Flávia R. C. Costa

RAPELD: a modification of the Gentry method for biodiversity surveys in long-term ecological research sites

Our objectives were to develop a method that would be appropriate for long-term ecological studies, but that would permit rapid surveys to evaluate biotic complementarity and land-use planning in Amazonia. The Amazon basin covers about 7 million km2. Therefore, even a sparse coverage, with one sample site per 10.000 km2, would require about 700 sampling sites. Financial considerations limit the number of sites and investment at each site, but incomplete coverage makes evaluation of biotic complementarity difficult or impossible (Reddy & Davalos 2003). Our next challenge is to install similar systems throughout Amazonia. The cost, based on modification of Al Gentrys original design is moderate (less than US

Markedly divergent estimates of Amazon forest carbon density from ground plots and satellites

50.000 per site if it is not necessary to immediately identify all vascular plants in plots) and we can obtain RAP results for most taxa in the short term at much lower cost. However, biological surveys will only be relevant if the local people participate and the surveys serve as much to teach the local communities about the value of their natural resources as they serve to teach the international community about biodiversity. Therefore, we want to see each site run as a long-term ecological research project by local people and institutions. Biological surveys are an important tool in land-use planning, but only the local people can implement those plans.

SELECTIVE LOGGING EFFECTS ON ABUNDANCE, DIVERSITY, AND COMPOSITION OF TROPICAL UNDERSTORY HERBS

Aim The accurate mapping of forest carbon stocks is essential for understanding the global carbon cycle, for assessing emissions from deforestation, and for rational land-use planning. Remote sensing (RS) is currently the key tool for this purpose, but RS does not estimate vegetation biomass directly, and thus may miss significant spatial variations in forest structure. We test the stated accuracy of pantropical carbon maps using a large independent field dataset. Location Tropical forests of the Amazon basin. The permanent archive of the field plot data can be accessed at: http://dx.doi.org/10.5521/FORESTPLOTS.NET/2014_1 Methods Two recent pantropical RS maps of vegetation carbon are compared to a unique ground-plot dataset, involving tree measurements in 413 large inventory plots located in nine countries. The RS maps were compared directly to field plots, and kriging of the field data was used to allow area-based comparisons. Results The two RS carbon maps fail to capture the main gradient in Amazon forest carbon detected using 413 ground plots, from the densely wooded tall forests of the north-east, to the light-wooded, shorter forests of the south-west. The differences between plots and RS maps far exceed the uncertainties given in these studies, with whole regions over- or under-estimated by > 25%, whereas regional uncertainties for the maps were reported to be < 5%. Main conclusions Pantropical biomass maps are widely used by governments and by projects aiming to reduce deforestation using carbon offsets, but may have significant regional biases. Carbon-mapping techniques must be revised to account for the known ecological variation in tree wood density and allometry to create maps suitable for carbon accounting. The use of single relationships between tree canopy height and above-ground biomass inevitably yields large, spatially correlated errors. This presents a significant challenge to both the forest conservation and remote sensing communities, because neither wood density nor species assemblages can be reliably mapped from space.

Historical Human Footprint on Modern Tree Species Composition in the Purus-Madeira Interfluve, Central Amazonia

Little is known about the impacts of selective logging on herbaceous plants of tropical forests. If logging impacts on nontimber species are low and little time is required for recovery, logged forests could be compatible with conservation of some elements of the understory flora. As many nontimber species may have commercial value, knowledge about the impacts of different logging intensities is necessary to determine levels of timber extraction compatible with multiple use of forests. In this study, we examined the effects of logging intensity, time after logging, and skidder tracks, on the composition and diversity of the ground-level herb community of a terra-firme forest in central Amazonia. Logging was carried out at varying intensities in eight 4-ha experimental plots in 1987, three plots in 1993, and five plots were controls. Herb community composition, analyzed with hybrid multidimensional scaling (HMDS), was not significantly affected by logging intensity, but was significantly related to the are...

Vertical distance from drainage drives floristic composition changes in an Amazonian rainforest

Background Native Amazonian populations managed forest resources in numerous ways, often creating oligarchic forests dominated by useful trees. The scale and spatial distribution of forest modification beyond pre-Columbian settlements is still unknown, although recent studies propose that human impact away from rivers was minimal. We tested the hypothesis that past human management of the useful tree community decreases with distance from rivers. Methodology/Principal Findings In six sites, we inventoried trees and palms with DBH≥10 cm and collected soil for charcoal analysis; we also mapped archaeological evidence around the sites. To quantify forest manipulation, we measured the relative abundance, richness and basal area of useful trees and palms. We found a strong negative exponential relationship between forest manipulation and distance to large rivers. Plots located from 10 to 20 km from a main river had 20–40% useful arboreal species, plots between 20 and 40 km had 12–23%, plots more than 40 km had less than 15%. Soil charcoal abundance was high in the two sites closest to secondary rivers, suggesting past agricultural practices. The shortest distance between archaeological evidence and plots was found in sites near rivers. Conclusions/Significance These results strongly suggest that past forest manipulation was not limited to the pre-Columbian settlements along major rivers, but extended over interfluvial areas considered to be primary forest today. The sustainable use of Amazonian forests will be most effective if it considers the degree of past landscape domestication, as human-modified landscapes concentrate useful plants for human sustainable use and management today.

Soil physical conditions limit palm and tree basal area in Amazonian forests

Background: Plant composition changes with topography and edaphic gradients that correlate with soil-water and nutrient availability. Data on soil water for the Amazon Basin are scarce, limiting the possibility of distinguishing between soil and soil-water influences on plant composition. Aim: We tested a new proxy for water table depth, the terrain height above nearest drainage (HAND), as a predictor of composition in trees, lianas, palms, shrubs, and herbs and compared HAND to conventional measures of height above sea level (HASL) and horizontal distances from nearest drainage (HDND). Methods: Plant-species composition in 72 plots distributed across 64 km2 of lowland evergreen terra firme forest was summarised using non-metric multidimensional scaling (NMDS). NMDS scores were regressed against estimates of HAND, HASL and HDND. Results: Plant composition was highly correlated with the vertical distance from water table, capturing up to 82% of variation. All life forms showed highest turnover rates in the zone with seasonally water-saturated soils, which can extend 350 m from stream margins. Conclusions: Floristic composition is closely related to water table depth, and HAND appears to be the most robust available topographical metric of soil-water gradients. Brazilian conservation laws protecting 30-m-wide riparian buffers are likely to be too narrow to encompass the full zone of highest floristic turnover and may be ineffective in safeguarding riparian plant diversity.

Temporary Pond Availability and Tadpole Species Composition in Central Amazonia

Background: Trees and arborescent palms adopt different rooting strategies and responses to physical limitations imposed by soil structure, depth and anoxia. However, the implications of these differences for understanding variation in the relative abundance of these groups have not been explored. Aims: We analysed the relationship between soil physical constraints and tree and palm basal area to understand how the physical properties of soil are directly or indirectly related to the structure and physiognomy of lowland Amazonian forests. Methods: We analysed inventory data from 74 forest plots across Amazonia, from the RAINFOR and PPBio networks for which basal area, stand turnover rates and soil data were available. We related patterns of basal area to environmental variables in ordinary least squares and quantile regression models. Results: Soil physical properties predicted the upper limit for basal area of both trees and palms. This relationship was direct for palms but mediated by forest turnover rates for trees. Soil physical constraints alone explained up to 24% of palm basal area and, together with rainfall, up to 18% of tree basal area. Tree basal area was greatest in forests with lower turnover rates on well-structured soils, while palm basal area was high in weakly structured soils. Conclusions: Our results show that palms and trees are associated with different soil physical conditions. We suggest that adaptations of these life-forms drive their responses to soil structure, and thus shape the overall forest physiognomy of Amazonian forest vegetation.

Near Infrared Spectroscopy Facilitates Rapid Identification of Both Young and Mature Amazonian Tree Species

Abstract Habitat availability for larval development is one of the main factors affecting the distribution of anuran species. However, little is known about the spatial distribution of these habitats, and estimates of the number of available ponds for a given reserve size are not available in Amazonia. Temporary water bodies were surveyed in a 30-m strip around a 144-km system of trails in a terra firme tropical forest, and tadpoles were collected to evaluate differences in species composition between isolated and streamside ponds. More than 90% of the ponds were <150 m from a stream, and the tadpole species composition differed between isolated and streamside ponds. Isolated ponds were less common, but were, on average, more stable in time than streamside ponds. Despite the limited distribution of isolated forest ponds, species of frogs dependent on them were found throughout the reserve. The presence of both types of ponds is important for the maintenance of the local pond-breeding anuran community. This study shows that isolated and streamside forest ponds maintain a distinct assemblage of frogs, and isolated ponds are much less common, but are, on average, more predictable in time than streamside ponds.

The spatial distribution of illegal logging in the Anavilhanas archipelago (Central Amazonia) and logging impacts on species

Precise identification of plant species requires a high level of knowledge by taxonomists and presence of reproductive material. This represents a major limitation for those working with seedlings and juveniles, which differ morphologically from adults and do not bear reproductive structures. Near-infrared spectroscopy (FT-NIR) has previously been shown to be effective in species discrimination of adult plants, so if young and adults have a similar spectral signature, discriminant functions based on FT-NIR spectra of adults can be used to identify leaves from young plants. We tested this with a sample of 419 plants in 13 Amazonian species from the genera Protium and Crepidospermum (Burseraceae). We obtained 12 spectral readings per plant, from adaxial and abaxial surfaces of dried leaves, and compared the rate of correct predictions of species with discriminant functions for different combinations of readings. We showed that the best models for predicting species in early developmental stages are those containing spectral data from both young and adult plants (98% correct predictions of external samples), but even using only adult spectra it is still possible to attain good levels of identification of young. We obtained an average of 75% correct identifications of young plants by discriminant equations based only on adults, when the most informative wavelengths were selected. Most species were accurately predicted (75–100% correct identifications), and only three had poor predictions (27–60%). These results were obtained despite the fact that spectra of young individuals were distinct from those of adults when species were analyzed individually. We concluded that FT-NIR has a high potential in the identification of species even at different ontogenetic stages, and that young plants can be identified based on spectra of adults with reasonable confidence.

Forest structure along a 600 km transect of natural disturbances and seasonality gradients in central-southern Amazonia

Amazonia is one of the worlds leading suppliers of timber and the Amazonian timber industry is an important source of regional income, however the economic benefits of this market are associated with environmental damage, mainly when the wood is removed illegally. The Anavilhanas National Park, located in the Brazilian state of Amazonas, has been subjected to illegal logging and elaboration of control programmes requires knowledge of the distribution of timber species and the intensity of logging. This study examines the density and growth rate of the five most harvested tree species in the Park, the spatial distribution of illegal logging operations and their effects on population structure. In total, 2332 trees with diameter at breast height greater than 10 cm, as well as stumps of cut trees, were sampled, and dendrochronology was used to estimate growth rates. Some size classes of Virola surinamensis trees and species within the family Lauraceae decreased in abundance as harvesting intensity increased. Growth rates of the most abundant species of Lauraceae, Ocotea cymbarum , were high, indicating stands may recover quickly when harvesting stops. The population structure of Calophyllum brasiliense showed no negative effects due to logging, but its low growth rate and stand distribution suggest that continued exploitation may endanger these populations. Logging had no detectable negative effects on the size structure of populations of Macrolobium acaciifolium or Hevea spp., and their high growth rates suggest that they will not be threatened by current logging rates. Overall growth rates in the Anavilhanas archipelago are higher than those recorded in other black-water floodplain forest (igapo). Logging of most species (except Lauraceae spp., which have the highest market value) is concentrated in the southern region of the Park, which has more human settlements close by. There was no general relationship between harvesting intensity and geographic distance to human settlements, but there was a tendency for harvesting to be higher in sites with concentrations of trees of high market value. Potential strategies to control illegal logging activities in the Anavilhanas archipelago include encouragement of sustainable logging in Park buffer zones and stimulation of ecotourism initiatives in the southern region of the Park. Ecotourism development can provide an economic alternative to illegal logging for local communities and inhibit logging by increasing vigilance.