Tree species composition and rain forest-environment relationships in the middle Caquet� area, Colombia, NW Amazonia

Abstract

As part of an integrated forest vegetation and soil survey, tree species composition (DBH > 10 cm) was recorded in 95 plots of 0.1 ha, distributed over the principal physiographic units in the middle Caquet~i area, Colombian Amazonia. A total of 1077 tree species was found, classified into 271 genera and 60 families. Leguminosae and Sapotaceae show high familial importance values in all physiographic units. Lauraceae, Chrysobalanaceae, Moraceae, and Lecythidaceae are more important on well drained (flood plain or upland) soils, while Palmae, Guttiferae, Bombacaceae, and Apocynaceae are more important in swamps and on podzolised ('white sand') soils. Plots on well drained soils show a lower degree of dominance than plots in swamps or on podzolised ('white sand') soils. The composition of the most dominant slSecies in the plots changes continuously. Most species (59%) are only recorded in one plot. Individual plot pairs generally show a low overlap of about 2-5 tree species, resulting in Jaccard coefficients below 20%.Complementary to a previous forest classification based on TWINSPAN analyses, detrended and canonical correspondence analyses were carried out, using CANOCO 3.1. Despite of a low amount of tree species variance explained (only 6.2% by the first two canonical axes), meaningful patterns of tree species composition were recognised. These are most strongly related to drainage, flooding, humus forms, and soil nutrient status. Forest types are well separated in the CCA ordination diagram. The most frequently found tree species are listed according to their preference with respect to drainage, flooding, and soil nutrient status.Tree species composition in the well drained upland forests was analysed separately. In view of the model explaining high NW Amazonian tree species diversity on the basis of dense community packing and high beta diversity along soil gradients, the canonical analysis here focused on the effect of soils. By means of partial canonical ordination it was found that patterns of tree species composition depended significantly on soil properties, even though the edaphic component explains only a small fraction of the tree species variance. The results show that the well drained uplands of the middle Caque~ area are covered by a complex of two intergrading tree species assemblages. The first assemblage (community of Goupia glabra-Clathrotropis macrocarpa) is associated to somewhat less poor, clayey soils developed in Andean origin deposits or Tertiary sediments from the Pebas formation. The second assemblage (community of Swartzia schomburgkii-Clathrotropis macrocarpa) shows affinities to very poor, loamy soils developed in parent materials derived from the Guiana shield. This simple dichotomous pattern of geology, soils, and forest types is incompatible with concepts of high soil heterogeneity and associated beta diversity controlling tree species diversity in well drained uplands of NW Amazonia. The gradient length of tree species in the detrended Correspondence analysis was low (3.7 SD), al...

Multi-scale comparisons of tree composition in Amazonian terra firme forests

“…Using pteridophytes and the family Melastomataceae, Tuomisto et al (2003a) demonstrated that environmental factors, especially soil type, were also important for species distribution and abundance patterns within terra firme forests in western Amazonia. Similar results were shown using the same taxa in a one-hectare plot in Ecuador (Poulsen et al, 2006), a 43-km long transect in northern Peru (Tuomisto et al, 2003b), palms in north-western Amazonia (Vormisto et al, 2004;Normand et al, 2006), species of trees with diameter ≥10 cm in specific areas in Colombia (Duivenvoorden, 1995), a network of 0.1 ha plots in south-western Amazonia (Phillips et al, 2003) and at a broader scale, using genera of trees from the whole of Amazonia (ter Steege et al, 2006).…”

Fine litter input to terrestrial humus forms in Colombian Amazonia

“…1) are described and mapped in recent studies, carried out within the framework of the Tropenbos programme in Colombia Lips 1993, 1995;Duivenvoorden 1994Duivenvoorden , 1995Duivenvoorden , 1996Hoorn 1994;Van der Hammen et al 1992a,b). At Araracuara (Fig.…”

“…The surface of the leaves was measured using image-processing computer software (Adobe Photoshop). Methods of sampling and aria- a pH=7, NH4OAc method b Ca, Mg, K, Na, and P in HF/H2SO 4 extract after combustion 500 ~ C, N according to Kjehldahl method c I<DBH<10 cm, >2 m height at a DBH>10 cm lyses of mineralsoil, ectorganic horizons, forest composition, and forest structure are described in Duivenvoorden and Lips (1993, 1995) Lips and Duivenvoorden 1996and Duivenvoorden (1995, 1996.…”

Changes in Forest Structure and Biomass over Ten Years in a Lowland Amazonian Forest

“…The plateau and baixio sites in the present study are characterized by clayish and sandy soils, respectively, and baixio areas are seasonally inundated. Duivenvoorden (1996) reported that the canopy height was higher at well-drained sites than at poorly drained sites in an upper Amazonian region. Aiba and Kitayama (2002) suggested that the high allocation of biomass to height growth was related to productive …”