气候变化和土地利用是影响生态系统服务的两类主要因素，然而其具体影响却很难量化区分。本研究基于生态系统服务与权衡综合评估模型（Integrated Valuation of Ecosystem Service and Trade-offs，InVEST）及修正土壤风蚀方程模型（Revised Wind Erosion Equstion，RWEQ），对青藏高原1990—2020年6个时期的水土保持服务和防风固沙服务进行情景分析，量化区分土地利用和气候变化对两项服务的影响。结果表明：气候变化主导了青藏高原大部分区域的水土保持和防风固沙服务（贡献度>70%），年降水量和年均气温是引起水土保持服务变化的主要影响因素，年均风速则是影响防风固沙服务的主要因素。然而，1990—2000年西北部是土地利用类型转化明显的区域，生态保护政策成功实施导致土地利用成为水土保持和防风固沙服务增加的主导因素；2000—2010年，青藏高原东北部农田向城镇用地转变主导了防风固沙服务的增加，西北部草地向未利用土地转变主导了水土保持服务和防风固沙服务的减少；2010—2020年，在西北部草地转变为未利用土地的地区以及东南部林地转变为草地的地区，土地利用主导了水土保持和防风固沙服务的减少。本研究有助于深入理解人类活动和气候变化对生态系统服务的影响，对青藏高原的土地利用政策制定及生态修复决策具有重要意义。

Climate change and land use are two main factors affecting ecosystem services， but their specific impacts are difficult to quantify and distinguish. This study conducted scenario analysis on soil retention and sand-fixation service in the Qinghai-Xizang （Tibet） Plateau for six periods from 1990 to 2020， based on the InVEST （Integrated Valuation of Ecosystem Service and Trade-offs） model and the RWEQ （revised wind erosion equation） model， in order to quantify and distinguish the effects of land use and climate change on these two services. The results show that climate change dominated the soil retention and sand-fixation service of most areas in the Qinghai-Xizang （Tibet） Plateau （contribution > 70%）， with annual precipitation and average annual temperature being the main influencing factors for soil retention service， and average annual wind speed being the main factor for sand-fixation service. However， in regions with significant land use type transformation in the northwest from 1990 to 2000， the successful implementation of ecological protection policies resulted in an increase in soil retention and sand-fixation service. From 2000 to 2010， the conversion of farmland to urban land in the northeast led to an increase in sand-fixation service， while the conversion of grassland to unused land in the northwest led to a decrease in soil retention and sand-fixation service. From 2010 to 2020， in areas where grassland in the northwest was converted to unused land and forest land in the southeast was converted to grassland resulted in a decrease in soil retention and sand-fixation service. This study helps to deepen our understanding of the impacts of human activities and climate change on ecosystem services， and has important implications for land use policies and ecological restoration decisions in the Qinghai-Xizang （Tibet） Plateau.