Estimating the global conservation status of more than 15,000 Amazonian tree species

Estimates of extinction risk for Amazonian plant and animal species are rare and not often incorporated into land-use policy and conservation planning. We overlay spatial distribution models with historical and projected deforestation to show that at least 36% and up to 57% of all Amazonian tree species are likely to qualify as globally threatened under International Union for Conservation of Nature (IUCN) Red List criteria. If confirmed, these results would increase the number of threatened plant species on Earth by 22%. We show that the trends observed in Amazonia apply to trees throughout the tropics, and we predict thatmost of the world’s >40,000 tropical tree species now qualify as globally threatened. A gap analysis suggests that existing Amazonian protected areas and indigenous territories will protect viable populations of most threatened species if these areas suffer no further degradation, highlighting the key roles that protected areas, indigenous peoples, and improved governance can play in preventing large-scale extinctions in the tropics in this century

One sixth of Amazonian tree diversity is dependent on river floodplains

Amazonia's floodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of floodplains, our understanding of their species composition and how this may differ from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape floodplain tree communities and the critical ecosystem functions they underpin. Here we address this gap by taking a spatially explicit look at Amazonia-wide patterns of tree-species turnover and ecological specialization of the region's floodplain forests. We show that the majority of Amazonian tree species can inhabit floodplains, and about a sixth of Amazonian tree diversity is ecologically specialized on floodplains. The degree of specialization in floodplain communities is driven by regional flood patterns, with the most compositionally differentiated floodplain forests located centrally within the fluvial network and contingent on the most extraordinary flood magnitudes regionally. Our results provide a spatially explicit view of ecological specialization of floodplain forest communities and expose the need for whole-basin hydrological integrity to protect the Amazon's tree diversity and its function.Naturali

Mapping density, diversity and species-richness of the Amazon tree flora

Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution

Aerogels Containing Metal, Alloy and Oxide Nanoparticles Embedded into Dielectric Matrices

Aerogels are regarded as ideal candidates for the design of functional nanocomposites based on supported metal or metal oxide nanoparticles. The large specific surface area together with the open pore structure enables aerogels to effectively host finely dispersed nanoparticles up to the desired loading and to provide nanoparticle accessibility as required to supply their specific functionalities. The incorporation of nanoparticles as a way to increase the possibility of the use of aerogels as innovative functional materials and the challenges in the controlled preparation of nanocomposite aerogels is reviewed in this chapter

FeCo-SiO2 nanocomposite aerogels by high temperature supercritical drying

FeCo-SiO2 nanocomposite aerogels were prepared by high temperature supercritical drying of alcogels obtained using tetraethoxysilane, iron nitrate and cobalt nitrate as precursors. The structural evolution of the samples at the various stages of the preparation was studied by thermal analysis, transmission electron microscopy, nitrogen physisorption measurements and X-ray diffraction. Different experimental conditions of the supercritical drying process give rise to different porous structures in the silica matrix which have a strong influence on the formation of the FeCo alloy nanoparticles. Bcc FeCo alloy nanoparticles of the expected composition are obtained in the microporous samples while in the mesoporous samples a bcc alloy with a lower Co content is obtained which is accompanied by pure fcc Co

Nickel oxide-silica and nickel-silica aerogel and xerogel nanocomposite materials

The sol-gel method was used to prepare nickel oxide-silica and nickel-silica nanocomposite materials and the corresponding silica matrices. Different drying conditions were used to obtain aerogel and xerogel materials. The samples were characterized by thermal analysis, x-ray diffraction, N2-physisorption, transmission electron microscopy techniques, and infrared spectroscopy. Aerogel samples had a much higher surface area than the xerogel samples; moreover, different supercritical drying conditions gave rise to a different porous structure, which influenced the size and distribution of the nanoparticles in the matrix

An EXAFS study on iron-cobalt-alumina nanocomposites prepared by the sol-gel method

The selectivity of the EXAFS (extended x-ray absorption fine structure) technique was used in order to gain insights on the structural evolution of the Fe and Co environment at different stages of the preparation of FeCo-Al 2O3 aerogels and xerogels. The gels, which were prepared using aluminium tri-sec-butoxide, iron nitrate and cobalt nitrates as precursors, were dried using different procedures in order to obtain xerogels and aerogels, respectively. After drying, the samples are treated either in air up to 900°C or in hydrogen up to 800°C

Iron-Cobalt-Silica aerogel nanocomposite materials

Iron-Cobalt-Silica nanocomposites were prepared in form of aerogels. X-ray diffraction, transmission electron microscopy and N2 physisorption at 77 K were used to investigate the structure, size and dispersion of the nanocrystals and the porous structure in the aerogels and in the final composites. The variation of the supercritical drying conditions gives rise to differences in the morphological features of the aerogels. These differences influence the size of the cobalt oxide nanoparticles in the aerogels. On the other hand, after the reduction treatment the average size of the alloy nanoparticles is the same in all the aerogel nanocomposites. The effect of reduction temperature on alloy formation and particle size is also discussed

Preparation of aerogel and xerogel nanocomposite materials

Sol-gel method was used to prepare nickel oxide-silica and iron oxide-silica nanocomposites materials in form of aerogels and xerogels. The samples were characterized by thermal analysis, X-ray diffraction, N2 physisorption and transmission electron microscopy techniques. The variation of the supercritical solvent extraction conditions gives rise to differences in the morphological characteristics of the aerogels. These differences influence the size of the nickel oxide nanoparticles in nickel containing aerogels. On the other hand they do not affect the structure and size of the iron oxide nanoparticles in iron containing aerogels. The differences between the xerogel and aerogel nanocomposites are discussed