Constraints on shrub cover and shrub-shrub competition in a U.S. southwest desert
Hanan, Niall P.
Browning, Dawn M.
Monger, H. Curtis
Peters, Debra P. C.
Bestelmeyer, Brandon T.
Archer, Steve R.
Ross, C. Wade
Lind, Brianna M.
Kumar, Sanath S.
AffiliationUniv Arizona, Sch Nat Resources & Environm
KeywordsJornada Basin Long-Term Ecological Research (LTER)
Southwestern US drylands
Special Feature: Dynamic Deserts
woody plant encroachment
MetadataShow full item record
CitationJi, W., Hanan, N. P., Browning, D. M., Monger, H. C., Peters, D. P. C., Bestelmeyer, B. T., Archer, S. R., Ross, C. W., Lind, B. M., Anchang, J., Kumar, S. S., and Prihodko, L.. 2019. Constraints on shrub cover and shrub–shrub competition in a U.S. southwest desert. Ecosphere 10( 2):e02590. 10.1002/ecs2.2590
Rights© 2019 The Authors. This is an open access article under the terms of the Creative Commons Attribution License.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at firstname.lastname@example.org.
AbstractThe cover of woody perennial plants (trees and shrubs) in arid ecosystems is at least partially constrained by water availability. However, the extent to which maximum canopy cover is limited by rainfall and the degree to which soil water holding capacity and topography impacts maximum shrub cover are not well understood. Similar to other deserts in the U.S. southwest, plant communities at the Jomada Basin Long-Term Ecological Research site in the northern Chihuahuan Desert have experienced a long-term state change from perennial grassland to shrubland dominated by woody plants. To better understand this transformation, and the environmental controls and constraints on shrub cover, we created a shrub cover map using high spatial resolution images and explored how maximum shrub cover varies with landform, water availability, and soil characteristics. Our results indicate that when clay content is below similar to 18%, the upper limit of shrub cover is positively correlated with plant available water as mediated by surface soil clay influence on water retention. At surface soil day contents >18%, maximum shrub cover decreases, presumably because the amount of water percolating to depths preferentially used by deep-rooted shrubs is diminished. In addition, the relationship between shrub cover and density suggests that self-thinning occurs in denser stands in most landforms of the Jomada Basin, indicating that shrub-shrub competition interacts with soil properties to constrain maximum shrub cover in the northern Chihuahuan Desert.
NoteOpen access journal
VersionFinal published version
SponsorsNational Science Foundation 
Showing items related by title, author, creator and subject.
Soil erosion as affected by shrub encroachment in northeastern PatagoniaParizek, B.; Rostagno, C. M.; Sottini, R. (Society for Range Management, 2002-01-01)Soil erosion is the primary cause of irreversible loss of soil productivity on most rangelands. In northeastern Patagonia, the increase in soil erosion has been closely associated with the increase in shrub cover in the grass or shrub-grass steppes. We used rainfall simulation to compare infiltration and sediment production from patches of grass, shrub-grass, and shrub steppes of the Punta Ninfas range site. Bare soil and gravel covers were higher and litter cover was lower in the shrub steppe than in the shrub-grass and the grass steppes. In the shrub inter-spaces of the shrub steppe, bulk density was greater and macroporosity and soil organic matter were lower (P less than or equal to 0.05) than in the mounds beneath shrubs and in the grass and shrub-grass areas. Infiltration rate was 60 to 65% lower in the shrub steppe than in the grass and shrub-grass steppes, respectively. On the contrary, total sediment production and concentration were higher (P less than or equal to 0.05) in the shrub steppe as compared to the grass and the shrub-grass areas. Gravel cover was the variable that best predicted infiltration and sediment production. The organic matter content of the sediment, mostly litter, in the shrub and the shrub-grass steppes were similar and greater (P less than or equal to 0.05) than in the grass steppe. Runoff litter removal may represent one of the processes that drive the transition from shrub-grass to shrub steppes. High rates of sediment removal, mainly litter, from the shrub interspaces of the shrub steppe may limit the natural recovery of the soil physical and hydrological properties. These degraded patches fail to capture incident rainfall and restrict the possibilities for the recovery of perennial grasses favoring the dominance of shrubs.