| The change of land use pattern often affects the structure and function of ecosystems,leading to changes in ecosystem service functions.At present,there were many studies on ecosystem services value(ESV)changes caused by land use pattern in large scale,but few studies conducted in small watersheds.And,the study of the impact of land use change on ecosystem services in small watershed is of great significance for enriching and improving the theories and methods of ecosystem services changes.In this paper,Samachang and Puzhehei were used as mountain and wetland ecological types respectively.Based on land use,experimental observations,and literature surveys,analyzed the characteristics of changes in land use quantity and structure of two periods(Samchang:2003,2017,Puzhehei:2010,2014).Meanwhile,the type of land use will be classified according to the type of ecosystem,and the core ecosystem types will be selected.Besides,according to the principle of index selection,the evaluation indexes were divided into several parts.And then,the environmental economic evaluation technology was used to evaluate the ecosystem service value.On this basis,the impacts and effects of land use change on ESV were analyzed.Finally,the main results and conclusions are as follows:(1)The research results of the Samachang showed that the forest and construction land had increased,and the cumulative increase of the former was 114.55 hm2 and the annual increase was7.63 hm2,whlie the latter was smaller(a cumulative increase of 11.14hm2).Moreover,the largest area change in all land types was farmland,which had reduced 116.74 hm2 in total.In general,the degree of land use began to weaken and gradually moved towards the rest period.At the same time,the results of two ESV calculations showed that they have shown an overall increase.At the same time,the results showed that the ESNs were increasing,and the total ESV reached 7.28×107 yuan in 2017,an increase of 1.16×107 yuan(18.84%).Although the contribution of woodland and farmland to total ESV increase were considerable,the forest was still the system that contributes most to the value of ESV.From the point of view of the internal services of each subsystem,the expansion of forest ecosystem services depended on the continuous enhancement of the benefits of conservation water resources and soil conservation services,while the farmland was derived from the strong value of grain crop production and related services.From the point of view of the value of the total ESV,the value of the ecological service was much greater than the direct economic value in both the early and late periods.Moreover,ecological services accounted for more than 80%of the total value,while forest contributed most(about 89%),unlike that,farmlands occupied a large part of direct value(86.85%and 89.16%).(2)The data of land use in Puzhehei showed that the area of farmland and unused land were decreasing,and the former decreased by 1395 hm2 while the latter decreased by 1001 hm2.In the core land area,the growth of woodland area was the highest,increasing by 1614 hm2,and the water area also had an expansion of 395 hm2.Hence,the land use and development level of Puzhhei was at the stage of development.In addition,according to the results of two periods of ESV accounting,the value increased from 29.55×108 yuan in the early stage to 41.82×108yuan in the late stage,showing a huge growth trend.The contribution of forest and wetland to regional total ESV increased from 76.64%to 81.16%.Furthermore,the service value provided by the wetland was most obvious and it occupied a large part of the total ESV in the two periods.The proportion of tourism leisure and temperature regulating and humidifying service was also changed from 48.78%to 58.33%.At the same time,with the expansion of the area,the benefits of species conservation and water conservation in the forest were also increased significantly,and the farmland also had a greater carbon release and oxygen release benefit on the premise of the large supply of food supply.The overall study also found that the proportion of direct value and ecological service value presented by Puzhehei was different in the two periods and the former had a larger increase than the latter.The ratio between the two was also changed from 2:5 to 7:10,and the main reason was the promotion of the value of wetland tourism and the continuous increase of yield per unit area of agricultural cultivation.(3)The effects of land use change on ESV in the two types of different ecosystem types showed that the response effect of wetland as the dominant ecological type of ESV on land use was more significant.The data of the magnitude of ESV changes in the two different ecological types showed that the average annual increment of the value of hill-dominated ecotypes was 82.46×104 yuan a-1,and the ESV of per unit area increased by 561.12 yuan a-1.For Puzhehei,where wetland is the dominant ecological type,the ESV’s rise rate was 3.07×108 yuan a-1 of per year,and the growth rate of per unit area was 7945.67 yuan a-1.Through comparative analysis,it could be found that there was little difference between the farmland and forest ESVs of per unit area in the two places,and the key factor that causes a large difference in the total ESV between the two regions was the huge ecological benefits generated by the wetlands.To sum up,with the change of land use pattern,the ESV of both Samachang and Puzhehei showed an upward trend,but there was a difference in the increase of ESV and the driving factors of the two types of ecosystem.The increase of ESV in Samachang was mostly driven by forests and the increase was relatively small,while the rise in ESV of Puzhehei was dependent on the increasing efficiency of wetlands.From the perspective of subsystems,although the value of ecological services has declined significantly after the reduction of farmland,the direct economic value has increased significantly,while the service benefits of ESV in other core ecological types have increased with the expansion of the area(in addition to the farmland).What’s more,it shows that the expansion of land use area will increase its ESV,and there is a good positive correlation between the two.And the factors that contribute to the increase and decrease of farmland ESV in the region are not only changes in area,but they are also affected by the production of various types of grain and agriculture cultivated in farmland and their sales prices.In addition,the proportion of each system in the total ESV is not affected by the increase or decrease in its area,but affected by the magnitude of the change in the total ESV. |
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