Efeito da disponibilidade de nutrientes no solo nos traços físicos foliares em linhagens de árvores tropicais na Amazônia Central

Abstract

Leaf traits related to resistance, as well as resistance strategies of plants, are expected to be selected under nutrient limitation, to protect plants from loss of tissues to herbivores where building of new tissues is costly. However, at local scales, other environmental stresses could interfere or even supersede the effects of nutrient limitation. To understand together the effects of soil water and nutrient limitation, we analyzed leaf mass per area (LMA), leaf thickness (LT), force to punch (FP), leaf dry matter content (LDMC) and leaf density (LD) of 10 tree lineages across gradients of these two environmental factors in two sites of terra-firme forests in central Amazonia. In the site with lower fertility and larger water availability variation, LMA and LT community means increased towards drier but more fertile clay soils, while in the more fertile site these traits increased towards the sand soils which combine both nutrient and water limitation. FP and LDMC increased only towards low fertility, not being affected by water gradients. Leaf resistance strategies differed among sites, with higher investments in LMA and LT in the less fertile white-sand plots of the higher fertility site, but higher investments in LDMC, FP and LD in all plots of the less fertile site. The different tree lineages tended to converge to the same mean response patterns to the environmental gradients, but divergence in some traits was observed, suggesting that allocation in few resistance traits may be enough to protect leaves. In conclusion, both fertility and water availability gradients select the leaf resistance traits in central Amazonian forests, and fertility is only the dominant driver if water is not limited.