“山地-绿洲-荒漠”复合系统土地利用变化的生态系统服务权衡与协同效应——以张掖市为例

开展复合生态系统土地利用变化的生态服务效应研究可为优化国土空间格局和强化生态系统管理提供重要的基础依据。以干旱区"山地-绿洲-荒漠"复合系统的典型区域张掖市为例,基于1987年、2000年和2018年3期土地利用数据,以乡级行政区为基本单元,引入相对优势度指数划分山地、绿洲、荒漠子系统,研究复合系统的土地利用变化特征及生态系统服务权衡/协同效应。结果表明：（1）张掖市复合系统呈现地域分异特征,由南部山地系统,中部绿洲系统和北部荒漠系统构成;山地系统以林地和草地为主,绿洲系统以耕地和建设用地为主,荒漠系统以未利用地为主。（2）从时间上看,2000-2018年各系统的土地利用变化更强烈,其中,绿洲系统的耕地面积增加量最大,为363.08km²,荒漠系统的建设用地面积增加幅度最大,为78.23%。各系统土地利用转移模式为：山地系统以草地转耕地为主,绿洲系统和荒漠系统以未利用地转耕地为主。（3）张掖市复合系统的生态服务价值呈增加趋势,其中,荒漠系统生态服务价值量的增幅最大,各子系统的价值量之间的关系表现为山地系统 > 绿洲系统 > 荒漠系统,耕地对各系统生态服务价值贡献量最大。（4）张掖市土地利用变化的协同效应大于权衡效应,其中荒漠系统的生态服务之间均为协同关系,山地系统中供给服务与其他服务呈现权衡关系,占比32.73%,绿洲系统中调节服务与其他服务呈现权衡关系,占比18.18%。

Ecosystem service tradeoffs and synergies effects of land use change in Mountain-Oasis-Desert complex system: A case study of Zhangye City

Research on the ecosystem service effects of land use change in complex ecosystem can provide an important basis for optimizing land spatial pattern and strengthening ecosystem management. Taking Zhangye City, a typical area of Mountain-Oasis-Desert complex system in arid area as an example, based on three phases of land use data in 1987, 2000 and 2018, taking the township administrative region as the basic unit, the comparative advantage index is introduced to divide the mountain, oasis and desert sub-system, and the land use change characteristics of the complex system and the trade-off/synergy effects of ecosystem services are studied. The results show that:(1) The complex system of Zhangye City presents the characteristics of regional differentiation, which is composed of southern mountain system, central oasis system and northern desert system. The mountain system is mainly consisted of forest land and grassland, the oasis system is mainly consisted of cultivated land and construction land, and the desert system is mainly consisted of unused land. (2) In terms of time change, the land use change of each system was more intense from 2000 to 2018. Among them, the increase of the cultivated land area of oasis system was the largest with 363.08 km², and the increase rang of the construction land area of desert system was the largest with 78.23%. The land use transfer mode of each system is as follows:the mountain system is mainly from grassland turn into cultivated land, and the oasis system and desert system are mainly from unused land turn into cultivated land. (3) The ecosystem service value of the complex system in Zhangye City shows an increasing trend. Among them, the increase rang of the ecosystem service value of the desert system is the largest. The relationship between the value of each sub-system is mountain system > oasis system > desert system, and compared with other land use types, the contribution of the cultivated land to the ecological service value of each system is the largest. (4) The synergy effect of land use change in Zhangye is greater than the trade-off effect. Among them, the ecosystem services of the desert ecosystem are all synergistic relationships. The supply service of the mountain system has a trade-off relationship with other services, accounting for 32.73% of the trade-off relationship, and the regulation service of the oasis system has a trade-off relationship with other services, accounting for 18.18% of the trade-off relationship.