Effect of anthropogenic disturbances on leaf traits of woody species from a subtropical dry forest of Argentina

Aim of study: To assess the effects of forest disturbances on two foliar attributes, leaf area (LA) and specific leaf area (SLA), of woody species in a semi-arid Chaco forest of Argentina. Disturbances are represented as different combinations of land management practices (removal of vegetation, logging, and fire). We evaluated intraspecific variation in LA and SLA of six native woody species using a quantitative approach. We also explored the effect of growth form (tree/shrub) and leaf periodicity (perennial/deciduous) on plant responses to disturbances, considering that these traits may determine variations in their behavior in response to such disturbances. Area of study: Subtropical semi-arid Chaco, Santiago del Estero Province, Argentina, South America. Material and methods: Leaves of mature individuals were measured in forests with three different land management histories: undisturbed for four decades (RC); rolled and subjected to selective wood extraction eight years before sampling (Rch+L); and rolled and followed by fire eight years before sampling (Rch+F). For each site, we measured 10 mature individuals of each of the six species studied, recording the maximum height and diameter at breast height (DBH), and harvested 20 leaves from each to measure leaf area (LA) and specific leaf area (SLA). Main results: All species significantly increased their LA and SLA in disturbed forests. Tree species had larger LA than shrubs, while shrubs exhibited higher SLA. Both traits presented higher values in deciduous species compared to perennial species, indicating that, after disturbances, these species could better capture released resources by increasing their foliar area. The community-weighted mean (CWM) of LA was highest in the Rch+L forest, likely reflecting the effect of increased light availability. Additionally, all disturbed forests showed a higher CWM of SLA. Research highlights: The changes observed in leaf traits at the species level, such as higher LA and SLA, which result in higher LA and SLA at the community level, suggest the adoption of more acquisitive strategies in disturbed communities, promoting higher resource capture and facilitating leaf tissue recovery. This may influence ecosystem functions, such as litter decomposition, productivity, and resource allocation for growth and reproduction. Monitoring foliar responses to disturbances in Chaco forests is critical for guiding sustainable management and conservation practices.