Abstract

RUEDA, Carla V; BALDI, Germán; VERON, Santiago R  and  JOBBAGY, Esteban G. Apropiación humana de la producción primaria en el Chaco Seco. Ecol. austral [online]. 2013, vol.23, n.1, pp.44-54. ISSN 1667-782X.

Human appropriation of primary production in the Dry Chaco: The Dry Chaco undergoes high rates of deforestation and productive transformation. Here we estimate human appropriation of net aboveground primary productivity (NPP) for this region, both through direct (livestock, logging, and agricultural production) and indirect pathways (burning), and present their regional distributions and their association with climatic and socioeconomic variables and their contrast between natural vegetation, pastures and crops. For all the 69 counties encompassed by the region we collected productive and climatic statistics and remote sensing data (2002-2006 period). We estimated aboveground NPP based on existing climatic models, forage appropriation based on livestock statistics and metabolic models, forest and agricultural product appropriation using national statistics, and indirect appropriation or consumption by fires based on remote sensing information. Livestock production, based on natural vegetation and pastures (90.9% of the area) appropriated 248 kgDM.ha-¹.yr- ¹, increasing in counties with larger pasture proportion, cattle grouped in large herds, and lower poverty levels. The appropriation of forest products, restricted natural vegetation (88.7% of the area), reached 64 kgDM.ha-¹.yr-¹, represented predominantly by charcoal and firewood, increasing in more humid counties. In the agricultural fraction of the territory (6.3% of the area), direct appropriation reached 2293 kgDM.ha-¹.yr-¹, represented mainly by soy and corn grain. The indirect appropriation of NPP through fires averaged 746 kgDM.ha-¹.yr-¹ for the whole territory. This flux was positively associated to the rate of deforestation, climbing from ~450 to >2000 kgDM.ha-¹.yr-¹ from counties with minimum to maximum deforestation rates. Currently, the low direct appropriation of NPP under natural vegetation in the Dry Chaco involves a strong incentive for its replacement with pastures and annual crops. More efficient livestock and forestry activities in these forest ecosystems represent a technological challenge and a policy making priority capable of reconciling production and conservation in the region.

Keywords : Fire; Forest; Land clearning; Livestock; Logging; Net primary productivity; Pasture.

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