Bhaskar, Radika , Dawson, Todd , Balvanera, Patricia .
Leaf and stem trait variation of a widespread tropical dry forest species along a post-disturbance successional gradient.
Large areas of seasonally dry tropical forest along the Pacific coast of Mexico are deforested for agriculture, and then often abandoned after several years of use. The impacts of this land-use pattern on plant trait expression can be assessed by comparing edaphic and biotic features of recovering patches with stands of undisturbed forests. In the state of Jalisco, long-term research sites have been established within a chronosequence of regenerating pastures that vary in years since abandonment (2-4, 6-8, 11-15) and within adjacent undisturbed forest. Each of these 4 stages has three replicate plots, in which microclimate data and woody tree species composition have been measured. In this study we focus on one legume species, Caesalpinia eriostachys, that is unique in its widespread distribution across all stages. We hypothesized that soil water availability and insolation would correlate with successional stage and, correspondingly, individuals in early stages would show greater drought tolerance than those in later stages. We measured leaf (specific leaf area (SLA), leaf size, leaf area:sapwood area) and stem traits (midday water potential, stem water content, wood density) of C. eriostachys early in the dry season. Neither gravimetric water content nor water retention capacity was associated with stage type; thus, soil water conditions appear decoupled from successional stage, contrary to our predictions. Stem traits co-varied with latitude but not successional stage. SLA, in contrast, differed with successional stage as predicted. However, the pattern was not linear; both canopy cover and SLA increased along the chronosequence, but both measures peaked in the oldest former pasture site (11-15 years) rather than the undisturbed forest. Prior land-use may therefore result in differing insolation levels at all regenerating stages compared to undisturbed forest. C. eriostachys' persistence across this heterogeneous landscape may stem from its plastic response to varying light and soil conditions.
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1 - Universidad Nacional Autónoma de México, Centro de Investigaciones en Ecosistemas, Antigua Carretera a Pátzcuaro # 8701, Col. Ex-Hacienda de San José de la Huerta, Morelia, Michoacan, 58190, México
2 - University of California, Berkeley, Department of Integrative Biology, 3060 Valley Life Sciences Bldg #3140, Berkeley, California, 94720, USA
specific leaf area
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 8:15 AM