Basin-wide variations in foliar properties of Amazonian forest: phylogeny, soils and climate

Abstract

We analysed 1040 individual trees, located in 62 plots across the Amazon Basin for leaf mass per unit area (M-A), foliar carbon isotopic composition (delta C-13) and leaf level concentrations of C, N, P, Ca, Mg, K and Al. All trees were identified to the species level with the dataset containing 58 families, 236 genera and 508 species, distributed across a wide range of soil types and precipitation regimes. Some foliar characteristics such as M-A, [C], [N] and [Mg] emerge as highly constrained by the taxonomic affiliation of tree species, but with others such as [P], [K], [Ca] and delta C-13 also strongly influenced by site growing conditions. By removing the environmental contribution to trait variation, we find that intrinsic values of most trait pairs coordinate, although different species ( characterised by different trait suites) are found at discrete locations along a common axis of coordination. Species that tend to occupy higher fertility soils are characterised by a lower M-A and have a higher intrinsic [N], [P], [K], [Mg] and delta C-13 than their lower fertility counterparts. Despite this consistency, different scaling patterns were observed between low and high fertility sites. Inter-relationships are thus substantially modified by growth environment. Analysing the environmental component of trait variation, we found soil fertility to be the most important predictor, influencing all leaf nutrient concentrations and delta C-13 and reducing M-A. Mean annual temperature was negatively associated with leaf level [N], [P] and [K] concentrations. Total annual precipitation positively influences M-A, [C] and delta C-13, but with a negative impact on [Mg]. These results provide a first basis for understanding the relationship between the physiological functioning and distribution of tree species across Amazonia

Crescimento e eficiência fotossintética de uso do nitrogênio e fósforo em espécies florestais da Amazônia na fase juvenil

“…Diversos estudos apontam que geralmente existe forte relação entre a fotossíntese e a concentração de N foliar, pois esse nutriente é componente essencial da enzima ribulose 1,5 bifosfato carboxilase/oxigenase (Rubisco), enzima-chave na fixação de carbono (KITAJIMA et al, 1997;FYLLAS et al, 2009). A importância do P está relacionada à sua participação na síntese de proteínas e no balanço energético da planta, existindo relação positiva entre taxa de fotossíntese e teor de P foliar (RAAIMAKERS et al, 1995).…”

“…Diversos estudos têm mostrado a importância do N e P na fotossíntese (REICH et al, 1999;FYLLAS et al, 2009), no entanto há pouca informação sobre os níveis críticos e ótimos de nutrientes para espécies florestais da Amazônia. Em Swietenia macrophylla e Brosimum alicastrum, conteúdos de nutrientes foliares abaixo de 10-14 mg g -1 (para N) e 0,6 mg g -1 (para P) são considerados deficientes para o crescimento (DRECHSEL; ZECH, 1991).…”

Nutrients limit photosynthesis in seedlings of a lowland tropical forest tree species

“…Annual precipitation averages 2,600 mm, less than 10% of which falls during the 4-month dry season. The soils consist of Endogleyic Cambisols and Acric Nitisols (Koehler et al 2009), and are relatively fertile for lowland tropical forest soils (Fyllas et al 2009;Dieter et al 2010;Wright et al 2011). …”

Large-scale climatic and geophysical controls on the leaf economics spectrum

“…5B): very low lying areas (<100 m), where alluvial deposition is greatest, had locally high P values (0.135%), but then declined at slightly higher elevations of 100-400 m in the Amazon lowlands. This pattern is driven by differences between floodplain forests containing enriched alluvium from the Andes and upland terra firme forests on dystrophic clay soils (34). P concentrations then increased to a mean of ∼0.15% at about 700-m elevation, and remained elevated to the Andean treeline.…”

“…7). These areas contain soils with much higher concentrations of rock-derived nutrients, including P and base cations (35), which subsequently support higher overall nutrient levels in forest canopy foliage (34). Nitrogen is generally held in higher concentrations in tropical forest canopies on soils with higher rock-derived nutrient availability, in part because of increased N fixation rates on higherfertility soils (36,37).…”