Phenological responses to small-scale spatial variation in snowmelt timing reveal compensatory and conservative strategies in subarctic-alpine plants

Background: In tundra ecosystems, the adjustment of phenological events, such as bud burst, to snowmelt timing is crucial to the climatic adaptation of plants. Natural small-scale variations in microclimate potentially enable plant populations to persist in a changing climate.

Aims: To assess how plant phenology responds to natural differences in snowmelt timing.

Methods: We observed the timing of eight vegetative and reproductive phenophases in seven dwarf-shrub species in relation to differences in snowmelt timing on a small spatial scale in an alpine environment in subarctic Finland.

Results: Some species and phenophases showed accelerated development with later snowmelt, thus providing full or partial compensation for the shorter snow-free period. Full compensation resulted in synchronous occurrence of phenophases across the snowmelt gradient. In other species, there was no acceleration of development. The timing of phenophases varied between two consecutive years and two opposing mountain slope aspects.

Conclusions: The results have shown three distinct patterns in the timing of phenophases in relation to snowmelt and suggest alternative strategies for adaptation to snowmelt timing. These strategies potentially apply to other species and tundra ecosystems and provide a framework, enabling one to compare and generalise phenological responses to snowmelt timing under different future climate scenarios.     

Grassland plant species occurring in extensively managed road verges are filtered by urban environments

Background: Urbanisation filters species in communities depending on their adaptability to conditions in built-up areas, especially in semi-natural habitats. Roadside vegetation is widespread along urban-rural gradients and is therefore a good place to study landscape-scale factors influencing plant community composition.

Aim: Our study aimed to assess how plant species distributions vary between urban and rural landscape contexts and to identify biological traits favoured in urban areas.

Methods: Presence/absence data for 63 indigenous common species were collected in 296 road verge patches distributed along the urban–rural gradient in three French cities. We investigated the effects of landscape composition on species assemblages and related individual species responses to urbanisation to functional traits associated with dispersal and persistence capacity.

Results: Many grassland species were negatively affected by increasing proportion of built-up areas in the landscape. Insect-pollination and high seed production appeared to be key traits favoured in grassland communities in urban areas, whereas dispersal modes were less related to plant distribution.

Conclusions: This study has demonstrated that urban filters affect common species of widespread, managed road verges. Better knowledge of the flora of these herbaceous roadsides may contribute to the conservation of common biodiversity within other grassland habitats found in urban areas.     

Subtidal macrozoobenthic community resilience to change following natural mouth breaching of the temporarily open/closed East Kleinemonde Estuary,South Africa

The East Kleinemonde Estuary, on the south-east coast of South Africa, typically opens for only short periods, usually <10 days. During a nine-month study in 2006, marine influence persisted for a near-continuous period of three months. This provided an opportunity to explore potential changes in the structure and pattern of the subtidal estuarine macrozoobenthic community. Salinity changes were minimal after mouth opening, decreasing by c. 4 and 8 in the lower and upper estuary, respectively. Salinity decrease was due to river dominance over tidal influence. Two biotic assemblages, structured by sediment characteristics, typified the community throughout the study: a sand-associated group near the mouth and a mud-associated group upstream. Amphipods were proportionally the most abundant group within each assemblage and on each sampling occasion. At the species level, high variability typified the community, with no trends or patterns observed. However, species richness declined from 27–30 to 23 after mouth opening. The number of species returned to former levels at the time of the final survey and just before final mouth closure. An analysis of the subtidal macrozoobenthos in the East Kleinemonde and other temporarily open/closed estuaries (TOCEs) of similar size in the bioregion indicated that communities were typically composed of relatively few, broadly tolerant euryhaline species with no species unique to TOCEs.     

Compositionally Graded Cathode Material with Long‐Term Cycling Stability for Electric Vehicles Application

Al is introduced into a compositionally graded cathode with average composition of Li[Ni_0.61Co_0.12Mn_0.27]O₂ (FCG61) whose Ni and Mn concentrations are designed to vary continuously within the cathode particle. The Al‐substituted full concentration gradient (Al‐FCG61) cathode is tested for 3000 cycles in a full‐cell, mainly to gauge its viability for daily charge/discharge cycles during the service life of electric vehicles (≈10 years). The Al‐substitution enables the Al‐FCG61 cathode to maintain 84% of its initial capacity even after 3000 cycles. It is demonstrated that the Al‐substitution strengthens the grain boundaries, substantiated by the mechanical strength data, thereby delaying the nucleation of microcracks at the phase boundaries which is shown to be the main reason for the cathode failure during long‐term cycling. It also shows that the Al‐substitution decreases the cation mixing and suppresses the deleterious formation of the secondary phase that likely initiates the microcracks. Unlike an NCA cathode, whose depth of discharge (DOD) must be limited to 60% for long‐term cycling, the proposed Al‐FCG61 cathode is cycled at 100% DOD for 3000 cycles to fully utilize its available capacity for maximum energy density and subsequent reduction in cost of the battery.     

Fungal disease incidence along tree diversity gradients depends on latitude in European forests

European forests host a diversity of tree species that are increasingly threatened by fungal pathogens, which may have cascading consequences for forest ecosystems and their functioning. Previous experimental studies suggest that foliar and root pathogen abundance and disease severity decrease with increasing tree species diversity, but evidences from natural forests are rare. Here, we tested whether foliar fungal disease incidence was negatively affected by tree species diversity in different forest types across Europe. We measured the foliar fungal disease incidence on 16 different tree species in 209 plots in six European countries, representing a forest‐type gradient from the Mediterranean to boreal forests. Forest plots of single species (monoculture plots) and those with different combinations of two to five tree species (mixed species plots) were compared. Specifically, we analyzed the influence of tree species richness, functional type (conifer vs. broadleaved) and phylogenetic diversity on overall fungal disease incidence. The effect of tree species richness on disease incidence varied with latitude and functional type. Disease incidence tended to increase with tree diversity, in particular in northern latitudes. Disease incidence decreased with tree species richness in conifers, but not in broadleaved trees. However, for specific damage symptoms, no tree species richness effects were observed. Although the patterns were weak, susceptibility of forests to disease appears to depend on the forest site and tree type.     

Tolerance to multiple climate stressors: a case study of Douglas‐fir drought and cold hardiness

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Environmental and spatial characterisation of an unknown fauna using DNA sequencing – an example with Himalayan Hydropsychidae (Insecta: Trichoptera)

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