广西不同退耕还林模式生态效益监测与评价

发布时间：2018-04-25 05:30

本文选题：退耕还林 + 植被特征　；参考：《广西大学》2015年硕士论文

【摘要】：退耕还林工程是我国实施自然生态系统修复的标志性工程,也是世界十大重点林业生态工程之一。广西自2001年实施退耕还林工程以来,已累计建成工程营造林106.3万hm2。退耕还林工程的实施,使广西直接增加的森林面积(已成林面积)88万hm2,使全区森林覆盖率提高了3.7%。随着工程建设的推进,如何科学有效的评价工程的生态效益已成为当今政府部门迫切关注的问题。本研究以广西平果任豆模式(Zenia insignis Chun)、平果尾叶桉(Eucalyptus urophyllaS)模式、东兰板栗(Castanea mollissima)模式、东兰香椿(Toona sinensis (A. Juss.) Roem)模式、兴宾尾叶桉模式、兴宾任豆六种模式为研究对象,并应用森林生态学、生态林业等理论对退耕区域物种多样性、生物量、土壤理化性质、地表径流水质及退耕后所取得的效益进行研究。为退耕还林工程的建设和科学评价提供科学依据与现实指导意义。结果表明：(1)实施退耕还林后,退耕地林下植被得到了很好的恢复,植被覆盖度都达到80%以上。不同退耕模式林下Margalef指数、Simpson指数及Shannon-Wiener指数均存在显著差异,灌木层Simpson指数、Shannon-Wiener指数均大于草本层。且植被Simpson指数及Shannon-Wiener指数都较对照组未退耕地高。同时,退耕地林下灌草生物量也大于对照组。(2)实施退耕还林后,退耕地的土壤结构得到了一定的改善,土壤容重较对照组未退耕地高,但土壤的孔隙度、最大持水量、田间持水量都较对照组的小,这是由于对照组受到人为耕作的的影响。土壤有机质含量、全氮、全磷、全钾、水解氮、速效磷、速效钾总体上都较对照组高,说明退耕还林后能有效的改善土壤肥力。(3)实施退耕还林后,退耕地的水土流失也得到了有效防治,林地蓄水、固土能力得到了加强,各退耕模式的径流量和泥沙量都远小于对照组。同时,林地地表径流水水质也得到了一定的改善,总N、总P和重金属含量较对照组低。(4)以效用价值论为理论依据,并采用“替代工程法”、“机会成本法”等方法,算出平果县、东兰县、兴宾区各模式产生的生态价值总额达到1.16×1010元,其中保护水资源价值、固碳释氧价值、生物多样性价值、净化环境价值、保育土壤价值分别占生态总价值的40%、33%、13%、10%、4%,生态效益主要体现在保护水资源和固碳释氧两方面。
[Abstract]:The project of returning cropland to forest is a landmark project for the restoration of natural ecosystem in China, and is also one of the ten key forestry ecological projects in the world. Since the implementation of the project of returning farmland to forestry in 2001, Guangxi has built up a total of 1.063 million hm2. With the implementation of the project of returning farmland to forest, the forest area (forest area) directly increased by 880000 hm ~ 2 in Guangxi, and the forest coverage rate of the whole area was increased by 3.7%. With the development of engineering construction, how to evaluate the ecological benefit of the project scientifically and effectively has become an urgent concern of the government. In this study, the model of Zenia insignis Chunli, Eucalyptus urophylla S, Castanea mollissima and Toona sinensis A. Juss.were used in this study. Roemmodel, Eucalyptus Xingbinensis model and Xingbinrendou model were used to study the species diversity, biomass and soil physical and chemical properties of returning cultivated areas by using forest ecology, ecological forestry and other theories. The water quality of surface runoff and the benefits obtained after returning farmland were studied. It provides scientific basis and practical guiding significance for the construction and scientific evaluation of the project of returning farmland to forest. The results showed that after returning farmland to forest, the vegetation under the forest was restored well, and the vegetation coverage was more than 80%. There were significant differences in Margalef index and Shannon-Wiener index between different forest models, and Simpson index of shrub layer was higher than that of herbaceous layer. The vegetation Simpson index and Shannon-Wiener index were higher than that of the control group. At the same time, the biomass of shrub under the converted farmland was also larger than that of the control group. (2) after returning farmland to forest, the soil structure of the returned farmland was improved to some extent, and the soil bulk density was higher than that of the control group, but the porosity and maximum water holding capacity of the soil were increased. The field water holding capacity was smaller than that of the control group because the control group was affected by artificial farming. The content of soil organic matter, total nitrogen, total phosphorus, total potassium, hydrolyzed nitrogen, available phosphorus and available potassium were all higher than that of the control group, which indicated that returning farmland to forest could effectively improve soil fertility. The soil and water loss of the returned farmland was also effectively controlled, and the water storage and soil consolidation capacity of the forest land were strengthened, and the runoff and sediment amount of each model were much smaller than that of the control group. At the same time, the water quality of forestland surface diameter running water has been improved to some extent. The contents of total N, total P and heavy metals are lower than those of the control group. The theoretical basis is utility value theory, and the methods of "alternative engineering method" and "opportunity cost method" have been adopted, such as "alternative engineering method", "opportunity cost method" and so on. The ecological value of Pingguo County, Donglan County and Xingbin District is 1.16 脳 1010 yuan, which includes the value of protecting water resources, the value of carbon sequestration, the value of releasing oxygen, the value of biodiversity and the value of purifying the environment. The value of soil conservation accounts for 40% of the total ecological value. The ecological benefits are mainly reflected in the protection of water resources and carbon sequestration and oxygen release.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S718.5;F326.2

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