Abstract
The spatial patterns of plant species reflect the competitive pressures on individuals. To generate Competition indices (CI), we measured the diameter at breast height (DBH), crown volumes (CV) and the distances between trees. In this study, Abies kawakamii were divided based on the dominant component of the understory (moss or bamboo) to (1) investigate the relationship between the CI and stand structural attributes (SSAs); (2) compare the inter- and intraspecies; CIs as well as living and dead individual CIs; and (3) examine the relationship between the DBH and CI. The current findings indicate that the understory composition affected the CI and SSAs. The interspecies CI was larger than the intraspecies CI when bamboo-dominated the understory. In contrast, the intraspecies CI was larger than the interspecies CI when the understory was dominated by moss. The CI of dead individuals was higher than that of live individuals due to the biological characteristics and regeneration needs of Abies. Additionally, sensitivity to the environment and available resources may exert more pressure on young individuals than mature individuals.
Highlights
Tree distribution and density depend on environmental conditions in the forest [1, 2]
We assume five hypotheses that (1) Competition indices (CI) based on variable distance would search more competitor trees than CI based on fixed distance; (2) CI would be positive corelated with stand structural attributes (SSAs); (3) Individuals of Taiwan fir would be sustain more competitive stress from intraspecies than interspecies; (4) Dead individuals would be sustain more competitive stress than living individuals; (5) There were negative relationship with CI and diameter at breast height (DBH) of target trees
We measured DBH and distance between individuals to quantify the level of competitive interaction
Summary
Tree distribution and density depend on environmental conditions in the forest [1, 2]. Forest communities are shaped by spatial variation [3, 4], seed spread, interspecies and intraspecies competition, heterogeneity of the environment, and different scales of variability that affect spatial patterns [5]. In the harsh environment of high-altitude forests, species may interact competitively or symbiotically. Investigating the relationships among adjacent trees of different sizes and species in forests at various spatial scales will allow us to better understand their coexistence mechanism. The competitive relationships between individual trees can be incredibly complex, reflecting the niches of individuals of various species and their resource and space needs [6, 7].
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