Trade-offs Of Regional Ecosystem Services

The purpose of the ecosystem service trade-offs study is to coordinate various ecosystem services and to achieve sustainable development.Specifically,it is to ensure the ecosystem away from the stress while speeding up socioeconomic benefits,and then to achieve a win-win between economic development and ecological environment.Understanding the trade-offs relationship between multiple ecosystem services in depth can provide scientific support for the regional management and policy-makers.Mountain ecosystem is very important guaranty for the ecological security and sustainable development in China,and it is also an nonnegligible issue in the study of ecosystem service trade-offs.This paper studied the trade-off relations between multiple ecosystem services from the perspective of the vertical space change in Xiaojiang River Basin of Yunnan Province.The natural and economic conditions were analyzed,including regional geological and geomorphologic situation,climatic condition,hydrological condition,soil condition,vegetational cover and socio-economic condition.Four key ecosystem services were screen out,carbon storage,water yield,soil conservation and habitat quality,which may influence the ecological function.Based on dividing the perpendicular band spectrum and the vertical space subdomains,the InVEST model,ArcGIS10.2 and SPSS were used for evaluating these four important ecosystem services.In this study,we analyzed the characteristics of spatial distribution for different ecosystem services,respectively.The different ecosystem services were overlaid and were discussed the spatial pattern of the trade-off and synergy for these ecosystem services by pairwise comparison.We quantified the benefit value of four ecosystem services and the two-two trade-off relation.Based on these,the relative benefit and the comprehensive benefits of ecosystem service was analyzed in the vertical space dimensions.Finally,we compared and discussed the variation in the trade-off relation between different ecosystem services in the vertical space,and the regional factors causing these differences were explored.The main results are as follows:(1)The spatial variation of ecosystem services was quite notable in Xiaojiang River Basin.The results showed that the carbon storage reached 11.59 Mt,the water yield was 1.106 billion m3,soil conservation quantity was 54.447 t and the habitat quality factor was about 0.577.In the dry-hot valleys region of the watershed,the water yield and carbon storage and habitat quality were relatively lower due to the natural and human factors,such as less rainfall,high temperature,more frequent human activities and more concentrated urban settlement spots.The interferential and restraint factors reduced with the altitude increased,leading to the relative service function was higher in the high-altitude area.However,the service function reduced in the mountain area.This was because the land use type changed from forest land to grass land or bare land,making the structure of ecosystem changed and reduced the service function in the mountain area.(2)The tradeoff relation of ecosystem services was dominated in the watershed.The habitat quantity was as the leading service in most area.The interaction relationship had a big difference in the regional vertical dimension.The area of habitat quality dominated was the largest,accounting for 33.87% of the total area in the watershed.The area of carbon storage dominated was 417.19 km2.The area of water yield dominated was 370.54 km2.The area of soil conservation dominated was just 84.05 km2.For the area of two kinds of services dominated together,carbon storage and habitat quantity took up the biggest area.For three kinds of ecosystem services,the area of carbon storage,water yield and habitat quality dominated was 192.52 km2,and the area of carbon storage,soil conservation and habitat quantity dominated was 110.42 km2.For the four kinds of services,the area of all services dominated was 99.17 km2,accounting for 3.3% of the total area.The strong trade-off area concentrated in the most part of central southern area,and the northern area.The area of high degree synergism was less,and mainly concentrated in the central northern area.In different vertical zonation,the dry-hot valleys region of the watershed showed week synergism effect,the evergreen broad-leaved and coniferous forest in the mountain region showed strong trade-off effect.The area of trade-off and synergism effect take a half respectively in the subalpine coniferous forest region.In the alpine meadow zone,the relation showed the high synergism effect as the principal.(3)The overall correlation was low or did not exist in the Xiaojiang River Basin,but the correlation significantly showed in the vertical space.The Person's coefficient of association was used to compared the ecosystem services between two and two in the Xiaojiang River Basin.In the whole watershed,the correlation between two and two are too low,which cannot meet the requirements of significance test.However,the correlation between most ecosystem services showed significantly(p=0.05)in the vertical space.Some of the services showed the correlation but not significant.The plus or minus of the correlation also indicated the trade-off or synergism relation of various ecosystem services.In addition,the differences between different vertical zones also identified the conclusion that the vertical space differences between the key ecosystem services in the Xiaojiang River Basin region.(4)The relative benefit value and trade-off relation of four ecosystem services in the watershed direct influence the comprehensive benefits of the river basin ecosystem.The minimum and maximum comprehensive benefits of Xiaojiang River Basin was 0.04 and 0.799,respectively.In the Xiaojiang main line of the whole watershed,this area has the lowest comprehensive benefits.The relative higher area was distributed in the south and east region of the watershed.However,the higher value area showed a discrete condition.The relative benefits of habitat quality were high in different vertical zones and hold the dominant position in the two-two relation.The relative benefits of soil conservation were lower,which result in big differences of the trade-off relation for two different services.The relative benefits of water yield were higher than those of carbon storage.The comprehensive benefits had a large variation and showed discretely in the dry-hot valleys region and alpine meadow steppe.However,the comprehensive benefits were more concentrative and more stable between ecosystem services in the evergreen broad-leaved and coniferous forest in the mountain region and the subalpine coniferous forest region.(5)There is a big difference in the relative benefit and the trade-off relation for two-two ecosystem services,especially in the vertical space.The relative and comprehensive benefits increased firstly and then decreased with the increase of altitudes,but except for the ecosystem service of soil conservation.The relative benefits of soil conservation had not significantly changed with the increase of altitudes,and gradually decreased in the higher area.For the variation of the two-two trade-off value,such as carbon storage-water yield,carbon storage-habitat quality,and water yield-habitat quality showed a big change in the vertical space.The variation of the trade-off relation showed differences in different vertical zonation.