增温和放牧对草地土壤和生态系统呼吸的影响

草地生态系统作为世界陆地生态系统的主体类型,其土壤呼吸和生态系统呼吸是陆地生态系统碳循环的重要组成部分,土壤呼吸是未经扰动的土壤由于代谢活动而产生CO2的过程,生态系统呼吸包括地下部分的土壤呼吸和地上部分植被的自养呼吸。研究增温和放牧对草地土壤和生态系统呼吸的影响,可为预测未来气候变化条件下的全球碳收支以及草地的可持续经营与管理提供重要的科学依据。该文扼要综述了关于草地土壤和生态系统呼吸对增温和放牧的响应方面的研究。结果表明:草地土壤和生态系统呼吸对增温和放牧的响应非常复杂,受多种因素的综合影响,无论是增温还是放牧对草地土壤和生态系统呼吸的影响均具有不确定性,因草地类型、增温幅度、增温时间、放牧强度、放牧频度和放牧方式的不同而不同。在此基础上,指出了以后应加强研究的方向,草地的利用离不开放牧,对于未来气候变化条件下的草地,温度升高和放牧这两个因素必然是同时存在的,以前多数实验是单独研究增温或放牧对它们的影响,然而,这两者对草地生态系统的影响并非可加的,因此,需要加强增温与放牧的耦合试验,同时加强关于生态系统呼吸不同组分对两者的响应的研究,以便更好地理解增温和放牧的影响机制。另外,草地土壤和生态系统呼吸对增温和放牧的响应会随着时间的推移而发生变化,因而加强长期连续的试验观测很有必要。

Effects of warming and grazing on soil and ecosystem respirations in grasslands: mini review

As one of the main types of terrestrial ecosystems,grasslands ecosystem plays an important role in global carbon cycle. Soil respiration is the process of undisturbed soil producing CO₂ as a result of metabolic activities. Ecosystem respiration includes underground soil respiration and autotrophic respiration of aboveground vegetation. Grasslands soil respiration and ecosystem respiration are important parts of terrestrial ecosystem carbon cycle. Researches on the effects of warming and grazing on soil and ecosystem respirations in grasslands can provide important scientific basis for predicting global carbon budget under future climate change conditions and sustainable operation and management of grasslands. This article briefly reviewed these studies and found that there were no consistent results about the response of soil and ecosystem respirations in grasslands to warming and grazing,which vary with warming methods,warming time and grazing intensity,frequency and the types of grassland. Based on our results,we pointed out the research fields that should be strengthened in the future. Grazing is one of the most important utilization modes of grasslands,and for the grasslands under climate change conditions in the future,the two factors,warming and grazing,will have effects on grassland soil and ecosystem respiration simultaneously. However,most experiments before were independent study on the influence of warming or grazing,therefore,interactive effects between warming and grazing on soil and ecosystem respirations in grasslands should be performed because they are non-additive effects of warming and grazing on them. Meanwhile,it is necessary to strengthen the study on the response of different components of the ecosystem respiration to warming and grazing,thus understanding the influential mechanism of the two better. In addition,the response of soil and ecosystem respiration to warming and grazing will change with time,so long-term continuous observations are necessary.