The factors that limit the maximum height of trees, whether ecophysiological or mechanical, are the subject of longstanding debate. Here, we examine the role of mechanical stability in limiting tree height and focus on trees from the tallest tropical forests on Earth, in Sabah, Malaysian Borneo, including the recently discovered tallest tropical tree, a 100.8 m Shorea faguetiana named Menara. We use terrestrial laser scans, in situ strain gauge data and finite element simulations, to map the architecture of tall tropical trees and monitor their response to wind loading. We demonstrate that a tree's risk of breaking due to gravity or self‐weight decreases with tree height and is much more strongly affected by tree architecture than by material properties. In contrast, wind damage risk increases with tree height despite the larger diameters of tall trees, resulting in a U‐shaped curve of mechanical risk with tree height. Our results suggest that the relative rarity of extreme wind speeds in north Borneo may be the reason it is home to the tallest trees in the tropics. Abstract in MALAY is available with online material.

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

No abstract

Context Intact tropical rainforests are considered robust to plant invasions. However, land-use change alters the structure and species composition of native forest, opening up tropical landscapes to invasion. Yet, the relative roles of key drivers on tropical forest invasions remain little investigated. Objectives We examine factors affecting plant invasion of rainforest remnants in oil-palm dominated landscapes in Sabah, Malaysian Borneo. We hypothesized that invasion is greater in highly fragmented landscapes, and in disturbed forests with lower native plant diversity (cf. old-growth rainforests). Methods Native and exotic plants were surveyed in 47 plots at 17 forest sites, spanning gradients in landscape-scale fragmentation and local forest disturbance. Using partial least squares path-modelling, we examined correlations between invasion, fragmentation, forest disturbance, propagule pressure, soil characteristics and native plant community. Results We recorded 6999 individuals from 329 genera in total, including eight exotic species (0-51% of individuals/plot, median = 1.4%) representing shrubs, forbs, graminoids and climbers. The best model (R 2 = 0.343) revealed that invasion was correlated with disturbance and propagule pressure (high prevalence of exotic species in plantation matrix), the Electronic supplementary material The online version of this article (

13The factors that limit the maximum height of trees, whether ecophysiological or mechanical, are the 14 subject of longstanding debate. Here we examine the role of mechanical stability in limiting tree 15 height and focus on trees from the tallest tropical forests on Earth, in Sabah, Malaysian Borneo, 16including the recently discovered tallest tropical tree, a 100.8 m Shorea faguetiana. We use 17 terrestrial laser scans, in situ strain gauge data and finite-element simulations to map the 18 architecture of tall broadleaf trees and monitor their response to wind loading. We demonstrate 19 that a tree's risk of breaking due to gravity or self-weight decreases with tree height and is much 20 more strongly affected by tree architecture than by material properties. In contrast, wind damage 21 risk increases with tree height despite the larger diameters of tall trees, resulting in a U-shaped 22 curve of mechanical risk with tree height. The relative rarity of extreme wind speeds in north Borneo 23 may be the reason it is home to the tallest trees in the tropics. 24