ABOVEGROUND NET PRIMARY PRODUCTIVITY AND COVER OF VEGETATION EXPOSED TO VARIOUS DISTURBANCES IN ARID ARGENTINA

We contrasted total herbaceous ANPP and cover between various disturbance types (Control, Burning, Shrub Control, Old Field 1, Old Field 2, Overgrazing) at a functional group (CSPG= cool- season perennial grasses; WSPG= warm-season perennial grasses; CSAG + D= cool-season annual grasses + dicots) and a species scale during 1984-1992. Results showed that (1) precipitation appeared to be more important than disturbance type in determining total ANPP (CSPG + WSPG + CSAG + Dicots); (2) CSPG made the greatest (P 0.05) ANPP most of the times during 1984-1992; (4) Total plant cover of CSAG+D was most often greater (P<0.05) than that of WSPG at the Old Field 1 and Overgrazing disturbances.