草原畜牧业温室气体排放现状、问题及展望

Abstract

草原畜牧业生产系统是一个涉及环境、经济、社会多层面、且系统内部气候-土壤-草地-家畜-管理之间相互作用的复杂的社会生态系统。草原不仅为人类提供所需要的肉奶，也提供了多种生态系统服务。然而，草原畜牧业也是主要的温室气体排放源之一。减缓畜牧业温室气体排放的研究已成为当前气候变化科学研究关注的焦点。综述了国内外草原畜牧业温室气体排放研究现状，指出现有研究的不足主要集中在以下3个方面：（1）虽然生命周期评价方法广泛应用于草原畜牧业温室气体排放研究，但是存在诸多问题，导致目前的研究框架体系尚不完善，特别体现在以下几方面：是否考虑外部输入、是否考虑土壤有机碳、畜牧业温室气体排放强度指标的选择等；（2）缺乏单一环节减缓措施对草原畜牧业整体温室气体减排效果的研究；（3）目前对影响草原畜牧业温室气体排放强度的因素主要集中在生态系统层面的分析，忽略了社会系统的作用，无法反映社会系统与生态系统的相互反馈机制，导致机制阐释不完善。综上所述，未来仍需从以下三方面开展研究：（1）完善草原畜牧业研究框架体系及提升研究方法；（2）加强对单一环节减缓措施对草原畜牧业温室气体整体减排效果的综合评价；（3）基于社会生态系统的角度深入研究影响草原畜牧业温室气体排放强度差异的机制。一方面，这有助于深入理解草原畜牧业温室气体排放强度情况，也为低碳型草原畜牧业发展政策的制定提供思路借鉴；另一方面对于科学合理的可持续利用草场和恢复草地生态环境均具有重要意义。;Grassland animal husbandry is a coupled social, environmental and economic system which is interrelated through complex interaction between climate, soil, grassland, livestock and management institutions. Grassland animal husbandry not only provides meat and dairy products to people, but also generates variety of significant ecological system services. However, grassland animal husbandry is also a major source of greenhouse gas (GHG) emissions, and how to mitigate GHG from animal husbandry has become a focus of current climate change study. In this article, we reviewed the published studies on grassland animal husbandry GHG emissions, and pointed out three shortages of current studies. First, although life-cycle evaluation method has been widely used to measure GHG emissions from livestock production, there still existed shortages and debates, particularly in terms of whether the external variables and soil organic carbon should be considered? How to select indicators to measure the level of GHG emission from livestock production? Second, few studies have focused on the impacts of mitigation measure at single stage on the overall GHG emission reduction of grassland animal husbandry; Third, current studies mainly focused on the impact analysis from ecosystem, while ignored the impacts from social system, which led to poorly describe the feedback mechanism between social and ecological system. Based on the review, we recommend the following topics for the future studies:1) Improving the life-cycle analytical framework and methods for measuring GHG emission from grassland animal husbandry; 2) Enhancing the comprehensive evaluation of single GHG mitigation measures on whole reduction effectiveness of grassland animal husbandry; and 3) Analyzing the mechanisms influencing GHG emission intensity from the coupled social-ecological system perspective. We believe that this review would help more in-depth understandings GHG emissions from grassland animal husbandry, and have more effective policy implications for low-carbon livestock production system. In addition, it also provides new insights on how to manage grassland ecosystems sustainably and restore grassland ecosystems.