REGIONAL CLIMATIC SIMILARITIES IN THE TEMPERATE ZONES OF NORTH AND SOUTH-AMERICA

We performed an analysis of the climatic patterns of the temperate zon es in North and South America using a global database of monthly preci pitation and temperature. Three synthetic variables, identified by a p rincipal component analysis (PCA) of the monthly data, were used: mean annual precipitation, mean annual temperature and the proportion of t he precipitation falling during summer. We displayed the spatial gradi ent of the three variables by constructing a composite colour raster i mage. We used a parallelepiped classification algorithm to locate area s in both continents that are climatically similar to five North Ameri can Long Term Ecological Research sites and to two South American long -term ecological research sites. The same algorithm was used to identi fy areas in South America which are climatically similar to some of th e major grassland and shrubland types of North America. There is subst antial overlap between the climates of North and South America. Most o f the climatic patterns found in South America are well represented in North America. However, there are certain climates in North America t hat are not found in South America. An example is a climate with relat ively low mean annual temperature and high summer precipitation. The c limatic signatures of three North American LTER sites (Cedar Creek, CP ER and Sevilleta) were not found in South America. The climatic signat ures of two LTER sites (Konza and Jornada) had some representation in South America. Two South American research sites (Rio Mayo and Las Chi lcas) were well represented climatically in North America. The climate s of six out of seven selected North American grassland and shrubland types were represented in South America. The northern mixed prairie ty pe was not represented climatically in South America. Our analysis sug gests that comparisons of North and South America can provide a powerf ul test of climatic control over vegetation.