José Julio de Toledo

Soil-induced impacts on forest structure drive coarse woody debris stocks across central Amazonia

Background: Coarse woody debris (CWD) is an essential component in tropical forest ecosystems and its quantity varies widely with forest types. Aims: Relationships among CWD, soil, forest structure and other environmental factors were analysed to understand the drivers of variation in CWD in forests on different soil types across central Amazonia. Methods: To estimate CWD stocks and density of dead wood debris, 75 permanent forest plots of 0.5 ha in size were assessed along a transect that spanned ca. 700 km in undisturbed forests from north of the Rio Negro to south of the Rio Amazonas. Soil physical properties were evaluated by digging 2-m-deep pits and by taking auger samples. Results: Soil physical properties were the best predictors of CWD stocks; 37% of its variation was explained by effective soil depth. CWD stocks had a two-fold variation across a gradient of physical soil constraints (i.e. effective soil depth, anoxia and soil structure). Average biomass per tree was related to physical soil constraints, which, in turn, had a strong relationship with local CWD stocks. Conclusions: Soil physical properties appear to control average biomass per tree (and through this affect forest structure and dynamics), which, in turn, is correlated with CWD production and stocks.

Influence of soil, topography and substrates on differences in wood decomposition between one-hectare plots in lowland tropical moist forest in Central Amazonia.

Understandinghowwooddecompositionvariesspatiallyatthemesoscale(between1-haplots)mayimprove carbon flux estimates in Amazonian forests. An experiment was carried out to test the influence of soil, slope, above- ground tree live biomass (biomass), fine-litter mass and characteristics of neighbouring trees on the variation of wood decomposition between 1-ha plots in four species of tropical trees that vary in wood density (Manilkara huberi - 0.86gcm −3 ,Couratariguianensis-0.54gcm −3 ,Huracrepitans-0.32gcm −3 andParkiapendula-0.29gcm −3 ).Awood sample from each species (30 × 5 × 2.5 cm) was placed in each of 71 plots within 64 km 2 of terra firme tropical moist forestinReservaFlorestalAdolphoDucke.Oneyearlater,sampleswerecollectedandweighed.Theeffectsofspecificity of decomposers was measured by the association of decomposition with the wood density and with the taxonomic group of the nearest tree with dbh ≥30 cm. Wood decomposition was independent of soil (texture and nutrients), slope, biomass and fine-litter mass at the mesoscale, except for C. guianensis, which showed greater decomposition in locations with greater biomass. Decomposition was also independent of wood density and taxonomic group of nearby large trees. In general, none of the variables was useful as a predictor of wood decomposition at the scale larger than 1 ha. Thus, the use of models that include soil and topography to improve estimates of carbon flux are limited because wood decomposition does not follow similar mesoscale patterns to that of biomass and fine-litter decomposition. Also, the results indicate that wood decomposition is more likely to be associated with generalist decomposers than with specialists associated with neighbouring trees.

Multi-taxa Surveys: Integrating Ecosystem Processes and User Demands

Globally, natural resource management agencies are increasingly recognizing the importance of long-term ecological research (LTER) for monitoring biodiversity, ranging from relatively simple, known, local-level issues, such as managing tourist impacts in a conservation park, to more complex, multifaceted, pervasive, and far-reaching impacts, such as global climate change. Much previous literature has confused protocols for LTER projects to answer current research questions, with developing a system for long-term ecological monitoring. Contrary to perceptions that these LTER systems are not driven by well-defined objectives, we argue that LTER systems can be designed and implemented with the specific objective of providing a basis for both LTER projects and long-term monitoring. We present an overview of RAPELD, an LTER system developed in Brazil, with comparable infrastructure established in Australia and Nepal. The standardized biodiversity infrastructure and research platform provides a long-term basis for powerful multi-disciplinary, multi-scale analyses.

Determinants of changes in fish diversity and composition in floodplain lakes in two basins in the Pantanal wetlands, Brazil

The aim of this study was to investigate the effects of physical characteristics on fish assemblages. To this end, we studied 42 lakes distributed in two river basins of the Brazilian Pantanal: the Negro River basins in the South Pantanal and the Cuiabá River basins in the North Pantanal. We hypothesized that fish diversity and composition change significantly between these basins in response to physical differences and landscape structure (the geographical position of the basins). The alternative hypothesis was that local assemblages are distributed randomly between the two basins because of a regional homogenizing factor in the system. Our analysis suggests that the physical characteristics (lake area, depth and distance from the river margin) and the effect of geographical position of the basin were the main factors determining the organization of fish assemblages in these basins. This would indicate that regional fish diversity is not uniform over large areas of these Pantanal floodplains, but that communities close to each other are more similar than those that are further apart. Although there was a small variation between the lakes, this was not sufficient to affect the communities of both basins, either in composition or in diversity. Our study also supports the hypothesis that fish assemblages in the littoral zone of the Cuiabá River are richer and more diverse than assemblages in the corresponding area of the Negro River and that these differences are related to landscape characteristics. Hence, our results strongly suggest that area lake, depth, position of the basin, and smaller contribution of distance from the river margin are the key factor determining fish assemblage structure in floodplain lakes in the Cuiabá River and Negro River basins.

Inter-site variation in allometry and wood density of Goupia glabra Aubl. in Amazonia

The present study aims to compare the allometry and wood density of Goupia glabra Aubl. (Goupiaceae) in two different terra-firme sites in Amazonian forest. A total of 65 trees ≥ 10 cm DBH was sampled in both sites, with 39 trees in Nova Olinda do Norte (NOlinda, near the Amazon River) and 29 trees in Apuí (near the southern edge of the Amazon forest). Except for the relationship between DBH (diameter at breast height) and Ht (total height), allometric relationships for G.glabra differed significantly between sites. Apuí had lower intercept and greater slope for log10 (DBH) versus log10 (Hs - stem height), and, conversely, greater intercept and lower slope for log10 (DBH) versus log10 (Ch - crown height). The slope differed significantly between the sites for DBH versus Cd (crown diameter), with greater slope found for NOlinda. Mean basic wood density in Apuí was 8.8% lower than in NOlinda. Our findings highlight the variation in adaptive strategy of G. glabra due to environmental differences between sites. This is probably because of different canopy-understory light gradients, which result in differentiation of resource allocation between vertical and horizontal growth, which, in turn, affects mechanical support related to wood density. We also hypothesize that differences in soil fertility and disturbance regimes between sites may act concomitantly with light.

The Fate of an Amazonian Savanna: Government Land-Use Planning Endangers Sustainable Development in Amapá, the Most Protected Brazilian State:

Although Amapá is the most protected Brazilian state, the same level of protection does not extend to its savannas. These are currently suffering increased pressure from threats including large-scale agriculture, particularly the expansion of soybean plantations. In September 2016, the Government of Amapá presented a zoning proposal (Zoneamento Socioambiental do Cerrado [ZSC]) that reserves most of the savannas for agricultural activities. Here, we outline how the methodology employed is flawed because it does not include fauna surveys, evaluations of ecosystem services or an assessment of the social importance of the savannas. The ZSC authors admit that, contrary to Brazilian legislation, the zoning was carried out with the single intention of increasing agriculture production. Current knowledge indicates that Amapá’s savannas are rich in biodiversity, including endemic and threatened species, and are also home to a rich culture of traditional populations. These savannas are important providers of ecosystem services that, if intact, could represent around US

Tree mode of death in Central Amazonia: Effects of soil and topography on tree mortality associated with storm disturbances

1.52 billion annually. We hold that the ZSC should be reformulated, with fair participation of stakeholders, in accordance with Brazil’s legal requirements. At least 30% of the savannas should be protected, local family farming should be supported, and the rights of traditional peoples must now be assured through recognition of their land rights.