Continental-scale patterns of canopy tree composition and function across Amazonia

Abstract

The world's greatest terrestrial stores of biodiversity and carbon are found in the forests of northern South America, where large-scale biogeographic patterns and processes have recently begun to be described. Seven of the nine countries with territory in the Amazon basin and the Guiana shield have carried out large-scale forest inventories, but such massive data sets have been little exploited by tropical plant ecologists. Although forest inventories often lack the species-level identifications favoured by tropical plant ecologists, their consistency of measurement and vast spatial coverage make them ideally suited for numerical analyses at large scales, and a valuable resource to describe the still poorly understood spatial variation of biomass, diversity, community composition and forest functioning across the South American tropics. Here we show, by using the seven forest inventories complemented with trait and inventory data collected elsewhere, two dominant gradients in tree composition and function across the Amazon, one paralleling a major gradient in soil fertility and the other paralleling a gradient in dry season length. The data set also indicates that the dominance of Fabaceae in the Guiana shield is not necessarily the result of root adaptations to poor soils (nodulation or ectomycorrhizal associations) but perhaps also the result of their remarkably high seed mass there as a potential adaptation to low rates of disturbance.

Arbuscular mycorrhizal community structure on co-existing tropical legume trees in French Guiana

“…The study was conducted at the Nouragues Research Station (within a National Nature Reserve) in central French Guiana (Bongers et al 2001; http://www.nouragues.cnrs.fr) with a diverse tree flora typical of much of the Guiana Shield (ter Steege et al 2006;Gonzalez et al 2009). The sampling was restricted to the Inselberg camp area (4°05'N; 52°41'W) in minimally disturbed tropical forest where two large sampling plots ('Grand Plateau' and 'Petit Plateau') have been delimited.…”

“…In this study, we examined the root associated AMF fungal community on three co-occurring leguminous tree species of French Guiana where legumes form many of the commonest tree species, making a significant contribution to stand basal area (ter Steege et al 2006). We hypothesised that: i) the Paris-mycorrhizal status of the target legume tree species could result from colonization by novel AMF taxa, ii) host tree and soil edaphic specific responses would be detectible in root colonizing fungal communities but iii) the co-ocurring trees would form a core AMF community with the potential to form common mycelial networks.…”

Low diversity and high host preference of ectomycorrhizal fungi in Western Amazonia, a neotropical biodiversity hotspot

“…Among hosts, Dipterocarpaceae and Amhersteae (Caesalpinioideae) form monodominant stands particularly in Tropical Asia and Africa. In neotropical forests, the monodominance of EcM vegetation is limited to a few regions in Northern Amazonia (ter Seege et al, 2006). Instead, many neotropical EcM plant lineages such as Gnetaceae, Pisonieae (Nyctaginaceae), Coccolobeae (Polygonaceae) and Aldineae (Papilionoideae) are usually scattered as shrubs and understorey trees among the dominant arbuscular mycorrhizal vegetation (Alexander and Lee, 2005 and references therein).…”

Floristic Diversity of Secondary Forest in the Eastern Amazon, State of Amapá

“…Understanding these mechanisms, we can advance in the understanding of diversity variation and richness in these environments. Forests in succession already allow us to establish relations between the bioecology of species, pointing elements which act in persistence for the formation of primary forests, such as: dispersion, predation, soil, temperature, water, luminosity and hydric regime (JONES et al, 2006;TER STEEGE et al, 2006). Besides these elements, the successional stage and the disturbance history of the forests may influence the number of species found in the community (TABARELLI;MANTOVANI, 1999).…”