Nutritional characteristics of mineral elements in tree species of tropical rain forest,West Sumatra,Indonesia

The nutritional characteristics of mineral elements in tree species were studied in a 1 ha permanent observation plot at Mt. Gadut area near Padang, West Sumatra, Indonesia. The elemental composition of the 42 leaf and the 457 bark samples from the 1 ha plot was analyzed. Most of the elements, such as S, K, AI, CI, Si, B, and Sr, showed a significant correlation between leaf and bark, suggesting that bark can also be used to study the nutritional characteristics of trees instead of leaves as the first approximation. The concentrations of elements in 457 bark samples showed a wide range, indicating the considerable diversity of nutritional characteristics of mineral elements among these tree species. The concentration ranges expressed in mg kg-¹ were Mn (0.1–3,800), Sr (0.1–1,070), Si (2–1,700), Fe (0.6–4,100), Al (10–46,000), Mg (10–7,200), Zn (0.4–290), K (60–22,000), Cu (0.8–150), P (19–2,540), CI (110–9,200), S (170–13,600), Ca (2,300–100,000), B (4–70), and N a (130–700). Accumulator species were defined as trees with concentrations higher than logarithmic mean + 2std., whereas excluder species were defined as trees with concentrations lower than logarithmic mean — 2std. Among the 113 tree species identified, the accumulators were A. maingayi, M. glaberrimus, M. laurinum, P. axillaris, S. javensis, and M. sericea for S, A. frutescens, A. maingayi, M. laurinum, M. corymbosus, and E. acuminata for Al, F. ribes for Ca, B. pendula and U. maerophyllum for Cl, M. affinis and M. sereea for Si, M. affinis, L. elegans, G. maerophyllum, C. seorteehinii, and E. decipiens for Na, G. macrophyllum, E. opaea, E. latifolia, and C. arborea for B, E. opaea for Cu, F. lepicarpa for Fe, G. maerophyllum and E. opaea for P, A. malaccensis for Zn. The excluders were L. conoearpus for S, V. umbonata, L. conocarpus, S. elongata, G. forbesii, and M. serieea for Al, V. umbonata, L. conocarpus, P. grandis, P. eaeruleseens, G. forbeii, and H. arthoearpoid for Ca, V. perakensis, L. conocarpus, C. seorteehinii, and P. grandis for Mg, V. perakensis, B. tokbrai, C. zollingeriana, G. forbesii, and E. fastigiata for Na, P. exeelsa for Cu, A. porteri for Fe, P. alnifolia for Mn, L. conocarpus and G. forbesii for Sr. Specific Al accumulators were observed. M. corymbosus and U. macrophyllum accumulated Al at very high concentrations, 40 and 20 g kg-¹, respectively. Moreover, Al was accumulated not only in the mature leaves but also in the new leaves. A significant correlation between Al and P concentrations in the 457 bark samples was also observed. These observations suggest that Al exerts a beneficial effect on plant growth for certain tree species in the plot by stimulating P absorption.