黄山松种群邻体范围与邻体竞争强度的研究

Study on neighborhood zone and neighborhood com-petition intensity in Pinus taiwanensis population

当环境中可利用的资源低于种群最佳生长需要时,种群内个体之间就会产生竞争。竞争常发生在邻近植物之间,植物地上部分和地下部分的竞争范围是不同的。目前,有很多度量竞争强度和确定竞争范围的方法,能否对这些方法进行改进,提出更具有说服力的方法,是本研究的出发点。黄山松是常见的针叶树种,分布范围广,生存能力强,是亚热带中部中山地区代表群系的建群种,也是较高海拔地区重要的造林树种,具有较强的代表性。对黄山松的邻体竞争研究发现:(1)改进的竞争指数有更强的说服力;(2)逐步扩大范围的方法能很好地确定植株间的竞争范围;(3)邻体竞争强度随影响范围的增加而增加,在一定的范围内增加的较快,而超出该范围后增加的幅度变小,可以此为依据来确定邻体范围;(4)不同径级的基株,邻体范围有一定的差异;(5)邻体竞争强度和影响范围的关系服从对数函数关系(CI=AlnC+B)。结果表明,改进的竞争指数能很好地度量竞争强度,采用逐步扩大范围的方法能有效地确定邻体范围。

Competition among trees within a population exists when resource availability falls below the sum requirement of the population for optimal growth. Competition for both aboveground and belowground resources takes place over different size zones. It is difficult,if it is not possible to define the zone of influence for use in a competition index （CI） for individual trees that includes all competitors and sources of competition for scarce resources. Generally, researchers have determined empirically that larger influence zones provide better correlations with tree growth. It is important to choose the suitable competition index and qualify the competition zone. Pinus taiwanensis is a common species, and it is one of the dominant species in subtropical area. The results show that： （1）the improved competition index is more suitable to study the neighborhood competition; （2）the method of increasing the range gradually can qualify the competition zone suitably; （3）the competition intensity in P. taiwanensis population increases with the increasing of zone, and in a certain zone, it increases very quickly while it has a little increase beyond the zone, by which the zone of neighborhood can be ascertained; （4）the plants with different diameter scale have different neighborhood zone; （5）the relationship between the competition intensity and the interference zone follows closely the following equation CI=AlnC＋B. A new approach to measure the competition intensity and to ascertain the neighborhood zone on studying the plant competition were provided in this paper.