Revitalization of a native Wyoming big sagebrush/bluebunch wheatgrass community in central Idaho : a ten year summary /

Abstract

Sagebrush steppe communities with impoverished although mostly native herbaceous layers may represent the best of what's left of the sagebrush steppe ecosystem in North America. The other 75% of this ecosystem has been lost or substantially changed by the combined forces of development, agriculture, fire, and livestock grazing. Can we revitalize these impoverished communities effectively and what's causing these communities to remain static over decades? This project assessed several approaches for returning the vigor and productivity to a Wyoming big sagebrush/bluebunch wheatgrass community in central Idaho. I took an experimental approach to assess restoration techniques. The project occurred on a single mapped soil unit within a single pasture of the Bureau of Land Management's Upper Pahsimeroi grazing allotment. Sample units all occurred on generally flat sites (slope = 0-5%) and similar elevations (2010-2075 m [6595-6810 ft]). Fifteen 4-ha (10 ac) sample units were positioned randomly within the project area prior to treatments being applied, and treatments (controls, mechanical crushing only, and mechanical crushing with seeding of native grasses) were assigned randomly to sample units. Half the area of each sample unit was fenced to exclude livestock. Each treatment was replicated 5 times. The total area encompassed by the sample units was 150 ha with 30 ha treated with mechanical crushing. Mechanical crushing of sagebrush and other shrubs was accomplished by 2 passes of a Lawson aerator over each treatment area during November 2003 after snow had fallen. A rangeland drill was used to seed a mixture of 90% bluebunch wheatgrass and 10% Indian ricegrass (at a rate of 11-13 kg/ha [10-12 lbs/ac]) immediately after crushing was completed. Sampling occurred in the year prior to application of treatments (2003) and in 3 subsequent years following treatment-2005, 2007, and 2012. Cover of plants, exposed soil, biological crust, and litter was the response metric for assessing treatment effects. Cover was estimated using 10 pointinterception transects in each treatment combination. Cover of Wyoming big sagebrush on control sites, both open to livestock grazing and closed, increased slightly (from 17-19% in 2003 to 23-25% in 2012). Mechanical crushing reduced Wyoming big sagebrush cover 63%from an average of 19% in 2003 (range: 11-32%) to an average of 7% in 2005 (range: 2-12%). By 2012, 9 growing seasons post-treatment, average big sagebrush cover had increased to 11% (range: 1-20%); an increase from 2005 of 42%. Crushing & seeding resulted in substantial increases in bluebunch wheatgrass cover from about 1-2% cover in 2003 to an average of 33% in 2012. The reduction in competition from sagebrush apparently resulted in increases in squirreltail cover (particularly in areas open to livestock grazing) and increases in needle and thread cover (particularly in areas protected from livestock grazing). The cover of exposed soil in areas treated with crushing fell below pretreatment levels on most treatments (except contro...

Uso Del Rodillo Aireador en La Restauración De Pastizales en Agua Prieta, Sonora

“…El tratamiento contó con zonas de control intactas, zonas aplastadas con rodillo y zonas donde además del aplastado con rodillo se sembraron pastos nativos. En ambos casos se favoreció la aparición de plantas, pero donde se sembraron pastos nativos se observaron resultados más notables debido a que la competencia con la artemisa disminuyó (Yeo, 2012).…”