Background/Question/Methods

Historically, dominant grassland communities have been displaced by woody shrubs over the last 150 years in the Jornada Basin, southern New Mexico.  Influence of landforms on shrub expansion and grassland resistance at the Jornada Basin is inadequately documented.   Digital vegetation maps from 1915-1916, 1928-1929, and 1998, in conjunction with a landform map were analyzed in a Geographical Information System (GIS) via overlay analysis to assess landform resistance and vulnerability to desertification.  By using these spatial datasets, we addressed the following question: On which landforms have desert grasslands been most persistent?  The survival of these remnant grasslands are strongly influenced by broad scale vegetation-landform relationships.  Landforms influence the persistence of desert grasslands to survive the unfavorable effects of desertification.

Results/Conclusions

Desert grasslands were less resistant and have exhibited a dramatic decline in spatial coverage of grassland species for the alluvial plain and bajadas landform units.  Desert grasslands that reside on the boundaries of landform units were more resistant to change than the alluvial plain and bajada landform units. Mountain uplands and playas are most resistant to change and provide a stronghold for desert grasslands to resist the detrimental effects of desertification, which in turn, produces the isolated grass patches that are observed today in the Jornada Basin.