1. We analyse the factors controlling seedling establishment of Scots pine at its southernmost geographical limit (southern Spain), by monitoring emergence, survival and growth for up to 4 years in ...the microhabitats to which seeds are dispersed. Naturally established seedlings were monitored in two mountain ranges, and experimental sowings were performed both in woodlands and in adjacent successional shrublands into which the forest could expand. 2. Emergence was high in all microhabitats, although it was highest under the canopy of shrubs. Overall survival was low, with c. 90% of seedlings dying in the first growing season (c. 98% after several growing seasons). Survival differed among microhabitats, being highest under shrubs and extremely low (or zero) under pines or in bare soil. 3. Seedling growth was the highest in areas of bare soil, intermediate under shrubs, and very low under pines. 4. Establishment under pines was prevented by both mortality and poor performance, and good performance cannot counteract high mortality in the open. Shrubs, however, acted as nurse plants, buffering summer drought without reducing radiation to levels critical for growth, and protecting seedlings from ungulate trampling, hail and frost heave. 5. Patterns of recruitment were similar for woodland stands and successional shrublands. In addition, patterns of survival for naturally established seedlings were similar to those of seedlings originating from experimental sowings. 6. Juveniles were positively associated with shrubs but negatively with bare soil or areas below pine canopies. The facilitative effect of shrubs on seedling survival therefore changes the spatial pattern of recruitment from that determined by germination. 7. Overall, processes controlling seedling establishment in these southern Scots pine forests differ sharply from those operating in its main distribution area. The comparison among contrasting geographical ranges may contribute to an understanding of the role of environmental conditions in the balance between competition and facilitation, and assist in forecasting plant regeneration responses to global climate change.
The wide distribution of Scots pine (
Pinus sylvestris L.) in Europe includes two relict populations in southern Spain (Sierra Nevada and Sierra de Baza), belonging to the subspecies
nevadensis. ...These populations are isolated in high mountains, which tends to protect them from the attack of a severe defoliating Mediterranean pest, the pine processionary moth
Thaumetopoea pityocampa. However, as a consequence of climate change, the pine processionary caterpillar has increasingly attacked populations of this pine in recent years. This work describes the detrimental effects of defoliation by the pine processionary caterpillar in
P. sylvestris subsp.
nevadensis in Sierra Nevada. Defoliation strongly reduced pine growth as well as all the reproductive parameters measured (female and male cone production, mature cone size, seed production and seed weight), in addition to some deaths. If winter temperatures continue to increase, the pine processionary caterpillar will have a dangerous impact in these relict pine populations, by further reducing the pine's weak regeneration capacity. We suggest some mitigation actions based on managing habitat structure, in order to reduce or avoid such negative impacts.
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•Cheap & efficient CWPO Fe-catalysts developed by integrating agricultural residues.•Efficiency of three Fe-impregnated catalysts is compared for simulated and real OMW.•55% TPh, 37% ...COD, and 71% H2O2 conversions under smooth operational conditions.•64% toxicity reduction and biodegradability enhancement after only 240 min.•High catalyst stability and reusability with Fe leaching <2.8 wt% after 4 runs.
A by-product of olive mill’s operation (olive stone, OS) was transformed into activated carbon (AC) and used as support to prepare Fe-based catalysts, which were employed on the catalytic wet peroxide oxidation (CWPO) of olive mill wastewater (OMW). Three Fe-impregnation routes were tested: incipient wetness impregnation (IWI), adsorption (Ads), and hydrothermal (HT), resulting in catalysts with distinct iron loadings, particle sizes and surface dispersion. OSAC-Fe catalysts were characterized by N2 and CO2 physisorption, XRD, XPS, FTIR, HRTEM, EDX, and HRSEM techniques. Catalysts’ activity and stability was first compared in the degradation of synthetic polyphenolic solutions. After one cycle (240 min), catalysts’ sorption capacity was considerably exhausted and OH radicals were found to be the main oxidative species responsible for total phenolic content (TPh) removal. OSAC-Fe-IWI and OSAC-Fe-Ads performed better than OSAC-Fe-HT after four consecutive cycles (53 and 48 vs. 38% TPh removals, respectively), also showing considerably lower cumulative Fe leaching values (2.2 and 2.8 vs. 10 wt%). The most promising materials were used for depuration of real OMW samples. Under smooth operational conditions (OSAC-Fe-IWI = 2.0 g/L, H2O2 = 0.5 g/L, pH0 ~ 4.9, T0 = 25 °C), 55% TPh removal was attained after 240 min, resulting in a significant reduction of the effluent’s toxicity (from 100% Vibrio fischeri bioluminescence inhibition to 36%), 37% chemical oxygen demand degradation, and 21% total organic carbon mineralization. Promising catalytic performances were also achieved by OSAC-Fe-Ads, despite its considerably lower iron loading, highlighting the importance of Fe surface dispersion.
We study the perception of acoustic contamination and its deleterious effects on students preparing to become school teachers and analyse their acoustic habits, with the aim of raising their ...awareness concerning this problem. We designed a number of activities, applied during a practical lesson, in which students evaluated some of their perceptions and attitudes towards noise, and recorded their hearing capacity. Students increased their noise awareness after performing the practice. We propose the introduction of activities similar to those proposed here, to prevent hearing loss from exposure to noise and promote such preventive activities among these future school teachers.
► Noise-induced hearing loss is becoming a serious health problem in young people. ► Prevention is hampered by the scant awareness concerning the harmful effects. ► Prevention in primary school depends of future school teachers. ► Practical activities in future school teachers raise their degree of awareness. ► Activities similar to those proposed here can prevent noise-induced hearing loss.
Carbon aerogels are nanostructured carbons obtained from the carbonization of organic aerogels, which are prepared from the sol–gel polycondensation of certain organic monomers. These materials have ...a great versatility both at the nanoscopic level in terms of their pore texture and at the macroscopic level in terms of their form. Thus, the surface area, pore volume, and pore size distribution are tuneable surface properties related to the synthesis and processing conditions, which can produce a wide spectrum of materials with unique properties. In addition, carbon aerogels can be obtained in the form of monoliths, beads, powders or thin films. All these properties make them promising materials for application in adsorption and catalysis. Metal-doped monolithic organic aerogels can be easily prepared by following three main strategies: by addition of the metal precursor to the initial mixture, by ion-exchange or by deposition of the metal precursor on the organic or the carbon aerogel by one of various methods. These metal-doped carbon aerogels have been used as catalysts and as electrodes for electrical double-layer capacitors. This article shows the preparation of metal-doped carbon aerogels, their physico-chemical surface properties and their applications as catalysts in various reactions.
A series of adsorbents was developed by physical (CO2) and chemical (KOH) activation of two bio-residues: olive stones (OS) and wood from olive tree pruning (OTP). The physicochemical properties of ...such materials were determined and correlated with their adsorptive performance in the removal of phenolic compounds of olive mill wastewater (OMW). Adsorption isotherms and kinetics of single phenolic acids, as well as the kinetics for competitive multi-compound adsorption, were fitted by applying different models, though Langmuir and pseudo-second order models fitted better the experimental results, respectively. The intraparticle diffusion model pointed out that mesoporosity reduces the influence of phenolic compounds’ restrictions in the external film diffusion of the adsorbent particle–solution interphase, but adsorption capacity linearly increases with the micropore volume accessible to N2 at −196 °C (and also with BET surface area), while diffusion into ultramicropores (<0.7 nm, determined by CO2-adsorption) is slow and presents minor influence on the total adsorption capacity. After saturation, thermal regeneration of spent adsorbents allows the removal of adsorbed products, enabling the reuse of samples whilst maintaining a significant performance.
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•Olive stone and tree pruning are used to synthesize a series of AC-biosorbents.•Single & competitive removal of olive mill wastewater phenolic compounds is studied.•Adsorption capacity and rate controlled by larger micropores and BET surface area.•Olive stone derived-AC capacity can be restored upon simple thermal regeneration.
From the most classic carbon materials (CMs) to the advanced ones, all of them integrate a promising catalyst set in terms of sustainability and energy efficiency for a greener future. Different ...synthetic strategies concerning to the catalytic synthesis of relevant N‐containing heterocycles are herein described to address the great potential of the referred catalysts flying over what has been done and all that remains to be done. Current trends in this field involve structure‐activity relationships establishment also considering the reaction mechanisms understanding and the identification of active catalytic sites, as function of both experimental datasets, emphasizing on operando characterization techniques, and theoretical studies which will significantly contribute to the design of custom‐made catalysts as a new horizon.
Building N‐heterocycles by using CMs. Current trends for the sustainable synthesis of significant N‐containing heterocycles, considering both different synthetic approaches to construct the heterocyclic core, and the role of CMs used as catalysts and catalyst supports, are reviewed. Establishment of structure‐activity relationships and reaction mechanisms understanding can contribute, in the future, to the rational catalyst design as a new horizon.
The role of herbivores in controlling plant population abundance and distribution is unclear. We experimentally determine the effect of damage by wild boars (
Sus scrofa) in recruitment rate and ...spatial pattern of a Mediterranean tree, the holm oak (
Quercus ilex). We monitored oak establishment in the Sierra Nevada of southeastern Spain during 4 years (1999–2002) in four plots, two fenced and two unfenced that were used as controls. In addition, we planted 1-year-old seedlings in all microhabitats, both in fenced and control plots, to experimentally determine the effect of wild boar on their microhabitat-dependent survival. Despite seedling abundance being similar inside and outside the fences, sapling abundance diminished up to 50% in unfenced plots compared to fenced plots. Wild boars also seemed to modify the spatial distribution of seedlings and saplings. Whereas seedlings were most abundant under pines both in fenced and control plots, sapling abundance was highest under pine trees in fenced plots, but similarly abundant under pines or shrubs in control plots. This change in spatial pattern was due to the effect of wild boars killing seedlings when looking for food under pines. The effects of the different mortality factors were not additive. Where ungulates are absent, recruitment is high and occurs under oaks and especially under pines. Where wild boars are present, recruitment diminishes and occurs mostly under shrubs and pines. Wild boars arrest population growth and modify the spatial pattern of recruitment.
Graphene oxide (GO) is used to enhance the photocatalytic activity of ZnO nanoparticles for the degradation of vanillic acid (VA) under simulated solar light and visible-LED (λ > 430 nm). ZnO-GO ...composites are prepared by a mixing and sonication process with different GO loadings (i.e., from 1.8 to 6.5 wt.%). The materials are extensively characterized by thermogravimetric analysis (TGA), physisorption of N2, X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), point of zero charge (pHPZC), and UV-Vis diffuse reflectance spectroscopy (DRUV). The presence of GO increases the photocatalytic activity of all the prepared composites in comparison with the pristine ZnO. The highest photocatalytic activity is found for the composite containing 5.5 wt.% of GO (i.e., ZnO-GO5.5), reaching a VA degradation of 99% and 35% under solar light and visible-LED, respectively. Higher TOC removal/VA degradation ratios are obtained from the experiments carried out under visible-LED, indicating a more effective process for the mineralization of VA than those observed under simulated solar light. The influence of hole, radical, and non-radical scavengers is studied in order to assess the occurrence of the reactive oxygen species (ROS) involved in the photocatalytic mechanism. The study of the photo-stability during three reuse experiments indicates that the presence of GO in the composites reduces the photocorrosion in comparison with pristine ZnO.
Predicting climate‐driven changes in plant distribution is crucial for biodiversity conservation and management under recent climate change. Climate warming is expected to induce movement of species ...upslope and towards higher latitudes. However, the mechanisms and physiological processes behind the altitudinal and latitudinal distribution range of a tree species are complex and depend on each tree species features and vary over ontogenetic stages. We investigated the altitudinal distribution differences between juvenile and adult individuals of seven major European tree species along elevational transects covering a wide latitudinal range from southern Spain (37°N) to northern Sweden (67°N). By comparing juvenile and adult distributions (shifts on the optimum position and the range limits) we assessed the response of species to present climate conditions in relation to previous conditions that prevailed when adults were established. Mean temperature increased by 0.86 °C on average at our sites during the last decade compared with previous 30‐year period. Only one of the species studied, Abies alba, matched the expected predictions under the observed warming, with a maximum abundance of juveniles at higher altitudes than adults. Three species, Fagus sylvatica, Picea abies and Pinus sylvestris, showed an opposite pattern while for other three species, such as Quercus ilex, Acer pseudoplatanus and Q. petraea, we were no able to detect changes in distribution. These findings are in contrast with theoretical predictions and show that tree responses to climate change are complex and are obscured not only by other environmental factors but also by internal processes related to ontogeny and demography.
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