Diverse patterns of stored water use among saplings in seasonally dry tropical forests

Document Type

Article

Publication Date

5-30-2015

Abstract

Tree species in seasonally dry tropical forests likely vary in their drought-survival mechanisms. Drought-deciduousness, which reduces water loss, and low wood density, which may permit dependence on stored water, are considered key traits. For saplings of six species at two distinct sites, we studied these and two associated traits: the seasonal amount of water released per stem volume (“water released”) and the hydraulic capacitance of the stem (C). Two deciduous species with low stem density, Cavanillesia platanifolia and Burserasimaruba, had high C and high dry-season stem water potential (Ψstem), but differed in dry-season water released. C. platanifolia did not use stored water during the dry season whereas B. simaruba, in a drier forest, released stored water. In both, water released was highest while flushing leaves, suggesting that stored water supports leaf flushing. In contrast, two deciduous species with intermediate stem density, Annona hayesii and Genipa americana, had intermediate C, low dry-season Ψstem, and high seasonal change in water released. Meanwhile, two evergreen species with intermediate stem density, Cojoba rufescens and Astronium graveolens, had relatively low C, low dry-season Ψstem, and intermediate seasonal change in water released. Thus, at least three, distinct stored-water-use strategies were observed. Additionally, bark relative water content (RWC) decreased along with Ψstem during the dry season while xylem RWC did not change, suggesting that bark-stored water buffers Ψstem seasonally. Together these results suggest that seasonal use of stored water and change in Ψstem are associated with functional groups that are characterized by combinations of deciduousness and stem density.

Publication Source (Journal or Book title)

Oecologia

First Page

925

Last Page

936

This document is currently not available here.

Share

COinS