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キーワード:
wood specific gravity; within-tree variation; growth strategies; pioneer; succession; flood; floodplain forest; Amazonia; Brazil
要旨:
Increases in wood specific gravity (SG) with distance from pith are associated with the growth strategies of trees and their environments. In the present study, radial gradients in SG were analysed for 20 species from nutrient-rich whitewater floodplains (varzea), including seven pioneer species, and for 15 species from nutrient-poor blackwater floodplains (igapo) in Central Amazonia. Average SG increased from pith to bark by 12% in the species from igapo, compared to 16% in the non-pioneers and 35% in the pioneers from varzea. The increases lie in the range of tropical dry forests. SG variation follows the growth strategies of the trees, The main trend in nutrient-rich varzea is fast growth, with low SG wood initially and higher increases in SG. In nutrient-poor igapo, the tendency is relatively constant, slow growth and low SG changes throughout tree life.
