Grassland Precipitation Use efficiency across a resource gradientonas templadas de Argentina mediante imágenes satelitarias.

PARUELO, J.M.; LAUENROTH, W.K.; BURKE, I.C.; SALA, O.E

ECOSYSTEMS (NEW YORK. PRINT)

SPRINGER

Lugar: Berlin; Año: 1999 vol. 29 p. 64 - 69

1432-9840

Aboveground net primary production (ANPP) ispositively related to mean annual precipitation, anestimate of water availability. This relationship isfundamental to our understanding and managementof grassland ecosystems. However, the slope ofthe relationship between ANPP and precipitation(precipitation-use efficiency, PUE) has been shownto be different for temporal compared with spatialprecipitation series. When ANPP and precipitationare averaged over a number of years for differentsites, PUE is similar for grasslands all over the world.Studies for two US Long Term Ecological ResearchSites have shown that PUE derived from a longtermdataset (temporal model) has a significantlylower slope than the value derived for sites distributedacross the US central grassland region (spatialmodel). PUE differences between the temporalmodel and the spatial model may be associated withboth vegetational and biogeochemical constraints.Here we use two independent datasets, one derivedfrom field estimates of ANPP and the other fromremote sensing, to show that the PUE is low at boththe dry end and the wet end of the annual precipitationgradient typical of grassland areas (200?1200mm), and peaks around 475 mm. The intermediatepeak may be related to relatively low levels of bothvegetational and biogeochemical constraints at thislevel of resource availability.