Global variability in leaf respiration in relation to climate, plant functional types and leaf traits

Summary: Leaf dark respiration (R _dark ) is an important yet poorly quantified component of the global carbon cycle. Given this, we analyzed a new global database of R _dark and associated leaf traits. Data for 899 species were compiled from 100 sites (from the Arctic to the tropics). Several woody and nonwoody plant functional types (PFTs) were represented. Mixed-effects models were used to disentangle sources of variation in R _dark . Area-based R _dark at the prevailing average daily growth temperature (T) of each site increased only twofold from the Arctic to the tropics, despite a 20°C increase in growing T (8-28°C). By contrast, R _dark at a standard T (25°C, R _dark ²⁵ ) was threefold higher in the Arctic than in the tropics, and twofold higher at arid than at mesic sites. Species and PFTs at cold sites exhibited higher R _dark ²⁵ at a given photosynthetic capacity (V _cmax ²⁵ ) or leaf nitrogen concentration ([N]) than species at warmer sites. R _dark ²⁵ values at any given V _cmax ²⁵ or [N] were higher in herbs than in woody plants. The results highlight variation in R _dark among species and across global gradients in T and aridity. In addition to their ecological significance, the results provide a framework for improving representation of R _dark in terrestrial biosphere models (TBMs) and associated land-surface components of Earth system models (ESMs).