High physiological recovery but strong reductions in growth and biomass after drought and rehydration in tree seedlings commonly used in Atlantic Forest restoration

Abstract

Although Brazil boasts exceptional forest biodiversity, there is limited knowledge on how its native tree species respond to intensifying drought events, a key uncertainty for restoration under climate change. Understanding morphophysiological responses to drought across tree species is particularly important for the implementation of restoration projects, when seedlings are most vulnerable to soil water restriction. Thus, this study investigated the impact of drought on the physiology and early growth of six Atlantic Forest tree species, as well as their capacity to recover after rehydration. Seedlings of pioneer (Schinus terebinthifolia, Luehea divaricata, and Peltophorum dubium) and non-pioneer (Cordia trichotoma, Cedrela fissilis, and Eugenia involucrata) species were subjected to an induced drought experiment in a greenhouse. Leaf water potential, chlorophyll a fluorescence, and gas exchange were measured over time, while growth and biomass were assessed at the end of the experiment. The species showed contrasting morphophysiological responses to drought, which were more consistently associated with differences along the isohydric-anisohydric continuum than with successional classification. S. terebinthifolia, C. fissilis, and E. involucrata exhibit predominantly isohydric behavior, whereas L. divaricata, P. dubium, and C. trichotoma are more anisohydric. With the exception of E. involucrata, drought strongly impaired physiological performance and both shoot and root growth, with overall growth reductions of up to 51%. Despite prolonged drought, all species demonstrated a high capacity to recover carbon assimilation after rehydration, indicating their potential for establishment in water-limited environments, albeit with substantial reductions in growth and biomass. The combined assessment of physiological recovery and growth impacts therefore contributes to the selection of species that maximize both growth and resilience in forest restoration projects in the Atlantic Forest and other biomes.