Ethnobotanical ground‐truthing: indigenous knowledge,floristic inventories and satellite imagery in the upper Rio Negro,Brazil

Aim To assess the utility of indigenous habitat knowledge in studies of habitat diversity in Amazonia. Location Baniwa indigenous communities in Rio Içana, upper Rio Negro, Brazil. Methods Six campinarana vegetation types, recognized and named by a consensus of Baniwa indigenous informants according to salient indicator species, were studied in 15 widely distributed plots. Floristic composition (using Baniwa plant nomenclature only, after frustrated attempts to obtain botanical collection permits), quantitative measures of forest structure and GPS waypoints of the 4‐ha composite plot contours were registered, permitting their location on Landsat satellite images. Non‐metric multidimensional scaling (NMDS) ordination was carried out using pc‐ord software. Results The NMDS ordinations of the plot data revealed a clear gradient of floristic composition that was highly correlated with three quantitative measures of forest structure: basal area, canopy height and satellite reflectance. Main conclusions Baniwa‐defined forest types are excellent predictors of habitat diversity along the structural gradient comprising distinctive white‐sand campinarana vegetation types. Indigenous ecological knowledge, as revealed by satellite imagery and floristic analyses, proves to be a powerful and efficient shortcut to assessing habitat diversity, promoting dialogue between scientific and indigenous worldviews, and promoting joint study and conservation of biodiversity.     

Understanding the Influences of Spatial Patterns on N Availability Within the Brazilian Amazon Forest

Nitrogen variations at different spatial scales and integrated across functional groups were addressed for lowland tropical forests in the Brazilian Amazon as follows: (1) how does N availability vary across the region over different spatial scales (regional × landscape scale); (2) how are these variations in N availability integrated across plant functional groups (legume × non-legume trees). Leaf N, P, and Ca concentrations as well the leaf N isotope ratios (δ¹⁵N) from a large set of legume and non-legume tree species were measured. Legumes had higher foliar N/Ca ratios than non-legumes, consistent with the high energetic costs in plant growth associated with higher foliar P/Ca ratios found in legumes than in non-legumes. At the regional level, foliar δ¹⁵N decreased with increasing rainfall. At the landscape level, N availability was higher in the forests on clayey soils on the plateau than in forests on sandier soils. The isotope as well as the non-isotope data relationships here documented, explain to a large extent the variation in δ¹⁵N signatures across gradients of rainfall and soil. Although at the regional level, the precipitation regime is a major determinant of differences in N availability, at the landscape level, under the same precipitation regime, soil type seems to be a major factor influencing the availability of N in the Brazilian Amazon forest.     

Islands in a green ocean: Spatially structured endemism in Amazonian white-sand vegetation

Here, we examine the influence of the spatial distribution of open white-sand campina (WSC) in the Amazon on the species richness and beta diversity of their vascular plants. It is well known that beta diversity tends to increase with geographical distance, but the influence of habitat insularity on floristic composition and endemism is still unclear. We surveyed WSC in central and southwestern Amazon, generating lists of species occurrences by rapid-inventory techniques to evaluate the influence of island area and connectivity on alpha and beta diversity among five landscapes in the Amazon Basin. Effects of insularity were assessed by comparing alpha and beta diversity within and among landscapes. A high proportion of species (~74%) and genera (~50%) were restricted to only one of the five landscapes and only three species and 28 genera were shared among all landscapes. At the regional scale, beta diversity increased significantly with distance. Partitioning of beta diversity showed that landscapes of higher connectivity have greater turnover and lower nestedness. We conclude that the flora of WSC is highly structured at regional scales, while at the local scale structure is evident only in low connectivity landscapes. Landscape metrics apparently play an important role in shaping patterns of diversity regionally as a result of processes operating at larger geographical scales. This emphasizes that conservation policy should not be local in its geographical focus and should account for connectivity at larger scales. This study is the first to empirically and explicitly evaluate the pattern of endemism in lowland WSC in the Amazon.