Respondence of Grassland Soil Respiration to Global Change
摘要
Grassland is one of the main terrestrial ecotypes and the dynamic change of its soil respiration can directly affect the global C cycle.Grassland responses more rapidly to global C cycle than other terrestrial ecosystems.Therefore,grassland soil respiration could be firstly affected by global climate change and land use change.The objective of this paper is to provide a scientific review on grassland soil respiration response to global change and human activities.The elevated atmospheric CO 2 and rising temperature can both stimulate, suppress or show no significant effect on grassland soil respiration,depending on whether changes of soil moisture,soil available N and other related factors occur or not.The Q 10 ,which is the temperature sensitivity index of soil respiration,of grassland soil respiration is affected by soil temperature,soil moisture,precipitation,soil depth,soil organic carbon,altitude,land use patterns,time scales and other related factors.This implies that the relationships between grassland soil respiration and soil temperature is affected by other factors and grassland soil respiration is actually affected by the combined effects of multiple factors.Increasing precipitation will generally stimulate grassland soil respiration.However,the decrease of soil temperature and soil permeability which are caused by precipitation will reduce soil respiration amount.Due to grazing intensity,grazing frequency and grazing forms,the impact of grazing on soil respiration appears to increase,decrease or show no significant effect.The effects of clipping on soil respiration and its components(soil heterotrophic respiration and root respi-ration)are different.When agricultural reclamation occurs in grassland,soil respiration could enhance and the soil carbon will lose approximately 20%-50%.Fertilization might increase,decrease or show no significant effect on grassland soil respiration,according to fertilizer type,loading levels and so on.In the arid and semi-arid