微地形对江西武夷山南方铁杉针阔混交林幼树更新的影响

为探讨江西武夷山南方铁杉针阔混交林内不同微地形中幼树更新特征的差异，明晰不同微地形生境对幼树天然更新的影响。以江西武夷山国家级自然保护区内海拔约1800m的南方铁杉针阔混交原始林为研究对象，基于在其中建立的中亚热带南方铁杉针阔混交林动态监测固定样地首次调查数据，将固定样地中160个20m×20m的样方根据其海拔、凹凸度和坡度3种地形参数通过C-均值模糊聚类划分成不同的微地形生境，比较这不同微地形下的更新幼树种类组成及幼树更新特征，包括幼树密度，幼树平均胸径、平均高、平均冠幅，空间分布格局，分析不同微地形下幼树更新特征与地形因子、林分因子之间的关系。结果显示：(1)通过聚类分析，最终将固定样地的微地形生境划分成4类，分别为陡坡、凹地、凸地、缓坡。(2)4类微地形更新幼树优势种组成类似，但优势程度存在差异。闽皖八角幼树在4类微地形中的重要值皆为第一，均大于43%。建群种南方铁杉的幼树在凸地的重要值为9.09%,具有一定优势；在陡坡的重要值为0.62%,优势程度较差。(3)陡坡的更新幼树密度最高，为399株/hm~2,高于凹地，凸地和缓坡；幼树平均胸径和平均高的大小表现为：缓坡>凸地&...

Effect of micro-topography on the saplings regeneration in the coniferous (Tsuga chinensis var. tchekiangensis) and broadleaf mixed forest in the Wuyishan, Jiangxi Province

Based on investigation data in permanent plot of coniferous (Tsuga chinensis var. tchekiangensis) and broadleaf mixed virgin forest in the Wuyishan National Natural Reserve of Jiangxi Province, species composition and renewal characteristics of saplings in different terrains were analyzed, and the relationship between saplings renewal and terrain factors were discussed, which provided scientific basis for maintaining biodiversity of forest ecosystem and conservation of rare and relic plant of T. chinensis var. tchekiangensis. The coniferous and broadleaf mixed virgin forest at an elevation around 1800 m was set as research site. One hundred and sixty samples of 20×20m plots were divided into different micro-topographies by fuzzy C-mean clustering analysis of three terrain factors; there are elevation, convexity and slope. Under different micro-topography habitats, we compared the species composition and regeneration characteristics of saplings, including saplings density, the average diameter at breast height (DBH), height, crown width and spatial distribution pattern of saplings. The relationship between regeneration characteristics and terrain factors and stand factors was analyzed. The results showed that:(1) through cluster analysis, the micro-topographic habitats in permanent plot were divided into four categories:steep slope, concave, ridge and gentle slope. (2) The compositions of the regeneration dominant saplings in four micro-topography types were similar, but the degrees of dominance were different. Illicium minwanense was in an absolute dominant position in these four types, and T. chinensis var. tchekiangensis saplings had certain advantages in ridge, but the degree of dominance in steep slope was poor. (3) The saplings density in steep slope was the highest, followed by concave, ridge and gentle slope. The average DBH and average height of saplings were as follows:gentle slope > ridge > concave > steep slope, and the average crown width of saplings was ridge > gentle slope > concave > steep slope, which showed saplings growth status in gentle slope was the best, followed by ridge, and saplings growth status in steep slope was the worst. (4) Regenerated saplings in different micro-topographies were all showed an aggregated distribution pattern spatially, and the order of aggregation intensity was gentle slope > ridge > concave > steep slope. The saplings dominant specie I. minwanense mostly gathered in the right lower part of the sample plot. The saplings dominant specie I. minwanense mostly gathered in the right lower part of the sample plot, while T.chinensis var. tchekiangensis saplings preferred a high-lying terrain. while T. chinensis var. tchekiangensis saplings preferred a high-lying terrain. (5) Only elevation of the terrain factors was associated with saplings regeneration, and some stand factors under four micro-topography categories were significantly correlated with saplings regeneration (P<0.05). Micro-topography had a certain influence on saplings regeneration in this virgin forest. Stand density was the major factor affecting saplings regeneration in different micro-topographies. Saplings were suitable for settlement and growth on steep slope and concave, and T. chinensis var. tchekiangensis saplings were more distributed on the micro-topography with the most abundant light. The results could provide scientific basis for maintaining stability and biodiversity of forest ecosystem and conversation of rare and relic plant of T. chinensis var. tchekiangensis.