Relationships of leaf dark respiration to leaf nitrogen , specific and leaf life - span : a test across biomes and functional groups leaf area

Based on prior evidence of coordinated multiple leaf trait scaling, we hypothesized that variation among species in leaf dark respiration rate (Rd) should scale with variation in traits such as leaf nitrogen (N), leaf life-span, specific leaf area (SLA), and net photosynthetic capacity (A,,,). However, it is not known whether such scaling, if it exists, is similar among disparate biomes and plant functional types. We tested this idea by examining the interspecific relationships between Rd measured at a standard temperature and leaf life-span, N, SLA and Amax for 69 species from four functional groups (forbs, broad-leafed trees and shrubs, and needle-leafed conifers) in six biomes traversing the Americas: alpine tundra/subalpine forest, Colorado; cold temperate forest/ grassland, Wisconsin; cool temperate forest, North Carolina; desert/shrubland, New Mexico; subtropical P.B. Reich @I) Department of Forest Resources, University of Minnesota, St. Paul, MN 55108, USA Fax 612-625-5212; e-mail: [email protected] M.B. Walters Faculty of Natural Resources and Environmental Studies, University of Northern British Columbia, Prince George, BC, Canada V2N 429