Impacts of Different Disturbances On vegetation Restoration on the Abandoned Farmland

27 Mar Impacts of Different Disturbances On vegetation Restoration on the Abandoned Farmland

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Abstract

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未实现植被恢复的退耕弃荒地。不同方式或不同强度的人 为干扰都会导致退耕弃荒地植被恢复效果发生偏差。研究选取滇西北维西县的退耕弃荒地为对象，通过分析放牧、围封和保 护 3 类不同干扰方式下植被恢复过程中群落物种多样性、地上生物量及主要恢复使用树种云南松(Pinus yunnanensis)幼苗生 长的差异，探讨不同干扰方式对退耕弃荒地植被恢复的影响。结果表明：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 多样性指数大小均表现为围封样地＞保护样地＞放牧样地(P<0.05)，即随着干扰 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”；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(P<0.001)；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(P<0.001)；因此，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。

English Abstract

Grain for green project is a key governmental forest restoration project in China, which aims to replant forest or grassland
on former agricultural land with over 25-degree slope. Unf, large areas of abandoned farmland have failed to achieve vegetation restoration in western China for a variety of complex reasons. However, restoration effect of vegetation on abandoned farmland
would deviate, which resultes from different types or intensity of anthropogenic disturbance. Here we chose abandoned farmland in
Weixi County of northwest Yunnan as a study object, and classified abandoned farmlands into 3 types of sample plots, grazing land,
fenced land and protected land, according to the different disturbance types. Then the paper analyzed differences of the biodiversity,
aboveground biomass, and growth of Pinus yunnanensis seedlings which was the main tree species for restoration on abandoned
farmland, with the vegetation restoration under differing circumstances, and discussed the impacts of different disturbances on
vegetation restoration. The results show that: The levels on the Margalef richness index and the Shannon-Wiener diversity index of
plant species were, grazing land > fenced land > protected land (P<0.05). With disturbance intensity increasing, species richness and diversity first increased, and then decreased, which supports the Intermediate Disturbance Hypothesis. The aboveground biomass size of the 3 plant communities in order, were protected land > fenced land > grazing land (P<0.001). The growth rate of Pinus yunnanensis seedlings on abandoned farmland under the influence of different disturbance in order, were also protected land > fenced
land > grazing land (P<0.001). As a whole, protecting or fencing supports vegetation restoration on abandoned farmland, while overgrazing hinders restoration, and might even lead to vegetation degradation.