【作者】 柳小康；

【导师】 欧晓昆； 张志明；

【作者基本信息】 云南大学 ， 生态学， 2011， 硕士

【摘要】 退耕还林还草是当前我国最为宏大的生态修复和重建工程。然而由于各种原因,我国西部地区仍然分布着较大面积退耕后并没有实现植被恢复的退耕弃荒地。随着人为干扰影响的增强,退耕弃荒地的管理和利用方式多样,所导致的植被恢复效果也是多样,而目前有关不同干扰对退耕弃荒地植被恢复的影响研究还少见报道。退耕弃荒地的群落特征是衡量退耕地恢复的关键指标,不同的群落特征反映了退耕地植被恢复的方向和速度。分阶段检验和分析退耕后不同干扰强度下植被恢复状况,对合理管理退耕弃荒地并实现植被恢复的目标极为重要。我们假设,不同干扰方式会导致退耕弃荒地的植被恢复效果出现显著差别,而这种差别可以由群落的结构、功能和动态等定量评价指标所反映。本文选取滇西北维西县退耕年限相同、土壤条件一致、地形地貌条件相近的退耕弃荒地为研究对象,并根据干扰方式的差异,将退耕弃荒地分为放牧、围封和保护3类样地。通过分析不同干扰方式下植被恢复生态过程所引起的植物群落物种多样性、地上生物量及云南松(Pinus yunnanensis)幼苗生长的变化,探讨不同干扰方式对退耕弃荒地植被恢复的影响。结果如下：(1)不同干扰方式下退耕弃荒地植物群落的物种组成、优势种、生活型结构、群落结构及物种多样性等特征表现出明显差异。放牧、围封和保护3种干扰方式下退耕弃荒地植物种的Margalef丰富度指数和Shannon-Wiener多样性指数大小都表现为围封样地>保护样地>放牧样地。随着干扰强度的增加,群落物种的丰富度和多样性先升高后降低,结果支持“中度干扰假说”。保护和围封干扰影响均有利于退耕弃荒地保持较高的物种多样性,其中围封干扰影响下物种丰富度和多样性最高。相反,放牧干扰则会导致退耕弃荒地物种显著丧失,不利于物种多样性保持。(2)3类退耕弃荒地植物群落地上生物量大小依次为保护样地>围封样地>放牧样地。保护下的退耕弃荒地植物群落地上生物量显著高于其他2类样地,即保护方式有利于退耕弃荒地生物量的恢复。相反,放牧和围封方式下,退耕弃荒地的地上生物量明显较低,不利于退耕弃荒地生物量的恢复。(3)云南松幼苗在不同干扰方式下的退耕弃荒地内生长优劣程度依次为保护样地>围封样地>放牧样地。干扰较小的保护样地和围封样地内云南松幼苗的生长状况均显著优于放牧样地,具有强干扰程度的放牧方式会抑制退耕弃荒地内云南松幼苗的生长,阻碍群落朝进展型植被演替的方向发展。(4)保护和围封方式均有利于退耕弃荒地的植被恢复,而自由放牧方式会阻碍植被恢复,甚至可能会导致植被退化。为了维持退耕弃荒地生物多样性和自然生态系统的正常运行,在以后的生物多样性保护、生产力维持以及植被恢复中应当明确考虑干扰过程的影响,选择更为合理和有效的生态管理措施。更多还原

【Abstract】 In China,’Grian for green’program is a key government forest restoration program which aims to replant forest or grassland on agricultural lands with a slope of over 25 degrees. However, larger areas of abandonded farmland which failed to achieve vegetation restoration distributes extensively in the west of China, due to divers reasons. Because the ways of abandonded farmland managment and using are various, the plant communities succession in abandonded farmland which resulted from different anthropogenic disturbances are various as well. However, few studies focus on the impacts of different disturbances on vegetation succession in abandonded farmland. The changes of plant community in abandonded farmland are the key indicator for measuring and evaluating the forest restoration and ecological consequences of the’grain for green’program. Characteristics of plant community reflect the direction and the speed of vegetation restoration. Therefore, it is distinctly important for properly managing abandonded farmland and realizing the aim of vegetation restoration, to examine and analyze the situation of vegetation restoration after conversion of farmland under different disturbances in certain stage.We hypothesized that different disturbances could result in significant difference of vegetation restoration effects in abandonded farmland, while the difference can be indicated by quantitative assessment index on plant community structure, function and dynamic. Here we choosed abandonded farmland with same de-farming time, coincident soil condition, and close topography and geomorphology condition as study object in Weixi County, northwest of Yunnan Province, and divided abandonded farmland into 3 sample plot, grazing land, fenced land and protected land, according to the different disturbance types. Then we analyzed how the biodiversity, aboveground biomass, and growth of Pinus yunnanensis seedlings of plant community in abandonded farmland changed, which resulted from ecological restoration under different disturbances, and discussed influence of different disturbances on vegetation restoration succession in abandonded farmland. Conclusions were as follows:(1) Plant species composition, dominant species, life form structure, community structure and species diversity were all different in abandonded farmland under different disturbances. The sizes of Margalef richness index and Shannon-Wiener diversity index of plant species in abandonded farmland under grazing, being fenced and being protected disturbances in order were grazing land> fenced land> protected land. With the disturbance intensity increased, species richness and species diversity showed the trend of increase firstly, and then decreased, which supported the intermediate disturbance hypothesis (IDH). Protecting and fencing disturbance both would benefit abandonded farmland to keep high level of plant species biodiversity, especially fencing disturbance. On the contrary, grazing disturbance would result in plant species loss significantly, and would not benefit to keep plant species biodiversity.(2) The aboveground biomass sizes of plant community in abandonded farmland under 3 types of disturbances in order were protected land> fenced land> grazing land. The aboveground biomass in grazing land was lowest, while the aboveground biomass in protected land was higher than others significantly (P<0.05). In other words, protecting disturbance would benefit abandonded farmland to restore biomass. On the contrary, it was low of aboveground biomass of community in abandonded farmland under grazing and fencing disturbance, and would not benefit to restore biomass.(3) The growth quality of Pinus yunnanensis seedlings in abandonded farmland under different disturbances in order were protected land> fenced land> grazing land. The growth of Pinus yunnanensis seedlings both in protected land and fenced land were better than that in grazing land significantly. Grazing with high disturbance intensity could restrain the growth of Pinus yunnanensis seedlings in abandonded farmland, and prevent the community from developing to the direction of progressive vegetation succession.(4) Protecting and fencing would positive affect the vegetation restoration in abandonded farmland, while over grazing precent vegetation from restoring, and even bring about vetetation degradation. For maintaining biodiversity and natural ecosystem operating normally in abandonded farmland, the influence of disturbance process must be considered in biodiversity protection, productivity maintainance and vegetation restoration, and choose more reasonable and effective ecological management measures.更多还原