The Spatial Distribution Patterns of Fagaceae Plants in Evergreen Broadleaf Forests and Their Influencing Fac-tors
The study area was set in the Shiwanda Mountain,Huaping,and Cengwanglao Mountain national nature reserves in the Guangxi Zhuang Autonomous Region.Nine fixed plots measuring 100 m×100 m were established,each divided into 25 subplots of 20 m×20 m,which were further divided into 16 small subplots of 5 m×5 m.Using the space-for-time substitution method(i.e.,size-class structure replacing age structure),individuals of Fagaceae species were categorized into three size classes based on diameter at breast height(DBH):small trees(1.0cm≤DBH＜5.0cm),medium trees(5.0cm≤DBH＜20.0 cm),and large trees(DBH≥20.0cm).All Fagaceae individuals with DBH≥1.0 cm in the plots were selected as the re-search subjects.For each tree,measurements were taken,including species name,DBH,tree height,crown width,height under the branch,and the positional coordinates of each tree were also recorded.Spatial aggregation was evaluated using altitude,longitude,latitude,annual precipitation,spring precipitation,summer precipitation,annual average tempera-ture,annual maximum temperature,annual minimum temperature,January average temperature,and July average temper-ature as influencing factors.Various statistical methods were employed,including the Kruskal-Wallis test(K-W test),Ripley's L function in conjunction with a Complete Spatial Randomness(CSR)model,linear regression analysis,and Pearson correlation analysis,to analyze the spatial distribution patterns of different size classes of Fagaceae and the effects of the influencing factors.The results showed that:(1)The distribution patterns of small trees,medium trees,and the o-verall group of Fagaceae predominantly exhibited clustered distribution,while large trees displayed random distribution.The degree of aggregation decreased with size class,in the order of small trees,medium trees,the overall group,and large trees.(2)The aggregation degree(L10)of small trees,medium trees,and the overall group at a spatial scale of 10 m was significantly positively correlated with annual precipitation,annual average temperature,annual maximum temperature,an-nual minimum temperature,January average temperature,and July average temperature(P＜0.05),with small trees being more influenced by climatic factors such as temperature and precipitation.The aggregation degree(L10)of large trees was significantly positively correlated with annual average temperature,annual maximum temperature,annual minimum temper-ature,and January average temperature(P＜0.05).The aggregation degree of Fagaceae across different size classes was significantly negatively correlated with latitude(P＜0.05)and negatively correlated with altitude.The spatial distribution patterns of Fagaceae were primarily influenced by dispersal limitations and climatic factors,with consistent correlation trends between different size classes of trees and the same climatic factor,although the degrees of impact varied.
Broad-leaved evergreen forestsFagaceae plantsSpatial distribution patternDiffusion limitation
万方数据
维普
