Ecology and management of savannas and semi-deserts of central Argentina

TitleEcology and management of savannas and semi-deserts of central Argentina
Publication TypeConference Paper
Year of Publication2007
AuthorsPeinetti H.R., Fernandez G., Kin A., Morici E.
Conference NameSociety for Range Mangement, 60th Annual Meeting and Trade Show
Date Published02/2007
Conference LocationReno/Sparks, NV
ARIS Log Number209029
KeywordsArgentina, caldera, ecology, management, savannas
AbstractVegetation of western pampas of central Argentina comprises: caldera, local name of a savanna to woodland ecosystem dominated by Prosopis caldenia; short-grassland and dune-grassland. The area include the central La Pampa and southern San Luis provinces, following a western precipitation gradient from 700 to 400 mm year-1. The caldenal typically occurs in valleys with loamy soils, while grasslands occur in flat uplands and sand dunes. The caldenal was originally featured by large sparse P. caldenia trees surrounded by a matrix of valuable thin short grasses dominated by Poa ligularis and Piptochaetium napostaense (flechillas). Shrub strata was only present in more marginal areas, as in dry slopes. Think grasses were also dominated in short (Stipa tenuis, P. napostaense, P. ligularis, Koeleria permollis), and dune grasslands (Sorgastrum pelitum). Nomadic cattle herding by Indians were widespread until mid 1800s. Major ecological changes occurred in early 1900s when livestock started being risen in fencing paddocks at high stocking rates. Sheep grazing was prevalent during the first half of 1900s and cattle grazing since then. Two severe periods of lodging for woods devastated the calendal in 1910s and 1940s. Lodging was also carried out to establish pastures and croplands. Human activities determine an increase in fire frequency. Currently, almost all calendal cover area comprises secondary forest with a poorly represented tall strata (6-10m) and well represented shrub strata. Grass strata shifted to bunch grasses of low palatability. Similarly, a shift to low valuable grasses and forbs occurred in grasslands. Woody encroachment mostly driven by the dispersion of P. caldenia seed by cattle, is a prevalent problem in both caldenal and grasslands. Woody encroachment increased the likelihood and intensity of fires. Current management focus in improving forage availability through controlled fires. However, there is need for an integrated management approach to restore degraded ecosystems.