Drought response strategies of deciduous and evergreen woody species in a seasonally dry neotropical forest
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COMMUNITY ECOLOGY – ORIGINAL RESEARCH
Drought response strategies of deciduous and evergreen woody species in a seasonally dry neotropical forest Bruno Cruz de Souza1 · Ellen Cristina Dantas Carvalho1 · Rafael S. Oliveira2 · Francisca Soares de Araujo3 · André Luiz Alves de Lima4 · Maria Jesus Nogueira Rodal5 Received: 11 January 2020 / Accepted: 15 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Deciduous and evergreen trees are usually considered the main coexisting functional groups in seasonally dry tropical forests (SDTF). We compared leaf and stem traits of 22 woody species in the Brazilian Caatinga to investigate whether deciduous (DC) and evergreen (EV) species have divergent water-use strategies. Our hypothesis was that DC trees compensate for their short leaf longevity by being less conservative in water use and showing higher variation in the seasonal water potential after leaf shedding. Evergreen species should exhibit a highly conservative water use strategy, which reduces variations in seasonal water potential and the negative effects of desiccation. Our leaf dynamics results indicate that the crown area of DC trees is more sensitive to air and soil drought, whereas EV trees are only sensitive to soil drought. Deciduous species exhibit differences in a set of leaf traits confirming their acquisitive strategy, which contrasts with evergreen species. However, when stomatal traits are considered, we found that DC and EV have similar stomatal regulation strategies (partially isohydric). We also found divergent physiological strategies within DC. For high wood density DC, the xylem water potential (Ψxylem) continued to drop during the dry season. We also found a negative linear relationship between leaf life span (LL) and the transpiration rate per unit of hydraulic conductivity (Λ), indicating that species with high LL are less vulnerable to hydraulic conductivity loss than early-deciduous species. Collectively, our results indicate divergence in the physiology of deciduous species, which suggests that categorizing species based solely on their leaf phenology may be an oversimplification. Keywords Leaf phenology · Water potential · Wood density · Isohydric strategy · Anisohydric strategy · Leaf functional traits
Introduction
Communicated by Russell K. Monson. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00442-020-04760-3) contains supplementary material, which is available to authorized users.
Several global climate change models (GCMs) project significant changes in temperature and rainfall for the next 85 years in many tropical regions (Intergovernmental Panel on Climate Change IPCC 2015). The seasonally dry tropical forest (SDTF) that occurs in the semi-arid region of northeastern of Brazil is especially vulnerable to climate change.
* Bruno Cruz de Souza [email protected]
2
Department of Plant Biology, Institute of Biology, University of Campinas, Campinas 13083‑970, Brazil
* Rafael S. Oliveir
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