南亚热带马尾松×红锥混交林红锥的天然更新及环境解释

Environmental Factors and Natural Regeneration of Castanopsis hystrix in a Tropical Pinus massoniana×C.hystrix Mixed Plantation in Subtropical China

关键词:  红锥  人工林  天然更新  环境解释

Key words:  Castanopsis hystrix  planted forests  natural regeneration  environmental factors

摘要:

为揭示影响南亚热带马尾松×红锥混交林下红锥天然更新的关键环境因子，本研究以1983年造林的马尾松×红锥人工林为对象，选取3个研究样地，设置50个2 m×2 m的调查样方，对红锥更新苗、土壤理化性质、林分结构与光环境等展开调查。结果表明，不同样地红锥天然更新密度为（132 353±7 050）~（174 219±15 580）株·hm^-2。5个高度级红锥更新苗密度差异显著，Ⅰ级最大，Ⅴ级最小，密度随高度级增加而递减。相关分析表明，土壤全磷含量对Ⅰ、Ⅴ级的红锥更新苗有明显的正效应，而对Ⅱ、Ⅲ级更新苗有明显的负效应；红锥Ⅰ级苗与土壤pH值呈极显著正相关；近地层透光系数与Ⅰ、Ⅱ、Ⅲ、Ⅳ级苗木密度呈负相关，与Ⅴ级呈正相关；林分上层平均叶倾角、近地层叶面积指数则与Ⅰ、Ⅱ、Ⅲ、Ⅳ级苗木密度呈正相关，与Ⅴ级呈负相关。研究所选择的25个林分结构与土壤环境因子组合对红锥天然更新分布格局的变异解释率达到66.01%，解释效果显著（F=2.022 9，P=0.027）。土壤全磷含量、土壤pH值、海拔高度、林分上层平均叶倾角、近地层叶面积指数、近地层透光系数等6个因子是影响南亚热带红锥天然更新分布格局的关键因子。

Abstract:

In order to reveal the key environmental factors affecting the natural regeneration of Castanopsis hystrix in a mixed plantation of Pinus massoniana×C.hystrix in South China, taking the P.massoniana×C.hystrix mixed plantations afforested in 1983 as the object, 3 experimental plots were selected and 50 investigation sample plots were set to investigate the regenerated seedlings of C.hystrix,soil physical and chemical properties, stand structure and light environment. The results showed that the natural regeneration density of C.hystrix varied from (132 353±7 050) individuals·hm^-2 to (174 219±15 580) individuals·hm^-2. There were significant differences among the density of the 5 height level of the regenerated seedlings. The density of the Ⅰ level was the largest, and Ⅴ level was the smallest. The density decreased as the growth stage increased. Correlation analysis showed that the total phosphorus content of soil had obvious positive effects on level Ⅰ and level Ⅴ renewed seedlings of C.hystrix,but had more obvious negative effects on the level Ⅱ and level Ⅲ seedlings. The level Ⅰ seedlings were significantly positively correlated to soil pH. The penetration coefficient of the near-surface layer was negatively correlated with the density of seedlings of level Ⅰ,Ⅱ,Ⅲ and Ⅳ, and positively correlated with level Ⅴ. The average leaf angle of the upper layer of the stand and the leaf area index of the near-surface layer were positively correlated with the seedling density of level Ⅰ,Ⅱ, Ⅲ and Ⅳ, and negatively correlated with level Ⅴ. The combination of 25 stand structures and soil environmental factors selected in the study had a significant explanatory effect on the variation of the distribution pattern of natural regeneration of the seedlings, reaching 66.01% (F=2.022 9,P=0.027). Six factors including soil total phosphorus content, soil pH, altitude, upper average leaf angle, near-surface layer area index and near-surface layer light transmission coefficient are the key factors affecting the natural regeneration distribution pattern of the tropical C.hystrix in South China.