Testing for functional significance of traits: Effect of the light environment in tropical tree saplings.

Functional traits have been examined to explain the growth rates of forest communities in different sites. However, weak or nonexistent relations are often found, especially due to the following methodological aspects: 1) lack of an environmental context (e.g.

Importance of hydraulic strategy trade-offs in structuring response of canopy trees to extreme drought in central Amazon.

Plant ecophysiological trade-offs between different strategies for tolerating stresses are widely theorized to shape forest functional diversity and vulnerability to climate change. However, trade-offs between hydraulic and stomatal regulation during natural droughts remain under-studied, especially in tropical forests. We investigated eleven mature forest canopy trees in central Amazonia during the strong 2015 El Niño.

How do silvicultural treatments alter the microclimate in a Central Amazon secondary forest? A focus on light changes.

Silvicultural treatments can change the microclimate inside tropical secondary forests and thus enable the artificial regeneration of ecologically and economically important tree species. Increasing levels of canopy tree refinement (diameter at breast height, DBH > 5 cm) were applied and combined with understory slashing to investigate how these silvicultural treatments affect the microclimate of a Central Amazon secondary forest. The refinement treatment was performed in six levels of basal area reduction (0, 20, 40, 60, 80, and 100%) in rectangular plots (2318 m) and was equally divided in two subplots that did (understory slashed) or did not (control) receive the application of understory slashing.

Causes of reduced leaf-level photosynthesis during strong El Niño drought in a Central Amazon forest.

Sustained drought and concomitant high temperature may reduce photosynthesis and cause tree mortality. Possible causes of reduced photosynthesis include stomatal closure and biochemical inhibition, but their relative roles are unknown in Amazon trees during strong drought events. We assessed the effects of the recent (2015) strong El Niño drought on leaf-level photosynthesis of Central Amazon trees via these two mechanisms.