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Sidney, MT, United States

Espeland E.K.,Pest Management Research Unit | Perkins L.B.,South Dakota State University
Ecological Restoration | Year: 2013

In agricultural, rangeland, and forest system revegetation projects, cover crops are used for competitive exclusion of weeds and to stabilize soil. Within revegetation projects, annual or short-lived perennial grasses are often sown at the same time as the perennial grasses that are the desired species for long-term landscape rehabilitation. When cover crops are utilized to control weeds, the same principle of competitive exclusion may apply to sown perennial grasses. In this project, we tested if an annual grass cover crop reduces the early stage performance of sown perennial grasses. We conducted four experiments to evaluate the effects of annual cover crops on perennial grasses. The experiments included ex situ growth chamber experiments in two soil types, an agronomic soil, and soil collected from a revegetation project in a trenched water pipeline in western North Dakota. We also performed two in situ experiments where the presence of annuals was manipulated. Annual cover crops only reduced perennial grass biomass ex situ in the agronomic soil. The disturbed pipeline soil was high in sulfur and sodium. Even when this soil was fertilized, annual cover crops did not reduce sown perennial performance. In stressful environments, or when there is natural microenvironmental variability, annual cover crops do not appear to be costly for the early-stage establishment of more long-term, desirable species. © 2013 by the Board of Regents of the University of Wisconsin System. © 2013 by the Board of Regents of the University of Wisconsin System.

Johnson R.C.,Plant Germplasm Research and Testing | Horning M.E.,Deschutes National Forest | Espeland E.K.,Pest Management Research Unit | Vance-Borland K.,Conservation Planning Institute
Evolutionary Applications | Year: 2015

Genetic variation for potentially adaptive traits of the key restoration species Sandberg bluegrass (Poa secunda J. Presl) was assessed over the intermountain western United States in relation to source population climate. Common gardens were established at two intermountain west sites with progeny from two maternal parents from each of 130 wild populations. Data were collected over 2 years at each site on fifteen plant traits associated with production, phenology, and morphology. Analyses of variance revealed strong population differences for all plant traits (P < 0.0001), indicating genetic variation. Both the canonical correlation and linear correlation established associations between source populations and climate variability. Populations from warmer, more arid climates had generally lower dry weight, earlier phenology, and smaller, narrower leaves than those from cooler, moister climates. The first three canonical variates were regressed with climate variables resulting in significant models (P < 0.0001) used to map 12 seed zones. Of the 700 981 km2 mapped, four seed zones represented 92% of the area in typically semi-arid and arid regions. The association of genetic variation with source climates in the intermountain west suggested climate driven natural selection and evolution. We recommend seed transfer zones and population movement guidelines to enhance adaptation and diversity for large-scale restoration projects. © 2014 The Authors.

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