Additive biomass models for Larix spp. single-trees sensitive to temperature and precipitation in Eurasia

The analysis of the biomass of larch (genus Larix spp.) trees on the total component composition based on regression equations having the additive biomass structure. Two trends of changes in the tree biomass structure are revealed: due to the mean January temperature and due to the mean annual precipitation. It was shown for the first time that both trends are mutually determined: the intensity of biomass trend in relation to the temperature is changing when depending on the level of precipitation, and the intensity of biomass trend in relation to precipitation level is changing during to a transition from the cold zone to the warm one and vice versa

Forest stand biomass of Picea spp.: an additive model that may be related to climate and civilisational changes

Since ancient times, climate change has largely determined the fate of human civilisation, which was related mainly to changes in the structure and habitats of forest cover. In the context of current climate change, one must know the capabilities of forests to stabilise the climate by increasing biomass and carbon-depositing abilities. For this purpose, the authors compiled a database of harvest biomass (t/ha) in 900 spruce (Picea spp.) sample plots in the Eurasian area and used the methodology of multivariate regression analysis. The first attempt at modelling changes in the biomass additive component composition has been completed, according to the Trans-Eurasian hydrothermal gradients. It is found that the biomass of all components increases with the increase in the mean January temperature, regardless of mean annual precipitation. In warm zonal belts with increasing precipitation, the biomass of most of the components increases. In the process of transitioning from a warm zone to a cold one, the dependence of all biomass components upon precipitation is levelled, and at a mean January temperature of ˗30°C it becomes a weak negative trend. With an increase in temperature of 1°C in different ecoregions characterised by different values of temperature and precipitation, there is a general pattern of decrease in all biomass components. With an increase in precipitation of 100 mm in different ecoregions characterised by different values of temperature and precipitation, most of the components of biomass increase in warm zonal belts, and decrease in cold ones. The development of such models for the main forest-forming species of Eurasia will make it possible to predict changes in the productivity of the forest cover of Eurasia due to climate change

Latitudinal pattern in community-wide herbivory does not match the pattern in herbivory averaged across common plant species

The latitudinal herbivory hypothesis (LHH) predicts that plant losses to herbivores decrease from low to high latitudes. Although the LHH is a community‐level hypothesis, it has been rarely tested with data on community‐wide herbivory, i.e. the percentage of annual production of foliar biomass consumed by insects from all plant species at a given site. Therefore, we asked whether community‐wide leaf herbivory follows the same latitudinal pattern as observed for an unweighted average of herbivory across common plant species.We selected 10 study sites in boreal forests from 60 to 69°N along a 1,000‐km long latitudinal gradient in NW Russia. We measured relative foliar losses to insect herbivores in seven woody plant species (jointly comprising over 95% of the community‐wide above‐ground biomass) and estimated their current‐year foliar biomass. We averaged leaf herbivory for all seven species and calculated community‐wide leaf herbivory by weighting the relative foliar losses of each plant species against the contribution of that species to the annual foliar biomass production.Leaf herbivory was five‐fold higher in deciduous species than in conifers. Latitudinal patterns in herbivory varied from a significant poleward decrease in all deciduous species to a significant poleward increase in Norway spruce. Herbivory values, averaged across seven plant species, decreased with latitude and followed the pattern observed in deciduous plants due to their higher foliar losses compared with conifers. By contrast, community‐wide herbivory did not change with latitude. This discrepancy emerged because the proportion of deciduous plant foliage in the community increased with increasing latitude, and this increase counterbalanced the simultaneous poleward decrease in losses of these species to insects.Synthesis. The herbivory measured by averaging relative losses of individual plant species and community‐wide herbivory is likely to show different latitudinal patterns in various plant communities. The contributions of plant species to the total foliar biomass production should be taken into account in studies of spatial patterns of herbivory which test community‐level hypotheses. This approach may provide new insight into macroecological research on biotic interactions and improve our understanding of the role of insect herbivores in ecosystem‐level processes. </p

Tallo: A global tree allometry and crown architecture database

Data capturing multiple axes of tree size and shape, such as a tree's stem diameter, height and crown size, underpin a wide range of ecological research—from developing and testing theory on forest structure and dynamics, to estimating forest carbon stocks and their uncertainties, and integrating remote sensing imagery into forest monitoring programmes. However, these data can be surprisingly hard to come by, particularly for certain regions of the world and for specific taxonomic groups, posing a real barrier to progress in these fields. To overcome this challenge, we developed the Tallo database, a collection of 498,838 georeferenced and taxonomically standardized records of individual trees for which stem diameter, height and/or crown radius have been measured. These data were collected at 61,856 globally distributed sites, spanning all major forested and non-forested biomes. The majority of trees in the database are identified to species (88%), and collectively Tallo includes data for 5163 species distributed across 1453 genera and 187 plant families. The database is publicly archived under a CC-BY 4.0 licence and can be access from: https://doi.org/10.5281/zenodo.6637599. To demonstrate its value, here we present three case studies that highlight how the Tallo database can be used to address a range of theoretical and applied questions in ecology—from testing the predictions of metabolic scaling theory, to exploring the limits of tree allometric plasticity along environmental gradients and modelling global variation in maximum attainable tree height. In doing so, we provide a key resource for field ecologists, remote sensing researchers and the modelling community working together to better understand the role that trees play in regulating the terrestrial carbon cycle.EEA Santa CruzFil: Jucker, Tommaso. University of Bristol. School of Biological Sciences; Reino UnidoFil: Fischer, Fabian Jörg. University of Bristol. School of Biological Sciences; Reino UnidoFil: Chave, Jérôme. Laboratoire Évolution et Diversité Biologique (EDB); FranciaFil: Chave, Jérôme. Université Toulouse; FranciaFil: Coomes, David A. University of Cambridge. Conservation Research Institute; Reino UnidoFil: Caspersen, John. University of Toronto. Institute of Forestry and Conservation; Canadá.Fil: Ali, Arshad. Hebei University. College of Life Sciences. Forest Ecology Research Group; China.Fil: Loubota Panzou, Grace Jopaul. Université de Liège, Gembloux Agro-Bio Tech; BélgicaFil: Loubota Panzou, Grace Jopaul. Université Marien Ngouabi. Faculté des Sciences et Techniques. Laboratoire de Biodiversité, de Gestion des Ecosystèmes et de l'Environnement (LBGE); Republica del CongoFil: Feldpausch, Ted R. University of Exeter. College of Life and Environmental Sciences; Reino UnidoFil: Falster, Daniel. University of New South Wales Sydney. Evolution & Ecology Research Centre; Australia.Fil: Usoltsev, Vladimir A. Ural State Forest Engineering University. Department of Forestry; Rusia.Fil: Usoltsev, Vladimir A. Botanical Garden of the Ural Branch of Russian Academy of Sciences. Department of Forest Dynamics; Rusia.Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Xiang, Wenhua. Central South University of Forestry and Technology. Faculty of Life Science and Technology; China

Electronic Structure and Coexistence of Superconductivity with Magnetism in RbEuFe4As4

In the novel stoichiometric iron-based material RbEuFe4As4, superconductivity coexists with a peculiar long-range magnetic order of Eu 4f states. Using angle-resolved photoemission spectroscopy, we reveal a complex three-dimensional electronic structure and compare it with density functional theory calculations. Multiple super-conducting gaps were measured on various sheets of the Fermi surface. High-resolution resonant photoemission spectroscopy reveals magnetic order of the Eu 4f states deep into the superconducting phase. Both the absolute values and the anisotropy of the superconducting gaps are remarkably similar to the sibling compound without Eu, indicating that Eu magnetism does not affect the pairing of electrons. A complete decoupling between Fe-and Eu-derived states was established from their evolution with temperature, thus unambiguously demonstrating that superconducting and a long-range magnetic orders exist independently from each other. The established electronic structure of RbEuFe4As4 opens opportunities for the future studies of the highly unorthodox electron pairing and phase competition in this family of iron-based superconductors with doping.We thank Matthew Watson for his critical reading of the manuscript. We thank Diamond Light Source for access to beamline I05 (Proposal No. SI15074 and No. SI19041) that contributed to the results presented here. Work was done using equipment from the LPI Shared Facility Center. K.S.P. and V.M.P. acknowledge support by the Russian Scientific Foundation (RSF Project No. 21-12-00394). A.V.S. and A.S.U. acknowledge support by the Russian Foundation for Basic Research (Project No. 21-52-12043). E.V.C. acknowledges funding by Saint Petersburg State University project for scientific investigations (ID No. 73028629). S.V.E. acknowledges support from the government research assignment for ISPMS SB RAS (Project FWRW-2019-0032). R.V. acknowledges funding by the Deutsche Forschungsgemeinschaft (DFG) TRR 288 (Project A05). V.B. thanks the Goethe University Frankfurt for computational resources and Daniel Guterding for providing the FS plotting software. K.K. thanks M. Valvidares, J. Herrero, H. B. Vasili, S. Agrestini, and N. Brookes for their support during the XMCD experiment at ALBA via IHR Proposal 2019063615. D.V.V. also acknowledges support from the Spanish Ministry of Economy (MAT-2017-88374-P

Evenness mediates the global relationship between forest productivity and richness

1. Biodiversity is an important component of natural ecosystems, with higher species richness often correlating with an increase in ecosystem productivity. Yet, this relationship varies substantially across environments, typically becoming less pronounced at high levels of species richness. However, species richness alone cannot reflect all important properties of a community, including community evenness, which may mediate the relationship between biodiversity and productivity. If the evenness of a community correlates negatively with richness across forests globally, then a greater number of species may not always increase overall diversity and productivity of the system. Theoretical work and local empirical studies have shown that the effect of evenness on ecosystem functioning may be especially strong at high richness levels, yet the consistency of this remains untested at a global scale. 2. Here, we used a dataset of forests from across the globe, which includes composition, biomass accumulation and net primary productivity, to explore whether productivity correlates with community evenness and richness in a way that evenness appears to buffer the effect of richness. Specifically, we evaluated whether low levels of evenness in speciose communities correlate with the attenuation of the richness–productivity relationship. 3. We found that tree species richness and evenness are negatively correlated across forests globally, with highly speciose forests typically comprising a few dominant and many rare species. Furthermore, we found that the correlation between diversity and productivity changes with evenness: at low richness, uneven communities are more productive, while at high richness, even communities are more productive. 4. Synthesis. Collectively, these results demonstrate that evenness is an integral component of the relationship between biodiversity and productivity, and that the attenuating effect of richness on forest productivity might be partly explained by low evenness in speciose communities. Productivity generally increases with species richness, until reduced evenness limits the overall increases in community diversity. Our research suggests that evenness is a fundamental component of biodiversity–ecosystem function relationships, and is of critical importance for guiding conservation and sustainable ecosystem management decisions

Native diversity buffers against severity of non-native tree invasions

Determining the drivers of non-native plant invasions is critical for managing native ecosystems and limiting the spread of invasive species$^{1,2}$. Tree invasions in particular have been relatively overlooked, even though they have the potential to transform ecosystems and economies$^{3,4}$. Here, leveraging global tree databases$^{5,6,7}$, we explore how the phylogenetic and functional diversity of native tree communities, human pressure and the environment influence the establishment of non-native tree species and the subsequent invasion severity. We find that anthropogenic factors are key to predicting whether a location is invaded, but that invasion severity is underpinned by native diversity, with higher diversity predicting lower invasion severity. Temperature and precipitation emerge as strong predictors of invasion strategy, with non-native species invading successfully when they are similar to the native community in cold or dry extremes. Yet, despite the influence of these ecological forces in determining invasion strategy, we find evidence that these patterns can be obscured by human activity, with lower ecological signal in areas with higher proximity to shipping ports. Our global perspective of non-native tree invasion highlights that human drivers influence non-native tree presence, and that native phylogenetic and functional diversity have a critical role in the establishment and spread of subsequent invasions