An empirical trait-based approach for the development of ecologically appropriate native plant materials

Background/Question/Methods

Our goal is to develop healthier plant populations that display ecological fitness for increasingly challenging and often-modified restoration sites, yet that are acceptable for commercial seed production.  We refer to plant materials that exhibit ecological fitness on their intended site, display compatibility with other members of the plant community, and demonstrate no invasive tendencies as ‘ecologically appropriate.’  For cross-pollinating species, we may employ plant breeding methodologies to increase genetic variation (via strategic hybridization) and to deliver critical functional traits for specific life-cycle stages (via artificial selection).  To ensure that selection does not inadvertently reduce genetic variation, care is taken to maintain high effective population sizes (N_e) and to monitor genetic variation using neutral markers.  This ‘assisted evolution’ approach may be applied in a local context, e.g., within seed transfer zones.

Results/Conclusions

The best meta-analysis data indicate that the average frequency of a local population’s fitness exceeding that of a randomly chosen non-local population is 71%.  Using this estimate, if 10 non-local populations are compared to a local population, the probability of local being best is (0.71)¹⁰ = 3.3%.  Non-local populations are often best, not because they are better on average than the local population, but simply because there are many from which to choose.  For example, when 39 bluebunch and Snake River wheatgrass populations were tested at three eastern Great Basin sites, aboveground biomass was high for eastern Washington populations, intermediate for local populations, and low for southern Idaho populations.  Better-adapted plant materials are needed when local genotypes prove to be weakly adapted to the increasingly frequent novel ecosystems that most desperately require restoration.  In developing ecologically appropriate plant materials, we consider locality, as it provides genetic variation pertinent to residual properties of a modified restoration site, but not at the expense of adaptation as measured empirically. 

Rather than adhering strictly to a single paradigm, we strive to provide pragmatic plant material solutions that foster functional restoration.  Our intention is that each generation of native plant materials establishes better and is more ecologically appropriate, genetically diverse, and/or less expensive than the previous generation.  Increasingly, new grass and forb species are brought into the marketplace through our strong partnership with the native seed industry.  We believe that it is both possible and desirable to respectfully combine principles derived from biological and agricultural disciplines to improve the currently low success rates of rangeland restoration efforts, thereby better conserving our rangeland resources.