Analysis of plant community successional series in the Ziwuling area on the Loess Plateau
Analysis of plant community successional series in the Ziwuling area on the Loess Plateau
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作者：
Fan Wei
黄土高原生态系统因土壤和地下水的枯竭而严重退化。加快该地区退化生态系统的恢复和恢复，对于改善西北地区的区域环境和提高生态系统生产力具有重要意义。子午岭地区拥有天然次生林地带，对保持甘肃东部和陕西北部的区域气候和生态可持续经济发展具有重要作用。本研究旨在量化子午岭地区植物群落的演替系列。该地区位于子午岭南部，隶属于陕西省寻义县马兰林区，中国，东经108°27‘~108°52’，北纬35°9‘~35°33’，东西长约40公里，宽约43公里。该区植被类型多样，具有不同的干扰历史。我们选择了在不同时间最后受干扰的地区，用空间序列代替时间进程来捕捉一系列演替阶段。在采样点的选择上，努力确保环境条件的一致性。我们建立了15，10和21个样地进行草本植物调查。该地区植物群落演替序列由草本型群落到灌木型群落再到乔木型群落，并对群落的物种组成、生活型组成、凋落物和腐殖质厚度的动态进行了比较。人工造林加速了演替进程，并创造了从刺槐或油松群落开始的交替演替路径。随着时间的推移，科、属和种的数量都在增加，演替早期的一年生植物所占的比例高于中晚期。多年生植物，特别是木本植物在整个演替系列中占主导地位。多年生草本和豆科植物在整个演替系列中保持一个恒定的比例。各生活型组的物种丰富度随着时间的推移而增加，组成比例变得更加一致。凋落物和腐殖质厚度随着演替时间的推移而增加，但凋落物和腐殖质的比例在不同演替阶段有所不同。人工次生林和天然次生林在物种组成、生活型群落组成、凋落物和腐殖质厚度方面存在差异。
The ecosystem on the Loess Plateau is seriously degraded due to soil and groundwater depletion.It is important to accelerate the recovery and restoration of degraded ecosystems in this area in order to ameliorate the regional environment and increase ecosystem productivity in Northwest China.The Ziwuling area contains zones of natural secondary forest and is important in maintaining regional climate and as a base for ecologically sustainable economic development in east Gansu and north Shaanxi provinces.The goal of this study was to quantify the successional series of plant communities in the Ziwuling area.The area studied is located in the south of Ziwuling,and belongs to the Malan forest area in Xunyi county,Shaanxi Province,China,at 108°27′～108°52′E,35°9′～35°33′N.It is about 40 km long from east to west,43 km in width.There are various vegetation types in the region which have different disturbance histories.We selected areas last disturbed at different times,using the space series to replace time courses to capture a range of successional stages.We endeavored to ensure consistency of environmental conditions in the selection of sampling sites.We established 15,10 and 21 sampling plots for investigating herb,shrub and tree communities respectively.The youngest communities are about 2～5 years post-abandonment and the oldest communities are about 130～150 years post-abandonment.The successional series was described using a combination of numerical classification and ordination.The dynamics of species composition,life form group composition,litter and humus thickness were compared across the successional series.The plant community successional series were divided into nine stages in this area with a trend over time from herb-to shrub-to tree-dominated communities. The climatic climax was a Quercus liaotungensis community.Artificial reforestation accelerated the succession process and created alternate successional paths beginning with Robinia pseudoacacia or Pinus tabulaeformis communities. Over time,the number of families,genera and species increased.The proportion of annuals in the early successional stages was higher than in the middle and late stages. Perennials,especially woody plants,became dominant in the middle to late stages.Perennial grasses and legumes maintained a constant ratio in the entire successional series.The species richness of every life form group increased and the compositional proportion became more consistent over time.Litter and humus thickness increased over successional time,however,the ratio of litter to humus differed among successional stages.Artificial and natural secondary forests had some differences in species composition,life form group composition,and litter and humus thickness.