Spatial variation in remnant black grama plants in a creosote-dominated bajada

TitleSpatial variation in remnant black grama plants in a creosote-dominated bajada
Publication TypeConference Paper
Year of Publication2004
AuthorsMariotto I., Peters DC, Havstad K, Murray L.W.
Conference NameSixth Symposium on the Natural Resources of the Chihuahuan Desert Region
Date PublishedOctober 15, 2004
Conference LocationAlpine, TX
ARIS Log Number171310
Keywordsblack grama, Bouteloua eriopoda, Chihuahuan Desert, creosote-dominated bajada, remediation, spatial variation
AbstractMuch of the Chihuahuan Desert has converted from perennial grasslands to shrub-dominated systems over the past century. Although shrub-dominated systems appear homogeneous with very few grass plants, observations suggest that perennial grasses can occur within these areas. Our overall objective was to quantify the presence and abundance of the perennial grass, Bouteloua eriopoda (black grama), in creosotebush-dominated bajadas at the Jornada Experimental Range in southern New Mexico. In 2002 and 2003, we obtained the geo-referenced location, aspect, two diameters, and location within shrub canopies for all black grama plants in a 530 m x 550 m area located inside and outside an exclosure constructed in the 1930s. Spatial data layers in a GIS were used as explanatory variables in our analyses. Our results show that a total of 3335 black grama plants were found with an average density of 0.01 plants/m2. Most black grama plants were found inside and adjacent to arroyos (66.7%), at a northern aspect (47%), and outside the exclosure (62%). Black grama most likely dominated this site in 1858, although by 1915 the area was dominated by tarbush, and by 1998 it was dominated by creosote. Thus, the source population for these current black grama plants is most likely remnant plants that historically dominated the area, although seed inputs from nearby mountainous pastures are also possible. Our results showing the location of black grama plants within creosote-dominated systems can be used for remediation of these areas.