Ecological Benefit Evaluation Of The Project Of Returning Farmland To Forests In Aksu Region

The project of returning farmland to forest is one of the major forestry ecological projects in China,and plays a key role in promoting the construction of ecological civilization in Xinjiang.The results of the project of returning farmland to forest in Xinjiang have initially appeared,which has played a positive role in improving the ecological environment and promoted the rapid development of the rural economy.Therefore,it is particularly important to quantify the ecological benefits of the project of returning farmland to forest for the implementation of forestry projects.This study refers to the related achievements of returning farmland to forest,using the data of the 2015 project of returning farmland to forestry and the monitoring data of the project of returning farmland to forestry in the Aksu region successively by the Xinjiang Academy of Forestry.Indoor analysis,to obtain soil organic matter content,available nitrogen,available phosphorus and available potassium and other parameters,to carry out soil nutrient analysis;at the same time for different types of vegetation restoration in Aksu region,vegetation restoration type,conversion of farmland to forest types of conservation soil function,solid The evaluation of ecological benefits such as the function of carbon release oxygen,accumulation of nutrients,purification of atmospheric environment and forest protection functions aims to quantify the ecological benefits of the project of returning farmland to forest in Aksu region,and to provide guidance for policy formulation and management system of the project in accordance with.the result shows:(1)After the implementation of the project of returning farmland to forest,the soil organic matter and available potassium content among the three returning farmland patterns in each soil layer were expressed as returning farmland to forest>abandoned mountains and afforestation>sealing and afforestation;soil available nitrogen and available phosphorus contents were all indicated as returning farmland to forest>forest closure>Barren mountains and wasteland.The model of returning cultivated land to forests has significant effects on soil available potassium content in various soil layers,and the model of returning cultivated land to forests has significant effects on soil organic matter,available nitrogen,and available phosphorus only in 0-20 cm soil layers.The contents of soil organic matter,available nitrogen and available phosphorus among the three types of abandoned farmland in each soil layer were the highest in economic forests,and the available potassium content was highest in shrub forests.And forest species have significant effects on soil organic matter content in each soil layer.(2)The soil organic matter,available nitrogen,available phosphorus,and available potassium increased significantly in the 5th year of the project after returning the cultivated land to forests;the soil organic matter of the enclosure and barren hills and wasteland models began to increase significantly in the 8th year of the project,the increase was relatively The mode of returning cultivated land to forests is relatively low.In the five years since the project was closed,the soil potassium content increased rapidly,and the increase rate was higher than that of returning farmland to forest.(3)Based on the theory of utility value theory,adopting methods such as "recovery cost method" and"opportunity cost method" to calculate the total ecological benefit value of the project of returning farmland to forests in Aksu region is 3.33 billion yuan;The highest total value is the model of barren hills and afforestation,which is 1.992 billion yuan,followed by the model of returning farmland to forests,which is 929 million yuan,and the lowest is the model of mountain closure and forestation,which is 410 million yuan.From the perspective of forest species,the highest total value is shrub forest at 1.317 billion yuan;the second is ecological forest at 1.268 billion yuan;the lowest is economic forest at 745 million yuan.From the perspective of each function,the value of each function is in order of forest protection function(61.0%),purification of the atmospheric environment(19.0%),carbon fixation and oxygen release function(13.0%),soil conservation function(6.0%),and function of accumulating nutrients(1.0%).