长江上游防护林体系不同林种的生态经济效益研究

通过对长江上游环境背景特征研究，探讨了防护林体系建立的重要性，并进行防护林体系配置，由此设置生态效益监测体系，以流域为单元，分层研究防护林体系的综合效益。研究表明：防护林体系配置后，坡面径流减少６２％，径流含沙量减少６９％，土壤肥力、土壤微生物活性均比荒坡高４～５倍；林地地温和气温均比农耕地低２～３℃，相对湿度提高３０％～４０％；流域的年地表径流减少，森林覆被率每增加１％，年地表径流减少４．１ｍｍ，年产沙量可减少５％～７％。生物措施可减少２５％的泥沙，工程措施减少２９％的泥沙。营建防护林后，经济效益明显：在中、低山区，林地直接经济效益净增值为９２１．５～９９２．４元／ｈm₂·ａ，四川盆地净增值为８５０．３～１４３８．６元／ｈm₂·ａ。

A STUDY ON THE ECO-ECONOMIC BENEFITS OF DIFFERENT FOREST CATEGORIES OF THE SHELTER FOREST SYSTEM IN THE UPPER REACHES OF THE YANTSE RIVER

Through the study on the environmental background features of the upper reaches of the Yanzse River, this paper approaches the importance of the construction of a shelter forest system and researches the disposition of a shelter forest system. On this basics,setting up a monitoring system for the ecological benefits of a watershed is designed. The results of the investigation show that after the disposition of a shelter forest system, the run-off on slops decreased 62%, the silt content dwindles 69%, the soil fertility and the microbe activity of the forest land are 4─5 times higher than those of the waste land, the ground and air temperatures in the forest land are 2─3℃ lower than those in the agricultural field, and the relative humidity is 30%─40% higher. The annual surface runoff and silt production will decrease 4.1mm and 5%─7% respectively if the forest coverage adds 1%. Moreover,biological methods can decrease 25% of the silt amount and engineering methods can lower 29% of the silt amount. In addition, the economic benefits also are very conspicuous after the construction of a shelter forest system. The net increase is 921.5─992.4 yuan/hm₂.a in the middle and low mountainous areas and it is 850.3─1438.6 yuan /hm₂.a in the Sichuan basin.