEP在中度刈割处理下较不刈割和重度刈割分别提高了21.4%和21.5%,NEE在中度刈割处理下较轻度刈割和重度刈割分别显著降低了54.4%和53.6%,但刈割对ER影响不显著。在不同刈割强度下,土壤温度和土壤无机氮含量是影响生态系统CO_(2)交换的重要因子。本研究结果表明中度刈割可以促进碳吸收而重度刈割会导致生态系统由碳汇转变为碳源,因此中度刈割为晋北赖草草地最适刈割强度。

Mowing is the main utilization method of grassland,and reasonable mowing intensity is important for maintaining ecosystem carbon balance in grassland.This study took the Leymus secalinus grassland ecosystem in Youyu,Shanxi Province as the research object to explore the response of grassland ecosystem CO_(2) exchange to different mowing intensities.We dynamically monitored the effects of no mowing,light mowing,moderate mowing,and heavy mowing on the net carbon exchange,ecosystem respiration,and gross ecosystem productivity during the growing season in 2021.The experimental results showed that mowing significantly affected the gross ecosystem productivity.Compared with no mowing,moderate mowing and heavy mowing increased it by 21.4%and 21.5%,respectively.In addition,net ecosystem carbon exchange under moderate mowing significantly reduced than light mowing by 54.4%and heavy mowing by 53.6%,respectively.But the effect of mowing on ecosystem respiration was not significant.Soil temperature and soil inorganic nitrogen content were important factors affecting ecosystem CO_(2) exchange under different mowing intensities.This study indicated that moderate mowing could promote carbon absorption,while heavy mowing could lead to the transformation of ecosystems from carbon sinks to carbon sources.Therefore,moderate mowing was the most suitable mowing intensity for the Leymus secalinus grassland ecosystem of Jinbei.