Summary: Impact of feedbacks on Chihuahuan desert grasslands:
Transience and metastability
Gregory S. Okin,1
and Steven R. Archer3
Received 26 July 2008; revised 9 October 2008; accepted 29 October 2008; published 24 January 2009.
 A simplistic model of grass-shrub dynamics was used to investigate the role of grass
demographic processes on grassland-shrubland dynamics when grasses are in competitive
advantage over shrubs. The model suggests that a feedback between grass biomass
and soil erosion may cause an abrupt transition to a shrubland state. The model explains
how a simple change in either grass recruitment or grass mortality, presumably linked
to climate change or grazing, could produce changes in Holocene flora and the conversion
of grasslands to shrublands, which has been observed throughout the southwestern U.S. in
the past 150 years.
Citation: Okin, G. S., P. D'Odorico, and S. R. Archer (2009), Impact of feedbacks on Chihuahuan desert grasslands: Transience and
metastability, J. Geophys. Res., 114, G01004, doi:10.1029/2008JG000833.
 Arid and semiarid regions cover more than 40% of the
Earth's land surface. Broad-scale land degradation in these
regions (i.e., desertification) directly impacts ca. 250 million