In order to determine the catalytic stability, PtSn structured catalysts supported on thin films of MgAl2O4 or ZnAl2O4 deposited on α‐Al2O3 spheres were studied through five reaction‐regeneration ...cycles in the n‐butane dehydrogenation. Bimetallic catalysts show good catalytic stability along the five reaction‐regeneration cycles. Among the different synthesized catalysts, the PtSn/Sp‐Zn‐CN catalyst showed the best catalytic behaviour, showing very good values of yields to butenes and excellent catalytic stability along the cycles, even better than the one of a structured commercial catalyst used industrially for the dehydrogenation of paraffins. The characterization results by temperature‐programmed reduction and X‐ray photoelectron spectroscopy showed some modifications in the metallic phase of the catalysts after the cycles, mainly in the Sn/Pt surface ratios and in segregation effects in some catalysts. However, the transmission electron microscopy (TEM) results are conclusive in the sense that, after the cycles, the bimetallic catalysts maintained a very high proportion of particles with sizes between 1–2 nm, and therefore, preserved a high metallic dispersion.
SEM image of (left) structured catalyst and (right) comparison of yields to butenes between the best synthesized catalyst and a commercial catalyst
Summary
In forests, ectomycorrhizal mycelium is pivotal for driving soil carbon and nutrient cycles, but how ectomycorrhizal mycelial dynamics vary in ecosystems with drought periods is unknown. We ...quantified the production and turnover of mycorrhizal mycelium in Mediterranean Pinus pinaster, Pinus sylvestris and Quercus ilex forests and related the estimates to standardised precipitation index (SPI), to study how mycelial dynamics relates to tree species and drought‐moisture conditions.
Production and turnover of mycelium was estimated between July and February, by quantifying the fungal biomass (ergosterol) in ingrowth mesh bags and using statistical modelling. SPI for time scales of 1–3 months was calculated from precipitation records and precipitation data over the study period.
Forests dominated by Pinus trees displayed higher biomass but were seasonally more variable, as opposed to Q. ilex forests where the mycelial biomass remained lower and stable over the season. Production and turnover, respectively, varied between 1.4–5.9 kg ha−1 d−1 and 7.2–9.9 times yr−1 over the different forest types and were positively correlated with 2‐month and 3‐month SPI over the study period.
Our results demonstrated that mycorrhizal mycelial biomass varied with season and tree species and we speculate that production and turnover are related to physiology and plant host performance during drought.
See also the Commentary on this article by Fernandez, 230: 1296–1299.
•Limited urban tree inventory data hinders urban forest biodiversity assessments.•Citizen science (CS) apps allow automatic taxonomic classification of urban trees.•We use remote sensing (RS), Deep ...Learning & CS apps to assess urban tree diversity.•Ground-level imagery can support automatic assessment of urban tree biodiversity.•Improved RS & AI technology can revolutionize urban forest biodiversity monitoring.
The positive impact of urban forests and trees on the well-being of urban residents worldwide is well known. Resistance to pests, diseases, and extreme weather events are among the most critical characteristics of resilient cities, closely related to species richness and, consequently, to the diversity of street trees. However, urban forest inventories are currently scarce worldwide. For this reason, urban trees' biodiversity and capacity to provide these ecosystem services are not developed enough. Three state-of-the-art species identification applications were tested, Plant.id, Pl@ntNet and Seek (iNaturalist) to identify a large number of tree families, genera, and species automatically. Two individual Google Street View images were queried for each tree in the study area, adjusting the Field of View and pitch parameters. The predictive capacity of the three apps was compared, and a biodiversity analysis was performed for different geospatial scales within the study area (i.e., at the whole study area, neighborhood, and street levels, respectively). Notably, our research contributes in an innovative way to the assessment and monitoring of the ecosystem services provided by street trees and sheds light on the great potential of combining remote sensing, citizen science and artificial intelligence for urban forest biodiversity assessments at multiple spatial and temporal scales.
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•Fe and Sn modify the Pt metallic phases on CN-P and CV supports in a different way.•On both supports prevail Fe ionic species which produce mainly a geometric effect.•Sn reduced ...species prevail on the bimetallic surfaces producing mainly an electronic effect.•PtFe catalysts with high Fe loadings show very high selectivities to UA.•Sn/Pt molar ratio <1 in PtSn catalysts is enough to obtain very high selectivities to UA.
In this paper, a study on the selective hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols (UA) by using two series of PtSn and PtFe catalysts with different metallic loadings and supported on carbon nanotubes and carbon Vulcan is reported. The catalysts were prepared by conventional impregnation using the corresponding metallic precursors, H2PtCl6, SnCl2, and FeCl3. Once reduced under hydrogen flow, the supported catalysts were characterized by temperature-programmed reduction (TPR), H2 chemisorption, test reactions of the metallic phase, and X-ray photoelectron spectroscopy (XPS). Hydrogenation results show that the addition of a second metal to Pt leads to important modification of the selectivity, although the highest selectivities to UA are reached with very different Fe or Sn loadings. The performance of the catalysts in the citral hydrogenation was related to the characteristics of the bimetallic phase. It was found that the Fe addition to Pt catalysts results in a typical behavior such as for an usual ionic promoter in contact with the active metal, reaching high selectivities to UA as the Fe loading and the Fe ionic species percentage increases, while for PtSn catalysts, a high selectivity to UA was found only with a very low amount of Sn ionic species in contact with a very high percentage of Sn reduced species. The best selectivity to UA (about 98%) was found for PtSn(1wt%)/CN-P catalyst treated with N2 at high temperature.
De Miguel discusses artificial intelligence (AI)-driven disruption in science production. AI and, in particular, generative AI based on large language models (LLM), and related applications such as ...the recently released ChatGPT by OpenAI, represent a disruptive technology that holds great potential to revolutionize science production in general and, of course, forest science in particular, too. With the ability to analyze and interpret human language, such technologies can disrupt traditional research methods and allow researchers to analyze large volumes of data and report their findings more quickly and accurately than ever before. The integration of such tools and methods in forest science production could significantly benefit the field by enhancing the quality of research papers and increasing the efficiency of the publication process. However, the potential uninformed, unsupervised and uncritical misuse of these methods is raising many concerns among the scientific community and beyond.
Replanting trees helps with avoiding desertification, reducing the chances of soil erosion and flooding, minimizing the risks of zoonotic disease outbreaks, and providing ecosystem services and ...livelihood to the indigenous people, in addition to sequestering carbon dioxide for mitigating climate change. Consequently, it is important to explore new methods and technologies that are aiming to upscale and fast-track afforestation and reforestation (A/R) endeavors, given that many of the current tree planting strategies are not cost effective over large landscapes, and suffer from constraints associated with time, energy, manpower, and nursery-based seedling production. UAV (unmanned aerial vehicle)-supported seed sowing (UAVsSS) can promote rapid A/R in a safe, cost-effective, fast and environmentally friendly manner, if performed correctly, even in otherwise unsafe and/or inaccessible terrains, supplementing the overall manual planting efforts globally. In this study, we reviewed the recent literature on UAVsSS, to analyze the current status of the technology. Primary UAVsSS applications were found to be in areas of post-wildfire reforestation, mangrove restoration, forest restoration after degradation, weed eradication, and desert greening. Nonetheless, low survival rates of the seeds, future forest diversity, weather limitations, financial constraints, and seed-firing accuracy concerns were determined as major challenges to operationalization. Based on our literature survey and qualitative analysis, twelve recommendations—ranging from the need for publishing germination results to linking UAVsSS operations with carbon offset markets—are provided for the advancement of UAVsSS applications.
Several bimetallic PtSn catalysts supported on multiwalled carbon nanotubes for ethanol electro‐oxidation were prepared by conventional impregnation‐reduction method. The Pt loading was kept at 20 ...wt.% and Pt:Sn atomic ratios of 5:1, 3:1, and 1:1 were selected. The catalysts were structurally characterized by temperature programmed reduction, X‐ray diffraction, X‐ray photoelectron spectroscopy, H2 chemisorption, cyclohexane dehydrogenation reaction, and transmission electron microscopy. The electrochemical characterization of the electrocatalytic materials was carried out in acid medium by cyclic voltammetry, linear sweep voltammetry, chronoamperometry, and CO stripping techniques. Among the different stoichiometries tested, the Pt(20)Sn(12.17)/CNT catalyst exhibited the highest electrocatalytic activity for ethanol oxidation reaction, with mass current density of 189.5 mA mgPt−1 at 796 mV (vs. Ag/AgCl).
Multiwalled carbon nanotubes and Vulcan carbon were functionalized with a 30 %v/v hydrogen peroxide solution and employed as supports for Pt and PtSn catalysts prepared by the polyol method. PtSn ...catalysts with a Pt loading of 20 wt.% and a Pt : Sn atomic ratio equal to 3 : 1 were evaluated in the ethanol electrooxidation reaction. The effects of the oxidizing treatment on the surface area and the surface chemical nature were analyzed through N2 adsorption, isoelectric point, and temperature‐programmed desorption measurements. Results showed that the H2O2 treatment affects the surface area of the carbons to a great extent. Characterization results indicated that the performance of the electrocatalysts strongly depends both on the presence of Sn and on the support functionalization. PtSn/CNT−H2O2 electrocatalyst displays a high electrochemical surface area and enhanced catalytic activity for ethanol oxidation in comparison to other catalysts in the present study.
H2O2 treatment caused substantial modifications in the carbon structures. Changes in the metal‐support interaction led to improved electrochemical behavior. A clear promoter effect of Sn is observed in both functionalized carbons, which shifts the CO oxidation peak to lower potentials. The current intensity of PtSn/CNT‐H2O2 catalyst is the highest of all prepared catalysts (380 mA mg Pt−1), followed by the other bimetallic catalyst supported on functionalized Vulcan carbon (296 mA mg Pt−1).
Clear-cutting is a common silvicultural practice. Although temporal changes in the soil fungal community after clear-cutting have been widely investigated, little is known about stand-level ...variations in the spatial distribution of soil fungi, particularly at the clear-cut edge. We performed spatial soil sampling in three clear-cuts (0.5 ha), edge habitats, and surrounding forests 8 years after clear-cutting to examine the impact of clear-cutting on the soil fungal community (diversity, composition, guilds, and biomass) and soil properties in a managed Pinus sylvestris forest in northern Spain. Our analyses showed small differences in the composition of the soil fungal community between edge, forest, and clear-cut zones, with <4 % of the species strictly associated with one or two zones. The richness, diversity, and evenness of the fungal community in the edge zone was not significantly different to that in the forest or clear-cut zones, although the clear-cut core had approximately a third fewer ectomycorrhizal species than the edge or the forest. Saprotrophic fungi were widespread across the clear-cut–forest gradient. Soil fungal biomass varied significantly between zones, ranging from 4 to 5 mg g−1 dry soil in the forest and at the forest edge to 1.7 mg g−1 dry soil in the clear-cut area. Soil organic matter, pH, nitrogen, and phosphorus did not differ significantly between edge, forest, and clear-cutting zones and were not significantly related to the fungal community composition. Overall, our study showed that small-scale clear-cut treatments are optimal to guarantee, in the medium-term, soil fungal communities within harvested areas and at the forest edge that are comparable to soil fungal communities in the forest, even though the amount of fungal biomass in the clear-cut zone is lower than at the forest edge or in the forest.
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•Spatial soil sampling was used to analyze a clear-cut–edge–forest gradient.•Medium-term changes in soil fungal biomass, composition and diversity were analyzed.•Small changes in soil fungal composition occurred along the gradient.•Fungal biomass was lower in the clear-cut zone than at the edge or in the forest.•No relationship between soil fungi and soil nutrient distribution (SOM, N, P, pH)
Aim
To determine the relationships between the functional trait composition of forest communities and environmental gradients across scales and biomes and the role of species relative abundances in ...these relationships.
Location
Global.
Time period
Recent.
Major taxa studied
Trees.
Methods
We integrated species abundance records from worldwide forest inventories and associated functional traits (wood density, specific leaf area and seed mass) to obtain a data set of 99,953 to 149,285 plots (depending on the trait) spanning all forested continents. We computed community‐weighted and unweighted means of trait values for each plot and related them to three broad environmental gradients and their interactions (energy availability, precipitation and soil properties) at two scales (global and biomes).
Results
Our models explained up to 60% of the variance in trait distribution. At global scale, the energy gradient had the strongest influence on traits. However, within‐biome models revealed different relationships among biomes. Notably, the functional composition of tropical forests was more influenced by precipitation and soil properties than energy availability, whereas temperate forests showed the opposite pattern. Depending on the trait studied, response to gradients was more variable and proportionally weaker in boreal forests. Community unweighted means were better predicted than weighted means for almost all models.
Main conclusions
Worldwide, trees require a large amount of energy (following latitude) to produce dense wood and seeds, while leaves with large surface to weight ratios are concentrated in temperate forests. However, patterns of functional composition within‐biome differ from global patterns due to biome specificities such as the presence of conifers or unique combinations of climatic and soil properties. We recommend assessing the sensitivity of tree functional traits to environmental changes in their geographic context. Furthermore, at a given site, the distribution of tree functional traits appears to be driven more by species presence than species abundance.
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