PLANT-RESPONSES TO ELEVATED ATMOSPHERIC CO2 AMONG TERRESTRIAL BIOMES

Although many researchers have stressed the importance of among-specie s variation in plant response to elevated CO2, none have quantitativel y tested whether variation exists among biomes. I compiled data from t he literature and found that, although C-3 plants did respond more tha n C-4 plants (as predicted), biome origin was a better predictor (acco unted for more of the variation) of plant response to elevated CO2 tha n mode of photosynthesis, Variation in plant response among biomes was found both between and within latitudinal zones, with plant species f rom tropical and temperate biomes responding more than plant species f rom a polar biome. Within the temperate zone, species from forested bi omes responded more than species from a grassland biome, and this prov ides further evidence that forests are acting as major sinks for incre asing levels of atmospheric CO2. A more than 4-fold difference was fou nd among ecosystems in coefficients of variation (calculated across me an species response within each ecosystem). Based on this difference, I suggest that ecosystems may vary in the amount of change in species composition in response to elevated CO2.