Growth of Prosopis caldenia Burk:: seedlings in central semi-arid rangelands of Argentina

Prosopis caldenia Burk. is one of the woody species increasing in abundance due to poor grazing management in the semi-arid regions of central Argentina. The objective of this study was to evaluate the effect of herb cover, cattle dung, soil compaction, and water supply on P. caldenia seedling growth on sites with different grazing history: a site exposed to a long-term (25 or more years) continuous grazing by cattle (grazed experimental site), and a site long-term (around 20 years) exclosure to domestic livestock (ungrazed experimental site). In both experimental sites, regardless of the study period, the highest height and main root length of P. caldenia seedlings were recorded in plots with the herb cover removed, soil disturbed, cattle dung presence, and water supply. Above- and below-ground biomass of P. caldenia seedlings showed a similar response. Direct and indirect effects of livestock grazing favoured P. caldenia seedlings growth, which might increase their establishment probabilities in sites under a chronic heavy grazing. Consequently, this might alter the grass-woody plant balance in the Caldenal causing a drastic reduction of the domestic livestock production in the region. (c) 2004 Elsevier Ltd. All rights reserved.