【作者】 刘洋；

【导师】 安韶山； 杨阳；

【作者基本信息】 西北农林科技大学 ， 水土保持与荒漠化防治， 2023， 博士

【摘要】 生态系统为人类提供了各种自然资源与生存环境,是人类社会发展的基础。近些年随着城市化进程加快和退耕还林（还草）等工程的实施,黄土高原土地利用发生剧烈变化,相应的生态系统也随之改变,这些变化极大的影响了人与自然生态系统间物质和能量转移过程,甚至对区域粮食红线、生物多样性红线、水土保持红线等造成潜在隐患。黄河流域作为我国重要的生态屏障,其生态保护和高质量发展对治理黄土高原水土流失、保障黄淮海等平原粮食生产、丰富东平湖等湿地生物多样性以及三江源等保护区水源涵养具有重要的战略意义。本研究选取1990、2000、2010、2015和2020年土地利用数据,通过InVEST模型评估黄河流域水源涵养量、碳储量、土壤保持和生境质量等生态系统服务,然后从流域和省域尺度探究生态系统服务的时空分布及演变特征,揭示土地利用变化对生态系统服务的影响机制,探究生态系统服务间权衡/协同关系,同时以供水服务和固碳服务为例可视化黄河流域人与生态系统之间供需过程,从而有助于黄河流域生态保护、协调黄河水沙关系、缓解水资源供需矛盾、促进全流域高质量发展。主要研究结果如下所示:（1）1990-2020年间,退耕还林（还草）、三北防护林等植被恢复工程的实施以及城市化进程的加快极大影响了黄河流域土地利用变化。1990-2020年间耕地面积持续减少,林地面积持续增加,草地面积先增加后降低。从变化率来看,建筑用地的变化率最高（153%）,其次是未利用地（-35.5%）、林地（18.93%）、耕地（-11.27%）、水域（7.46%）、草地（1.64%）。不同土地利用类型间转化情况为:耕地主要转化为草地（19.76%）和建筑用地（5.28%）;林地主要转化为草地（3.09%）和耕地（2.18%）;草地主要转化为耕地（6.63%）、林地（3.21%）和未利用地（1.63%）;未利用地的转化比例最大,约57%的未利用地发生了相互转化,其中49.75%的未利用地转化为草地,4.29%未利用地转化为耕地,1.58%的未利用地转化为建筑用地。（2）黄河流域不同土地利用类型生境质量表现为林地>草地>水域>未利用地>耕地>建设用地。1990-2020年间耕地生境质量持续降低,林地和未利用地先提高后降低,而林地表现为逐年提高。除延安生境质量较高外,其他区域整体呈现“西高东低、北高南低”的空间分布特征。整体来看,青海省、山东省、四川省的生境质量维持较好,甘肃省、陕西省、内蒙古自治区生境质量波动较为明显。耕地向林地、草地、水域转换时,对生境质量提高有积极作用。（3）2000-2020年黄河流域中游水土流失治理效果显著。黄河流域水源涵养量在2000年前后呈现明显的先减少后增加趋势,这也表明植被恢复和水土流失治理效果显著。不同土地类型中水源涵养量最大的是草地>耕地>林地>未利用地>建筑用地>水域,而不同土地利用类型单位面积水源涵养量表现为:未利用地>建筑用地>林地>草地>耕地。不同省水源涵养的主要贡献值不同,如甘肃省水源涵养量主要由草地贡献,而河南省水源涵养量主要由耕地贡献。2000年前后黄河流域土壤保持总量呈先增加后减少趋势,土壤侵蚀程度逐年放缓。从空间来看,黄河流域土壤保持总量呈现“南多北少,东多西少”特征。总体来看,甘肃省、内蒙古自治区、宁夏回族自治区、青海省和四川省的水土保持总量主要由草地贡献,其贡献比例均高于50%,而陕西省、陕西省、河南省和山东省的林地贡献占比最大,远大于其它土地利用类型（4）黄河流域不同生态服务间权衡与协同关系区域差异明显。水源涵养量与土壤保持之间权衡关系主要分布在甘肃省、内蒙古自治区、山西省和陕西省,而协同关系主要分布在青海省和甘肃省。生境质量与土壤保持（HQ-SC）的协同关系分布范围远大于其它生态系统服务间的协同区域,占整个黄河流域面积64.2%,主要分布在甘肃省、内蒙古自治区、青海省、山西省和陕西省。草地、林地和耕地是影响生态系统服务权衡关系主要土地利用类型。水源涵养量与土壤保持之间权衡在林地和耕地分布更为广泛,而水源涵养量与生境质量、水源涵养量与碳储量之间的权衡主要由草地贡献,其权衡分布区域远大于协同区域。土壤保持与碳储量之间的协同关系分布草地、林地和耕地,其中耕地和林地其协同区域远大于权衡区域。生境质量与碳储量之间的协同关系主要分布在林地,其协同分布区域远大于权衡区域。（5）黄河流域供水服务和固碳服务存在明显的供需矛盾,即供给区和受益区不一致导致空间错配和供需不平衡。从水服务流结果可以看出黄河流域中上游具有较高的供水潜力,较高的需水量主要发生在工业区和城市区,分布在黄河流域下游。供水量主要与农田、草地和水域面积有关,对供水量产生显著影响。就碳源总量而言,鄂尔多斯碳排放量最高(9×10⁷ TC·y^-1),就单位面积排放量而言,临沂和张掖远超其他城市。从单位面积固碳能力来看,汉中市固碳能力最强,其次是商洛和安康市。从固碳服务的流动比率结果可以看出除海南藏族自治州和果洛藏族自治州为固碳服务需求型区域外,黄河流域其他区域皆为固碳服务供给型区域。黄河流域由西向东固碳服务自给率逐渐增强。以弱碳源为中心,流动比率沿四周递增,范围内零星分布流动比率较高的市县。更多还原

【Abstract】 Ecosystems provide human beings with various natural resources and living environments,and are the foundation of human social development.In recent years,the irrational use of natural resources by human beings has led to serious damage to the structure and stability of ecosystems,which has greatly damaged ecosystem services and threatened human well-being.The Yellow River Basin is an important ecological barrier in China,and its ecological protection and high-quality development are of great strategic significance for controlling soil erosion on the Loess Plateau,ensuring grain production in plains such as the Huang-Huai-Hai Dynasty,enriching the biodiversity of wetlands such as Dongping Lake and water conservation in protected areas such as Sanjiangyuan.In this study,land use data from1990,2000,2010,2015 and 2020 were selected to evaluate ecosystem services such as water conservation,carbon storage,soil conservation and habitat quality in the Yellow River Basin through the InVEST model,and then explored the spatial and temporal distribution and evolution characteristics of ecosystem services from the sub-basin and provincial scales,revealed the impact mechanism of land use change on ecosystem services,and explored the trade-off/synergy relationship of ecosystem services.Taking water supply services and carbon sequestration services as examples,this paper conducts a preliminary study on ecosystem service flows in the Yellow River Basin,which provides important theoretical data for ecosystem service assessment and ecological service flow research.It will contribute to the ecological protection and governance of the Yellow River Basin,ensure the long-term peace and stability of the Yellow River,and promote the high-quality development of the entire basin.The main findings are as follows:（1）From 1990 to 2020,the implementation of vegetation restoration projects such as returning farmland to forest（grassland）and shelter forests in the three north and the acceleration of urbanization greatly affected the land use change in the Yellow River Basin.From 1990 to 2020,the cultivated land area continued to decrease,the forest land area continued to increase,and the grassland area first increased and then decreased.In terms of the rate of change,the change rate of construction land was the highest（153%）,followed by unused land（-35.5%）,forest land（18.93%）,arable land（-11.27%）,water area（7.46%）,and grassland（1.64%）.The conversion between different land use types was as follows:cultivated land was mainly converted to grassland（19.76%）and building land（5.28%）;Forest land was mainly converted to grassland（3.09%）and arable land（2.18%）;Grassland was mainly converted into arable land（6.63%）,forest land（3.21%）and unused land（1.63%）.About 57%of unused land was converted into grassland,49.75%of unused land was converted into grassland,4.29%was converted into arable land,and 1.58%was converted into construction land.（2）From 1990 to 2020,the habitat quality of different land use types in the Yellow River Basin is manifested as forest land>grassland>water area>unused land>arable land>construction land.From 1990 to 2020,the quality of arable land habitat continued to decrease,and forest land and unused land first increased and then decreased,while forest land improved year by year.Except for the high quality of Yan’an habitat,the spatial distribution characteristics of"high in the west and low in the east,high in the north and low in the south"were generally displayed in other areas.On the whole,the habitat quality of Qinghai,Shandong and Sichuan Provinces remained good,while the fluctuation of habitat quality in Gansu Province,Shaanxi Province and Inner Mongolia Autonomous Region was obvious.When cultivated land is converted to forest land,grassland and water area,it has a positive effect on the improvement of habitat quality.Overall,the sum of land use HQCI values in each year from 1990 to 2020 was-455,indicating that the habitat quality of the Yellow River Basin was decreasing.（3）From 2000 to 2020,the effect of soil erosion control in the middle reaches of the Yellow River Basin was remarkable.The water conservation in the Yellow River Basin showed a clear trend of decreasing first and then increasing around 2000,which also showed that vegetation restoration and soil erosion control had remarkable effects.Among the different land types,the largest water conservation was grassland>arable land>forest land>unused land>construction land>waters,while the water conservation per unit area of different land use types was as follows:unused land>building land>forest land>grassland>arable land.The main contribution value of water conservation in different provinces is different,for example,the water conservation in Gansu Province is mainly contributed by grassland,while the water conservation in Henan Province is mainly contributed by cultivated land.Around2000,the total soil conservation in the Yellow River Basin showed a trend of first increasing and then decreasing,and the degree of soil erosion slowed down year by year.From a spatial point of view,the total soil conservation in the Yellow River Basin shows the characteristics of"more south and less north,and more east and less west".In general,the total water and soil conservation of Gansu Province,Inner Mongolia Autonomous Region,Ningxia Hui Autonomous Region,Qinghai Province and Sichuan Province is mainly contributed by grassland,and its contribution proportion is>50%,while the contribution of forest land in Shaanxi Province,Shaanxi Province,Henan Province and Shandong Province is the largest,much larger than other land use types.（4）There are obvious regional differences in trade-offs and synergies between different ecological services in the Yellow River Basin.The trade-off between water conservation and soil conservation was mainly distributed in Gansu Province,Inner Mongolia Autonomous Region,Shanxi Province and Shaanxi Province,while the synergistic relationship was mainly distributed in Qinghai Province and Gansu Province.The synergistic relationship between habitat quality and soil conservation（HQ-SC）was much larger than that between other ecosystem services,accounting for 64.2%of the entire Yellow River Basin,mainly distributed in Gansu Province,Inner Mongolia Autonomous Region,Qinghai Province,Shanxi Province and Shaanxi Province.Grassland,woodland and arable land are the main land-use types that affect the trade-off between ecosystem services.The trade-offs between water conservation and soil conservation are more widely distributed in forest land and arable land,while the trade-offs between water conservation and habitat quality,water conservation and carbon storage are mainly contributed by grassland,and the trade-off distribution area is much larger than that of the synergy area.The synergistic relationship between soil conservation and carbon storage was distributed in grassland,forest land and cultivated land,and the synergistic area of cultivated land and forest land was much larger than that of the trade-off area.The synergistic relationship between habitat quality and carbon storage is mainly distributed in forest land,and its synergistic distribution area is much larger than that of the trade-off area.（5）There is an obvious contradiction between supply and demand in water supply services and carbon sequestration services in the Yellow River Basin,that is,the inconsistency between supply areas and beneficiary areas leads to spatial mismatch and imbalance between supply and demand.From the results of water service flow,it can be seen that the middle and upper reaches of the Yellow River Basin have high water supply potential,and the higher water demand mainly occurs in industrial areas and urban areas,distributed in the lower reaches of the Yellow River Basin.Water supply is mainly related to the area of farmland,grassland and water,which has a significant impact on water supply.In terms of total carbon sources,Ordos has the highest carbon emissions(9×107 TC·y^-1),and Linyi and Zhangye far surpass other cities in terms of emissions per unit area.From the perspective of carbon sequestration capacity per unit area,Hanzhong City has the strongest carbon sequestration capacity,followed by Shangluo and Ankang City.From the results of the current ratio of carbon sequestration services,it can be seen that except for Hainan Tibetan Autonomous Prefecture and Guoluo Tibetan Autonomous Prefecture,which are carbon sequestration service demand areas,other areas in the Yellow River Basin are carbon sequestration service supply areas.The self-sufficiency rate of carbon sequestration services in the Yellow River Basin has gradually increased from west to east.Centered on weak carbon sources,the current ratio increases along all sides,and cities and counties with high flow ratios are scattered in the range.更多还原