Short-Term Response of Shrubs, Graminoids, and Forbs to Mechanical Treatment in a Sagebrush Ecosystem in Colorado

Declines in Gunnison sage grouse populations are thought to be related to habitat loss, fragmentation, and human induced habitat changes. In an attempt to improve the quality of early brood rearing habitat the Bureau of Land Management, Gunnison Field Office in Gunnison Colorado implemented a series of mechanical treatments designed to reduce sagebrush canopy cover and increase cover of graminoids and forbs. Brush mowing and Dixie harrow were utilized in 2005 to treat 30 percent of six 14 ac sites. In 2006 and 2007 shrub canopy cover, graminoid cover, forb cover, heights, and species richness were assessed to determine the vegetative response to each treatment. Sagebrush canopy cover was reduced to approximately 15 percent by both treatments. Mowing appeared to have no effect on forb or non-sagebrush shrub canopy cover, however, graminoid cover increased slightly post-treatment. Sites treated with the Dixie harrow had increased non-sagebrush shrub canopy cover, graminoid cover, and forb cover in post treatment years as compared to pretreatment. Heights for graminoids and forbs did not differ pre and post treatment ( p \u3e 0.05) nor did species richness (p \u3e 0.05) for either treatment

Toward standardized test methods to determine the effectiveness of filtration media against airborne nanoparticles

The filtration of airborne nanoparticles is an important control technique as the environmental, health, and safety impacts of nanomaterials grow. A review of the literature shows that significant progress has been made on airborne nanoparticle filtration in the academic field in the recent years. We summarize the filtration mechanisms of fibrous and membrane filters; the air flow resistance and filter media figure of merit are discussed. Our review focuses on the air filtration test methods and instrumentation necessary to implement them; recent experimental studies are summarized accordingly. Two methods using monodisperse and polydisperse challenging aerosols, respectively, are discussed in detail. Our survey shows that the commercial instruments are already available for generating a large amount of nanoparticles, sizing, and quantifying them accurately. The commercial self-contained filter test systems provide the possibility of measurement for particles down to 15 nm. Current international standards dealing with efficiency test for filters and filter media focus on measurement of the minimum efficiency at the most penetrating particle size. The available knowledge and instruments provide a solid base for development of test methods to determine the effectiveness of filtration media against airborne nanoparticles down to single-digit nanometer rang