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基于防护林的定位观测数据,利用AHP法建立了防护林生态效益评价指数,并用该指数评价了民勤绿洲不同状态防护林的生态效益。结果表明,防风效益是决定民勤农田防护林的关键因素,林网内温湿度改变率、土壤有机质和土壤水分的改变率等因素对防护效益的影响也较大。防护林层次结构和疏透度是影响防护效益的主要参数。综合评价结果表明,疏透结构、林下乔灌草结构完整的林网防护效益相对较高,而通风结构或紧密结构、林下层次结构不完整的防护效益并不高。
Based on the observation data of shelterbelts, the ecological benefit evaluation index of shelterbelts was established by using AHP method, and the ecological benefits of different status shelterbelt in Minqin Oasis were evaluated. The results showed that the windbreaking benefit was the key factor to decide the farmland protection forest in Minqin. The factors such as the change rate of temperature and humidity in forest network, the rate of change of soil organic matter and soil moisture also had a great influence on the protection benefit. Shelterbelt hierarchy and permeability are the main parameters that affect the efficiency of protection. The results of comprehensive evaluation showed that the protective effect of dredging structure and the under-grove shrub-grass structure is relatively high, while the ventilation structure or compact structure is not effective in protecting the under-layer structure incompletely.