Where are those new trees go in the wind-shaped forest in the southernmost of Taiwan?

Background/Question/Methods

Tree recruitment is important for long-term forest dynamics, determined by the regeneration habitat and species' shade tolerance. The Lanjenchi Forest Dynamic Plot is a wind stress forest that differentiates into different species compositions under different strengths of the Northeast monsoon wind. To understand how recruit tree species with different wind exposure select the regeneration habitat under the wind stress forest, we use the recruit tree point data in 5.28-ha of Lanjenchi Forest Dynamic plot between 2013 and 2019. Each tree was tagged, mapped, and identified into species. The g-function with 999 times of Monte-Carlo simulation was used to detect the significance of spatial patterns among recruit trees and three regeneration habitats, including parent tree (same species as recruit trees), large dead tree gap (DBH ≥ 17.2 cm), and small dead tree gap (DBH < 17.2 cm) in Lanjenchi plot, southern Taiwan. Last, we extract the result of aggregation patterns at different distances under three regeneration habitats and test the association of three regeneration habitats for each species by the randomized test with 1,000-time sampling.

Results/Conclusions

Our results show that 59 of 128 species increased ≥ 15 individuals in 2019. Melastoma candidum, Illicium arborescens, and Psychotria rubra are the species that increase the most individuals in the 2019 census at the study site. Moreover, 47 of 59 species have a specific association in each regeneration habitat. Trees with high photosynthetic capacity tend to regenerate under the large dead tree gap. Shade-tolerant species survived under the parent trees. And the species distributed on the windward side tend to regenerate under the small dead tree gap. This result provides multiple regeneration habitats for different species to recruit depending on their shade tolerance and characteristics in different environments.