Spatio-Temporal Dynamics of Woody Plant Encroachment in Semiarid Rangelands of Argentina

Mariano Gonzalez-Roglich, Duke University, mariano.gr@duke.edu (Presenter)
Jennifer Swenson, Duke University, jswenson@duke.edu

Land cover change dynamics alter ecosystem and climate functioning primarily through changes in matter cycles and energy fluxes. Woody plant encroachment in semiarid rangelands is a global process of land cover change. The widespread increase in woody plant cover alters ecosystem distribution of carbon and other nutrients and influences the radiative balance due to the different reflective properties of grasses, soil and woody plants. This study is aimed to analyze the consequences of woody plant encroachment on ecosystem carbon stocks and albedo changes at regional scale in the Western Pampas grasslands, Argentina. One of the goals of this study is to estimate how encroachment has changed in the past in this region of Argentina, greatly understudied regarding carbon dynamics and shrub encroachment. Using panchromatic aerial photographs and China–Brazil Earth Resources Satellite 2 panchromatic images the coverage of woody plants was estimated for the 1960s and 2009 respectively. Thirty six 4 km by 4km plots were randomly located in the study area of 11,200 km, covering 5% of the area. In each of these plots, woody plants cover was estimated. In the analyzed sites, woody plants covered 42.6% in the 1960s, and the area was reduced to 30.7% in 2009 representing a net reduction of 28.0% over a 50-year period. However, this rate is the net result of clearing in 63.4% of the original woody plant area and woody encroachment representing 35.4% of the same area. Fifteen percent of the area remained covered by woody plants, and of that area 61% become denser in the last 50 years. These results show for the first time a qualitative estimate of the dynamics of woody plant cover and density in the semiarid central region of Argentina, where land conversion to agriculture and woody plant encroachment are opposite and co-occurring processes.

Presentation: 2011_Poster_GonzalezRoglich_182_246.pdf (26295k)

Presentation Type:  Poster

Session:  Other   (Tue 11:30 AM)

Associated Project(s): 

• Swenson, Jennifer: Spatio-temporal dynamics of woody plant encroachment in semiarid rangelands of Argentina: changes in C stocks and climate change implications ...details

Poster Location ID: 182