Long-Term Ecosystem Impacts of an Introduced Grass in the Northern Great Plains

Abstract

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Semiarid Old‐field Restoration: Is Neighbor Control Needed?

“…Succession in our old field was accompanied by an increase in the cover of the introduced perennial grass Agropyron cristatum to 25%, suggesting that this old field is susceptible to invasion by nonnative species. In contrast, fields abandoned during the 1930s-1950s returned to dominance by native prairie (Judd 1940, Coffin et al 1996, Christian and Wilson 1999. The difference in the successional end points may have two causes: A. cristatum has been widely planted since the 1930s, so dispersal from planted stands into unplanted abandoned fields has increased over time, and the seed bank of native species probably had been extirpated by the time our field was abandoned (Bekker et al 1997, Wilson 2002.…”

“…We worked in Grasslands National Park (49Њ11Ј N, 107Њ43Ј W), about 140 km south of Swift Current, Saskatchewan, Canada. The natural vegetation of the region is mixed-grass prairie dominated by blue grama (Bouteloua gracilis), needle-and-thread grass (Stipa comata), and spikemoss (Selaginella densa; Christian and Wilson 1999). weather data from the nearest meteorological station (Val Marie, 10 km southeast; Environment Canada, unpublished data) showed that annual precipitation was 313 mm, with almost half falling during May-July.…”

“…Seeding times (late May), rates, and mixes (Table 1) were identical for broadcast and drilled plots. The seed mix was dominated by Bouteloua gracilis, reflecting its relative abundance in native vegetation (Christian and Wilson 1999). Other species varied in abundance among years according to the availability of seed, so the total number of seeds varied among years (Table 1).…”

Conversion From Agriculture To Grassland Builds Soil Organic Matter On Decadal Timescales

“…Unfortunately, it has been difficult to isolate the role of the vegetation factor in previous studies because they observed abandoned agricultural fields where vegetation colonization and succession dynamics are unavoidable (Odum 1960. Model results have suggested that certain invasive grasses have the potential to alter SOC content differently than native plants (Ogle et al 2004), and a study that compared converted and abandoned grass-lands with different vegetation composition found differences in ecosystem properties, including SOC, between grassland types (Christian and Wilson 1999).…”

Contingency of Grassland Restoration on Year, Site, and Competition From Introduced Grasses

“…One of the species most commonly used for restoration is the C 3 tussock grass Agropyron cristatum, native to Russia but planted on 6-10 ϫ 10 6 ha of the Great Plains (Lesica and DeLuca 1996) and on ϳ7.5 ϫ 10 6 ha of the US intermontane west during [1985][1986][1987] (Pyke 1990). Compared with similarly aged fields dominated by native prairie species, A. cristatum stands are characterized by low plant diversity and soils that are low in moisture, carbon, and nitrogen (Christian and Wilson 1999). Introduced grasses have also altered diversity and ecosystem function in Hawaii (D'Antonio and Vitousek 1992) and the intermontane west (Mack and Pyke 1984).…”