植被恢复对西南喀斯特地区土壤气候韧性的提升作用

Vegetation restoration enhances the resilience of soil quality to climate change in the southwest karst region

土壤质量提升是生态系统应对气候变化能力增强的关键。为探究气候变化背景下不同植被恢复方式对喀斯特地区土壤质量的影响,基于黔桂喀斯特地区气候梯度样带84个样方土壤物理、化学和生物性质综合分析,分别以耕地和次生林作为退化和顶级恢复对照,探讨了自然恢复(灌木林)和人工恢复(人工林)的土壤质量提升效应及其对气候变化的响应。结果表明:(1)植被恢复不仅显著提高了土壤细菌、真菌、放线菌等微生物丰度以及有机碳、全氮、速效氮等养分含量,也对土壤质地有一定改善;(2)自然恢复和人工恢复均提高了土壤质量,两种恢复方式之间土壤质量指数无显著差异,但与次生林依然存在差距。灌木林和人工林的土壤质量仅约为次生林土壤质量的62%—66%;(3)耕地土壤质量随年均温和年平均降雨量的增加而下降,次生林的土壤质量随年平均降雨量的增加而上升,植被恢复对土壤质量的提升率与年均温和年平均降雨量呈正相关关系。阐明了在一定范围的气候变化下进行植被恢复可以显著提升喀斯特地区土壤的气候韧性,揭示了喀斯特地区植被恢复对土壤质量的提升主要是由于提高了土壤碳氮养分含量及改善了土壤微生物群落结构,这为全球气候变化背景下喀斯特退化土地生态恢复和管理提供了理论依据。

The karst region is one of the fragile ecological regions in the world.Under the background of global climate change,the karst region in Southwest China is highly sensitive and vulnerable to changes in climate,has become a hotspot of vegetation restoration.Improving soil quality is the key to enhancing the ability of ecosystems to cope with climate change.In order to explore the effects of different vegetation restoration methods on soil quality in karst areas under the background of climate change,this study was based on comprehensive analysis of physical,chemical and biological properties of soil in 84 quadrat transect zones with climatic gradient in Qian⁃Gui karst area.Cropland and the secondary forest were taken as the control of degradation and top restoration,respectively.The effects of natural restoration(shrubland)and artificial restoration(plantation forest)on soil quality improvement and their responses to climate change were discussed.The results showed that:(1)vegetation restoration not only significantly increased the abundance of soil bacteria,fungi,actinomyces and other microbial abundance,as well as the contents of organic carbon,total nitrogen,available nitrogen and other nutrients,but also improved the soil texture.(2)Both natural and managed restoration improved soil quality.There was no significant difference in soil quality index between the two restoration methods,but there was still a gap between them and the secondary forest.The soil quality of shrubland and plantation forest was only about 62—66%of that of the secondary forest.(3)The soil quality of cropland decreased with the increase of mean annual temperature and mean annual precipitation,and the soil quality of secondary forest increased with the increase of mean annual temperature and mean annual precipitation.The improvement rate of soil quality of vegetation restoration was positively correlated with mean annual temperature and mean annual precipitation.In general,vegetation restoration can improve soil quality index,and the increase of average annual moderate annual rainfall can also improve soil quality improvement rate.This study illustrates that vegetation restoration in a certain range of climate change can significantly improve the climatic toughness of soil in karst areas,and reveals that the improvement of soil quality by vegetation restoration in karst areas is mainly due to the increase of soil carbon and nitrogen content and the improvement of soil microbial structure.This provides a theoretical basis for ecological restoration and management of karst degraded land under the background of global climate change.