Relationships between mass-based maximum respiration rates (R  _max-mass) of plants and environmental variables, basal respiration, and leaf traits. These include A) mean maximum temperature of the warmest month (MMTWM), B) mean annual precipitation (MAP), C) mass-based respiration at 25 °C (R  _25-mass), D) leaf mass per area (LMA), E) mass-based leaf nitrogen (N_mass), and F) mass-based phosphorus (P_mass). The linear regression in A) (P < 0.05; see Table 1 for the equation) is through site-mean data (larger points; means ± SE, n = 19). Smaller points indicate species-site mean data (n = 191 for A), B), and D); n = 190 for C); and n = 142 for E) and F)). In C)–F), standardized major axis regressions through site-species mean data show significant relationships (P < 0.05; see Table 2 for equations). Abbreviations for biomes are as follows: Tu, tundra; BF, boreal forest; TeDF, temperate deciduous forest; TeRF, temperate rainforest; TeW, temperate woodland; TrRF_up, high elevation tropical rainforest; TrRF_lw, lowland tropical rainforest.