Crown damage and the mortality of tropical trees

Abstract

What causes individual tree death in tropical forests remains a major gap in our understanding of the biology of tropical trees and leads to significant uncertainty in predicting global carbon cycle dynamics. We measured individual characteristics (diameter at breast height, wood density, growth rate, crown illumination and crown form) and environmental conditions (soil fertility and habitat suitability) for 26 425 trees ≥ 10 cm diameter at breast height belonging to 416 species in a 52-ha plot in Lambir Hills National Park, Malaysia. We used structural equation models to investigate the relationships among the different factors and tree mortality. Crown form (a proxy for mechanical damage and other stresses) and prior growth were the two most important factors related to mortality. The effect of all variables on mortality (except habitat suitability) was substantially greater than expected by chance. Tree death is the result of interactions between factors, including direct and indirect effects. Crown form/damage and prior growth mediated most of the effect of tree size, wood density, fertility and habitat suitability on mortality. Large-scale assessment of crown form or status may result in improved prediction of individual tree death at the landscape scale.

A mechanistic and empirically supported lightning risk model for forest trees

“…Many lightning-damaged trees die from their injuries (Anderson, 1964;Furtado, 1935;Rakov & Uman, 2003), and the higher incidence of lightning damage to large trees explains why lightning is responsible for 40%-50% of large tree mortality on BCI (Yanoviak et al, 2020). Accordingly, it is possible that the positive relationships between the mortality rate of large trees and the exposure of their crowns to light (Arellano, Medina, Tan, Mohamad, & Davies, 2018;Rüger, Huth, Hubbell, & Condit, 2011) or proximity to fragment edges (Laurance, Delamônica, Laurance, Vasconcelos, & Lovejoy, 2000) results at least in part from the greater frequency of lightning damage for these highly exposed trees. The effect of crown exposure is consistent with the expectation that taller trees are more likely to be struck by lightning (Anderson, 1964;Yanoviak et al, 2015), and this association shows that the distribution of lightning damage has a deterministic component, particularly at small spatial grain (<15 m).…”

Afromontane Forest Diversity and the Role of Grassland-Forest Transition in Tree Species Distribution

“…The null expectations for each species were obtained after 999 constrained torus translations, an adaptation of the standard or unconstrained torus translation (see Appendix A for more details on standard (unconstrained) and constrained torus translations). During a standard torus translation, all individuals are translated together as a rigid cloud of points [39][40][41]. The spatial pattern of the species (the spatial aggregation) is respected, but the relationship with the habitat map (the grass vs. forest map, or the streams, or the elevation) is broken.…”

“…Torus translation tests are routinely used in analysis of plant-habitat associations [40][41][42]. The rationale underlying torus translation tests is to contrast the observations with the expectations under the assumption of lack of relationship between a given species and the habitat.…”

Long-Term Impacts of Selective Logging on Amazon Forest Dynamics from Multi-Temporal Airborne LiDAR

“…Leaning trees and canopy damage caused by treefalls also contribute to the delayed mortality that tends to decrease in the years following logging (Figure 8). Partial crown damage has been shown to predict mortality in intact forest in the Lambir Hills National Park in Malaysia [64]. Thus, estimates of carbon emissions caused by logging will be underestimated if they only account for immediate mortality of trees [65].…”