FUNCTIONAL AND STRUCTURAL CONVERGENCE OF TEMPERATE GRASSLAND AND SHRUBLAND ECOSYSTEMS

We analyzed the similarity of structural and functional characteristic s of temperate grassland and shrubland ecosystems of North and South A merica. We based our analyses on correlative models that describe the climatic controls of grassland and shrubland structure and functioning at regional scales. We evaluated models that describe the regional di stribution of plant functional types (C-3 and C-4 grasses and shrubs), soil organic carbon (SOC), and aboveground net primary production (AN PP) and its seasonality. To evaluate the predictive power of the model s, we compared their estimates against observed data. We derived data sets. independent from those used to generate the models in North Amer ica, from climatically similar areas in South America. Our results sup port the notion that, in climatically similar regions, structural and functional attributes such as plant functional type composition, SOC, ANPP, and ANPP seasonality have similar environmental controls, indepe ndent of the evolutionary history of the regions. The study suggests t he existence of an important degree of convergence at regional scales in both functional and structural attributes. It also points out diffe rences in the regional patterns of some attributes that require furthe r analyses.