| In the 21st century,China’s rapid economic development has accelerated the development and utilization of resources.Land,as the most fundamental space and production resources for human survival,life and development,changes in its area structure will inevitably affect the function of the ecosystem.Bosten Lake Watershed is located in the hinterland of China with arid climate and complex landforms.For many years,ecological water conveyance has played an important ecological role in the lower reaches of Tarim River.Therefore,based on the land use data from 2000 to 2020,the temporal and spatial changes of land use in Bosten Lake Watershed were analyzed by using land use dynamic attitude,transfer matrix and time series tracking analysis.Secondly,the Ecosystem Service Value（ESV）evaluation system was constructed,and the spatial and temporal evolution of ESV was explored by using grid method and trend analysis method.The spatial response characteristics of ESV and LUCC were analyzed based on the new perspective of ESV spatial change combined with LUCC（Land use and Land Cover change）process level.The driving factors of ESV differentiation and their interaction effects were analyzed by using geographic detector model.Finally,three scenarios,namely natural development scenario,sustainable development scenario and cultivated land protection scenario,were set up to predict the change of land use and ecosystem service value in 2025 by using PLUS model.To explore the dynamic evolution mechanism of land use and ecosystem service value.The main conclusions are as follows:Based on land use data from 2000 to 2020,the temporal and spatial changes of land use in Bosten Lake Watershed were analyzed by using dynamic attitude of land use,transfer matrix and time series tracking analysis.Secondly,an ecosystem service value assessment system was constructed to explore the spatio-temporal evolution of ESV by using grid method,hot spot analysis and trend analysis,and to analyze the driving factors and interaction effects of ESV differentiation by using geographic detector model.Finally,three scenarios,namely natural development scenario,sustainable development scenario and cultivated land protection scenario,were set up to predict the changes of land use and ecosystem service value of multiple scenarios in 2025 by using PLUS model.The main conclusions are as follows:（1）The land area structure of the study area is desert>meadow>bare land>grassland>dry land>wetland>water area>glacier>coniferous forest>construction land>shrub>broad-leaved forest>paddy field.The main land types in Bosten Lake Watershed are desert,meadow and bare land.The proportion of paddy watershed was the lowest.From 2000 to 2020,the area of dry land,construction land and water area in Bosten Lake Watershed increased continuously.Desert,meadow,wetland,shrub,broad-leaved forest and paddy field showed fluctuant growth trend.Bare land,grassland and glacier snow showed a fluctuating decreasing trend.The land use structure of Bosten Lake Watershed has not changed even though the area of bosten Lake Watershed has changed in different degrees.In addition,desert,meadow and grassland are the main sources of dryland and construction land expansion.The land use types less affected by human activities,such as vast desert,bare land and meadow,do not change significantly,but they are frequently transferred to each other and have a large area base.From 2000 to 2020,the dynamic attitude of comprehensive land use increased firstly and then decreased.The results of land use tracking analysis showed that the maximum trajectory type of Bosten Lake Watershed from 2000 to 2020 was stable,and its total area reached 4.76×106 hm2,accounting for 60.41%of the total area of the Watershed.Among the change trajectory types,the gradient type is the main change trajectory type,accounting for34.91%,which is mainly distributed among the stable types,accounting for 2.54%of the watershed area.Moderate variation,regression and intense variation were mainly distributed in oasis area.（2）The ESV of Bosten Lake Watershed showed a decreasing,increasing,decreasing and increasing trend in the past 20 years,and the total value of ecosystem services increased by3.292 billion yuan（5.41%）.From the perspective of different ecosystems,meadow value was the largest in the five study periods,followed by water area and wetland.The main contributing factors and sensitive factors of ESV in Bosten Lake Watershed from 2000 to 2020 are water area,meadow,wetland and grassland ecosystem.The main positive contributing factors were water area,dryland and meadow ecosystem.The main negative contributing factor is grassland ecosystem.Therefore,water area,wetland,meadow and grassland are important ecological land,especially grassland,which has caused negative ecological impact and needs to be protected.（3）The overall spatial distribution of ecosystem service value in the Watershed is"higher in the north and lower in the south".The variation trend of ESV in the northern part of the Watershed has a strong spatial difference.The LUCC tracking grade is generally low,and ESV mostly shows a slight variation trend.The ESV basically invariant region in the south is widely distributed.Meanwhile,the spatial response characteristics of ESV change trend and LUCC trajectory grade in oasis area are as follows:ESV slight decrease（medium change type）,ESV slight increase（gradual change type）,ESV slight decrease（medium change type）.（4）According to the geographic detector model,it is found that 10 km×10 km is the optimal spatial scale to study the driving analysis of spatial differentiation of ESV in Bosten Lake Watershed,and the driving factors of spatial differentiation of each ESV at this research scale are ranked as follows according to the size of Q statistic:NDVI>average annual rainfall>DEM>land use degree>NPP>average temperature>soil erosion>Slope>GDP>population.In general,the impact of natural climate on ESV is significantly stronger than that of social and economic factors,and the explanatory power of interaction of any two driving factors is greater than that of any single driving factor on spatial differentiation of ESV.（5）Based on the 2015 land use status and driving factor data,the PLUS model is used to obtain the simulation data of 2020 land use after debugging the software and parameters.The Kappa coefficient is≥75%after verification,which meets the accuracy requirements.The results show that under the natural development scenario,In 2025,the area of glacier snow,grassland and desert in Bosten Lake Watershed will decrease slightly,while the area of meadow,shrub,dry land,broad broad-leaved forest,bare land,construction land,wetland,paddy field,water area and coniferous forest will increase.Compared with natural development,the area of dryland under sustainable development is small,and part of building land and dryland is converted to wetland,broadleaf and other ecological land,which is conducive to the construction of ecological security pattern in arid area.Under the cultivated land protection scenario,the area of dryland increased by 0.15×10~3·hm~2,while the area of other land types had little difference.The largest ESV development scenario in Bosten Lake Watershed in 2025 is sustainable development scenario,followed by cultivated land protection scenario,and the smallest is natural development.The land use structure of bosten Lake Watershed is stable from 2000 to 2020,and the conversion intensity among land use types in oasis region with strong human activities is greater than that in non-oasis region.Under the comprehensive influence of natural climate and social economy,the overall spatial distribution pattern of ESV was"higher in the north and lower in the south".Meanwhile,the change trend of ESV and its LUCC process in the oasis showed a circular corresponding distribution from inside to outside.Through simulation,it is found that the ESV of the basin is the largest under the scenario of sustainable development in 2025. |
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