近日，中国科学院亚热带农业生态研究所环江喀斯特生态系统观测研究站研究员王克林团队在西南喀斯特地区植被恢复对土壤碳固持研究方面取得新进展。

土地利用变化是全球气候变化的主要来源和组成部分。不合理的土地利用方式会减少土壤碳固持，加速温室气体排放。植被恢复是提高土壤碳固持的重要途径，但当前不同植被恢复方式和环境因子对土壤碳固持影响的综合研究较为缺乏。

西南喀斯特地区是我国最大面积的连片贫困区域，是非地带性的生态脆弱带，石漠化综合治理直接关系该区社会经济可持续发展以及长江、珠江上游生态安全屏障建设。围绕喀斯特地区石漠化治理与生态恢复，国家先后在喀斯特地区实施了天然林保护、退耕还林还草等一系列生态恢复工程。人工植被恢复和自然封育，是喀斯特石漠生态系统修复的两种主要方式，但目前两种方式下长期土壤碳固持潜力尚缺乏有效评价。另一方面，喀斯特区地质背景独特，土层浅薄且不连续、异质性强，从而形成了喀斯特生态系统与生境类型的多样性，关于生境异质性对植被恢复下的土壤碳固持效应的影响也缺乏明确认识。

针对这一科学问题，在王克林和张伟指导下，研究组以耕地为对照，通过分析人工恢复方式（人工牧草、人工经济林）和自然恢复方式（撂荒草地、灌木林、次生林）下土壤有机碳变化特征并记录相应的环境因子信息，解析了不同恢复模式（人工恢复和自然恢复）土壤有机碳积累变化规律，并揭示了其相应的环境驱动因子。研究发现，自然恢复模式土壤有机碳含量显著高于人工恢复模式和耕地，而短期内（9年）人工恢复模式和耕地之间有机碳含量无显著差异。不考虑基岩出露对土壤有机碳储量影响，各植被类型之间有机碳储量无显著差异，剔除基岩出露影响后，自然恢复植被下有机碳储量显著高于人工恢复植被和耕地。方差分解表明，人工恢复方式下土壤有机碳含量和储量仅部分变异受环境因子（如基岩出露率、土壤容重、海拔）影响；而在自然恢复方式下，环境因子能有效解释有机碳含量和储量的大部分变异，且随着植被正向演替解释量逐渐增加，但有机碳含量和储量的环境驱动因子并不相同，前者受多个环境因子共同驱动（如土壤容重、基岩出露率、土层深度、pH等），后者则主要受基岩出露率驱动。基于对不同恢复模式下有机碳含量和储量变化分析及其环境驱动因子评估结果表明，相比人工恢复模式，短期内自然恢复更有利于土壤碳固持，且上述环境因子可作为评估自然恢复模式下土壤碳库变化的重要指标。

相关研究成果发表在Land degradation & Development上。该研究得到了国家重点研发计划、国家自然科学基金等的资助。（来源：中国科学院亚热带农业生态研究所）

EFFECTS OF ENVIRONMENTAL FACTORS ON SOIL ORGANIC CARBON UNDER NATURAL OR MANAGED VEGETATION RESTORATION

Abstract  To expand the scientific understanding of soil organic carbon (SOC) accumulation in restored ecosystems, we used 246 soil samples from a rocky catchment (10.24 km2) in an ecologically fragile karst area of southwest China and measured the effects of environmental factors under different vegetation restoration types (managed, including forage grassland and plantation forest, or natural, including grassland, shrubland, and secondary forest) on soil organic carbon content (SOCC) and soil organic carbon density (SOCD). Significantly higher SOCC and SOCD were found in natural vegetation than in managed vegetation and tillage land, but no differences in SOCC or SOCD were detected between managed vegetation and tillage land. The environmental factors include rock outcrop ratio (ROR), bulk density (BD), altitude, soil depth, slope gradient, and pH, all showing significant effect on SOC. The proportion of variations in SOCC and SOCD explained by environmental factors was higher in natural vegetation restoration than in managed vegetation restoration, and this proportion increased along the successional gradient. However, the environmental factors driving variations in SOCC and SOCD differed according to vegetation type. Soil BD had the strongest effect on SOCC variation in all vegetation types, except for forage grassland, in which the variation was instead controlled by ROR. The variation of SOCD was mainly driven by ROR in most vegetation types, except for tillage land and forage grassland, in which the driving factor was altitude. This results indicated that natural vegetation restoration is more beneficial to SOC sequestration than managed vegetation restoration and thus for mitigating global climate change. Accordingly, future studies should take these different environmental drivers under different vegetation restoration types into consideration when modeling SOC and guiding restoration management.

原文链接：http://onlinelibrary.wiley.com/doi/10.1002/ldr.2876/pdf