Sala, O. E. 2001. NPP Grassland: Rio Mayo, Argentina, 1983-1989. Data set. Available on-line [http://www.daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.
The Rio Mayo study site (45.68 S 70.27 W) is situated in south-western Chubut, typical of the temperate dry steppe of South America, with extremely low rainfall. Patagonia is a large region of 500,000 km2, and few estimates of NPP have been published. Rio Mayo is sited within the Occidental District of Patagonia, one of five floristic divisions dominated by grasses or shrubs.
Quarterly dynamics of above ground live biomass and standing dead matter are available for the grass layer in 1984-1985, with annual peak biomass data for four additional years during 1983-1989. ANPP of the shrub layer was estimated directly by a different method, based on observations of current-year growth.
Over five years, ANPP ranged from 21 to 75 g/m2/yr, with an average of about 60 g/m2/yr. ANPP for 1984-1985 was slightly higher (79 g/m2/yr) using a different algorithm for estimation. Grasses accounted for about two-thirds of productivity. ANPP was reduced in a drought year, but did not increase in relatively wet years, suggesting that it may not be linearly related to precipitation.
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