# Interspecific variation of functional traits in saplings of three Amazonian species under drought stress and recovery

## TL;DR

This study compares how three Amazonian tree species respond to drought stress and recovery, showing that slow-growing species are more resistant while fast-growing ones are more vulnerable.

## Contribution

The study reveals species-specific drought response strategies in Amazonian tree saplings, emphasizing the role of growth rate and functional traits.

## Key findings

- Tachigali vulgaris, a fast-growing species, showed high drought vulnerability with 80% mortality.
- Bertholletia excelsa and Dipteryx odorata, slow-growing species, exhibited drought resistance with no mortality.
- Drought-stressed plants allocated more biomass to roots and less to leaves, aiding drought avoidance strategies.

## Abstract

Extreme events (e.g. severe drought) can hinder the establishment of saplings in tropical forest plantations. To assess the resistance and recovery of three commercially important Amazonian tree species under drought conditions and to identify their key functional strategies for drought response, we conducted a controlled drought experiment exposing saplings of Bertholletia excelsa, Dipteryx odorata, and Tachigali vulgaris to water deficit followed by recovery. Tachigali vulgaris (fast-growing species) was more vulnerable to drought, as 80% of the drought-treated plants died. Nevertheless, the individuals who survived demonstrated a rapid recovery of physiological performance following rewatering. Bertholletia excelsa and D. odorata (slow-growing species) were more resistant to drought stress, as evidenced by lack of mortality in these species. Drought-stressed plants had the lowest growth rates, more biomass allocated to roots and less leaf biomass. The greater biomass allocation to roots in B. excelsa and D. odorata, together with their more conservative functional traits compared to T. vulgaris, appears to play an important role in their lower sensitivity to drought. These species exhibited strategies consistent with drought avoidance. Our results highlight the specific strategies of these species under water-deficit conditions and can help guide decisions on species selection and plantation management for reforestation under climate change scenarios.

A greenhouse experiment was conducted to assess interspecific variation in functional traits of seedlings subjected to drought stress and subsequent recovery. Three commercially important Amazonian tree species—Bertholletia excelsa, Dipteryx odorata, and Tachigali vulgaris—were grown under well-watered and drought-stressed conditions. The fast-growing T. vulgaris exhibited high vulnerability to drought, with 80% mortality under water deficit. In contrast, B. excelsa and D. odorata (slow-growing species) were more resistant to drought stress, as evidenced by the lack of mortality in these species. These species adopted strategies such as conservative functional traits and increased biomass allocation to roots to cope with water limitation. Our findings reveal clear species-dependent patterns in drought responses among Amazonian plants and offer valuable guidance for species selection and plantation management for reforestation and ecological restoration under climate change.