| With the rapid economic and social development and urbanization in the region,the increasing human activities continue to threaten the natural ecosystem,while the change of land use patterns and irrational utilization have affected the landscape pattern and ecosystem to varying degrees,damaging the structure and function of the ecosystem and exacerbating ecological risks,seriously hindering the benign development of the region.The phenomenon of rock desertification in karst watershed areas is prominent,and ecosystem issues have become more sensitive.Therefore,how to monitor and assess the ecological risks and changes in ecosystem functions in this region more objectively and comprehensively is an important issue that needs to be addressed urgently at present.Taking the Guizhou section of the Hongshui River Basin as an example,this paper selects land use data in 2000,2010 and 2020,and combines socioeconomic and other data to construct a landscape ecological risk evaluation model and an ecosystem service value accounting model,quantitatively analyzes the spatial and temporal evolution patterns of landscape ecological risk and ecosystem service value in the study area in the past 20 years,and constructs an ecological The study also proposes zoning control and development suggestions to effectively reduce regional ecological risks and improve ecosystem service values.The main conclusions of the study are as follows:(1)During the period of 2000-2020,the changes in land use types in the Hongshui River Basin show a pattern of"three increases,two decreases and one flat",i.e.,grassland,water area and construction land increase,forest land and arable land continue to decrease,and the overall change in unused land is not significant.The rate of change of land use types in the study area as a whole is accelerating,and the comprehensive index of land use degree is fluctuating and increasing.During the period of 2000-2020,the total area of land use types shifted in the Hongshui River basin was 149230.17hm~2,and the interconversion between forest land,grassland and cropland was significantly higher than other types,with the largest area of forest land shifted out(78639.66hm~2)and the largest area of grassland shifted in(60619.68hm~2).(2)In 2000,2010 and 2020,the landscape ecological risk index of Hongshui River Basin was 0.1263,0.1228 and 0.1232,respectively.The overall ecological safety state of the region is better while the landscape ecological risk index is fluctuating and decreasing,and the landscape ecological risk level in the three periods is dominated by the low risk zone,lower risk zone and medium risk zone of the landscape ecology,accounting for About 85%of the watershed area.The spatial distribution of different landscape ecological risk levels varies significantly,with the low-risk and low-risk areas of the landscape ecology widely distributed in the south and part of the northeast of the study area,the medium-risk areas of the landscape ecology mostly located in the spatial transition position between the low-risk and high-risk areas,and the high-risk and high-risk areas of the landscape ecology partially distributed in the main stream of the Hongshui River and around the urban areas of the county.The spatial characteristics of landscape ecological risk are"high in the north and low in the south";during 2000-2020,the area of the improvement zone of landscape ecological risk in Hongshui River Basin is much larger than that of the deterioration zone,and the level of regional landscape ecological risk has decreased in the past 20 years.The transfer between different landscape ecological risk levels mainly occurs between neighboring risk levels,and the ecological risk level is more significantly transferred to a lower level,which makes the regional ecological environment improve,but there is still a potential risk of increasing ecological risk in local areas.(3)The ecosystem service value(ESV)of the Hongshui River Basin from 2000 to 2020 is 38.793 billion yuan,39.457 billion yuan,and39.162 billion yuan,respectively,with forest land ESV contributing the largest amount to the ESV of the basin,accounting for more than 71%of the ESV of the basin.The value of regulating and supporting services of ecosystems is much greater than the value of supply and cultural services,with climate regulation,hydrological regulation,and soil conservation in the first tier(over 58%combined),biodiversity,gas regulation,and purification of the environment in the second tier(over 29%combined),and aesthetic landscape,raw material production,food production,maintenance of nutrient cycles,and water supply in the third The spatial heterogeneity of ESVs is obvious,and the ESVs in the three periods show the spatial distribution characteristics of"high in the south and low in the north",in which the low ESV areas are mainly distributed in the urban areas in the north of the basin;the lower ESV areas are mainly distributed in the periphery of the low ESV areas;the medium ESV areas are widely distributed in the basin,with the central and southern regions being more concentrated;the higher and higher ESV areas are mainly distributed in the urban areas.During the period 2000-2020,the ESV-rising zone mainly occurs in the main stream area of the Hongshui River,and the ESV-lowering zone mainly occurs in the northern part of Ziyun County and the northeastern part of Huishui County,and the land-use changes caused by the ESV changes can be attributed to the interconversion of forest land,water area and other areas.(4)Based on the spatial correlation model of landscape ecological risk and ecosystem service value,four types of ecological zoning were obtained:high-risk-high-value zones are mainly clustered in the main stream of the Hongshui River and the confluence with its tributary Mengjiang River in the south of the study area;low-risk-low-value zones are distributed in a strip-like pattern in the marginal areas of the watershed;low-risk-high-value zones are distributed in a"group"distribution pattern,mainly in the central part of Luodian County,the junction of Ziyun County and Wangmo County,etc.;high-risk-low-value areas show a"group"and"strip"distribution pattern,mainly gathered in the northern part of the basin Xixiu District,the central part of Huaxi District to the northwestern part of Huishui County,and the western part of Pingtang County.Spatially,the more obvious changes in the ecological zoning of the Red River Basin occur in the southern part of the study area. |
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