延安城郊刺槐林下物种多样性与生物量研究

Understorey Species Diversity and Biomass of Artificial Robinia pseudoacacia Forests in Yan'an Suburb

以延安城郊刺槐林为研究对象,采用"空间序列代替时间序列"法,对其进行样地调查,比较分析林下植物多样性和生物量随林龄、林分密度和坡向变化而变化的规律。结果表明:1)刺槐林下共有植物52种,隶属于26科44属,分布较广的有菊科、豆科、蔷薇科、毛茛科和禾本科。2)阴坡刺槐林下各指标均优于阳坡,说明阳坡的自然条件较差,可选择更能适合其条件的抗旱树种在适宜的栽植密度下进行造林,如沙棘、山杏等,造林时注意构建合理的模式配置,促进林分的健康发育。3)刺槐林下物种多样性与生物量间有一定的相关关系,主要表现在Margalef指数与地上生物量相关性极显著(p=0.000 04),与地下生物量相关性极显著(p=0.007 74),与地上生物量/地下生物量相关性显著(p=0.024 76);而Shannon-Wiener指数与地上生物量相关性极显著(p=0.003 80),与地上生物量/地下生物量相关性显著(p=0.027 61)。研究表明,综合物种多样性与生物量的指标来看,延安城郊刺槐林的栽植密度在950株·hm-2左右时利于其林下群落生长发育;而在刺槐进入中龄林后即可对其进行适当的抚育改造,包括间伐乔木,补植灌草等一系列措施,丰富林下层次结构,利于其可持续发育。

Methods of ＂substituting space series for time series＂ and ＂contrastive analysis＂ were adopted to investigate the understory species diversity and biomass of artificial Robinia pseudoacacia forests in Yan＇an suburb. 1） Under the R. pseudoacacia forest, 52 plant species were found, belonging 26 families and 44 genuses, in which the widely distributed species were in the families of Compositae, Leguminosae, Rosaceae, Ranunculaceae and Gramineae. 2） In the same period, the biodiversity indexes were obviously higher on shady slopes than those on sunny slopes, suggesting that the natural conditions of sunny slopes were worse, and it would more likely to plant some trees which could adapt the conditions, such as Hippophae rhamnoides, Arrneniaca sibirica and so on in proper plant density. At the same time, reasonable mode configuration should be constructed to promote the healthy development of the forests. 3） Species diversity of forests was correlated to the biomass. There existed most significant correlation between Margalef index and the below-ground biomass （p=0. 000 04）, above-ground biomass （p=0. 007 74）, and the Margalef index also was significantly correlated to above-ground/below-ground biomass ratios （p = 0. 024 76）.Shannon-Wiener index was most significantly correlated to above-ground biomass （p=0. 003 80） and sig- nificantly correlated to the above-ground /below-ground biomass ratios （p=0. 027 61）. In the views of species diversity and the biomass indexes, it was beneficial to the growth and development of the understo- ry plants when the plant density of R. pseudoacacia was about 950 plant per hm2. After the the forests were in their middle-age stage, proper management measures should be adopted, including thinning arbor, replanting shrub-grass, and so on to enrich the structure composition of the species under the forest, and for the sustainable development.