Carbon leakage and capacity-based allocations: Is the EU right?

Competitiveness and carbon leakage are major concerns for the design of CO₂ emissions permits markets. In the absence of a global carbon tax and of border carbon adjustments, output-based allocation is a third-best solution and is actually implemented (Australia, California, New Zealand). The EU has followed a different route; free allowances are allocated to existing or new capacities in proportion to a benchmark, independent of actual production. This paper compares these two schemes in a formal setting and shows that the optimal one is in fact a combination of both schemes, or output-based allocation alone if uncertainty is limited. A key assumption of our analysis is that the short-term import pressure depends both on the existing capacities and the level of demand, which is typical in capital intensive and internationally traded sectors. A calibration of the model is used to discuss the EU scheme for the cement sector in the third phase of the EU-ETS (2013–2020). This allows for a quantification of various policies in terms of welfare, investment, production, company profits, public revenues and leakage.     

Negative effects of nitrogen deposition on Swiss butterflies

Nitrogen (N) deposition from agriculture and combustion of fossil fuels is a major threat to plant diversity, but its effects on organisms at higher trophic levels are unclear. We investigated how N deposition may affect species richness and abundance (number of individuals per species) in butterflies. We reviewed the peer-reviewed literature on variables used to explain spatial variation in butterfly species richness and found that vegetation variables appeared to be as important as climate and habitat variables in explaining butterfly species richness. It thus seemed likely that increased N deposition could indirectly affect butterfly communities via its influence on plant communities. To test this prediction, we analyzed data from the Swiss biodiversity monitoring program for vascular plants and butterflies in 383 study sites of 1 km² that are evenly distributed throughout Switzerland. The area has a modeled N deposition gradient of 2–44 kg N ha⁻¹ year⁻¹. We used traditional linear models and structural equation models to infer the drivers of the spatial variation in butterfly species richness across Switzerland. High N deposition was consistently linked to low butterfly diversity, suggesting a net loss of butterfly diversity through increased N deposition. We hypothesize that at low elevations, N deposition may contribute to a reduction in butterfly species richness via microclimatic cooling due to increased plant biomass. At higher elevations, negative effects of N deposition on butterfly species richness may also be mediated by reduced plant species richness. In most butterfly species, abundance was negatively related to N deposition, but the strongest negative effects were found for species of conservation concern. We conclude that in addition to factors such as intensified agriculture, habitat fragmentation, and climate change, N deposition is likely to play a key role in negatively affecting butterfly diversity and abundance.     

Influence of ozone on the sampling and storage of volatile organic compounds in canisters

A dynamic dilution system was used for the study of the influence of ozone on the sampling and storage of volatile organic compounds (VOCs) at 0, 4, 7 and 14 days in “TO-Can” canisters at two ozone concentrations, 60 and 150 ppbv. Among the 31 ozone precursors VOCs, a representative mixture containing five alkenes, five aromatics, acetylene and 1,3 butadiene was selected using the Clausius–Clapeyron equation. Here, we demonstrate that the presence of ozone have no influence on the concentrations of VOCs after 14 days storage period and consequently no problem of representativity of the sampling appears after 14 days of storage. The main explanation is the degradation of ozone in contact with deactivated walls of canisters.     

Geographical gradients in diet affect population dynamics of Canada lynx

Geographical gradients in the stability of cyclic populations of herbivores and their predators may relate to the degree of specialization of predators. However, such changes are usually associated with transition from specialist to generalist predator species, rather than from geographical variation in dietary breadth of specialist predators. Canada lynx (Lynx canadensis) and snowshoe hare (Lepus americanus) populations undergo cyclic fluctuations in northern parts of their range, but cycles are either greatly attenuated or lost altogether in the southern boreal forest where prey diversity is higher. We tested the influence of prey specialization on population cycles by measuring the stable carbon and nitrogen isotope ratios in lynx and their prey, estimating the contribution of hares to lynx diet across their range, and correlating this degree of specialization to the strength of their population cycles. Hares dominated the lynx diet across their range, but specialization on hares decreased in southern and western populations. The degree of specialization correlated with cyclic signal strength indicated by spectral analysis of lynx harvest data, but overall variability of lynx harvest (the standard deviation of natural-log-transformed harvest numbers) did not change significantly with dietary specialization. Thus, as alternative prey became more important in the lynx diet, the fluctuations became decoupled from a regular cycle but did not become less variable. Our results support the hypothesis that alternative prey decrease population cycle regularity but emphasize that such changes may be driven by dietary shifts among dominant specialist predators rather than exclusively through changes in the predator community.     

Species-specific defense strategies of vegetative versus reproductive blades of the Pacific kelps <Emphasis Type="Italic">Lessonia nigrescens</Emphasis> and <Emphasis Type="Italic">Macrocystis integrifolia</Emphasis>

Chemical defense is assumed to be costly and therefore algae should allocate defense investments in a way to reduce costs and optimize their overall fitness. Thus, lifetime expectation of particular tissues and their contribution to the fitness of the alga may affect defense allocation. Two brown algae common to the SE Pacific coasts, Lessonia nigrescens Bory and Macrocystis integrifolia Bory, feature important ontogenetic differences in the development of reproductive structures; in L. nigrescens blade tissues pass from a vegetative stage to a reproductive stage, while in M. integrifolia reproductive and vegetative functions are spatially separated on different blades. We hypothesized that vegetative blades of L. nigrescens with important future functions are more (or equally) defended than reproductive blades, whereas in M. integrifolia defense should be mainly allocated to reproductive blades (sporophylls), which are considered to make a higher contribution to fitness. Herein, within-plant variation in susceptibility of reproductive and vegetative tissues to herbivory and in allocation of phlorotannins (phenolics) and N-compounds was compared. The results show that phlorotannin and N-concentrations were higher in reproductive blade tissues for both investigated algae. However, preferences by amphipod grazers (Parhyalella penai) for either tissue type differed between the two algal species. Fresh reproductive tissue of L. nigrescens was more consumed than vegetative tissue, while the reverse was found in M. integrifolia, thus confirming the original hypothesis. This suggests that future fitness function might indeed be a useful predictor of anti-herbivore defense in large, perennial kelps. Results from feeding assays with artificial pellets that were made with air-dried material and extract-treated Ulva powder indicated that defenses in live algae are probably not based on chemicals that can be extracted or remain intact after air-drying and grinding up algal tissues. Instead, anti-herbivore defense against amphipod mesograzers seems to depend on structural traits of living algae.     

Impact of global warming on European tidal estuaries: some evidence of northward migration of estuarine fish species

The aim of this study was to determine whether the latitudinal distribution of fish species that use estuaries to complete their entire life cycle has shifted northward as an expected consequence of global warming. The mean latitude of past fish species distributions found in 1970s’ literature was compared with the mean latitude of distributions today based on fish density indices collected in 55 tidal estuaries along the Atlantic European seaboard, from Portugal to Scotland. Among the 15 most common species, 11 displayed a positive difference between current and past mean latitudes suggesting a northward shift of the populations. Using the occurrence of subtropical species in temperate areas as an indicator of water warming, the northernmost range limit of 10 subtropical species was subsequently focused on. Six of them were recorded up to their past northern latitudinal limit. These results reinforced the idea that a number of fish species associated to estuaries have migrated northwards over the last 30 years, possibly due to water warming. These ecological changes can get important managerial implications, i.e. in the assessment of the ecological status in European directives.     

Permanganate oxidation of polycyclic aromatic compounds (PAHs and polar PACs): column experiments with DNAPL at residual saturation

Environmental Science and Pollution Research - Permanganate is an oxidant usually applied for in situ soil remediation due to its persistence underground. It has already shown great efficiency for...