Heterogeneity of soil surface ammonium concentration and other characteristics, related to plant specific variability in a Mediterranean-type ecosystem

Heterogeneity and dynamics of eight soil surface characteristics essential for plants—ammonium and nitrate concentrations, water content, temperature, pH, organic matter, nitrification and ammonification rates—were studied in a Mediterranean-type ecosystem on four occasions over a year. Soil properties varied seasonally and were influenced by plant species. Nitrate and ammonium were present in the soil at similar concentrations throughout the year. The positive correlation between them at the time of greatest plant development indicates that ammonium is a readily available nitrogen source in Mediterranean-type ecosystems. The results presented here suggest that plant cover significantly affects soil surface characteristics.     

Secondary metabolites of the leaf surface affected by sulphur fertilisation and perceived by the diamondback moth

Summary. Summary. Oilseed rape, Brassica napus L. (cv Express), plants were grown under three different sulphur regimes: sulphur-free (S₀), normal sulphur (S_n, normal field concentration) and a sulphur-rich (S₊, 2 × concentration of S_n). We performed dual choice oviposition assays with the diamondback moth, Plutella xylostella, using real plants and, for the first time with this insect, artificial leaves sprayed with methanolic leaf-surface extracts. The results mirrored those of a separate study of preferences for whole plants. Females laid more eggs on surrogate leaves that were treated with S_n extracts than on S₀ plants, while only a slight, not significant, difference was observed between extracts of normal and sulphur-rich plants. This shows that chemical compounds on the leaf surface mediate the oviposition preference and that the female insect can perceive the quality of the host-plants in terms of their fertilisation status.Since leaf volatiles are known to be oviposition stimulants, we investigated the effects of leaf-surface extracts on insect olfactory responses using electroantennograms (EAGs). In agreement with the behavioural data, we found that extracts of sulphur-treated plants yielded higher EAG amplitudes than the S₀ extracts. Since the leaf content of the volatiles isothiocyanates is influenced by sulphur nutrition, we analysed the extracts for these compounds. Above the detection threshold of our GC-MS system, no isothiocyanates were found. Thus, other compounds present in the surface extracts must be perceived by the antenna.However, the HPLC analysis revealed 11 different glucosinolates. Progoitrin (2-Hydroxy-3-butenyl) and gluconapoleiferin (2-Hydroxy-4-pentenyl), which belong to the hydroxy-alkene class of glucosinolates, were the most abundant compounds. The total glucosinolate content sharply increased from S₀ to S_n plants, whereas it was slightly lower in _n versus S₊ plants. Since it is known that glucosinolates can stimulate oviposition, it seems likely that the increased content we observed was influencing the insect preference in this study too.     

Spatial variability in reproductive cycle of the gorgonians <Emphasis Type="Italic">Paramuricea clavata</Emphasis> and <Emphasis Type="Italic">Eunicella singularis</Emphasis> (Anthozoa,Octocorallia) in the Western Mediterranean Sea

Paramuricea clavata (Risso, 1826) and Eunicella singularis (Esper, 1794) are the most representative gorgonian species in hard bottoms sublittoral communities in the Western Mediterranean Sea. Reproductive cycles of two populations of both species were studied in two distinct locations approximately 600 km apart (Medes Islands and Cape of Palos), in order to assess interpopulation variability on a relevant geographic scale. Seasonal variation of lipid concentration levels in the gorgonian tissue was used as a tool to quantify energy storage by each studied population in order to explain possible interpopulation differences in gonadal output. Sex ratio in Medes Islands populations of both species was 1:1, while in Cape of Palos sex ratio was significantly male biased (1:7) in P. clavata, and female biased (1.7:1) in E. singularis populations. Spawning timing occurred in all cases coinciding with a marked increase in sea-water temperature in spring, and after the most successful feeding season, but comparing localities there was a clear temporal shift in the time of gametes release, appearing well linked to the shift in sea-water temperature rising in spring in both sites at the depth where populations are placed. Therefore, in this study the temperature appears as the main synchronizing factor of gonadal development within these populations. Significant differences in gonadal volume per polyp were found in both species owing mainly to differences in the number of gonads per polyp between populations, with Cape of Palos populations displaying higher values in both studied species, suggesting that the exposition to different local conditions may be reverted in a different gonadal output. But the observed patterns in lipid concentrations levels in gorgonians disable us to conclude that lipid concentration levels explain the observed differences in gonadal output found in this study.     

Energy crops on landfills: functional,environmental, and costs analysis of different landfill configurations

The cultivation of energy crops on landfills represents an important challenge for the near future, as the possibility to use devalued sites for energy production is very attractive. In this study, four scenarios have been assessed and compared with respect to a reference case defined for northern Italy. The scenarios were defined taking into consideration current energy crops issues. In particular, the first three scenarios were based on energy maximisation, phytotreatment ability, and environmental impact, respectively. The fourth scenario was a combination of these characteristics emphasised by the previous scenarios. A multi-criteria analysis, based on economic, energetic, and environmental aspects, was performed. From the analysis, the best scenario resulted to be the fourth, with its ability to pursue several objectives simultaneously and obtain the best score relatively to both environmental and energetic criteria. On the contrary, the economic criterion emerges as weak, as all the considered scenarios showed some limits from this point of view. Important indications for future designs can be derived. The decrease of leachate production due to the presence of energy crops on the top cover, which enhances evapotranspiration, represents a favourable but critical aspect in the definition of the results.     

Synthesis,characterization, and application of 2D/2D TiO2-GO-ZnFe2O4 obtained by the fluorine-free lyophilization method for solar light-driven photocatalytic degradation of ibuprofen

Environmental Science and Pollution Research - In this study, we report the potential of 2D/2D TiO2-GO-ZnFe2O4 photocatalyst obtained using the fluorine-free lyophilization technique for the...     

Too small to count? Making Land Use Transformations in Chiquitano communities of San Ignacio de Velasco,East Bolivia,visible

ABSTRACT

The Santa Cruz lowlands, east Bolivia, are one of South America’s most dynamic agricultural frontiers. In the Chiquitania, bordering Brazil, San Ignacio de Velasco was in 2017 ranked first nationally in terms of deforestation. There, two deforestation fronts meet with mechanized agriculture expanding from the West and South and cattle ranching from the East. Chiquitano communities are demographically dominant locally but often face land scarcity. Because of their comparatively low impact on forest vegetation, they are not well represented in broad-scale quantitative Land Use/Land Cover (LULC) studies. Based on an empirical, human geographical approach, this paper investigates the transformation of the local indigenous productive matrix, the associated land-use patterns and potential socio-ecological implications. The overall aim is to bear witness to the rapid and profound reconfiguration of traditional livelihoods with their integration in the market economy and to highlight the significance of micro-scale LULC-processes at global scale.     

Sorption of mercury (II) in Amazon soils from column studies

The sorption of Hg (II) onto four different types of Amazon soils from the A-horizon was investigated by means of column experiments under saturation conditions and controlled metal load. Higher organic matter contents in the soil resulted in higher Hg (II) adsorptions, reaching values as high as 3.8 mg Hg g⁻¹ soil. The amount of mercury adsorbed on a soil column (Q) shows a very poor correlation with soil clay content (r² = 0.2527), indicating that Hg sorption in these topsoil samples is chiefly governed by the organic matter content. Desorption experiments using Negro River (Amazon) waters were conducted using soil saturated with Hg (II) in order to better understand the metal leaching mechanism. The amount of Hg (II) released from soils was around 30% of the total sorbed mercury upon saturation, suggesting that mercury sorption in the soils present in the catchment area of the Negro River basin is not a reversible process.     

The missing pieces for better future predictions in subarctic ecosystems: A Torneträsk case study

Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01381-1) contains supplementary material, which is available to authorized users.