不同放牧管理模式对高寒草甸草原土壤呼吸特征的影响

为探讨不同放牧管理模式对青藏高原东缘高寒草甸草原土壤呼吸速率的影响，于2014年5－10月用土壤呼吸测量仪（LI-8100A，LI-COR，Lincoln，USA）对禁牧（NG）、全生长季休牧（RG）、传统夏季休牧（TG）和全年连续放牧（CG）4种不同放牧管理模式高寒草甸草原土壤呼吸速率进行测定，并分析了土壤呼吸速率与其影响因子间的关系。结果表明：1）不同放牧管理模式高寒草甸草原土壤呼吸速率月动态均表现出先增加后降低的变化态势，峰值出现在8月，除 CG 外，8月显著高于其余月份；2）在整个生长季，NG，RG 和 TG 平均土壤呼吸速率显著高于 CG，其中，NG 和 RG 间无显著差异，但均显著高于 TG；3）除 CG 外，NG，RG 和 TG 土壤呼吸速率与土壤温度呈显著正相关，Q10值排序为：NG＞RG＞TG＞CG；4）土壤质量含水量对土壤呼吸速率的影响存在一个临界值，30％左右为临界值，在此之前二者呈正相关，此后呈负相关；5）地上、地下生物量均与土壤呼吸速率呈显著正相关。在保障牧民收入稳定的前提下，为实现草地资源的可持续利用与牧草的更新，相对于全年禁牧，全生长季休牧既可充分利用牧草资源，也能有效保护草地系统稳定与生态恢复，是青藏高原高寒草甸草原类草地放牧管理的理想选择。

Analysis of soil respiration under different grazing management patterns in the alpine meadow-steppe of the Qinghai-Tibet Plateau

In recent decades,the carbon cycle of terrestrial ecosystems has become a hot topic in global climate change research.Soil respiration is the main route by which soil organic carbon (SOC)enters the atmosphere, and also the main contributor to increased atmospheric carbon globally.As the earth’s largest terrestrial eco-system,grassland is a very important carbon sink that stores one-quarter of the world’s SOC.The alpine meadow-steppe of the Qinghai-Tibet Plateau is known as the roof of the world,as it is the highest,largest, and most unique type of grassland in the world.The Qinghai-Tibet Plateau alpine meadow-steppe is becoming seriously degraded because of its unique geographical location and harsh natural environmental conditions,com-bined with recent global climate change,human occupation and animal grazing,and rats and insect pests.Rea-sonable grazing management is one of the main measures to restore the grassland ecosystem,and has important implications for the healthy development and sustainable use of grassland.However,there is little information on soil respiration under different grazing management models in the Qinghai-Tibet Plateau.In this study,an LI-8100A Automated Soil CO2 Flux system was used to investigate soil respiration under four grassland man-agement strategies:no grazing (NG);grazing rest at the growing stage (RG);traditional grazing rest in sum-mer (TG);and continuous grazing (CG).The aim of this study was to deepen our understanding of soil respi-ration in the alpine meadow-steppe ecosystem,to assess the impacts of global warming,and to evaluate the effects of rest grazing on the alpine meadow-steppe ecosystem.The results showed that:1)soil respiration dif-fered from month to month under the different grazing patterns,first increasing and then decreasing.In all of the treatments except for CG,the highest soil respiration rates were in August,and were significantly higher than those in the other months.There was no significant difference in soil respiration between August and Sep-tember in the CG treatment,but the rates in both months were significantly higher than those in other months. 2)In the growing season,soil respiration was significantly higher in the NG,RG,and TG plots than in the CG plot,and there was no significant difference in soil respiration between the NG and RG plots.3)There was a significant positive correlation between soil respiration and soil temperature under all of the rest grazing pat-terns,but not under CG.Based on their Q10 values,the plots were ranked as follows:NG>RG>TG>CG.4) There was a threshold at which the effects of soil water content on soil respiration changed;that is,the two were positively correlated at soil water contents of 30% or lower,and negatively correlated at soil water con-tents of >30%.5)Soil respiration was significantly correlated with aboveground and belowground biomass. Considering the economic income stability of the herdsmen,the management pattern of grazing rest at the growing stage could promote the efficient use of grassland resources,and help to restore forage productivity and maintain the grassland ecosystem.Therefore,grazing rest at the growing stage is the best management strategy for the alpine meadow-steppe grassland in the Qinghai-Tibet Plateau.