Mineral nutrient concentrations in sapwood and heartwood: a literature review

Patterns in mineral nutrient concentrations in sapwood and heartwood are investigated from published data for N, P, K, Ca and Mg in 22 species of Gymnosperms and 71 species of Angiosperms. The average value of heartwood/sapwood concentration ratio is element-specific, increasing in the following order: P (0.36) < N (0.76) < K (0.78) < Mg (1.20) ≈ Ca (1.25). Concentrations of P, N and K are mostly lower in heartwood compared to sapwood. Large variation exists in the concentration pattern of Ca and Mg, whose functional significance is unclear. A phylogenetic pattern is confirmed, Gymnosperms having lower mineral nutrient concentrations in wood compared to Angiosperms, most strikingly so for N, K and Mg in sapwood. Heartwood and sapwood concentrations are positively correlated across species, and species with nutrient-poor sapwood have disproportionately poorer heartwood. The results are discussed in relation to the hypothesis that mineral nutrients are recycled from senescing sapwood.