Encroachment of shrubs into subalpine grasslands in the Pyrenees modifies the structure of soil fungal communities and soil properties

Grau O., Saravesi K., Ninot J.M., Geml J., Markkola A., Ahonen S.H., Peñuelas J. (2019) Encroachment of shrubs into subalpine grasslands in the Pyrenees modifies the structure of soil fungal communities and soil properties. FEMS microbiology ecology. 95: 0-0.
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Doi: 10.1093/femsec/fiz028

Resum:

The encroachment of shrubs into grasslands is common in terrestrial ecosystems dominated by grass. Land abandonment and favourable climatic trends in recent decades have favoured the expansion of shrubs into subalpine grasslands in many mountainous regions across Europe. The advance of the succession from grassland to shrubland is expected to have a major impact on ecosystem functioning. We used DNA metabarcoding to assess whether the structure of soil fungal communities varied along the succession from subalpine grassland to shrubland in the Pyrenees, and investigated whether shrub encroachment was associated with changes in soil properties. The expansion of shrubs increased the soil C:N ratio and/or reduced the N, P or K contents. Plant-driven changes in soil properties were strongly associated with the compositional turnover of fungi, including arbuscular mycorrhizal, ectomycorrhizal, ericoid, root endophytic, saprotrophic, lichenised and pathogenic fungi. Total richness and the richness of most functional groups were correlated with soil P, N and the C:N or N:P ratios. We show that the interplay between abiotic factors (changes in soil properties) and biotic factors (occurrence and identity of shrubs) played a key role in the structure and uniqueness of soil fungal communities along the succession. © FEMS 2019.

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Traditional plant functional groups explain variation in economic but not size-related traits across the tundra biome

Thomas H.J.D., Myers-Smith I.H., Bjorkman A.D., Elmendorf S.C., Blok D., Cornelissen J.H.C., Forbes B.C., Hollister R.D., Normand S., Prevéy J.S., Rixen C., Schaepman-Strub G., Wilmking M., Wipf S., Cornwell W.K., Kattge J., Goetz S.J., Guay K.C., Alatalo J.M., Anadon-Rosell A., Angers-Blondin S., Berner L.T., Björk R.G., Buchwal A., Buras A., Carbognani M., Christie K., Siegwart Collier L., Cooper E.J., Eskelinen A., Frei E.R., Grau O., Grogan P., Hallinger M., Heijmans M.M.P.D., Hermanutz L., Hudson J.M.G., Hülber K., Iturrate-Garcia M., Iversen C.M., Jaroszynska F., Johnstone J.F., Kaarlejärvi E., Kulonen A., Lamarque L.J., Lévesque E., Little C.J., Michelsen A., Milbau A., Nabe-Nielsen J., Nielsen S.S., Ninot J.M., Oberbauer S.F., Olofsson J., Onipchenko V.G., Petraglia A., Rumpf S.B., Semenchuk P.R., Soudzilovskaia N.A., Spasojevic M.J., Speed J.D.M., Tape K.D., te Beest M., Tomaselli M., Trant A., Treier U.A., Venn S., Vowles T., Weijers S., Zamin T., Atkin O.K., Bahn M., Blonder B., Campetella G., Cerabolini B.E.L., Chapin III F.S., Dainese M., de Vries F.T., Díaz S., Green W., Jackson R.B., Manning P., Niinemets Ü., Ozinga W.A., Peñuelas J., Reich P.B., Schamp B., Sheremetev S., van Bodegom P.M. (2019) Traditional plant functional groups explain variation in economic but not size-related traits across the tundra biome. Global Ecology and Biogeography. 28: 78-95.
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Doi: 10.1111/geb.12783

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Aim: Plant functional groups are widely used in community ecology and earth system modelling to describe trait variation within and across plant communities. However, this approach rests on the assumption that functional groups explain a large proportion of trait variation among species. We test whether four commonly used plant functional groups represent variation in six ecologically important plant traits. Location: Tundra biome. Time period: Data collected between 1964 and 2016. Major taxa studied: 295 tundra vascular plant species. Methods: We compiled a database of six plant traits (plant height, leaf area, specific leaf area, leaf dry matter content, leaf nitrogen, seed mass) for tundra species. We examined the variation in species-level trait expression explained by four traditional functional groups (evergreen shrubs, deciduous shrubs, graminoids, forbs), and whether variation explained was dependent upon the traits included in analysis. We further compared the explanatory power and species composition of functional groups to alternative classifications generated using post hoc clustering of species-level traits. Results: Traditional functional groups explained significant differences in trait expression, particularly amongst traits associated with resource economics, which were consistent across sites and at the biome scale. However, functional groups explained 19% of overall trait variation and poorly represented differences in traits associated with plant size. Post hoc classification of species did not correspond well with traditional functional groups, and explained twice as much variation in species-level trait expression. Main conclusions: Traditional functional groups only coarsely represent variation in well-measured traits within tundra plant communities, and better explain resource economic traits than size-related traits. We recommend caution when using functional group approaches to predict tundra vegetation change, or ecosystem functions relating to plant size, such as albedo or carbon storage. We argue that alternative classifications or direct use of specific plant traits could provide new insights for ecological prediction and modelling. © 2018 The Authors Global Ecology and Biogeography Published by John Wiley & Sons Ltd

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Plant functional trait change across a warming tundra biome

Bjorkman A.D., Myers-Smith I.H., Elmendorf S.C., Normand S., Rüger N., Beck P.S.A., Blach-Overgaard A., Blok D., Cornelissen J.H.C., Forbes B.C., Georges D., Goetz S.J., Guay K.C., Henry G.H.R., HilleRisLambers J., Hollister R.D., Karger D.N., Kattge J., Manning P., Prevéy J.S., Rixen C., Schaepman-Strub G., Thomas H.J.D., Vellend M., Wilmking M., Wipf S., Carbognani M., Hermanutz L., Lévesque E., Molau U., Petraglia A., Soudzilovskaia N.A., Spasojevic M.J., Tomaselli M., Vowles T., Alatalo J.M., Alexander H.D., Anadon-Rosell A., Angers-Blondin S., Beest M., Berner L., Björk R.G., Buchwal A., Buras A., Christie K., Cooper E.J., Dullinger S., Elberling B., Eskelinen A., Frei E.R., Grau O., Grogan P., Hallinger M., Harper K.A., Heijmans M.M.P.D., Hudson J., Hülber K., Iturrate-Garcia M., Iversen C.M., Jaroszynska F., Johnstone J.F., Jørgensen R.H., Kaarlejärvi E., Klady R., Kuleza S., Kulonen A., Lamarque L.J., Lantz T., Little C.J., Speed J.D.M., Michelsen A., Milbau A., Nabe-Nielsen J., Nielsen S.S., Ninot J.M., Oberbauer S.F., Olofsson J., Onipchenko V.G., Rumpf S.B., Semenchuk P., Shetti R., Collier L.S., Street L.E., Suding K.N., Tape K.D., Trant A., Treier U.A., Tremblay J.-P., Tremblay M., Venn S., Weijers S., Zamin T., Boulanger-Lapointe N., Gould W.A., Hik D.S., Hofgaard A., Jónsdóttir I.S., Jorgenson J., Klein J., Magnusson B., Tweedie C., Wookey P.A., Bahn M., Blonder B., van Bodegom P.M., Bond-Lamberty B., Campetella G., Cerabolini B.E.L., Chapin F.S., III, Cornwell W.K., Craine J., Dainese M., de Vries F.T., Díaz S., Enquist B.J., Green W., Milla R., Niinemets Ü., Onoda Y., Ordoñez J.C., Ozinga W.A., Penuelas J., Poorter H., Poschlod P., Reich P.B., Sandel B., Schamp B., Sheremetev S., Weiher E. (2018) Plant functional trait change across a warming tundra biome. Nature. 562: 57-62.
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Doi: 10.1038/s41586-018-0563-7

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The tundra is warming more rapidly than any other biome on Earth, and the potential ramifications are far-reaching because of global feedback effects between vegetation and climate. A better understanding of how environmental factors shape plant structure and function is crucial for predicting the consequences of environmental change for ecosystem functioning. Here we explore the biome-wide relationships between temperature, moisture and seven key plant functional traits both across space and over three decades of warming at 117 tundra locations. Spatial temperature–trait relationships were generally strong but soil moisture had a marked influence on the strength and direction of these relationships, highlighting the potentially important influence of changes in water availability on future trait shifts in tundra plant communities. Community height increased with warming across all sites over the past three decades, but other traits lagged far behind predicted rates of change. Our findings highlight the challenge of using space-for-time substitution to predict the functional consequences of future warming and suggest that functions that are tied closely to plant height will experience the most rapid change. They also reveal the strength with which environmental factors shape biotic communities at the coldest extremes of the planet and will help to improve projections of functional changes in tundra ecosystems with climate warming. © 2018, Springer Nature Limited.

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Changes in nutrient concentrations of leaves and roots in response to global change factors

Sardans J., Grau O., Chen H.Y.H., Janssens I.A., Ciais P., Piao S., Peñuelas J. (2017) Changes in nutrient concentrations of leaves and roots in response to global change factors. Global Change Biology. 23: 3849-3856.
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Doi: 10.1111/gcb.13721

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Global change impacts on biogeochemical cycles have been widely studied, but our understanding of whether the responses of plant elemental composition to global change drivers differ between above- and belowground plant organs remains incomplete. We conducted a meta-analysis of 201 reports including 1,687 observations of studies that have analyzed simultaneously N and P concentrations changes in leaves and roots in the same plants in response to drought, elevated [CO2], and N and P fertilization around the world, and contrasted the results within those obtained with a general database (838 reports and 14,772 observations) that analyzed the changes in N and P concentrations in leaves and/or roots of plants submitted to the commented global change drivers. At global level, elevated [CO2] decreased N concentrations in leaves and roots and decreased N:P ratio in roots but no in leaves, but was not related to P concentration changes. However, the response differed among vegetation types. In temperate forests, elevated [CO2] was related with lower N concentrations in leaves but not in roots, whereas in crops, the contrary patterns were observed. Elevated [CO2] decreased N concentrations in leaves and roots in tundra plants, whereas not clear relationships were observed in temperate grasslands. However, when elevated [CO2] and N fertilization coincided, leaves had lower N concentrations, whereas root had higher N concentrations suggesting that more nutrients will be allocated to roots to improve uptake of the soil resources not directly provided by the global change drivers. N fertilization and drought increased foliar and root N concentrations while the effects on P concentrations were less clear. The changes in N and P allocation to leaves and root, especially those occurring in opposite direction between them have the capacity to differentially affect above- and belowground ecosystem functions, such as litter mineralization and above- and belowground food webs. © 2017 John Wiley & Sons Ltd

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