Continental mapping of forest ecosystem functions reveals a high but unrealised potential for forest multifunctionality

(2018) Continental mapping of forest ecosystem functions reveals a high but unrealised potential for forest multifunctionality. . : -.
Link
Doi: https://doi.org/10.1111/ele.12868

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Isotopic methods for non-destructive assessment of carbon dynamics in shrublands under long-term climate change manipulation

Andresen L.C., Domínguez M.T., Reinsch S., Smith A.R., Schmidt I.K., Ambus P., Beier C., Boeckx P., Bol R., de Dato G., Emmett B.A., Estiarte M., Garnett M.H., Kröel-Dulay G., Mason S.L., Nielsen C.S., Peñuelas J., Tietema A. (2018) Isotopic methods for non-destructive assessment of carbon dynamics in shrublands under long-term climate change manipulation. Methods in Ecology and Evolution. 9: 866-880.
Link
Doi: 10.1111/2041-210X.12963

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Long-term climate change experiments are extremely valuable for studying ecosystem responses to environmental change. Examination of the vegetation and the soil should be non-destructive to guarantee long-term research. In this paper, we review field methods using isotope techniques for assessing carbon dynamics in the plant–soil–air continuum, based on recent field experience and examples from a European climate change manipulation network. Eight European semi-natural shrubland ecosystems were exposed to warming and drought manipulations. One field site was additionally exposed to elevated atmospheric CO2. We discuss the isotope methods that were used across the network to evaluate carbon fluxes and ecosystem responses, including: (1) analysis of the naturally rare isotopes of carbon (13C and 14C) and nitrogen (15N); (2) use of in situ pulse labelling with 13CO2, soil injections of 13C- and 15N-enriched substrates, or continuous labelling by free air carbon dioxide enrichment (FACE) and (3) manipulation of isotopic composition of soil substrates (14C) in laboratory-based studies. The natural 14C signature of soil respiration gave insight into a possible long-term shift in the partitioning between the decomposition of young and old soil carbon sources. Contrastingly, the stable isotopes 13C and 15N were used for shorter-term processes, as the residence time in a certain compartment of the stable isotope label signal is limited. The use of labelled carbon-compounds to study carbon mineralisation by soil micro-organisms enabled to determine the long-term effect of climate change on microbial carbon uptake kinetics and turnover. Based on the experience with the experimental work, we provide recommendations for the application of the reviewed methods to study carbon fluxes in the plant–soil–air continuum in climate change experiments. 13C-labelling techniques exert minimal physical disturbances, however, the dilution of the applied isotopic signal can be challenging. In addition, the contamination of the field site with excess 13C or 14C can be a problem for subsequent natural abundance (14C and 13C) or label studies. The use of slight changes in carbon and nitrogen natural abundance does not present problems related to potential dilution or contamination risks, but the usefulness depends on the fractionation rate of the studied processes. © 2018 The Authors. Methods in Ecology and Evolution © 2018 British Ecological Society

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Assessing ecosystem isoprene emissions by hyperspectral remote sensing

Balzarolo M., Peñuelas J., Filella I., Portillo-Estrada M., Ceulemans R. (2018) Assessing ecosystem isoprene emissions by hyperspectral remote sensing. Remote Sensing. 10: 0-0.
Link
Doi: 10.3390/rs10071086

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This study examined the relationship between foliar isoprene emissions, light use efficiency and photochemical reflectance index (PRI) throughout the canopy profile and explored the contribution of xanthophyll cycle pigments versus other carotenoid pigments to the isoprene/PRI relationship. Foliar isoprene emissions within the canopy profile were measured in a high-density poplar plantation in Flanders (Belgium) during the 2016 growing season. The results confirmed that PRI was a promising estimator of isoprene emissions at canopy level. Interestingly, xanthophyll cycle pigments contributed more to isoprene biosynthesis than chlorophyll and drove the isoprene/PRI relationship. The simple independent pigment index and novel defined indices, such as the hyperspectral isoprene index and simple hyperspectral isoprene index, showed promising results and could be suitable estimators of isoprene emissions due to their strong relationship with the xanthophyll pool. © 2018 by the authors.

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Trophic transfer from aquatic to terrestrial ecosystems: a test of the biogeochemical niche hypothesis

Bartrons M., Sardans J., Hoekman D., Peñuelas J. (2018) Trophic transfer from aquatic to terrestrial ecosystems: a test of the biogeochemical niche hypothesis. Ecosphere. 9: 0-0.
Link
Doi: 10.1002/ecs2.2338

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Matter and energy flow across ecosystem boundaries. Transfers from terrestrial to aquatic ecosystems are frequent and have been widely studied, but the flow of matter from aquatic to terrestrial ecosystems is less known. Large numbers of midges emerge from some lakes in northern Iceland and fly to land. These lakes differ in their levels of eutrophication due to different intensities of geothermal warming and nutrient inputs. In the context of this material transfer from an aquatic to a terrestrial ecosystem, we investigated the relationships between the deposition of midges and the elemental composition and stoichiometry of organisms in low-productivity terrestrial ecosystems. We analyzed several terrestrial food webs in northeastern Iceland with similar food web compositions of terrestrial arthropods but different inputs of midges and analyzed the stoichiometric composition of the different trophic groups. Elemental composition differed among trophic groups and taxa much more than within each trophic group or taxa across the midge deposition gradient. Specifically, the change in N concentration was significant in plants (up to 70% increase in the site with maximum input) but not in predators, which had a more homeostatic elemental composition. These results thus show (1) a significant movement of matter and nutrients from an aquatic to a terrestrial habitat via the emergence of aquatic insects and the deposition of insect carcasses, (2) a larger impact on the elemental composition of plants than arthropods, and (3) support for the biogeochemical niche hypothesis, which predicts that different species should have a specific elemental composition, stoichiometry, and allocation as a consequence of their particular metabolism, physiology, and structure. © 2018 The Authors.

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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.
Link
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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Satellite passive microwaves reveal recent climate-induced carbon losses in African drylands

Brandt M., Wigneron J.-P., Chave J., Tagesson T., Penuelas J., Ciais P., Rasmussen K., Tian F., Mbow C., Al-Yaari A., Rodriguez-Fernandez N., Schurgers G., Zhang W., Chang J., Kerr Y., Verger A., Tucker C., Mialon A., Rasmussen L.V., Fan L., Fensholt R. (2018) Satellite passive microwaves reveal recent climate-induced carbon losses in African drylands. Nature Ecology and Evolution. : 1-9.
Link
Doi: 10.1038/s41559-018-0530-6

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The African continent is facing one of the driest periods in the past three decades as well as continued deforestation. These disturbances threaten vegetation carbon (C) stocks and highlight the need for improved capabilities of monitoring large-scale aboveground carbon stock dynamics. Here we use a satellite dataset based on vegetation optical depth derived from low-frequency passive microwaves (L-VOD) to quantify annual aboveground biomass-carbon changes in sub-Saharan Africa between 2010 and 2016. L-VOD is shown not to saturate over densely vegetated areas. The overall net change in drylands (53% of the land area) was −0.05 petagrams of C per year (Pg C yr−1) associated with drying trends, and a net change of −0.02 Pg C yr−1 was observed in humid areas. These trends reflect a high inter-annual variability with a very dry year in 2015 (net change, −0.69 Pg C) with about half of the gross losses occurring in drylands. This study demonstrates, first, the applicability of L-VOD to monitor the dynamics of carbon loss and gain due to weather variations, and second, the importance of the highly dynamic and vulnerable carbon pool of dryland savannahs for the global carbon balance, despite the relatively low carbon stock per unit area. © 2018 The Author(s)

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Global trait–environment relationships of plant communities

Bruelheide H., Dengler J., Purschke O., Lenoir J., Jiménez-Alfaro B., Hennekens S.M., Botta-Dukát Z., Chytrý M., Field R., Jansen F., Kattge J., Pillar V.D., Schrodt F., Mahecha M.D., Peet R.K., Sandel B., van Bodegom P., Altman J., Alvarez-Dávila E., Arfin Khan M.A.S., Attorre F., Aubin I., Baraloto C., Barroso J.G., Bauters M., Bergmeier E., Biurrun I., Bjorkman A.D., Blonder B., Čarni A., Cayuela L., Černý T., Cornelissen J.H.C., Craven D., Dainese M., Derroire G., De Sanctis M., Díaz S., Doležal J., Farfan-Rios W., Feldpausch T.R., Fenton N.J., Garnier E., Guerin G.R., Gutiérrez A.G., Haider S., Hattab T., Henry G., Hérault B., Higuchi P., Hölzel N., Homeier J., Jentsch A., Jürgens N., Kącki Z., Karger D.N., Kessler M., Kleyer M., Knollová I., Korolyuk A.Y., Kühn I., Laughlin D.C., Lens F., Loos J., Louault F., Lyubenova M.I., Malhi Y., Marcenò C., Mencuccini M., Müller J.V., Munzinger J., Myers-Smith I.H., Neill D.A., Niinemets Ü., Orwin K.H., Ozinga W.A., Penuelas J., Pérez-Haase A., Petřík P., Phillips O.L., Pärtel M., Reich P.B., Römermann C., Rodrigues A.V., Sabatini F.M., Sardans J., Schmidt M., Seidler G., Silva Espejo J.E., Silveira M., Smyth A., Sporbert M., Svenning J.-C., Tang Z., Thomas R., Tsiripidis I., Vassilev K., Violle C., Virtanen R., Weiher E., Welk E., Wesche K., Winter M., Wirth C., Jandt U. (2018) Global trait–environment relationships of plant communities. Nature Ecology and Evolution. 2: 1906-1917.
Link
Doi: 10.1038/s41559-018-0699-8

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Plant functional traits directly affect ecosystem functions. At the species level, trait combinations depend on trade-offs representing different ecological strategies, but at the community level trait combinations are expected to be decoupled from these trade-offs because different strategies can facilitate co-existence within communities. A key question is to what extent community-level trait composition is globally filtered and how well it is related to global versus local environmental drivers. Here, we perform a global, plot-level analysis of trait–environment relationships, using a database with more than 1.1 million vegetation plots and 26,632 plant species with trait information. Although we found a strong filtering of 17 functional traits, similar climate and soil conditions support communities differing greatly in mean trait values. The two main community trait axes that capture half of the global trait variation (plant stature and resource acquisitiveness) reflect the trade-offs at the species level but are weakly associated with climate and soil conditions at the global scale. Similarly, within-plot trait variation does not vary systematically with macro-environment. Our results indicate that, at fine spatial grain, macro-environmental drivers are much less important for functional trait composition than has been assumed from floristic analyses restricted to co-occurrence in large grid cells. Instead, trait combinations seem to be predominantly filtered by local-scale factors such as disturbance, fine-scale soil conditions, niche partitioning and biotic interactions. © 2018, The Author(s), under exclusive licence to Springer Nature Limited.

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ORCHIDEE-SOM: Modeling soil organic carbon (SOC) and dissolved organic carbon (DOC) dynamics along vertical soil profiles in Europe

Camino-Serrano M., Guenet B., Luyssaert S., Ciais P., Bastrikov V., De Vos B., Gielen B., Gleixner G., Jornet-Puig A., Kaiser K., Kothawala D., Lauerwald R., Peñuelas J., Schrumpf M., Vicca S., Vuichard N., Walmsley D., Janssens I.A. (2018) ORCHIDEE-SOM: Modeling soil organic carbon (SOC) and dissolved organic carbon (DOC) dynamics along vertical soil profiles in Europe. Geoscientific Model Development. 11: 937-957.
Link
Doi: 10.5194/gmd-11-937-2018

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Current land surface models (LSMs) typically represent soils in a very simplistic way, assuming soil organic carbon (SOC) as a bulk, and thus impeding a correct representation of deep soil carbon dynamics. Moreover, LSMs generally neglect the production and export of dissolved organic carbon (DOC) from soils to rivers, leading to overestimations of the potential carbon sequestration on land. This common oversimplified processing of SOC in LSMs is partly responsible for the large uncertainty in the predictions of the soil carbon response to climate change. In this study, we present a new soil carbon module called ORCHIDEE-SOM, embedded within the land surface model ORCHIDEE, which is able to reproduce the DOC and SOC dynamics in a vertically discretized soil to 2gm. The model includes processes of biological production and consumption of SOC and DOC, DOC adsorption on and desorption from soil minerals, diffusion of SOC and DOC, and DOC transport with water through and out of the soils to rivers. We evaluated ORCHIDEE-SOM against observations of DOC concentrations and SOC stocks from four European sites with different vegetation covers: A coniferous forest, a deciduous forest, a grassland, and a cropland. The model was able to reproduce the SOC stocks along their vertical profiles at the four sites and the DOC concentrations within the range of measurements, with the exception of the DOC concentrations in the upper soil horizon at the coniferous forest. However, the model was not able to fully capture the temporal dynamics of DOC concentrations. Further model improvements should focus on a plant- A nd depth-dependent parameterization of the new input model parameters, such as the turnover times of DOC and the microbial carbon use efficiency. We suggest that this new soil module, when parameterized for global simulations, will improve the representation of the global carbon cycle in LSMs, thus helping to constrain the predictions of the future SOC response to global warming. © Author(s) 2018.

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Foliar C, N, and P stoichiometry characterize successful plant ecological strategies in the Sonoran Desert

Castellanos A.E., Llano-Sotelo J.M., Machado-Encinas L.I., López-Piña J.E., Romo-Leon J.R., Sardans J., Peñuelas J. (2018) Foliar C, N, and P stoichiometry characterize successful plant ecological strategies in the Sonoran Desert. Plant Ecology. 219: 775-788.
Link
Doi: 10.1007/s11258-018-0833-3

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Ecological processes are centered to water availability in drylands; however, less known nutrient stoichiometry can help explain much of their structure and ecological interactions. Here we look to the foliar stoichiometry of carbon (C), nitrogen (N), and phosphorus (P) of 38 dominant plant species from the Sonoran Desert, grouped in four different functional types to describe ecological characteristics and processes. We found that foliar N, C:N, C:P, and N:P stoichiometric ratios, but not P, were higher than those known to most other ecosystems and indicate P but not N limitations in leaves. Biological N fixers (BNF) had even higher leaf N concentrations, but bio-elemental concentrations and stoichiometry ratios were not different to other non-N-fixing legume species which underscores the need to understand the physiological mechanisms for high N, and to how costly BNF can succeed in P-limiting drylands environments. Stoichiometry ratios, and to lesser extent elemental concentrations, were able to characterize BNF and colonizing strategies in the Sonoran Desert, as well as explain leaf attribute differences, ecological processes, and biogeochemical niches in this dryland ecosystem, even when no direct reference is made to other water-limitation strategies. © 2018, Springer Science+Business Media B.V., part of Springer Nature.

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Correction to: Spatial Variation of Soil CO2, CH4 and N2O Fluxes Across Topographical Positions in Tropical Forests of the Guiana Shield (Ecosystems, (2018), (1-14), 10.1007/s10021-018-0232-6)

Courtois E.A., Stahl C., Van den Berge J., Bréchet L., Van Langenhove L., Richter A., Urbina I., Soong J.L., Peñuelas J., Janssens I.A. (2018) Correction to: Spatial Variation of Soil CO2, CH4 and N2O Fluxes Across Topographical Positions in Tropical Forests of the Guiana Shield (Ecosystems, (2018), (1-14), 10.1007/s10021-018-0232-6). Ecosystems. : 0-0.
Link
Doi: 10.1007/s10021-018-0281-x

Abstract:

This paper was published with several formatting errors. It will be republished with corrections in place. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.

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