Abstract:

Clarifying the impact of neighborhood interactions on tree growth and TS (temporal stability) is crucial for evaluating the productivity and stability of natural forests. However, relevant studies remain scarce. This study takes the dominant tree species Liriodendron tulipifera and the non-dominant tree species Fagus grandifolia in the permanent plots of a temperate secondary forest as examples. This work uses BAI (basal area increment) to represent tree growth, and analyzed the impact of neighborhood interactions on tree growth and TS. The results showed that: 1) The growth rate and TS of both tree species increased significantly with increasing diameter at breast height. The two species differed in that the growth rate of Liriodendron tulipifera increased more rapidly with diameter at breast height than that of Fagus grandifolia. 2) The mean BAI was more important for TS than the standard deviation of BAI. In addition, neighborhood competition reduced the growth of target trees, and thus reduced tree TS; 3) Intraspecific and interspecific competition impacted the growth and TS of dominant and non-dominant tree species differently. The growth and TS of Liriodendron tulipifera were significantly negatively correlated with the intraspecific and interspecific competition intensity (p<0.05), while the growth and TS of Fagus grandifolia were only significantly negatively correlated with the interspecific competition intensity (p<0.05). In conclusion, reducing the number of trees of the same and different species helps increasing the growth rate and TS of Liriodendron tulipifera. Only reducing interspecific competition can increase the growth rate and TS of Fagus grandifolia.

Key words: neighborhood interaction, temporal stability, intraspecific competition, interspecific competition, tree ring, secondary forest

摘要：

明确邻体相互作用对树木生长及生长时间稳定性（TS）的影响对于评估天然林生产力和稳定性十分重要，然而目前相关研究较少。该文以温带次生林中优势树种北美鹅掌楸（Liriodendron tulipifera）和非优势树种美国水青冈（Fagus grandifolia）为例，使用BAI（胸高断面积增量）表征树木生长，分析了邻体相互作用对树木生长及TS的影响。结果表明：1）两树种的生长速率和稳定性均随胸径增大而显著提高，但北美鹅掌楸的增长幅度显著大于美国水青冈；2）平均BAI对树木TS的重要性高于BAI标准差，邻体树木通过竞争抑制对象木生长进而降低树木TS；3）种内竞争和种间竞争对优势树种和非优势树种生长及TS的影响存在差异，北美鹅掌楸生长及TS与种内和种间竞争强度均呈显著负相关（p<0.05），而美国水青冈仅与种间竞争强度呈显著负相关（p<0.05）。综上所述，降低同种和异种树木数量可增强北美鹅掌楸生长，并提高其TS。仅降低异种竞争便可提高美国水青冈生长速率和TS。

关键词: 邻体相互作用, 时间稳定性, 种内竞争, 种间竞争, 树木年轮, 次生林