COS 76-1
Partition when necessary: Life-history trade-offs in forests emerge when resources are scarce
Extreme volatility of seed production in forests coupled with recruitment limitation suggests that reproductive trade-offs could control forest diversity in ways that are poorly understood. Does the tendency to mast seed differ between species due to the need to trade off reproduction and growth? If so, is this tendency most severe in stressful environments? Empirical studies on single species or sites have shown contrasting conclusions. For example, allocation to growth and reproduction could trade off for individuals in stressful environments and years, or could track environmental conditions across sites and years. Here we compare the cross-correlations of growth and fecundity for reproductively-mature individuals from 37 species in 11 forests throughout the southeastern U.S over 12 years to identify species that appeared to exhibit allocation trade-offs or resource tracking. Then we assess the role of environmental conditions in mediating patterns within species.
Results/Conclusions
We show that reproductive allocation patterns in these communities are highly diverse, both within and across species. All species experienced trade-offs at some point in our observation period and half showed signals of lagged investment in future reproduction, indicative of resource tracking. Within species, reproductive allocation patterns were conditional on the species’ resource tolerance and the individual’s microhabitat. This diversity has implications for the dynamics of tree communities. Differences among species in the timing of reproductive investment can enhance resource partitioning while differences in environmental responses can enhance differential success in changing environments.