放猪干扰对四川夹金山植物群落特征和生物量的影响

Abstract

选择四川省夹金山针阔混交林，采用典型样地法调查、RDA二维排序分析高山高地植物群落的物种多样性与地上地下生产力的关系及两者对不同等级放猪干扰的响应，结果显示：（1）夹金山针阔混交林群落共有植物55科117属172种，乔木层、灌木层在各程度干扰下优势种变动较小，川滇长尾槭（Acer caudatum var.prattii）、箭竹（Fargesia spathacea）等始终占据首要地位，草本层优势种变化较大；（2）随干扰程度增加，一年生草本重要值升高，多年生草本重要值降低，其中适口性较强的禾草类植物重要值降低，且草本层地下与地上生物量比值明显降低；（3）乔灌草三层物种多样性水平在轻度干扰下最高，重度干扰下最低；（4） RDA结果分析显示，灌、草本层各物种多样指数（除Pielou均匀度指数外）与各层次生物量呈正相关，乔木层各多样性指数与灌木层地上地下生物量、枯落物量均呈正相关；（5）轻度干扰梯度下幼苗占比显著高于其他干扰梯度，I级下林内几乎未发现成活的乔木优势种幼树，群落更新能力最差。综上，建议将重度、较重度（Ⅱ级）干扰样地（即距养猪场2000 m范围内）的管理措施设置为禁牧或轮牧，重点维护川滇长尾槭、糙皮桦（Betula utilis）的幼树生长以促进更新。;The coniferous and broad-leaved mixed forest in Jiajin Mountain, Sichuan Province was selected to analyze the relationship between the species diversity of the alpine vegetation community and the aboveground and underground productivity and the response of the two to different levels of grazing disturbance by using typical sampling method and DCA two-dimensional ordering. The results showed that:(1) there were 172 species of trees, shrubs and herbs belonging to 55 families and 117 genera in the coniferous and broad-leaved mixed forest communities of Jiajin Mountain. The dominant species in the tree layer and shrub layer changed little under various levels of disturbance, and Acer caudatum var. prattii and Fargesia spathacea always occupied the first place, while the dominant species in herbaceous layer changed greatly; (2) With the increase of the grazing disturbance (from Ⅳ to Ⅰ), the important value of annual herbs increased, while that of perennial herbs decreased, and that of gramineous grasses decreased. The ratio of underground to aboveground biomass in herbaceous layer decreased significantly; (3) The species diversity level of tree, shrub and herbs was the highest under the level IV and the lowest under the level I; (4) The results of redundancy analysis showed that the species diversity index of shrubs and herbs (except Pielou evenness index J_sw) was positively correlated with the biomass of each layer, and the diversity indexes of tree layer were positively correlated with the aboveground and underground biomass of shrub layer and litter fall; (5) The proportion of saplings under level IV was significantly higher than that under other levels. But there were almost no dominant saplings in the forest under severe disturbance (level I), so the regeneration ability of the community was the worst. It is recommended to set the management measures for Ⅰ and Ⅱ (that is, within 2000 m from the pig farm) to grazing prohibition or rotation grazing, and focus on maintaining the growth of saplings of Acer caudatum var. prattii and Betula utilis to promote the regeneration of vegetation communities.