Woody Plant-Cover Dynamics in Argentine Savannas from the 1880s to 2000s: The Interplay of Encroachment and Agriculture Conversion at Varying Scales

• Published in: Ecosystems (New York) Vol. 18; no. 3; pp. 481 - 492
• Main Authors: González-Roglich, Mariano, Swenson, Jennifer J, Villarreal, Diego, Jobbágy, Esteban G, Jackson, Robert B
• Format: Journal Article
• Language: English
• Published: Boston Springer-Verlag 01.04.2015; Springer Science+Business Media; Springer US; Springer; Springer Nature B.V
• Subjects: Agricultural land; Analysis; Biomedical and Life Sciences; cropland; data collection; Datasets; Ecology; Ecosystem services; Ecosystems; Encroachment; Energy crops; Environmental Management; Geoecology/Natural Processes; Grasslands; Human factors; humans; Hydrology/Water Resources; land cover; Land surveys; Land use; Life Sciences; Net losses; Panicum virgatum; Pasture; pastures; phase transition; Plant Sciences; Regions; Remote sensing; Savannahs; savannas; Statistical models; trees; Woodlands; Woody plants; Zoology; Argentina; United States > US; caldén; agriculture frontier; caldenal; Pampa; semiarid; historical maps; deforestation
• ISSN: 1432-9840; 1435-0629
• DOI: 10.1007/s10021-015-9841-5

Woody plant-cover dynamics can alter the provisioning of ecosystem services that humans rely on. However, our understanding of such dynamics today is often limited by the availability of reliable and detailed land-cover information in the past, before the onset of remote sensing technologies. In this study, we carefully extracted information from historical maps of the Caldenal savannas of central Argentina in the 1880s to generate a woody cover map that we compared to a 2000s dataset. Over about the last 120 years, woody cover increased across approximately 12,200 km²(14.2% of the area). During the same period, about 5,000 km²of the original woody area was converted to croplands and around 7,000 km²to pastures, about the same total land area as was affected by encroachment. A smaller area, fine-scale analysis between the 1960s and the 2000s revealed that tree cover increased overall by 27%, shifting from open savannas to a mosaic of dense woodlands along with additional agricultural clearings. Statistical models indicate that woody cover dynamics in this region were affected by a combination of environmental and human factors. Over about the last 120 years, increases in woody plant cover have stored significant amounts of C (95.9 TgC), but not enough to compensate for losses from conversions to croplands and pastures (166.7 TgC), generating a regional net loss of 70.9 TgC. C losses could be even larger in the future if, as predicted, energy crops such as switchgrass, would trigger a new land-cover change phase in this region.