Citation. Shipley, B.; Lechoweicz, M.J.; Wright, I.; Reich, P.B. 2006 Fundamental trade-offs generating the worldwide leaf economics spectrum. ECOLOGY 87:535-541.

Abstract. Recent work has identified a worldwide “economic” spectrum of correlated leaf traits that affects global patterns of nutrient cycling and primary productivity and that is used to calibrate vegetation–climate models. The correlation patterns are displayed by species from the arctic to the tropics and are largely independent of growth form or phylogeny. This generality suggests that unidentified fundamental constraints control the return of photosynthates on investments of nutrients and dry mass in leaves. Using novel graph theoretic methods and structural equation modeling, we show that the relationships
among these variables can best be explained by assuming (1) a necessary trade-off between allocation to structural tissues versus liquid phase processes and (2) an evolutionary trade-off between leaf photosynthetic rates, construction costs, and leaf longevity.

Key words: comparative ecology, leaf life span, leaf longevity, leaf mass per area, LMA, leaf nitrogen content, net photosynthetic rate, path analysis, specific leaf area, SLA, structural equations modeling, SEM, vanishing tetrads