Table 1 Traits, structural characteristics of trees with high trait values and their ecological meaning. This table summarises the information presented in more detail in the section “Tree architectural traits” of the Supplementary Methods 2

Branch/trunk surface area divided by branch/trunk woody volume

Trunk and branch thickness

High trait values indicate a higher proportion of metabolically inactive wood⁶. This is linked to lower support of aerial structures for light capture and productivity. On the other hand, higher values indicate higher interaction with the atmosphere, including higher respiration rates of the living tissues⁵.

Relative crown width

Horizontal crown size relative to DBH

High trait values indicate trees that develop wide crowns, usually linked to limited access to light^77,86, although it can be limited by competition from neighbours⁸⁷. Shade-tolerant trees can also expand their crowns to maintain minimal leaf overlap for light capture and withstand falling debris⁸⁸.

Relative crown depth

Vertical crown size relative to tree height, often caused by multi-stemming

In high-light environments trees invest in deep crowns to better compete with neighbours¹⁷. Multi-stemming also leads to large relative crown depths, as our algorithm also considers the crown as of the upper segments from any multi-stemming point.

Path fraction

Umbrella-shaped tree crown

Longer paths of trunks, branches and twigs prioritise sun exposure and light capture. This leads to longer water and nutrient transport distances that require high costs related to construction tissue⁷. High path fraction values represent umbrella-shaped crowns that prioritise sun exposure and light capture but are structurally expensive to build and are hydraulically less efficient¹⁰.

Asymmetry

Wood allocation in branches and trunks shifted relative to the trunk’s vertical axis

Tree asymmetry is a result of competitive pressure from neighbouring trees⁷⁸. Asymmetrical crowns can maximise capture of solar radiation by shifting their trunks and branches towards canopy gaps or away from their neighbours to avoid competition⁴³. However, asymmetrical trees have lower mechanical stability and are more vulnerable to winds³⁰, which is a major cause of mortality of fragmented Amazonian forests¹⁹.