Unravelling the coordination between leaf and stem economics spectra through local and global scale approaches

The existence of a coordination between leaf and stem economic spectra in woody species has been postulated repeatedly in the literature, with contrasting results. Here, we postulated that this coordination is conditioned by climate factors, being stronger in stressful environments. To test this hypothesis we explored the coordination between leaf and stem economic spectra in a seasonally dry forest in central Argentina and at the global scale, we analysed if the outcome of their coordination varies along a climatic gradient. At the local scale, we characterized leaf and stem economic spectra in 37 woody species by measuring six leaf and stem functional traits related to resource acquisition and use, and two functional traits used as proxies of water transport and use capacities. At the global scale, a meta-regression was performed to analyse if the outcome of the coordination among leaf and stem traits varies along gradients of the mean precipitation of the driest quarter and of the minimum temperature of the coldest month. At the local scale, we observed a high integration among the measured leaf and stem traits, and this coordination seemed to be linked to hydraulic properties. At the global scale, we found not only that the overall weighted mean effect size of the correlation between specific leaf area and wood density was significant and negative but also that the coordination between leaf and stem traits seemed to be shaped by climate and tends to become stronger under harsh climate conditions. Furthermore, although our results seem to suggest that their coordination is context-dependent, alternative strategies could be observed under stressful conditions.