WIKINDX Resources
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Rimer, R. L., & Evans, RD. (2006). Invasion of downy brome (bromus tectorum l.) causes rapid changes in the nitrogen cycle. American Midland Naturalist, 156, 252–258.
Added by: Eric Peterson 2007-10-19 22:40:00
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Categories: General
Creators: Evans, Rimer
Collection: American Midland Naturalist
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Number of views: 71
Popularity index: 46.41%
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Abstract
ABSTRACT.—Invasion of exotic species threatens the stability of ecosystems and is regarded
as a significant component of global ecological change. One of the most successful invasive
species of the intermountain west of the United States is Bromus tectorum L. (downy brome)—
an annual Eurasian grass that was first observed in North America in the late 1800s in areas
of Washington, Oregon and Utah and now covers ca. 40,000,000 ha. The prevalence of
B. tectorum raises concerns regarding its potential effects on ecosystem structure and function.
In this study we investigated the effects of invasion of B. tectorum on an ungrazed grassland in
Canyonlands National Park, Utah. Because the invasion occurred on previously established
study transects, we were able to assess the short-term effects of an invasion with a known entry
date. We conducted long-term soil incubations in the laboratory to obtain data on cumulative
nitrogen mineralization which was used to calculate the size of the labile pool of soil nitrogen.
We also measured in situ soil inorganic nitrogen and net nitrogen mineralization. We found
that, 2 y following the invasion of B. tectorum, the labile pool of soil nitrogen was 50% smaller
for invaded sites compared to uninvaded sites. In addition, invaded sites had significantly
reduced in situ inorganic nitrogen and net nitrogen mineralization compared to uninvaded
sites. The mechanisms for these changes in soil nitrogen cycling and nitrogen availability may
be related to differences in the phenology, litter composition and biomass of B. tectorum
compared to native grass species. These findings suggest availability of key resources is
dramatically influenced by invasion of B. tectorum at these sites.
Added by: Eric Peterson
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