马尾松-木荷不同比例混交林种内和种间竞争强度

分析不同比例组成的马尾松(Pinus massoniana)-木荷(Schima superba)混交林树木间的竞争关系,可为营造种间关系协调的马尾松混交林提供参考依据。以马尾松-木荷混交林为研究对象,根据其混交比例分别类型Ⅰ(对照,10马)、类型Ⅱ(8马2木)、类型Ⅲ(7马3木)、类型Ⅳ(6马4木) 4种类型设置标准地进行调查,运用Hegyi单木竞争指数对马尾松种内、种间竞争强度和总竞争强度进行分析。结果表明:马尾松种内平均竞争指数大小排序为类型Ⅰ>类型Ⅱ>类型Ⅲ>类型Ⅳ,且在所有径级中类型Ⅰ与类型Ⅱ、类型Ⅲ及类型Ⅳ均有显著性差异(P<0.05),而类型Ⅱ、类型Ⅲ、类型Ⅳ之间差异不显著(P>0.05);种间平均竞争指数则为类型Ⅱ、类型Ⅲ均与类型Ⅳ差异显著(P<0.05),而类型Ⅱ与类型Ⅲ之间差异性不显著(P>0.05);马尾松的总竞争指数、种内及种间竞争指数与其胸径拟合效果较好的模型均为幂函数或指数函数,其竞争压力与胸径大小呈负相关。马尾松-木荷混交林中,马尾松的竞争压力主要来自种内,胸径大于20 cm时受到的竞争压力变化较小且维持在较低水平。

Intraspecific and interspecific competition intensity in mixed plantation with different proportion of Pinus massoniana and Schima superba

Understanding individual competition in Pinus massoniana and Schima superba forests with different mixed proportions can provide references for the construction of P. massoniana mixed plantation with harmonious interspecific relationship. We examined the intraspecific,interspecific and total competition intensities of P. massoniana by using Hegyi single-tree competitive index in four types of mixed forests,including type Ⅰ( control,ten P. massoniana),type Ⅱ( eight P. massoniana and two S. superba),type Ⅲ( seven P. massoniana and three S. superba)and type Ⅳ( six P. massoniana and four S. superba). The average intraspecific competition indices of P. massoniana were following the order of type Ⅰ > type Ⅱ > type Ⅲ > type Ⅳ. In all diameter classes,there was a significant difference between typeⅠand typesⅡ,Ⅲ,Ⅳ( P<0.05),while there was no difference between types Ⅱ,Ⅲ and Ⅳ( P>0.05). The average interspecific competition index of types Ⅱ and Ⅲ were significantly different from that of type Ⅳ( P<0.05),while there was no difference between types Ⅱ and Ⅲ( P>0.05). The power function or exponential function was the best fitting models between the total,intraspecific,interspecific competition indices and diameter at breast height( DBH) of P. massoniana. There was a negative correlation between competition intensity and DBH. In the mixed plantation of P. massoniana and S.superba,the competition pressure of P. massoniana mainly came from intra-specific level,which remained stable and kept at a low level under DBH > 20 cm.