This work aimed to evaluate the relationship between natural pasture yield and climate variability in the district of Salto (Uruguay), and to analyze the possible implications of future climate change. Daily and monthly data from Salto meteorological station for the period 1961-1990 were used together with experimental data of pasture yield for the period 1980-1994. Moreover, NCEP reanalyses of daily data as well as daily outputs from General Circulation Models HadCM3 and CSIRO-Mk2 were analyzed. The simple correlations between the climatic variables and the pasture yield confirm in quantitative terms the sensitivity of pasture yield to climate variability, accounting for 20% up to 58% of the variance. The highest associations were found in fall (mainly with precipitation variables), followed by summer. No significant associations were found in winter. The joint effect of the climatic variables on yield could explain between 36% and 86% of the pasture variability. The increments projected for the minimum and maximum temperatures may, respectivaly, reduce the probabilities of occurrences of temperatures below the minimum threshold considered for pasture (10ºC) and increase the probabilities of thermal stress, mainly in summer, respectively. Modeled increments in precipitation may raise the occurrences of precipitation excess during winter. On the other hand, the modeled precipitation increments during summer would not be enough to compensate the high water demand caused by the greater temperatures.
climate variability and change; pasture growth; Salto
