Abstract
The specific leaf area (SLA) has been related to environmental disturbances, showing a positive correlation between the disturbances intensities and SLA in a plant community. These studies, however, assessed the responses of plant community as a whole, neglecting species attributes, such as the position in the vertical stratum of forests. Considering the importance of SLA to understand forest ecological processes, this study aimed to determine the influence of the disturbance regime on the SLA of understory species, considering that, unlike for communities as a whole, an increase in the disturbance intensity implies a decrease in SLA of understory species. This study was conducted in nine understories of seasonal forests in Brazil. The most abundant species were selected and their SLA were evaluated. The variability of SLA among populations in different forests was analyzed by Student's t-tests. The SLA of the understories (SLAU) was also compared by an adaptation of the Community-weighted mean index. The comparison of species SLA showed significant differences among the populations of understories under different disturbance regime, showing a decrease in SLA with an increase in the disturbance intensity. Similar results were found for the SLA of understories communities (SLAU), corroborating our hypothesis. The correlation between a reduction in species SLA and in SLA of understory with an increase in disturbance intensity, contradicted the trend observed in the literature for the community as a whole. This study highlights the importance of the evaluation of SLA in understories, as an indicator of the successional stage of communities.
Highlights
A functional trait is an attribute with a potential influence on the establishment, survival or fitness of a species in a natural environment (Reich et al, 2003)
The SLA of the understories (SLAU) values obtained by the functional traits index ranged from 20.18 mm2.mg–1 (SLAA4, Area 4) to 11.85 mm2.mg–1 (SLAA5, Area 5)
The greatest variation between the values of SLAU was observed for understories under medium disturbance intensity, where the highest was SLAA7 (18.09 mm2.mg–1) and the lowest, SLAA10 (13.94 mm2.mg–1)
Summary
A functional trait is an attribute with a potential influence on the establishment, survival or fitness of a species in a natural environment (Reich et al, 2003). Quantifying changes in these traits is important to understand the patterns of species distribution and to predict vegetation responses to environmental changes (Silva and Batalha, 2009; Freitas et al, 2012). Variations in leaf functional traits, especially in specific leaf area (SLA), have guided many studies of functional ecology, which have addressed important ecological correlations, such as relative growth rate and the photosynthetic efficiency of a species (Reich et al, 2003; Zhang et al, 2012). Shade leaves show a low foliar construction cost, since they are less thick and with lower concentrations of photosynthetic enzymes per area, which increases their SLA (Westoby et al, 2002)
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