人为干扰对尼泊尔中部丘陵森林物种多样性、更新和碳密度的影响

全球近四分之三的森林正在遭受人为干扰,尼泊尔三分之二以上的森林受到不同类型的干扰。在社区森林中,当地社区在生计的各个方面都依赖于森林提供的生态系统服务,这些服务以各种方式干扰森林的自然条件和生态系统的功能。本研究在尼泊尔中部丘陵区的两个社区管理森林中,研究了对植物物种多样性、更新(幼苗和树苗)、生物量、土壤有机碳(SOC)和总碳密度的主要干扰因子。以树桩数、断苗、砍伐和放牧践踏作为主要人为干扰的衡量指标,从89个随机选取的250 m2的样地中收集了必要的数据,利用广义线性模型(GLM)对人为干扰的响应进行了分析。结果表明,森林砍伐对生物量和总碳密度平衡的影响最大。森林砍伐程度越高,森林碳储量越低。SOC对上述类型的人为干扰均无显著反应。木本物种丰富度和幼树数量随着树桩数量的增加而增加,说明中间干扰是有益的。然而,较高的砍伐强度降低了幼树密度。放牧/践踏是抑制幼苗生长的最显著干扰,在践踏强度较高的森林地区,幼苗和树苗数量较少。这些结果将为尼泊尔多目标森林管理以及如何降低其他地区类似社会经济环境中的人为干扰的影响提供指南。

Implications of Anthropogenic Disturbances for Species Diversity,Recruitment and Carbon Density in the Mid-hills Forests of Nepal

Almost three-fourths of forests are experiencing anthropogenic disturbances globally, and more than two-thirds of the forests in Nepal receive different types of disturbances. In community forests(CFs), local communities are dependent on the ecosystem services provided by the forests for various aspects of their livelihoods, which disturb the forests’ natural conditions and ecosystem functioning in a variety of ways. This study tested the major disturbance factors that had influential roles on plant species diversity, recruitment(seedlings and saplings), biomass, soil organic carbon(SOC) and total carbon density in two community-managed forests in the Mid-hills of Nepal. The stump number, cut-off seedlings and saplings, lopping, dropping, and grazing/trampling were used as measures of the major anthropogenic disturbances. The necessary data were collected from 89 randomly selected sample plots, each with an area of 250 m2. The responses to anthropogenic disturbances were analyzed using Generalized Linear Models(GLM). The results showed that forest lopping was the most significant anthropogenic disturbance for biomass and total carbon density balance. A higher degree of lopping in the forests resulted in a lowering of the forests’ carbon stock in the study area. SOC showed no significant response to any of the tested anthropogenic disturbances. Woody species richness and number of saplings increased with an increasing number of stumps, which signifies that intermediate disturbance was beneficial. However, a higher intensity of lopping reduced the sapling density. Grazing/trampling was the most significant disturbance for inhibiting seedling growth. Areas in the forests with a higher intensity of trampling showed lower numbers of seedlings and saplings. These results will be a guide for managing anthropogenic disturbances in multiple-use forests in Nepal, as well as those in similar socio-economic environments worldwide.