Intraspecific Variation in Ecophysiology of Three Dominant Prairie Grasses Used in Restoration: Cultivar Versus Non‐Cultivar Population Sources

Summary Land managers choose seed from a variety of provenances for restoration projects. By selecting seed of the local ecotype, managers can increase establishment in the short term and prevent the disruption of local adaptations and genetic swamping in the long term. However, local seed may be disadvantageous if populations are inbred or maladapted to managed restoration environments. Seed selection may be further confounded by propagation methods. Three dominant C4 grasses, Andropogon gerardii, Bouteloua curtipendula and Sorghastrum nutans, from three types of seed provenances (remnant, restoration and nursery) were planted as seeds and plugs into experimental plots at three established tallgrass prairie restorations in western Minnesota, USA. Using a common garden design, we tested whether (i) provenance and (ii) site of planting influence germination and first‐season survival and growth both (iii) for seeds directly planted in the field and for transplants (plugs). Seed provenance impacted germination and seedling survival in all cases, except S. nutans seeded directly in the field. Andropogon gerardii and B. curtipendula nursery seedlings were consistently taller than those of the other provenance types. When directly seeded, germination, survival and vigour differed among restoration sites; however, the results were species specific. Sorghastrum nutans germination varied among sites depending on provenance, indicating that this species may be particularly sensitive to environmental conditions. Germination was 3–12 times greater for plugs than for seeds directly planted in the field in summer, but mortality after planting in the field was low for both groups. Synthesis and applications. Provenance and restoration site had varying effects among species, indicating that the dominant C4 grasses used in this study ought not to be considered ecological equivalents. While we found little evidence of local adaptation, use of local remnant seeds diminishes the risk of spreading maladapted genotypes. Germination limited establishment when sowing seeds directly in summer. Supplemental use of plugs may increase species diversity in restorations.

Section: Discussionsupporting

confidence: 92%

“…Additionally, plant diversity in restorations often decreases as productivity of dominant grasses increases (Baer et al . ; Wilsey ; Lambert, Baer & Gibson ; Gibson et al . ; Grman, Bassett & Brudvig ).…”

Section: Discussionmentioning

confidence: 99%

Seed source impacts germination and early establishment of dominant grasses in prairie restorations

Gallagher

Wagenius²

2015

“…; Johnson, Vellend & Stinchcombe ; Schröder & Prasse ). There are differences between local ecotypes and cultivars in their competitive ability and physiological characteristics (Gustafson, Gibson & Nickrent ; Lambert, Baer & Gibson ; Wilson et al . ).…”

Section: Introductionmentioning

confidence: 99%

Phylogenetic diversity reveals hidden patterns related to population source and species pools during restoration

Khalil

Gibson

Baer

2016

Self Cite

Summary A phylogenetic perspective of community assembly can reveal new insights into how variation within dominant species interacts with the local species pool to influence the structure of restored plant communities. Many studies have examined the effect of dominant species in structuring plant communities, but few have investigated their effect on phylogenetic diversity (PD). We established grassland in a post‐agricultural field using two population sources (cultivars and local ecotypes) of three dominant grasses (Sorghastrum nutans, Andropogon gerardii and Schizachyrium scoparium) with three unique pools of subordinate species that varied in PD but not taxonomic or life‐form diversity. We tested the effect of the population source treatment on two metrics of community PD (net relatedness index [NRI] and nearest taxon index [NTI]) during the first 4 years of restoration. The NRI measures the overall pairwise phylogenetic distance between all pairs of taxa in a community. By contrast, NTI measures the pairwise distance between closely related taxa in a community. Population sources had a transitory effect on community phylogenetic structure over time. Local ecotypes decreased the abundance of closely related eudicots, monocots (low +NRI and +NTI values) and volunteer species (−NTI) more than cultivars. However, population sources did not affect ecologically conservative species (i.e. species with intermediate‐to‐poor ecological tolerance and a high degree of fidelity to prairie habitats). Thus, cultivars might have a positive effect on community phylogenetic diversity more than local ecotypes by decreasing the abundance of a phylogenetically diverse community of less closely related volunteer species. Differences in PD of seed mixes were maintained in the community of high‐fidelity species, but did not affect PD of the unsown (volunteer) species in the assembling community. Synthesis and applications. This is the first experiment to show consequences of using different seed sources on phylogenetic diversity (PD) in grassland restoration. Phylogenetics can reveal the effects of population sources on the abundance of volunteer species not evident through traditional analyses of species diversity. The PD of seed mixes or establishing communities, or other assessments of phylogenetic relationships, by restoration practitioners is recommended as a metric to allow consequences of the evolutionary patterns among species to be included in conservation planning. Increased accessibility of phylogenetic tools will allow the application of PD in restoration monitoring.

“…First, while a cultivar approach may help restore some EFs (e.g. enhanced performance of cultivars may lead to increased productivity; Lambert, Baer & Gibson ), the development of cultivars can lead to a reduction in GD and therefore may diminish positive effects of GD on ecosystems. Secondly, cultivars may hybridize with surrounding, locally adapted genotypes leading to ‘genetic pollution’ (Lesica & Allendorf ; Rowe & Leger ; but see Casler et al .…”

Section: Approaches To Sourcing Propagules For Restorationmentioning

confidence: 99%

EDITOR'S CHOICE: Application of genetic diversity–ecosystem function research to ecological restoration

Kettenring

Mercer

Adams

et al. 2014

140

142

Summary1. Three common goals for restoration are (i) rapid plant establishment, (ii) long-term plant persistence and (iii) restoration of functioning ecosystems. Restoration practitioners often use cultivars optimized for rapid plant establishment under highly disturbed conditions to achieve the first goal; locally adapted genotypes are championed for the second because they can be well suited for local environmental conditions. Restoring functioning ecosystems is considered a loftier goal that practitioners struggle to achieve because we lack proven techniques. 2. Similar to the demonstrated benefits of species, functional and phylogenetic diversity for ecosystem functions (EFs), recent genetic diversity (GD)-ecosystem function (EF) experiments have shown that increases in plant GD can positively influence many different EFs. Would the introduction of diverse plant genotypes of a given species into a restoration enhance ecosystem functioning and the evolutionary potential of restored populations? 3. In this review, we first examine three propagule-sourcing approaches: cultivar, local adaptation and GD. Next, we raise questions that if addressed, could help practitioners implement a GD approach in restoration: (i) How might the selection, relatedness and arrangement of genotypes be optimized to restore functioning ecosystems, (ii) How do traits that affect an EF relate to neutral or adaptive diversity, more common measures of GD and (iii) at which spatial and temporal scales does GD influence EFs in restorations? 4. Synthesis and applications. Although each propagule-sourcing approach may be best suited for a particular restoration goal, each approach may simultaneously benefit other goals. Yet cultivars and locally adapted populations that have experienced artificial and/or natural selection may not possess the levels of diversity that will confer expected benefits to different ecosystem functions. Future research should determine the relative value of each approach (or a combination of approaches) for simultaneously achieving multiple restoration goals. Restoration experiments, where plant genetic diversity (GD) is manipulated and monitored over scales relevant to restoration, could reveal the true promise of a GD approach to restoration.