Long-term response of forest productivity to climate change is mostly driven by change in tree species composition

Morin X., Fahse L., Jactel H., Scherer-Lorenzen M., García-Valdés R., Bugmann H. (2018) Long-term response of forest productivity to climate change is mostly driven by change in tree species composition. Scientific Reports. 8: 0-0.
Link
Doi: 10.1038/s41598-018-23763-y

Abstract:

Climate change affects ecosystem functioning directly through impacts on plant physiology, resulting in changes of global productivity. However, climate change has also an indirect impact on ecosystems, through changes in the composition and diversity of plant communities. The relative importance of these direct and indirect effects has not been evaluated within a same generic approach yet. Here we took advantage of a novel approach for disentangling these two effects in European temperate forests across a large climatic gradient, through a large simulation-based study using a forest succession model. We first showed that if productivity positively correlates with realized tree species richness under a changed climate, indirect effects appear pivotal to understand the magnitude of climate change impacts on forest productivity. We further detailed how warmer and drier conditions may affect the diversity-productivity relationships (DPRs) of temperate forests in the long term, mostly through effects on species recruitment, ultimately enhancing or preventing complementarity in resource use. Furthermore, losing key species reduced the strength of DPRs more severely in environments that are becoming climatically harsher. By disentangling direct and indirect effects of climate change on ecosystem functioning, these findings explain why high-diversity forests are expected to be more resilient to climate change. © 2018 The Author(s).

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How to spend a dwindling greenhouse gas budget

Obersteiner, M., Bednar, J., Wagner, F., Gasser, T., Ciais, P., Forsell, N., Frank, S., Havlik, P., Valin, H., Janssens, I.A., Peñuelas, J., Schmidt-Traub, G. (2018) How to spend a dwindling greenhouse gas budget. Nature Climate Change. 8: 7-10.
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Doi: 10.1038/s41558-017-0045-1

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High planktonic diversity in mountain lakes contains similar contributions of autotrophic, heterotrophic and parasitic eukaryotic life forms

Ortiz-Álvarez R., Triadó-Margarit X., Camarero L., Casamayor E.O., Catalan J. (2018) High planktonic diversity in mountain lakes contains similar contributions of autotrophic, heterotrophic and parasitic eukaryotic life forms. Scientific Reports. 8: 0-0.
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Doi: 10.1038/s41598-018-22835-3

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A rich eukaryotic planktonic community exists in high-mountain lakes despite the diluted, oligotrophic and cold, harsh prevailing conditions. Attempts of an overarching appraisal have been traditionally hampered by observational limitations of small, colorless, and soft eukaryotes. We aimed to uncover the regional eukaryotic biodiversity of a mountain lakes district to obtain general conclusions on diversity patterns, dominance, geographic diversification, and food-web players common to oligotrophic worldwide distributed freshwater systems. An unprecedented survey of 227 high-altitude lakes comprising large environmental gradients was carried out using Illumina massive tag sequencing of the 18S rRNA gene. We observed a large Chrysophyceae dominance in richness, abundance and novelty, and unveiled an unexpected richness in heterotrophic phagotrophs and parasites. In particular, Cercozoa and Chytridiomycota showed diversity features similar to the dominant autotrophic groups. The prominent beta-dispersion shown by parasites suggests highly specific interactions and a relevant role in food webs. Interestingly, the freshwater Pyrenean metacommunity contained more diverse specific populations than its closest marine oligotrophic equivalent, with consistently higher beta-diversity. The relevance of unseen groups opens new perspectives for the better understanding of planktonic food webs. Mountain lakes, with remarkable environmental idiosyncrasies, may be suitable environments for the genetic diversification of microscopic eukaryotic life forms. © 2018 The Author(s).

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Critical temperature and precipitation thresholds for the onset of xylogenesis of Juniperus przewalskii in a semi-arid area of the north-eastern Tibetan Plateau

Ren P., Rossi S., Camarero J.J., Ellison A.M., Liang E., Peñuelas J. (2018) Critical temperature and precipitation thresholds for the onset of xylogenesis of Juniperus przewalskii in a semi-arid area of the north-eastern Tibetan Plateau. Annals of Botany. 121: 617-624.
Link
Doi: 10.1093/aob/mcx188

Abstract:

Background and Aims The onset of xylogenesis plays an important role in tree growth and carbon sequestration, and it is thus a key variable in modelling the responses of forest ecosystems to climate change. Temperature regulates the resumption of cambial activity, but little is known about the effect of water availability on the onset of xylogenesis in cold but semi-arid regions. Methods The onset of xylogenesis during 2009-2014 was monitored by weekly microcoring Juniperus przewalskii trees at upper and lower treelines on the north-eastern Tibetan Plateau. A logistic regression was used to calculate the probability of xylogenic activity at a given temperature and a two-dimensional reverse Gaussian model to fit the differences between the observed and estimated days of xylogenesis onset at given temperatures and precipitation within a certain time window. Key Results The thermal thresholds at the beginning of the growing season were highly variable, suggesting that temperature was not the only factor initiating xylem growth under cold and dry climatic conditions. The onset of xylogenesis was well predicted for climatic thresholds characterized by a cumulative precipitation of 17.0 ± 5.6 mm and an average minimum temperature of 1.5 ± 1.4 °C for a period of 12 d. Conclusions Xylogenesis in semi-arid regions with dry winters and springs can start when both critical temperature and precipitation thresholds are reached. Such findings contribute to our knowledge of the environmental drivers of growth resumption that previously had been investigated largely in cold regions without water shortages during early growing seasons. Models of the onset of xylogenesis should include water availability to improve predictions of xylem phenology in dry areas. A mismatch between the thresholds of temperature and moisture for the onset of xylogenesis may increase forest vulnerability in semi-arid areas under forecasted warmer and drier conditions. © 2017 The Author(s). Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.

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Glacial refugia and mid-Holocene expansion delineate the current distribution of Castanea sativa in Europe

Roces-Díaz, J.V., Jiménez-Alfaro, B., Chytrý, M., Díaz-Varela, E.R., Álvarez-Álvarez, P. (2018) Glacial refugia and mid-Holocene expansion delineate the current distribution of Castanea sativa in Europe. Palaeogeography, Palaeoclimatology, Palaeoecology. 491: 152-160.
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Doi: 10.1016/j.palaeo.2017.12.004

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The spatial level of analysis affects the patterns of forest ecosystem services supply and their relationships

Roces-Díaz, J.V., Vayreda, J., Banqué-Casanovas, M., Díaz-Varela, E., Bonet, J.A., Brotons, L., de-Miguel, S., Herrando, S., Martínez-Vilalta, J. (2018) The spatial level of analysis affects the patterns of forest ecosystem services supply and their relationships. Science of the Total Environment. 626: 1270-1283.
Link
Doi: 10.1016/j.scitotenv.2018.01.150

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Zero-sum landscape effects on acorn predation associated with shifts in granivore insect community in new holm oak (Quercus ilex) forests

Ruiz-Carbayo, H., Bonal, R., Pino, J., Espelta, J.M. (2018) Zero-sum landscape effects on acorn predation associated with shifts in granivore insect community in new holm oak (Quercus ilex) forests. Diversity and Distributions. : 0-0.
Link
Doi: 10.1111/ddi.12701

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Vapor–pressure deficit and extreme climatic variables limit tree growth

Sanginés de Cárcer, P., Vitasse, Y., Peñuelas, J., Jassey, V.E.J., Buttler, A., Signarbieux, C. (2018) Vapor–pressure deficit and extreme climatic variables limit tree growth. Global Change Biology. 24: 1108-1122.
Link
Doi: 10.1111/gcb.13973

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Changes in tree resistance, recovery and resilience across three successive extreme droughts in the northeast Iberian Peninsula

Serra-Maluquer X., Mencuccini M., Martínez-Vilalta J. (2018) Changes in tree resistance, recovery and resilience across three successive extreme droughts in the northeast Iberian Peninsula. Oecologia. : 1-12.
Link
Doi: 10.1007/s00442-018-4118-2

Abstract:

Understanding which variables affect forest resilience to extreme drought is key to predict future dynamics under ongoing climate change. In this study, we analyzed how tree resistance, recovery and resilience to drought have changed along three consecutive droughts and how they were affected by species, tree size, plot basal area (as a proxy for competition) and climate. We focused on the three most abundant pine species in the northeast Iberian Peninsula: Pinus halepensis, P. nigra and P. sylvestris during the three most extreme droughts recorded in the period 1951–2010 (occurred in 1986, 1994, and 2005–2006). We cored trees from permanent sample plots and used dendrochronological techniques to estimate resistance (ability to maintain growth level during drought), recovery (growth increase after drought) and resilience (capacity to recover pre-drought growth levels) in terms of tree stem basal area increment. Mixed-effects models were used to determine which tree- and plot-level variables were the main determinants of resistance, recovery and resilience, and to test for differences among the studied droughts. Larger trees were significantly less resistant and resilient. Plot basal area effects were only observed for resilience, with a negative impact only during the last drought. Resistance, recovery and resilience differed across the studied drought events, so that the studied populations became less resistant, less resilient and recovered worse during the last two droughts. This pattern suggests an increased vulnerability to drought after successive drought episodes. © 2018 Springer-Verlag GmbH Germany, part of Springer Nature

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Lethal effects of Cr(III) alone and in combination with propiconazole and clothianidin in honey bees

Sgolastra, F., Blasioli, S., Renzi, T., Tosi, S., Medrzycki, P., Molowny-Horas, R., Porrini, C., Braschi, I. (2018) Lethal effects of Cr(III) alone and in combination with propiconazole and clothianidin in honey bees. Chemosphere. 191: 365-372.
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Doi: 10.1016/j.chemosphere.2017.10.068

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