SPLINE MODELS OF CONTEMPORARY, 2030, 2060 AND 2090 CLIMATES FOR MICHOACAN STATE, MEXICO. IMPACTS ON THE VEGETATION

Climate data from 149 weather stations of Michoacan State, at Western Mexico, were extracted from a spline climate model developed for Mexico's contemporary climate (1961-1990), and for climate projected for the decades centered in years 2030, 2060 and 2090. The model was constructed using outputs from three general circulation models (GCMs: Canadian, Hadley and Geophysical Fluid Dynamics) from two emission scenarios (A "pessimistic" and B "optimistic"). Mean annual temperature (MAT), mean annual precipitation (MAP), annual degree days > 5 degrees C (DD5), and annual aridity index (DD5(0.5)/MAP) were mapped for Michoacan at an 1 km(2) scale, and means were estimated averaging all weather stations. The state average in GCMs and emission scenarios point out that mean annual temperature would increase 1.4 degrees C by year 2030, 2.2 degrees C by year 2060 and 3.6 degrees C by year 2090; whereas annual precipitation would decrease 5.6 % by year 2030, 5.9 % by year 2060 and 7.8 % by year 2090. Climate models can be used for inferring plant-climate relationships and for developing programs to counteract global warming effects. Climate variables were estimated also at Pinus hartwegii and Pinus pseudostrobus growth locations, at Pico de Tancitaro in Central Western Michoacan and Nuevo San Juan Parangaricutiro (near Tancitaro), respectively. According to the annual aridity index values estimated for such locations, it is necessary to conduct assisted migration to match current genotypes to projected climates. This translates into an altitudinal shift of 400 to 450 m higher to match 2030 climates predicted by Canadian Model scenario A2, and 600 to 800 m to match 2060 climates.