Localization and general climate characteristics of the study sites.

Localization and general climate characteristics of the study sites.</p

Correlations between wood anatomical traits.

Each point represents the mean value of a single tree. Fitted linear regression. r, Pearson’s correlation. In C and H, the red line and associated values were estimated by removing data from S. purpurea (see text for details).</p

Pearson correlation.

In tropical dry forests, studies on wood anatomical traits have concentrated mainly on variations in vessel diameter and frequency. Recent research suggests that parenchyma and fibers also play an important role in water conduction and in xylem hydraulic safety. However, these relationships are not fully understood, and wood trait variation among different functional profiles as well as their variation under different water availability scenarios have been little studied. In this work, we aim to (1) characterize a set of wood anatomical traits among six selected tree species that represent the economic spectrum of tropical dry forests, (2) assess the variation in these traits under three different rainfall regimes, and (3) determine the relationships between wood anatomical traits and possible functional trade-offs. Differences among species and sites in wood traits were explored. Linear mixed models were fitted, and model comparison was performed. Most variation occurred among species along the economic spectrum. Obligate deciduous, low wood density species were characterized by wood with wide vessels and low frequency, suggesting high water transport capacity but sensitivity to drought. Moreover, high cell fractions of carbon and water storage were also found in these tree species related to the occurrence of abundant parenchyma or septate fibers. Contrary to what most studies show, Cochlospermum vitifolium, a succulent tree species, presented the greatest variation in wood traits. Facultative deciduous, high wood density species were characterized by a sturdy vascular system that may favor resistance to cavitation and low reserve storage. Contrary to our expectations, variation among the rainfall regimes was generally low in all species and was mostly related to vessel traits, while fiber and parenchyma traits presented little variation among species. Strong functional associations between wood anatomical traits and functional trade-offs were found for the six tree species studied along the economic spectrum of tropical dry forests.</div

F values from the ANOVA of each wood trait.

In tropical dry forests, studies on wood anatomical traits have concentrated mainly on variations in vessel diameter and frequency. Recent research suggests that parenchyma and fibers also play an important role in water conduction and in xylem hydraulic safety. However, these relationships are not fully understood, and wood trait variation among different functional profiles as well as their variation under different water availability scenarios have been little studied. In this work, we aim to (1) characterize a set of wood anatomical traits among six selected tree species that represent the economic spectrum of tropical dry forests, (2) assess the variation in these traits under three different rainfall regimes, and (3) determine the relationships between wood anatomical traits and possible functional trade-offs. Differences among species and sites in wood traits were explored. Linear mixed models were fitted, and model comparison was performed. Most variation occurred among species along the economic spectrum. Obligate deciduous, low wood density species were characterized by wood with wide vessels and low frequency, suggesting high water transport capacity but sensitivity to drought. Moreover, high cell fractions of carbon and water storage were also found in these tree species related to the occurrence of abundant parenchyma or septate fibers. Contrary to what most studies show, Cochlospermum vitifolium, a succulent tree species, presented the greatest variation in wood traits. Facultative deciduous, high wood density species were characterized by a sturdy vascular system that may favor resistance to cavitation and low reserve storage. Contrary to our expectations, variation among the rainfall regimes was generally low in all species and was mostly related to vessel traits, while fiber and parenchyma traits presented little variation among species. Strong functional associations between wood anatomical traits and functional trade-offs were found for the six tree species studied along the economic spectrum of tropical dry forests.</div

Fixed effect coefficients predicted by the linear mixed model.

Fixed effect coefficients predicted by the linear mixed model.</p

Model selection through the AIC and the LRT.

In tropical dry forests, studies on wood anatomical traits have concentrated mainly on variations in vessel diameter and frequency. Recent research suggests that parenchyma and fibers also play an important role in water conduction and in xylem hydraulic safety. However, these relationships are not fully understood, and wood trait variation among different functional profiles as well as their variation under different water availability scenarios have been little studied. In this work, we aim to (1) characterize a set of wood anatomical traits among six selected tree species that represent the economic spectrum of tropical dry forests, (2) assess the variation in these traits under three different rainfall regimes, and (3) determine the relationships between wood anatomical traits and possible functional trade-offs. Differences among species and sites in wood traits were explored. Linear mixed models were fitted, and model comparison was performed. Most variation occurred among species along the economic spectrum. Obligate deciduous, low wood density species were characterized by wood with wide vessels and low frequency, suggesting high water transport capacity but sensitivity to drought. Moreover, high cell fractions of carbon and water storage were also found in these tree species related to the occurrence of abundant parenchyma or septate fibers. Contrary to what most studies show, Cochlospermum vitifolium, a succulent tree species, presented the greatest variation in wood traits. Facultative deciduous, high wood density species were characterized by a sturdy vascular system that may favor resistance to cavitation and low reserve storage. Contrary to our expectations, variation among the rainfall regimes was generally low in all species and was mostly related to vessel traits, while fiber and parenchyma traits presented little variation among species. Strong functional associations between wood anatomical traits and functional trade-offs were found for the six tree species studied along the economic spectrum of tropical dry forests.</div

Variation in wood anatomy among the studied tree species.

A.Cochlospermum vitifolium had the largest vessels and the lowest density. B. Lysiloma divaricatum had narrow vessels and the largest proportion of fibers. C-D. The highest vessel density was associated with denser wood species, group III (C, L. divaricatum; D, Haematoxylum brasiletto). E-F. The largest diameter and thin-walled fibers were found in strict drought deciduous species with low wood density, group I (E, C. vitifolium; F, Spondias purpurea). G-H. Narrower, thick-walled fibers were associated with high wood density species, groups II and III (G, H. brasiletto; H, Pithecellibium dulce). I. C. vitifolium showed nonlignified parenchyma and the highest fraction of this cell type. J. L. divaricatum showed the lowest parenchyma fraction and the highest fiber fraction. K. S. purpurea had a high proportion of thin-walled fibers. L. S. purpurea individuals with a vessel fraction above 20%. Bar is 300 μm in A-D, I-L; 20 μm in E-H.</p

Image analysis of wood cross-sections for cell fraction measurements.

A Full image showing the grid and the marked points for each cell type (11.76 mm2, 1872 grid points). B. Close-up showing the arrangement of the points and distance between each grid point. In this example, 0, vessels; 1, fibers; 3 axial parenchyma; 4, radial parenchyma.</p

Location of study sites and Walter-Liet climate diagram.

Location of study sites and Walter-Liet climate diagram.</p

Traits measured in the wood of six tree species from tropical dry forest.

Traits measured in the wood of six tree species from tropical dry forest.</p