Barger NN, Archer SR, Campbell JL, Huang C, Morton JA, Knapp AK. Woody plant proliferation in North American drylands: A synthesis of impacts on ecosystem carbon balance. Journal of Geophysical Research. 2011;116. doi:10.1029/2010JG001506.

Knapp AK, Briggs JM, Collins SL, et al. Shrub encroachment in North American grasslands: Shifts in growth form dominance rapidly alters control of ecosystem carbon inputs. Global Change Biology. 2008;14:615 -623. doi:10.1111/j.1365-2486.2007.01512.x.

Wessman CA, Schimel DS, Archer SR, et al. New technologies for remote sensing of ecosystem change in rangelands. Rangelands in A Sustainable Biosphere. 1996:139 -142.