喀斯特峰丛洼地区生态系统服务的权衡机制及尺度效应

The topics of ‘Karst ecosystem services trade-offs mechanism and their scaling effects’ are selected as the core of this study. Two types of key ecosystem services, soil conservation and soil water retention, were focused on to conduct the study of ‘water and soil processes, ecosystem service trade-offs, and spatial scale integration’, because they are important for Karst rocky desertification containment. The peak-cluster depression is the most representative geomorphic type for Karst region, where the threat of rocky desertification is serious. The Sanchahe basin, located in peak-cluster depression region, was selected as the study area. By the comprehensive application of field observation and laboratory experiments, statistical analysis and mechanism models, the project was designed as follows. Firstly, the correlation between ecological processes, including relationships between slope runoff and soil erosion, and relationships between soil water dynamic, surface runoff, infiltration and evapotranspiration, at different observation sites, and the coupling mechanisms will be investigated. And then, this study will detect the trade-offs between soil conservation service and water yield, and between soil water retention services with surface water yield, loss to groundwater and evapotranspiration. Furthermore, the trade-offs mechanism can be revealed by the combination of gradient analysis on topography, spatial analysis on land cover change and scenario analysis. And last, by extending the spatial scales to consist of patch or calculation raster, landscape, catchment and basin, the multi-scaled analysis on Karst ecosystem service trade-offs will be carried out to reveal the scaling difference and relevance, and further, to finish the integrated scaling study. The research findings could make important contribution to promoting the studies on the transitive relations between ecological processes, ecosystem services and their trade-offs, and on the spatial scales synthesis, and furthermore, this study will be helpful for deepening studies of Earth’s Critical Zone science and Integrated Physical Geography in Karst region.

针对喀斯特峰丛洼地区面临的石漠化威胁，本项目围绕土壤保持和土壤水分涵养两项关键的生态系统服务类型，选择在地貌特征和生态问题等方面具有代表性的三岔河流域，开展 “水土过程耦合-服务权衡机制-空间尺度集成”的研究。研究内容设计为：综合应用野外观测和实验、统计分析、数值模型等手段，首先，从样地尺度，剖析坡面产沙和产流过程之间，以及土壤水分动态与地表产流、地下漏失、蒸散发等过程之间的相互关系与耦合机理；进而，在流域尺度上，结合典型样地的观测和模拟，以及地形梯度和地表覆被变化等空间分析和情景分析途径，探究土壤保持服务与产水量之间，土壤水分涵养服务与地表产水量、地下渗漏量及蒸散发量之间的权衡关系与影响机制；最后，辨识喀斯特生态系统服务权衡关系随斑块/栅格-景观-子流域等多级空间尺度的转换而表现出来的差异性和关联性特征。通过上述研究可期推动喀斯特生态过程-服务-权衡级联关系的明晰与地理学空间尺度的综合。

在围绕喀斯特生态系统服务权衡关系作用机制和尺度效应薄弱的背景下，项目设计三个研究内容：一是典型样地水土过程的耦合关系与作用机理研究；二是生态系统服务权衡的时空特征与主控机制探究；三是生态系统服务权衡的尺度差异与集成效应研究。.在四年多的项目执行期间，始终遵循地理学“过程耦合——服务权衡——尺度效应”理论，按照既定研究计划，首先，基于野外观测实验，借助单点陆面过程模式和统计方法，剖析典型样地水土过程关系与相互作用机理，包括分析坡面尺度产水与产沙的相互关系与非线性变化特征，对比地表径流和壤中流对于土壤流失的作用程度，刻画植被属性、土壤特性及地形参数对地表水文过程、土壤流失过程及其耦合关系的综合影响；进而，借助流域尺度陆面过程模式和半分布式水文模型，估算不同生态系统服务的物理量；以此为基础，围绕土壤保持和土壤水分涵养两项生态系统服务类型，采用定性、半定量与定量的权衡表征方法，通过地形梯度和情景分析方法，阐释生态系统服务权衡关系的时空变化特征及其主导控制因子和驱动机制，剖析不同自然地理特征条件影响下的生态系统服务权衡关系动态变化过程与空间异质性，为阐释生态系统服务之间关系的驱动机制提供依据。最后，将单一样地和斑块/栅格尺度的研究结果，拓展到不同尺寸景观（水文响应单元）、子流域等统计尺度，以辨识生态系统服务权衡关系随尺度转换而呈现的差异性与关联性特征。得益于上述研究工作的顺利开展，已全面完成项目既定计划和内容，全部实现项目研究目标。.在项目的支持下，共发表论文33篇，其中SCI论文22篇，CSCD论文11篇；培养博士生研究生3名，硕士研究生1名；出版专著1部；同时参加国际学术会议4次，广泛宣传相关研究成果。总之，研究结论不仅可以推进生态系统服务权衡关系的表达与认知深化，而且是石漠化遏制和生态恢复过程中的重要参考依据。