The Ecological Benefits Evaluation On The Second Phase Of Forestry Project In Sandification Combating Program For Areas In The Vicinity Of Beijing

This study takes the second phase of forestry project in sandification combating program for areas in the vicinity of Beijing as the research object,and evaluates the ecological benefits generated by the project in the past five years.Based on the summary analysis of relevant research at home and abroad,combined with the actual situation of the project and the local standards of Beijing,an index system suitable for evaluating the ecological benefits of the project was constructed.Based on consecutive 121 sample plot survey data,the project operation design data and related research results,fourteen evaluation indicators of six functional categories,such as water conservation,so1l conservation,carbon fixation and oxygen released,air purification,forest nutrient elements storage and vegetation biodiversity conservation were selected.The evaluation index,using the evaluation method of the combination of material quality and value,quantitative evaluation and analysis of the annual ecological benefits of typical projects in 2015 with the most comprehensive types of projects and forest types;On this basis,the ecological benefits of the 2013—2017 project were fully accounted for and evaluated.The results were as follow:In 2015—2017,the 2015 project adjusted a total water regulation of 44.43 miilion cubic meters,225.2 thousand tons of solid fixation,12.6 thousand tons of fertilizer conservation,124.1 thousand tons of carbon fixation,287.7 thousand tons of oxygen release,857.8 thousand tons of dust detention,absorbing 4.22 thousand tons of pollutants,generating the negative ion volume by 7998.85×1019,and 1 732.54 tons of forest nutrient element storage.The total value of accumulated ecological benefits in the three years was 1.295 billion yuan,of which the total value of water conservation,carbon sequestration and oxygen storage and vegetation diversity protection was 1.103 billion yuan,accounting for 85%of the total value of ecological benefits.It is the mainly reflected of ecological benefits in the three years of the project;The cumulative ecological benefit value of each project type in three years is:379 million yuan for low-functional forest improvement project,280 million yuan for artificial afforestation project,and 636 million yuan for the closed forest project;Among the districts and forest farms,Mentougou District,Miyun District and Yanqing District are the main beneficiaries of the project.The total value of ecological benefits accounted for 44.6%in three years.The highest annual ecological benefit value per unit area of each forest type is Pinus tabulaeformis,Platyeladus orientalis and broadleaf mixed forest,which is 38,400 yuan/hmmZa,and the lowest is shrub forest,only 28,300 yuan/hm2·a.The average annual ecological benefits per unit area of all forest types is 32,700 yuan/hm2·a.In 2013—2017,The second phase of forestry project in sandification combating program for areas in the vicinity of Beijing has a total water regulation of 129.9662 million cubic meters,678.1 thousand tons of solid fixation,39.2 thousand tons of fertilizer conservation,354.2 thousand tons of carbon fixation,819.0 thousand tons of oxygen release,2.7049 million tons of dust detention,absorbing 15.1 thousand tons of pollutants,generating the negative ion volume by 22,354.70×1019,and 4392.11 tons of forest nutrient element storage.As of 2017,the total value of ecological benefits is 3.768 billion yuan,of which the total ecological benefits of the projects from 2013 to 2017 were 260 million yuan,467 million yuan,1.295 billion yuan,1.122 billion yuan,623 million yuan.The cumulative ecological benefit value of each functional category in the five years was:1.314 billion yuan for water conservation,1.244 billion yuan for carbon fixation and oxygen release,103 million yuan for soil conservation,425 million yuan for air purification,62 million yuan for forest nutrient elements storage,and 620 million yuan for vegetation biodiversity conservation.The project has produced huge ecological benefits in past five years.In order to ensure the ecological benefits of the later projects,it is recommended to appropriately improve the investment standards of engineering construction,improve the management responsibility system to consolidate the existing construction results,and pay attention to the construction of mixed forests in the later afforestation transformation process to optimize the stand structure.