云南苍山西坡森林木本植物幼苗组成的海拔梯度格局及其年际动态

Elevation Gradient Pattern and Interannual Dynamics of Forest Tree Species Seedlings on the Western Slope of Cangshan Mountain

为探讨云南苍山西坡木本幼苗组成的海拔梯度格局与其年际动态,以3个海拔建立的样地为平台,样方中胸径小于1 cm的木本植物幼苗为研究对象,设置192个2 m×2 m幼苗样方。通过2020—2022年连续3年的幼苗监测调查,对样地内木本植物幼苗组成及个体数量的海拔分布格局及其年际动态进行分析。结果显示:(1)调查期间共记录33种木本植物幼苗。3个样地的优势物种相似,但各样地之间物种组成差异较大。(2)幼苗数量随着调查时间推移逐渐减少,样地内重要值前6位的物种总数占样地幼苗总数的80%以上。(3)随着海拔升高,树种幼苗物种丰富度和Shannon-Wiener多样性指数均先增加后下降,而幼苗数量、Simpson多样性指数和Pielou均匀度指数均表现出随着海拔升高而逐渐降低的趋势。(4)Jaccard相似性指数显示,随海拔的升高,两个群落之间的幼苗物种组成相似性呈现降低趋势。研究结果为典型脆弱的退化森林生态系统恢复与保护提供科研支撑。

Understory seedlings are an important part of forest ecosystems and play an important role in forest renewal and ecological restoration.In order to understand the elevation gradient pattern and interannual dynamics of woody seedlings on the western slope of Cangshan Mountain,Yunnan,192 seedling quadrats of size 2 m×2 m were set up using the plots established at three altitudes as a platform.Through the seedling monitoring survey for three consecutive years from 2020 to 2022,the elevation distribution pattern and interannual dynamics of the composition and number of woody plants in the plot were analyzed.The results showed that a total of 33 woody plant seedlings were investigated during the survey period.In three years,only sample C was newly added in 2020-2021,and no new species were found in other plots.The dominant species of the three plots were similar,but the species composition varied greatly between the plots.The number of seedlings gradually decreased with the time of investigation,and the total number of species with the top 6 important values in each plot could account for more than 80%of the total number of seedlings in the plot.With the increase of altitude,the species richness of seedlings and the Shannon-Wiener diversity index both increased and then decreased,while the number of seedlings,Simpson diversity index and Pielou uniformity index showed a trend of gradual decrease with altitude.The Jaccard similarity index indicates that the similarity of species composition between the two elevation zones decreases with increasing altitude.This study aims at the changes of seedling species composition and their inter-annual dynamics under different altitude gradients on the western slope of Cangshan Mountain,which is helpful for us to explain and predict the dynamic changes of community composition,provide important theoretical and data basis for biodiversity conservation and sustainable forest management in the region in the future,and provide scientific research support for the restoration and protection of typical fragile degraded forest ecosystems.