极端气候胁迫下西南喀斯特山区生态系统脆弱性遥感评价

全球气候变暖导致极端天气事件频发,针对西南喀斯特山区的特殊地理国情(水土流失和石漠化严重),引入了大尺度景观格局指数(香农均匀性指数和蔓延度指数)和极端气候指数(极端高温日数、极端低温日数和极端降雨日数),构建了生态系统脆弱性遥感评价体系,进而分析和探讨了该地区近13年的生态系统脆弱性时空变化格局和驱动机制,研究结果表明:西南喀斯特山区的生态系统则属于轻-中度脆弱,其分布格局表现为以川滇黔为核心向周边减小的趋势。2000—2013年,西南喀斯特山区的生态系统脆弱性表现为先增加后减小的趋势。近13年西南喀斯特山区的生态系统脆弱性时空变化格局受人类活动(不同产业GDP和人口密度)、降水、地形地貌、水土流失、石漠化等因素影响较为显著。本研究可以为西南喀斯特山区的生态系统保护及生态环境的恢复与治理提供决策依据和技术支持。

Study of an evaluation method of ecosystem vulnerability based on remote sensing in a southwestern karst mountain area under extreme climatic conditions

During the past several decades, extreme weather conditions have become frequent because of global warming. This study introduces a large-scale landscape pattern index (Shannon uniformity index and contagion index) and extreme climate index (extreme high/low temperature days and extreme precipitation days) to establish an evaluation system for the ecosystem''s vulnerability, considering the unique geographical conditions (serious soil erosion and rocky desertification) in the karst mountain region of Southwest China. Next, the spatial and temporal changes in the ecosystem''s vulnerability during the past 13 years were analyzed and discussed. The results indicated that the ecosystem vulnerability in the karst mountain regions belonged to the mild-moderate level, which decreased from the Sichuan-Yunnan-Guizhou zones to the marginal zones. The severe and extreme vulnerable zones were mainly distributed in the central and northern areas because of severe karst rocky desertification, low vegetation coverage, and intensive disturbance due to human activity. Conversely, the slight and mild vulnerable zones were mainly distributed in the southeastern and southwestern areas because of the high vegetation coverage, abundant precipitation, and lower disturbance due to human activity. From 2000 to 2013, the ecosystem vulnerability in the southwestern karst mountain areas increased at first and then decreased. Zones of moderate and severe increases in vulnerability were mostly concentrated in the northeastern portion of the study region, whereas zones of moderate and severe decreases were mainly distributed in the northwestern part. During the past 13 years, the temporal and spatial patterns of the ecosystem''s vulnerability changes were significantly affected by human activities (different industrial GDP and population density), precipitation, topography, soil erosion, and rock desertification. This research can provide a decision-making foundation and technical support for protection of the ecosystem and restoration of the ecological environment in the karst mountain regions of Southwestern China.