Restoring wetland prairies: tradeoffs among native plant cover, community composition, and ecosystem functioning

Abstract

Abstract. Despite a U.S. goal of 'no-net-loss' of wetland structure and function, restoration performance standards are typically based on limited criteria, with soil carbon, nutrient, and microbial criteria being particularly rare. We examined plant community composition, diversity, and various soil functional variables for two different restoration techniques, topsoil-removal and solarization, in wetland prairies in Oregon, USA. We compared three site-level replicates of each treatment to three high-quality remnant wetland prairies. We found significant tradeoffs among diversity, native cover, and ecosystem functioning between restoration treatments. Wetlands with topsoil removed had similar diversity to remnants, but lower productivity, soil carbon and nitrogen, microbial biomass, and arbuscular mycorrhizal fungal infection rates. Solarization sites had the highest native cover, but diversity was approximately half that of remnant wetlands. We attribute this to both a priority effect of seeded native perennial bunchgrasses establishing early in the restoration process and competitively excluding other species, and to a lack of microtopographic variation in the restored sites. Our results suggest that restoration projects should evaluate both structural and functional processes, since they may reveal tradeoffs among important goals. Mitigation efforts should strive to understand the mechanisms causing these tradeoffs among structure and function and try to minimize these in restoration designs.

Efficacy of Exotic Control Strategies for Restoring Coastal Prairie Grasses

“…Past research suggests that topsoil removal can be effective to reduce exotic competition and restore grassland habitats in upland conditions or to restore wet meadows in combination with introduction of native wetland plant propagules (Buisson et al 2006;Farrell et al 2007;Klimkowska et al 2010;Pfeifer-Meister et al 2012). Topsoil removal, however, causes extensive damage to the ecosystem, including removing the native seed bank and microbial communities (Diaz et al 2008;Pfeifer-Meister et al 2012), and requires somewhere to dispose of the soil.…”

“…Topsoil removal, however, causes extensive damage to the ecosystem, including removing the native seed bank and microbial communities (Diaz et al 2008;Pfeifer-Meister et al 2012), and requires somewhere to dispose of the soil. In our experiment, removing the top layer of soil was not effective in reducing exotic cover at our study site, which is flat, deep soiled, and includes small patches of herbaceous freshwater wetlands.…”

Climate change alters plant biogeography in Mediterranean prairies along the West Coast, USA

“…At peak growing season (May-June, determined individually by site and treatment), we measured plant cover by species using the point intercept method (Elzinga et al, 1998;Pfeifer-Meister et al, 2012). In each plot, we established two 1-m 2 quadrats that we sampled in 2010 (pretreatment), 2011 (year 1), and 2012 (year 2).…”

“…If current climate models are correct (Mote & Salath e, 2010), our data suggests that the increases in warm-season soil moisture deficits predicted for the Pacific Northwest will result in reductions of the perennial species that currently dominate these systems, with forbs being particularly vulnerable. This reduction in forbs at all sites in response to warming may pose substantial challenges for sustaining prairie diversity as the maintenance of forbs in the face of grass dominance is an ongoing challenge for conservation practitioners (Pfeifer-Meister et al, 2012).…”

A new model to simulate climate‐change impacts on forest succession for local land management

“…Current vegetation, however, is often strongly determined by the legacy of previous land use and land cover. Priority effects can be important determinants of future successional dynamics (Pfeifer-Meister et al 2012). Thus, DGVMs may provide projections that further diverge from current and future conditions if their assessment of growing conditions does not match that of the current landscape (Van Vuuren et al 2011).…”