| Qinling is a vital ecological barrier and dividing line between the northern and southern climates in China.With the border,which forms Yellow River and Yangtze River two major water systems.Being the main water protection area of Shaanxi Province and the South-North Water Diversion Project,is known as"Central Water Tower".The ecological status of Qinling Mountain has a decisive influence on the overall ecological quality and safety of Guanzhong region of Shaanxi and even the central region of China.Although the environmental quality continues to improve under the continuous strengthening of protection,the task of restoration and governance caused by the degradation of its ecological function is still laborious,among which the quantitative results of ecosystem services are not clear,it is necessary to carry out in-depth exploration using a variety of technical means.Based on In VEST model,this paper assessed the temporal and spatial variation of four ecosystem services in Shaanxi Qinling(Weihe River Basin)from 2001 to 2020,in terms of water conservation,soil protection,carbon storage and habitat quality.Used SPSS/Origin to calculate the services of different land use types,analyzed the main driving factors and classified the comprehensive importance combined with the spatial analysis tools of Arc GIS platform.In order to create a basis for the formulation of ecological remediation measures and management decisions,the conclusions of the study area as follows:(1)From 2001 to 2020,the average annual water retention depth was 106.04 mm,of which the strongest was in 2003(232.39 mm)and the weakest was in 2016(47.66 mm).The average total amount was 9.94×10~8 m~3 and increased with 1.05×10~8 m~3/a,its spatial differentiation pattern did not change significantly,showing that the south was slightly higher than the north.The average annual contribution rate of the main types of land use was forest(41.96%)>grassland(36.05%)>arable land(18.76%).Precipitation,actual evapotranspiration and topographic factors are the main driving factors,among which the variation rule of water conservation coincides with precipitation and is opposed to evapotranspiration.Since the terrain factor is influenced by both slope and altitude,the change pattern between them was weaker.(2)The average annual soil retention capacity of study area was approximately 471.94 t/hm~2,of which the strongest was in 2003(690.76 t/hm~2)and the weakest was in 2016(352.33t/hm~2).The average total amount of soil was maintained at 4.43×10~8 t,and with the amplitude of 1.01×10~8 m~3/a,the spatial distribution was"low at the eastern and western ends,high in the middle and higher in the south than in the north".The average total annual contribution rates of the main types were forest land(24.58%)>grassland(19.45%)>arable land(11.49%).Precipitation,slope and DEM have the strongest influences,and the relationship between these three is limited by various interval ranges,when the slope is between 0-5°,the precipitation between 500-650 mm and the altitude between 1000 and1500 m,the regional soil retention capacity is the strongest.(3)The average annual carbon storage capacity of study area was 303.22 t/hm~2,with the strongest carbon storage capacity occurred in 2001(303.74 t/hm~2)and the smallest was in2020(302.01 t/hm~2).The average amount of annual carbon storage was 284.3623×10~4 t,which has decreased since 2010 with an amplitude of 0.99×10~4 t/a,its spatial distribution is heterogeneous,the overall pattern is"high in the south and low in the north,high in the west and low in the east".Among the different types of land use,the average annual carbon storage of forest land,farmland land and grassland were the largest,with contribution rates of 48.11%,26.18%and 13.92%respectively.(4)The average annual habitat index was 2.573394,which has the characteristics"low in the north and high in the south,low in the west,and high in the east".As the two dominant land types,forest and grassland had the largest average habitat quality index with 0.994093and 0.995159 respectively.While habitat levels in woodlands have remained at a high level and have improved,habitat levels in grasslands and arable land have declined.(5)In addition to the relationship between water conservation and carbon storage,which was manifested as a trade-off,there was a coordination relationship between several other services.The comprehensive importance of ecological services was mainly in the extremely important areas,accounting for 51.81%,with Qinling Forest in the west being the most dense;the area of very and relatively important areas was 18.48%and 28.47%respectively,while the grassland shrubland in the middle as the main composite;the proportion of generally important areas was only 1.24%,mainly concentrated in the northern agricultural farming area. |
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