Wednesday, November 15, 2006

Soil Hydrological and Physical Changes Due to Bromus tectorum L. (Cheatgrass) Establishment in Northern Nevada, USA.

Joshua J. Boxell, Patrick Drohan, and Colin Robins. UNLV, Geoscience Dept, 4505 Maryland Pkwy, Las Vegas, NV 89154-4010

The introduction of Bromus tectorum (cheatgrass) into western rangelands has had a profound effect on the diversity and health of native ecosystems.  Introduced in the late 19th century, B. tectorum has rapidly out-competed native species and colonized large areas of the Great Basin region (Mack, 1981).  The proliferation of grazing by domestic livestock, along with fire events, has allowed B. tectorum a foothold into previously pristine habitats.  Grace et al. (2001) noted that B. tectorum invasion leads to a decrease in the fire recurrence interval due to the dense stands of fine materials associated with colonization.  Changes to soil textural properties were noted by Brooks et al (2004), with sites invaded by B. tectorum showing an increase in percent silt.  The changes to soil nutrients, decreased soil biotic diversity, and hypothesized alterations of hydrological conditions have prohibited native species from regaining the territory which B. tectorum has invaded (Knapp, 1996).  However, the effects of B. tectorum colonization on hydrological properties such as infiltration and percolation of water through the soil profile have thus far been left unquantified by previous work.  This paper measures infiltration rates of both B. tectorum and sagebrush dominated habitats and documents the changes to soil physical properties caused by B. tectorum invasion.