Differential Growth Responses to Water Balance of Coexisting Deciduous Tree Species Are Linked to Wood Density in a Bolivian Tropical Dry Forest

Abstract

A seasonal period of water deficit characterizes tropical dry forests (TDFs). There, sympatric tree species exhibit a diversity of growth rates, functional traits, and responses to drought, suggesting that each species may possess different strategies to grow under different conditions of water availability. The evaluation of the long-term growth responses to changes in the soil water balance should provide an understanding of how and when coexisting tree species respond to water deficit in TDFs. Furthermore, such differential growth responses may be linked to functional traits related to water storage and conductance. We used dendrochronology and climate data to retrospectively assess how the radial growth of seven coexisting deciduous tree species responded to the seasonal soil water balance in a Bolivian TDF. Linear mixed-effects models were used to quantify the relationships between basal area increment and seasonal water balance. We related these relationships with wood density and sapwood production to assess if they affect the growth responses to climate. The growth of all species responded positively to water balance during the wet season, but such responses differed among species as a function of their wood density. For instance, species with a strong growth response to water availability averaged a low wood density which may facilitate the storage of water in the stem. By contrast, species with very dense wood were those whose growth was less sensitive to water availability. Coexisting tree species thus show differential growth responses to changes in soil water balance during the wet season. Our findings also provide a link between wood density, a trait related to the ability of trees to store water in the stem, and wood formation in response to water availability.

Detecting long‐term growth trends using tree rings: a critical evaluation of methods

“…Simply expressing growth as basal area has the advantage of avoiding curve fitting procedures (as performed in CD and RCS; Table 2) and also because BAI is a meaningful expression of tree functioning, for example conducting xylem surface (e.g. Mendivelso et al, 2013;Sterck et al, 2014). However, this conversion may thus not suffice to remove the age/size trends and additional steps are necessary to account for the remaining age/size trend when using BAC.…”

No evidence for consistent long‐term growth stimulation of 13 tropical tree species: results from tree‐ring analysis

“…Finally, tree-ring width measurements were converted to cross-sectional area growth (basal area increment, BAI) as BAI is a meaningful expression of tree functioning, for example conducting xylem surface (e.g. Mendivelso et al, 2013;Sterck et al, 2014) and better represents a tree's biomass growth (henceforth the term tree growth refers to BAI). The annual nature of ring formation has been previously demonstrated for the Bolivian species by Lopez et al (2012).…”

Does Cedrela always form annual rings? Testing ring periodicity across South America using radiocarbon dating

“…Tropical tree rings and their associated characteristics can be used to reconstruct climate (e.g. Baker et al 2016;Mendivelso et al 2013;Schöngart et al 2006;Vlam et al 2014;Xu et al 2015), inform sustainable forest management (e.g. Brienen and Zuidema 2006;De Ridder et al 2013;Schöngart 2008), study forest dynamics (e.g.…”

“…During an extreme dry period, water stress can result in cambial dormancy and this may be accompanied by discernible changes to the structure of the xylem, thus resulting in a growth band or tree ring (Bräuning et al 2008b;Mendivelso et al 2013;Worbes 1999Worbes , 2002. Deciduous trees shed their leaves in Communicated by S. Leavitt. response to the water stress, only to flush their leaves again and thereby reactivate the cambium once tree water status has been restored (Borchert 1999).…”