2015 Climate Change & Seed Zones
Identifying genetically suitable native plant materials for specific restoration sites and establishing populations that can persist under climate change are two critical challenges facing ecological restoration efforts. Climate change in particular means that “local is best” may not be true for long. Effective solutions to these problems have included common garden and genecology studies used to develop seed transfer zones or transfer functions for individual species (Kilkenny 2015). However, extending such species-specific analyses, which have been conducted for relatively few focal groups, to the hundreds to thousands of other important restoration species is difficult. Because of funding constraints, and because climate impacts on plant populations have already begun, it is critical to develop methods that rely on detailed analyses of workhorse species but that can be extended to other important restoration taxa.
One way to extend common garden research is through identification of the functional traits associated with local adaptive divergence among populations in existing common gardens. Plant performance is mediated by functional traits – organismal characteristics that determine responses to the local environment (Lavorel and Garnier 2002), and we know that there are strong relationships between functional traits and the environment (Wright et al. 2004; Swenson et al. 2011). However, we know little about which functional traits are relatively genetically constrained, and which are more plastic, a distinction that is critical for development of seed transfer guidelines. For example, we have shown that specific leaf area (SLA), a critical integrator of the “leaf economics spectrum” (Wright et al. 2004), exhibits significant broad-sense heritability among populations of Bouteloua gracilis (blue grama grass) grown in a common garden, and is strongly correlated with source location temperature (Butterfield and Wood, In review). While population-specific SLA may serve as a good indicator of suitable climate niche in this species, more data are needed from a reasonable sample of model restoration species. Whether such easy to measure functional traits can be used to predict habitat suitability of different seed sources for many species, both under current and future climates, remains an open question.
To this end, our specific objectives are to:
- Measure a suite of standard functional traits on plants in existing common gardens
- Assess genetic variation in these functional traits
- Determine the environmental correlates of functional trait variation
These objectives represent an important first step toward extending the utility of common garden research on a limited set of species in informing generalized transfer guidelines.