Importance, but not intensity of plant interactions relates to species diversity under the interplay of stress and disturbance

The lack of clarity on how the intensity and importance of plant interactions change under the co-occurrence of stress and disturbance strongly impedes assessing the relative importance of plant interactions for species diversity. We addressed this issue in subalpine grasslands of the French Pyrenees. A natural soil moisture gradient further experimentally stretched at both ends was used and a mowing disturbance treatment was applied at each position along the soil moisture gradient. Changes in intensity and importance of plant interactions were assessed by a neighbour removal experiment using four target ecotypes. A structural equation modelling approach was used to assess the relative impact of stress, disturbance, the intensity and importance of plant interactions on diversity at both the neighbourhood and community scales. Without mowing, changes in intensity and importance of plant interactions only diverged in the dry part of the soil moisture gradient. The intensity of plant interactions linearly shifted from competition to facilitation with increasing stress, while the importance followed a hump-shaped relationship. Species diversity components were tightly related to the importance of plant interactions only, both the neighbourhood and community scales. Mowing disturbance strongly reduced the importance of facilitation along the soil moisture gradient, and suppressed the relationship between the importance of plant interactions and diversity components. Together, our results highlight that 1) the importance is the best predictor of variations in species diversity in this subalpine herbaceous system, and 2) that fine-scale processes such as plant interactions can affect the entire plant communities. Finally, our results suggest that high level of constraints due to co-occurring stress and disturbance can inhibit the effects of plant interactions on species diversity, highlighting their potential role in regulating diversity and the maintenance/extinction of plant communities. The co-occurrence of stress (i.e. factors such as drought limiting plant growth, sensu Grime 1973) and disturbance (drastic events such as mowing removing plant biomass) can lead to a rapid loss of diversity. Co-occurring negative effects of stress and disturbance on diversity and ecosystem functioning are specific to severe environments such as alpine grasslands or dry steppes OIKOS How plant interactions change along environmental gradients is an unsolved debate, particularly when both stress and disturbance interact. This lack of clarity explains why the relative impact of plant interactions (intensity and importance) on species diversity has been rarely assessed. Using an experimental approach, we found that the importance of plant interactions highly contributed to variation in species diversity, confirming that neighbourhood scale processes such as plant interactions can affect the entire plant communities. The co-occurrence of stress and disturbance inhibited the effects of plant interactions, highlighting that plant interactions may regulate drops of diversity and the maintenance/ extinction of plant communities. Synthesi

Traits of neighbouring plants and space limitation determine intraspecific trait variability in semi-arid shrublands

Understanding how intraspecific trait variability (ITV) responds to both abiotic and biotic constraints is crucial to predict how individuals are assembled in plant communities, and how they will be impacted by ongoing global environmental change.Three key functional traits [plant height, leaf area (LA) and specific leaf area (SLA)] were assessed to quantify the range of ITV of four dominant plant species along a rainfall gradient in semi-arid Mediterranean shrublands. Variance partitioning and confirmatory multilevel path analyses were used to assess the direct and indirect effects of rainfall, space limitation (crowding) and neighbouring plant traits on ITV.The direct effect of the local neighbourhood on the trait values of subordinate individuals was as strong as the effect of rainfall. The indirect effect of rainfall, however, mediated by the effect of the local neighbourhood on the trait values of subordinate individuals, was weak. Rainfall decreased the height and SLA of subordinate individuals, but increased their LA. Neighbouring plant traits were just as strong predictors as crowding in explaining changes in ITV.Synthesis. Our study provides a framework to disentangle the direct effects of abiotic factors and their indirect effects on ITV mediated by the local neighbourhood. Our results highlight that abiotic and biotic constraints are both substantial sources of trait variations at the individual level, and can blur processes underlying changes in ITV. Considering and disentangling combined sources with an individual perspective would help to refine our predictions for community assembly and functional ecology

TRY plant trait database - enhanced coverage and open access

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Soil fungal abundance and plant functional traits drive fertile island formation in global drylands

Dryland vegetation is characterized by discrete plant patches that accumulate and capture soil resources under their canopies. These “fertile islands” are major drivers of dryland ecosystem structure and functioning, yet we lack an integrated understanding of the factors controlling their magnitude and variability at the global scale.EEA BarilocheFil: Ochoa-Hueso, Raúl. Universidad Autónoma de Madrid. Department of Ecology; EspañaFil: Eldridge, David J. University of New South Wales. School of Biological, Earth and Environmental Sciences; AustraliaFil: Delgado-Baquerizo, Manuel. University of Colorado. Cooperative Institute for Research in Environmental Sciences; Estados Unidos. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; EspañaFil: Soliveres, Santiago. University of Bern. Institute of Plant Sciences; SuizaFil: Bowker, Matthew A. Northern Arizona University. School of Forestry; Estados UnidosFil: Gross, Nicolás. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; España. Institut Nationale de la Recherche Agronomique; Francia. Université La Rochelle. Centre d’étude biologique de Chizé; FranciaFil: Le Bagousse-Pinguet, Yoann. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; EspañaFil: Quero, José L. Universidad de Córdoba. Escuela Técnica Superior de Ingeniería Agronómica y de Montes. Departamento de Ingeniería Forestal: EspañaFil: García-Gómez, Miguel. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; EspañaFil: Valencia, Enrique. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; EspañaFil: Arredondo, Tulio. Instituto Potosino de Investigación Científica y Tecnológica. División de Ciencias Ambientales; MéxicoFil: Beinticinco, Laura. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Bran, Donaldo Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Cea, Alex. Universidad de La Serena. Departamento de Biología; ChileFil: Coaguila, Daniel. Instituto de Ensino Superior de Rio Verde; BrasilFil: Dougill, Andrew J. University of Leeds. School of Earth and Environment; Gran BretañaFil: Espinosa, Carlos I. Universidad Técnica Particular de Loja. Departamento de Ciencias Naturales; EcuadorFil: Gaitan, Juan Jose. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; ArgentinaFil: Guuroh, Reginald T. University of Cologne. Botanical Institute. Range Ecology and Range Management Group; Alemania. CSIR-Forestry Research Institute of Ghana; GhanaFil: Guzmán, Elizabeth. Universidad Técnica Particular de Loja. Departamento de Ciencias Naturales; EcuadorFil: Gutiérrez, Julio R.. Universidad de La Serena. Departamento de Biología; Chile. Centro de Estudios Avanzados en Zonas Áridas (CEAZA); Chile. Instituto de Ecología y Biodiversidad; ChileFil: Hernández, Rosa M. Universidad Experimental Simón Rodríguez. Centro de Agroecología Tropical. Laboratorio de Biogeoquímica; VenezuelaFil: Huber-Sannwald, Elisabeth. Instituto Potosino de Investigación Científica y Tecnológica. División de Ciencias Ambientales; MéxicoFil: Jeffries, Thomas. Western Sydney University. Hawkesbury Institute for the Environment; AustraliaFil: Linstädter, Anja. University of Cologne. Botanical Institute. Range Ecology and Range Management Group; AlemaniaFil: Mau, Rebecca L. Northern Arizona University. Center for Ecosystem Science and Society: Estados UnidosFil: Monerris, Jorge. Université du Québec à Montréal. Pavillon des Sciences Biologiques. Département des Sciences Biologiques; CanadáFil: Prina, Anibal. Universidad Nacional de La Pampa. Facultad de Agronomía; ArgentinaFil: Pucheta, Eduardo. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales. Departamento de Biología; ArgentinaFil: Stavi, Ilan. Dead Sea and Arava Science Center, IsraelFil: Thomas, Andrew. Aberystwyth University. Department of Geography and Earth Sciences; Gran BretañaFil: Zaady, Eli. Agricultural Research Organization. Gilat Research Center. Natural Resources; IsraelFil: Singh, Brajesh K. Western Sydney University. Hawkesbury Institute for the Environment; Australia. Western Sydney University. Global Centre for Land-Based Innovation; AustraliaFil: Maestre, Fernando T. Universidad Rey Juan Carlos. Escuela Superior de Ciencias Experimentales y Tecnología. Departamento de Biología y Geología, Física y Química Inorgánica; Españ

Soil fungal abundance and plant functional traits drive fertile island formation in global drylands

International audience1.Dryland vegetation is characterised by discrete plant patches that accumulate and capture soil resources under their canopies. These “fertile islands” are major drivers of dryland ecosystem structure and functioning, yet we lack an integrated understanding of the factors controlling their magnitude and variability at the global scale.2.We conducted a standardized field survey across two hundred and thirty-six drylands from five continents. At each site, we measured the composition, diversity and cover of perennial plants. Fertile island effects were estimated at each site by comparing composite soil samples obtained under the canopy of the dominant plants and in open areas devoid of perennial vegetation. For each sample, we measured fifteen soil variables (functions) associated with carbon, nitrogen and phosphorus cycling and used the Relative Interaction Index to quantify the magnitude of the fertile island effect for each function. In eighty sites, we also measured fungal and bacterial abundance (quantitative PCR) and diversity (Illumina MiSeq).3.The most fertile islands, i.e. those where a higher number of functions were simultaneously enhanced, were found at lower-elevation sites with greater soil pH values and sand content under semiarid climates, particularly at locations where the presence of tall woody species with a low specific leaf area increased fungal abundance beneath plant canopies, the main direct biotic controller of the fertile island effect in the drylands studied. Positive effects of fungal abundance were particularly associated with greater nutrient contents and microbial activity (soil extracellular enzymes) under plant canopies.4.Synthesis. Our results show that the formation of fertile islands in global drylands largely depends on: (i) local climatic, topographic and edaphic characteristics, (ii) the structure and traits of local plant communities and (iii) soil microbial communities. Our study also has broad implications for the management and restoration of dryland ecosystems worldwide, where woody plants are commonly used as nurse plants to enhance the establishment and survival of beneficiary species. Finally, our results suggest that forecasted increases in aridity may enhance the formation of fertile islands in drylands worldwide

Space Division Multiplexing in Optical Fibres

Optical communications technology has made enormous and steady progress for several decades, providing the key resource in our increasingly information-driven society and economy. Much of this progress has been in finding innovative ways to increase the data carrying capacity of a single optical fibre. In this search, researchers have explored (and close to maximally exploited) every available degree of freedom, and even commercial systems now utilize multiplexing in time, wavelength, polarization, and phase to speed more information through the fibre infrastructure. Conspicuously, one potentially enormous source of improvement has however been left untapped in these systems: fibres can easily support hundreds of spatial modes, but today's commercial systems (single-mode or multi-mode) make no attempt to use these as parallel channels for independent signals.Comment: to appear in Nature Photonic

TRY plant trait database - enhanced coverage and open access

This article has 730 authors, of which I have only listed the lead author and myself as a representative of University of HelsinkiPlant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.Peer reviewe

TRY plant trait database – enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

TRY plant trait database - enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives