Long-term changes in liana loads and tree dynamics in a Malaysian forest

Background

Increasingly lianas are recognized as one of the most important growth form in seasonal tropical forest, yet there has been limited research that has studied the effects in other forests. This study discusses the effect of lianas on tree growth, reproduction, and survivorship in a Southeast Asian Dipterocarp forest.

Goals & Methods

The goal of this study is to answer the following questions: "(1) Do lianas occur as frequently in the crowns of the Dipterocarpaceae as in the crowns of other tree families? (2) Do lianas affect the reproduction of their host trees during a strong, general flowering event? Do lianas affect host survival and growth? (3) Have lianas changed in importance between 2002 and 2014? To do so, the authors quantified flower and seed production by lianas and tress for 13 years, assessed liana loads in the crowns of all trees larger than 30 cm in diameter at breast height (1.3 m) in 2002 and 2014, and assessed levels of reproduction for the same trees during a strong general flowering event in 2014 for the 50-ha forest dynamics plot at the Pasoh Forest Reserve, Malaysia.

Conclusions & Takeaways

The found that, in the study site, liana presence or infestation reduced host tree growth and survival. Thus, the authors examine how an increase in lianas may affect the structure of the forest. Wright et al. also discuss how lianas may be increasing in the Neotropics and not in other tropical regions due to the higher percentage of Neotropical lianas that are wind-dispersed. Since hunters reduce frugivore populations (seed dispersers), trees and other zoochorous species suffer the consequences while lianas are unaffected and continue to reproduce through wind dispersion. Hunting may not have the same effect in Asian or African tropics because a similar proportion of lianas and trees are zoochorous. Thus, in the Neotopics, liana reproduction is not negatively affected by hunting whereas in other tropical regions, lianas and trees are both negatively affected by hunting.