Dendroecology of Prosopis flexuosa woodlands in the Monte desert: Implications for their management

In the Monte desert of Argentina open woodlands of several species of Prosopis occur in areas with accessible underground water. The great latitudinal extent of the Monte (26–43°S) exhibits strong climatic gradients involving temperature, rainfall seasonality, and wind regime. Prosopis woodlands have been a source of subsistence for human communities for several centuries and continue to be exploited by the local inhabitants. The “mining” of this resource has led to severe desertification and consequent impoverishment of the local people. In order to suggest strategies for the better management and recuperation of these woodlands we studied the population structure and productivity of Prosopis flexuosa from multiple plots at Pipanaco (27°58′S), Telteca (32°20′S), and Ñacuñán (34°03′S). For each plot we measured the density of P. flexuosa trees, number of stems, basal diameter (DAB), height and canopy diameter of each tree. Tree ring data were used to determine the growth rates, annual wood production and biological rotation age for each area. The ecological structure of the woodlands differs between the three sites. Along this north–south transect, there is a decrease in adult tree density, mean basal diameter, mean tree height, canopy cover, productivity and total wood biomass. Consequently, the potential sustainable use of these woodlands varies. Only the northern, Pipanaco, woodlands have the potential for lumber production. In contrast, the short, multi-stem and low-productivity trees in the Telteca and Ñacuñán areas can only sustain a combination of local firewood production and activities such as extensive grazing by livestock. The present, uniform regulations for harvesting wood in these areas must be changed to acknowledge these differences in order to optimize wood production in, and conservation of, these woodlands.