Crown structural properties, wood density, and liana load: influence on growth and mortality in subtropical forests

Wood density (WD) and other wood mechanical and structural properties may have a strong functional relationship with demographic patterns and allometry of trees. We analyzed the influence of WD, structural properties, architectural traits, and community-level attributes on growth rates (GRs) and mortality modes of canopy tree species in a subtropical forest of Argentina. Stem WD and the WD, strength, stiffness, toughness, and hardness of branches were measured in 10 canopy species. Architectural traits and liana load were also determined. Strength and hardness of branches were linearly correlated to branch WD, and GRs were linearly correlated to stem WD across species. At the individual level, trees with greater hardness and toughness in branches died mostly uprooted, and trees with greater branch stiffness and susceptibility to colonization by lianas were mostly broken. At the community level, the suppressed trees died mostly broken. The dominant trees with high local tree density died mostly broken, whereas more isolated trees died mostly uprooted. Mortality modes were determined not only by mechanical properties, but also by community properties such as liana load, crown canopy position, and number of neighboring trees. Other biophysical traits besides WD are important explanatory variables when dry wood is used to describe functional characteristics of trees.

Automated summary

The study found that wood mechanical properties are related to growth rates and mortality modes of trees in a subtropical forest in Argentina. Trees with greater hardness and toughness in branches had higher uprooted mortality, while trees with greater branch stiffness were mostly broken. Mortality modes were also influenced by community properties such as liana load and number of neighboring trees.