Spatial structure analysis of Cupressus funebris plantations of different site types
To explore the spatial structure characteristics of different site types of Cupressus funebris plantation,15 standard plots of Cupressus funebris plantation at the Qiqu Mountain State-owned Forest Farm in Zitong County,Sichuan Province were divided into different site types.The stand spatial structure unit was constructed based on Voronoi diagram,and the spatial structure characteristics at different site types were analyzed using five indices,namely:uniform angle index,neighborhood comparison,competition index,openness,and storey index of stands.The results showed that according to the site factors(slope and soil thickness)with significant influence on the average height of dominant trees,Cupressus funebris forest comprised three types of site(Ⅰ,Ⅱ,Ⅲ);of which the most common spatial structure unit of Cupressus funebris across all three site types comprised one central tree and six neighboring trees.The average uniform angle index of Cupressus funebris plantation on site types Ⅰ,Ⅱ,and Ⅲ was 0.39,0.37,and 0.38,respectively,and the overall spatial distribution pattern was uniform;average neighborhood comparison values were 0.49,0.50,and 0.51,respectively.The size differentiation degree was similar,and the growth trend was moderate.The average openness was 0.20,0.32,and 0.30,respectively.The light transmission condition of the stands was poor,and growth space was insufficient.There were significant differences in the storey index among the three site types(P＜0.05).Vertical stratification of the cypress wood plantations was most obvious at type-Ⅲsites and vertical structure was simplest at type-Ⅰsites.There were significant differences in competition index among the three site types(P＜0.01).Competition for stand space was fiercest at type-Ⅲ sites and weakest at type-Ⅰ sites.Based on the present situation of Cupressus funebris plantation in the study area,appropriate forest activities is conducted depending on the different types of tree growth sites.
Cupressus funebris plantationVoronoi diagramsite typespatial structure of stand
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