Summary1. Until very recently there have been no digital data from satellites for studying events that occur at scales of 10-1000 m 2 over large areas (100-100 000 ha). Many phenomena of interest to ecologists, such as impacts of selective logging on forest processes, occur over large extents but at local scales. Here we report results from a pilot project to evaluate through visual interpretation the potential of newly available 1-m panchromatic and 4-m multi-spectral data from the IKONOS satellite, for studying forest structure, dynamics and logging impacts in logged and old-growth tropical moist forest. 2. The study area, the Mil Madeireira Itacoatiara Ltda site of Precious Woods Amazon, near Itacoatiara, Amazonas, Brazil, is managed using reduced-impact logging practices to minimize environmental impacts, and thus represents a lower bound for logging impacts in tropical rain forests. 3. The IKONOS image was georeferenced using uncorrected global positioning system (GPS) locations for 10 control trees whose crowns were clearly visible in the image. The root mean square error (RMSE) of the geometric transformation was 4 m, while the mean crown diameter of 50 randomly chosen trees in old-growth forest was 9·4 m. The fact that the RMSE was less than half the average crown diameter implies that it will usually be possible to locate from the ground crowns that are distinct on the image, given sufficiently accurate GPS locations. 4. IKONOS data are well suited for evaluating and monitoring logging impacts. Many impacts of logging were clearly observable in the image, including major and some minor roads, logging patios and larger logging gaps. Smaller extraction roads and logging gaps were not observable. 5. Many individual trees were distinct on the IKONOS image, indicating that it is now feasible to conduct demographic studies of tropical rain forest canopy trees based on repeated satellite observations. Linking these remotely sensed data to ground data will require improved GPS positions, because it is currently difficult to obtain accurate GPS readings in tropical rain forest understoreys. 6. Synthesis and applications. IKONOS 1-m and 4-m data were found to be useful for identifying individual trees as well as some logging management features in a tropical moist forest in central Amazonia. These data will have many applications for research and management of intervened and old-growth tropical forests, including planning and assessment of logging activities, as well as monitoring adherence to certification criteria such as those of the Forest Stewardship Council. Rapid development of these applications will come from building on existing data on forest structure and function, and by fostering collaborations between remote sensing scientists, ecologists and natural resource managers.

White-sand vegetation (WSV) is a rare vegetation type in the Amazon basin that grows in nutrient impoverished sandy soils that occur as patches of variable size. Associated with this vegetation is bird assemblage that has not yet been fully characterized. Based on published species inventories and our own field data we compile a checklist of bird species recorded in WSV. In addition, we compared the avifauna of WSV with that found in savanna patches, another type of Amazonian open vegetation. WSV hosted a distinctive avifauna including endemic and threatened species. The number of bird species was lower in WSV compared to nearby terra firme forests, seasonally flooded forests and Amazonian savannas. Despite its low diversity, the avifauna of WSV has a distinctive species composition and makes a significant contribution to Amazonian beta diversity. At least 35 bird species can be considered as indicator species for this environment. Previously identified areas of endemism within the Amazon basin house at least one WSV indicator bird including cases of congeneric species with allopatric distributions. Seven of the WSV indicator species (20% of this avifauna) are in an IUCN threatened category, with one species Polioptila clementsi considered Critically Endangered. Their isolated distribution, small area occupied, and fragility to human-driven disturbances makes WSV one of the most threatened vegetation types in the Amazon basin. The study of WSV avifauna contributes to a better understanding of mechanisms that generate and maintain species diversity as well as of the environmental history of the most biologically diverse biome of the planet.

Following perturbation, different assemblages that originate under the same abiotic conditions initiate successional pathways that may continue to diverge or converge toward an eventual climax. Forest regeneration in the Central Amazon begins with alternative successional pathways associated with prior land use. In a 12-yr study of secondary forests, initially ranging between 2 and 19 yrs after abandonment, we compared species compositions through time along two pathways, abandoned clear-cuts dominated by Cecropia and abandoned pastures dominated by Vismia; prior results at these sites have not directly evaluated species composition. At all ages, the Chao-Jaccard similarity index of species composition was highest comparing pasture transects to each other, lowest comparing pastures transects to clear-cut transects, and intermediate comparing clear-cut transects to each other. Through time, clear-cut transects became less similar to each other, as did pasture transects. Changes in similarity reflected declining dominance along both pathways, but Cecropia dominance of clear-cut transects declined more rapidly than Vismia dominance of pasture transects. A rich association of species replaced Cecropia in clear-cut transects, resulting in decreased similarity among them. In pasture transects one genus, Bellucia, replaced the lost Vismia, so similarity of Vismia transects was maintained despite some turnover in dominance. Overall, even with turnover of individuals and decline of the dominant pioneers, the alternative pathways exhibited strikingly different species assemblies after two decades of succession, suggesting that the effect of land use persists well beyond initial floristic composition.Abstract in Portuguese is available in the online version of this article.

Aim  The aim of this study was to use compositional changes in tree species along the Amazon River floodplain in Brazil to identify and characterize biogeographic regions that would serve as broad surrogates for conservation planning.Location  The main course of the Amazon River in Brazil, covering a river distance of approximately 2800 km.Methods  Two sampling methods were employed at specific sites: standardized transects and/or individual‐based samples. Seventy‐three samples were collected from 26 sites at approximately 100‐km intervals along the floodplain. Biogeographic regions were identified by non‐metric multidimensional scaling (NMDS) ordination and by a hierarchical cluster analysis. The relative influence of environmental components (flood depths, annual rainfall, and length of the dry season) on tree species composition and one spatial component (longitude) were analysed by multiple regressions against a one‐dimensional NMDS ordination axis.Results  Based on tree species composition, three main biogeographic regions were identified: a western region between Tabatinga and the Negro River confluence; a central region from the Negro River confluence to the Xingu confluence; and an estuarine region from the Xingu confluence to Santana. The regions identified were consistent using different data sets and analytical techniques. Mixed environmental and spatial effects explained most of the variation, but the spatial effect alone had a greater influence on species composition than environmental effects alone.Main conclusions  The regions delimited in the analyses differed from those based on geomorphology or World Wildlife Fund (WWF) ecoregions. These results reinforce the need for surrogates to be tested against biological data before they are used to shape approaches to conservation planning. Although a protected area coverage of 25% gives the impression of extensive conservation management on the floodplain, less than 1% of the Amazon’s floodplain in Brazil is strictly protected. The significant compositional differences between regions and the strong spatial variation along the Amazon indicate that strict protection areas should be distributed much more evenly within and between regions.

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