Climate regulation processes are linked to the functional composition of plant communities in European forests, shrublands, and grasslands

Terrestrial ecosystems affect climate by reflecting solar irradiation, evaporative cooling, and carbon sequestration. Yet very little is known about how plant traits affect climate regulation processes (CRPs) in different habitat types. Here, we used linear and random forest models to relate the community-weighted mean and variance values of 19 plant traits (summarized into eight trait axes) to the climate-adjusted proportion of reflected solar irradiation, evapotranspiration, and net primary productivity across 36,630 grid cells at the European extent, classified into 10 types of forest, shrubland, and grassland habitats. We found that these trait axes were more tightly linked to log evapotranspiration (with an average of 6.2% explained variation) and the proportion of reflected solar irradiation (6.1%) than to net primary productivity (4.9%). The highest variation in CRPs was explained in forest and temperate shrubland habitats. Yet, the strength and direction of these relationships were strongly habitat-dependent. We conclude that any spatial upscaling of the effects of plant communities on CRPs must consider the relative contribution of different habitat types.

Different Ecological Niches of Poisonous Aristolochia clematitis in Central and Marginal Distribution Ranges-Another Contribution to a Better Understanding of Balkan Endemic Nephropathy

Aristolochia clematitis L. is a perennial herbaceous plant distributed throughout Europe, Asia Minor and Caucasus. It has been used as a medicinal plant since antiquity but not in recent times because it contains poisonous aristolochic acid, causing progressive kidney failure. The aim of this work was to study Aristolochia clematitis ecology on the basis of vegetation plots from the European Vegetation Archive, and to investigate the differentiation of its ecological niche using a co-occurrence-based measure of ecological specialization (ESI). The ecological niche was studied on three spatial scales: on the entire distribution area, its differentiation across 200 × 200 km grid cells and the differences between three central and three marginal regions. Our results suggest that Aristolochia clematitis has a very broad ecological niche occurring in a range of different habitats and climatic conditions, with a trend of a niche width decrease with the distance from the geographical center. The plant prefers more stable communities with less anthropogenic influence moving towards the margin of the distribution area. Specialization towards the marginal area is a result of evolutionary history, which refers to the recent anthropogenically induced spread from its original home range. A high incidence of Aristolochia clematitis in the vegetation of arable lands and market gardens as well as anthropogenic herbaceous vegetation in the distribution center corresponds to the geographical incidence of Balkan Endemic Nephropathy.

Climate-trait relationships exhibit strong habitat specificity in plant communities across Europe

Ecological theory predicts close relationships between macroclimate and functional traits. Yet, global climatic gradients correlate only weakly with the trait composition of local plant communities, suggesting that important factors have been ignored. Here, we investigate the consistency of climate-trait relationships for plant communities in European habitats. Assuming that local factors are better accounted for in more narrowly defined habitats, we assigned > 300,000 vegetation plots to hierarchically classified habitats and modelled the effects of climate on the community-weighted means of four key functional traits using generalized additive models. We found that the predictive power of climate increased from broadly to narrowly defined habitats for specific leaf area and root length, but not for plant height and seed mass. Although macroclimate generally predicted the distribution of all traits, its effects varied, with habitat-specificity increasing toward more narrowly defined habitats. We conclude that macroclimate is an important determinant of terrestrial plant communities, but future predictions of climatic effects must consider how habitats are defined.

Dimensions of invasiveness: Links between local abundance, geographic range size, and habitat breadth in Europe's alien and native floras

Understanding drivers of success for alien species can inform on potential future invasions. Recent conceptual advances highlight that species may achieve invasiveness via performance along at least three distinct dimensions: 1) local abundance, 2) geographic range size, and 3) habitat breadth in naturalized distributions. Associations among these dimensions and the factors that determine success in each have yet to be assessed at large geographic scales. Here, we combine data from over one million vegetation plots covering the extent of Europe and its habitat diversity with databases on species' distributions, traits, and historical origins to provide a comprehensive assessment of invasiveness dimensions for the European alien seed plant flora. Invasiveness dimensions are linked in alien distributions, leading to a continuum from overall poor invaders to super invaders-abundant, widespread aliens that invade diverse habitats. This pattern echoes relationships among analogous dimensions measured for native European species. Success along invasiveness dimensions was associated with details of alien species' introduction histories: earlier introduction dates were positively associated with all three dimensions, and consistent with theory-based expectations, species originating from other continents, particularly acquisitive growth strategists, were among the most successful invaders in Europe. Despite general correlations among invasiveness dimensions, we identified habitats and traits associated with atypical patterns of success in only one or two dimensions-for example, the role of disturbed habitats in facilitating widespread specialists. We conclude that considering invasiveness within a multidimensional framework can provide insights into invasion processes while also informing general understanding of the dynamics of species distributions.

Magnetism of nanotwinned martensite in magnetic shape memory alloys

Heusler-type magnetic shape memory alloys (MSMAs) exhibit a martensitic transformation (MT) accompanied by a complex magnetic reordering, strongly affected by an intricate martensitic microstructure. The hierarchic twin structure of martensite, formed as a result of minimization of elastic energy down to atomic scale, is under intensive study nowadays. On the other hand, the much more sophisticated problem of the relationship between nanoscale twin structure and the magnetism in MSMAs has being tackled only recently. It will be shown in this topical review that the nanotwin structure affects not only the basic magnetic parameters of MSMAs, but also can change qualitatively its magnetic nature and related magnetodynamic and magnetoresistance properties. This will be primarily illustrated, both theoretically and experimentally, on the prototype Ni-Mn-Ga and Ni(Co)-Mn-Sn MSMAs in the form of epitaxial thin films, but the conclusions are also valid for other Heusler-type MSMAs, both in the form of thin films, ribbons and bulk single crystals and polycrystals. The following new and remarkable phenomena will be highlighted. (i) A strong ferromagnetic exchange coupling is observed between the submicron twin components in Ni-Mn-Ga ferromagnetic martensite. It results in the modification of the average magnetic anisotropy and the formation of a non-collinear magnetic structure, whereby a negative magnetoresistance appears in a wide temperature range. (ii) Weak antiferromagnetic coupling occurs between the ferromagnetically ordered twin components in Ni(Co)-Mn-Sn martensite. This coupling enabled to explain the exchange bias and magnetic resonance spectra in the same terms as for artificial antiferromagnetically coupled multilayered structures.

Similar factors underlie tree abundance in forests in native and alien ranges

AIM

Alien plant species can cause severe ecological and economic problems, and therefore attract a lot of research interest in biogeography and related fields. To identify potential future invasive species, we need to better understand the mechanisms underlying the abundances of invasive tree species in their new ranges, and whether these mechanisms differ between their native and alien ranges. Here, we test two hypotheses: that greater relative abundance is promoted by (a) functional difference from locally co-occurring trees, and (b) higher values than locally co-occurring trees for traits linked to competitive ability.

LOCATION

Global.

TIME PERIOD

Recent.

MAJOR TAXA STUDIED

Trees.

METHODS

We combined three global plant databases: sPlot vegetation-plot database, TRY plant trait database and Global Naturalized Alien Flora (GloNAF) database. We used a hierarchical Bayesian linear regression model to assess the factors associated with variation in local abundance, and how these relationships vary between native and alien ranges and depend on species' traits.

RESULTS

In both ranges, species reach highest abundance if they are functionally similar to co-occurring species, yet are taller and have higher seed mass and wood density than co-occurring species.

MAIN CONCLUSIONS

Our results suggest that light limitation leads to strong environmental and biotic filtering, and that it is advantageous to be taller and have denser wood. The striking similarities in abundance between native and alien ranges imply that information from tree species' native ranges can be used to predict in which habitats introduced species may become dominant.

Magnetic properties of epitaxial discontinuous Fe/MgO multilayers

We report magnetic, dynamic and transport properties of discontinuous metal-insulator multilayers Fe/MgO grown on amorphous Corning glass and single-crystalline MgO (001) substrates. The films of structure Substrate/MgO (3 nm)/[Fe (0.6 nm)/MgO (3.0 nm)] x 10 were prepared in ultra-high vacuum conditions using Pulsed Laser Deposition. It was shown that conditions of epitaxial growth are favorable for MgO substrates. As a result a substantial increase of tunneling magnetoresistance caused by spin-filtering effect was observed and reasonably theoretically explained. The value of TMR - 9.2% at room temperature in 18 kOe magnetic field is three times higher comparing to that for the samples grown on Corning glass substrates.

Phase separation in the itinerant metamagnetic transition of Sr4Ru3O10

We have investigated the electronic transport properties of the triple-layered ruthenate Sr4Ru3O10. We observed surprising anomalous features near its itinerant metamagnetic transition, including ultrasharp magnetoresistivity steps, a nonmetallic temperature dependence in resistivity for upward field sweeps, and a resistivity drop in temperature dependence for downward field sweeps. These features suggest that the metamagnetic transition of Sr4Ru3O10 occurs via an electronic phase separation process with magnetic domain formation.