JOBBAGY GAMPEL Esteban Gabriel
capítulos de libros
The Grasslands and Steppes of Patagonia and the Río de la Plata Plains (Chapter 14)
PARUELO JM; EG JOBBÁGY; M OESTERHELD; RA GOLLUSCIO; MR AGUIAR
Physical Geography of South America
Oxford University Press
Lugar: Oxford; Año: 2007; p. 232 - 248
The Patagonian steppes and the Río de la Plata grasslandsoccupy a vast proportion of the plains, plateaus, and hillsof southern South America, and are characterized by thealmost absolute absence of trees. Prairies and steppes(grass and low shrubs) are the dominant physiognomictypes, and forests are restricted to some riparian corridors.Savannas become important only in the ecotones of theseregions, whereas meadows may be locally important underparticular topographic or edaphic conditions. The Ríode la Plata grasslands (RPG), one of the most importantgrassland regions in the world, extend between 28°S and38°S latitude, covering about 700,000 km2 of eastern Argentina,Uruguay, and southern Brazil (fig. 14.1). Theboundaries of these grasslands include the Atlantic coastlineto the east, dry temperate forests to the south andwest, and subtropical humid forests to the north. Woodyvegetation within the region is restricted to small areasnear water bodies, such as the gallery forests along thelarge Paraná and Uruguay rivers and their tributarystreams. The Patagonian steppes occupy the southern tipof the continent from approximately 40°S, and are framedby the Andes to the west and the Atlantic coast to the eastand south and cover more than 800,000 km2 of Chile andArgentina. Toward the west, the region displays a sharpecotone with the subantarctic forests, whereas to the northit grades into a broad zone of Monte scrublands in centralArgentina. The RPG and the Patagonian steppes areseparated by a wide strip of woody vegetation, the Monteand Espinal phytogeographic units (see chapter 10;Cabrera and Willkins, 1973).In this chapter, we describe the heterogeneity and maincharacteristics of the dominant ecosystems of the Patagoniansteppes and the RPG, focusing on environmentalcontrols and human-induced changes. Although numerouscriteria have been applied to describe the internal heterogeneityof both regions, we emphasize here the structuraland functional attributes of vegetation as integrators ofclimate, physiography, and land use.