Batllori E., De Cáceres M., Brotons L., Ackerly D.D., Moritz M.A., Lloret F. (2019) Compound fire-drought regimes promote ecosystem transitions in Mediterranean ecosystems. Journal of Ecology. 107: 1187-1198.EnllaçDoi: 10.1111/1365-2745.13115
Understanding ecosystem responses to compound disturbance regimes and the influence of specific sequences of events in determining ecosystem shifts remains a challenge. We use a modelling framework for Mediterranean-type ecosystems to assess the effects of fire–drought interactions on long-term vegetation dynamics and to identify disturbance-driven changes in trait composition (tree seeder vs. tree resprouter prevalence) and ecosystem state (forest vs. non-forest). Changes in tree seeder and the tree resprouter dominance show nonlinear, threshold-type trends over gradients of increasing compound disturbance frequency. Vegetation composition thresholds mostly occur in a narrow range of the compound fire–drought disturbance space. Additionally, trait compositional switches and the likelihood of sudden changes in ecosystem state are promoted by fire-drought interactions. Distinct sequences of disturbance events cause vegetation transitions, disrupting ecosystem resilience, even under moderate recurrence of individual disturbances. An extreme drought year followed by one or two large fire events promotes shifts from resprouter- to seeder dominance. Contrastingly, a large crown fire followed by an extreme drought promotes changes from seeder to resprouter dominance. This disturbance sequence is also a mechanism strong enough to trigger sudden shifts in ecosystem state (from forest to non-forest). Synthesis. Thresholds of change in vegetation composition occur over a narrow range of the modelled gradients of compound fire-drought recurrence, and the loss of ecosystem resilience is contingent on particular sequences of disturbance events. Overall, our findings highlight that disturbance interactions define the relative location of tipping points in ecosystem state, and that effects and feedbacks of compound disturbance regimes increase the long-term likelihood of sudden ecosystem shifts and, therefore, uncertainty in predicting vegetation state. © 2018 The Authors. Journal of Ecology © 2018 British Ecological Society
Barba, J., Lloret, F., Poyatos, R., Molowny-Horas, R., Yuste, J.C. (2018) Multi-temporal influence of vegetation on soil respiration in a droughtaffected forest. IForest. 11: 189-198.EnllaçDoi: 10.3832/ifor2448-011
Dornelas M., Antão L.H., Moyes F., Bates A.E., Magurran A.E., Adam D., Akhmetzhanova A.A., Appeltans W., Arcos J.M., Arnold H., Ayyappan N., Badihi G., Baird A.H., Barbosa M., Barreto T.E., Bässler C., Bellgrove A., Belmaker J., Benedetti-Cecchi L., Bett B.J., Bjorkman A.D., Błażewicz M., Blowes S.A., Bloch C.P., Bonebrake T.C., Boyd S., Bradford M., Brooks A.J., Brown J.H., Bruelheide H., Budy P., Carvalho F., Castañeda-Moya E., Chen C.A., Chamblee J.F., Chase T.J., Siegwart Collier L., Collinge S.K., Condit R., Cooper E.J., Cornelissen J.H.C., Cotano U., Kyle Crow S., Damasceno G., Davies C.H., Davis R.A., Day F.P., Degraer S., Doherty T.S., Dunn T.E., Durigan G., Duffy J.E., Edelist D., Edgar G.J., Elahi R., Elmendorf S.C., Enemar A., Ernest S.K.M., Escribano R., Estiarte M., Evans B.S., Fan T.-Y., Turini Farah F., Loureiro Fernandes L., Farneda F.Z., Fidelis A., Fitt R., Fosaa A.M., Daher Correa Franco G.A., Frank G.E., Fraser W.R., García H., Cazzolla Gatti R., Givan O., Gorgone-Barbosa E., Gould W.A., Gries C., Grossman G.D., Gutierréz J.R., Hale S., Harmon M.E., Harte J., Haskins G., Henshaw D.L., Hermanutz L., Hidalgo P., Higuchi P., Hoey A., Van Hoey G., Hofgaard A., Holeck K., Hollister R.D., Holmes R., Hoogenboom M., Hsieh C.-H., Hubbell S.P., Huettmann F., Huffard C.L., Hurlbert A.H., Macedo Ivanauskas N., Janík D., Jandt U., Jażdżewska A., Johannessen T., Johnstone J., Jones J., Jones F.A.M., Kang J., Kartawijaya T., Keeley E.C., Kelt D.A., Kinnear R., Klanderud K., Knutsen H., Koenig C.C., Kortz A.R., Král K., Kuhnz L.A., Kuo C.-Y., Kushner D.J., Laguionie-Marchais C., Lancaster L.T., Min Lee C., Lefcheck J.S., Lévesque E., Lightfoot D., Lloret F., Lloyd J.D., López-Baucells A., Louzao M., Madin J.S., Magnússon B., Malamud S., Matthews I., McFarland K.P., McGill B., McKnight D., McLarney W.O., Meador J., Meserve P.L., Metcalfe D.J., Meyer C.F.J., Michelsen A., Milchakova N., Moens T., Moland E., Moore J., Mathias Moreira C., Müller J., Murphy G., Myers-Smith I.H., Myster R.W., Naumov A., Neat F., Nelson J.A., Paul Nelson M., Newton S.F., Norden N., Oliver J.C., Olsen E.M., Onipchenko V.G., Pabis K., Pabst R.J., Paquette A., Pardede S., Paterson D.M., Pélissier R., Peñuelas J., Pérez-Matus A., Pizarro O., Pomati F., Post E., Prins H.H.T., Priscu J.C., Provoost P., Prudic K.L., Pulliainen E., Ramesh B.R., Mendivil Ramos O., Rassweiler A., Rebelo J.E., Reed D.C., Reich P.B., Remillard S.M., Richardson A.J., Richardson J.P., van Rijn I., Rocha R., Rivera-Monroy V.H., Rixen C., Robinson K.P., Ribeiro Rodrigues R., de Cerqueira Rossa-Feres D., Rudstam L., Ruhl H., Ruz C.S., Sampaio E.M., Rybicki N., Rypel A., Sal S., Salgado B., Santos F.A.M., Savassi-Coutinho A.P., Scanga S., Schmidt J., Schooley R., Setiawan F., Shao K.-T., Shaver G.R., Sherman S., Sherry T.W., Siciński J., Sievers C., da Silva A.C., Rodrigues da Silva F., Silveira F.L., Slingsby J., Smart T., Snell S.J., Soudzilovskaia N.A., Souza G.B.G., Maluf Souza F., Castro Souza V., Stallings C.D., Stanforth R., Stanley E.H., Mauro Sterza J., Stevens M., Stuart-Smith R., Rondon Suarez Y., Supp S., Yoshio Tamashiro J., Tarigan S., Thiede G.P., Thorn S., Tolvanen A., Teresa Zugliani Toniato M., Totland Ø., Twilley R.R., Vaitkus G., Valdivia N., Vallejo M.I., Valone T.J., Van Colen C., Vanaverbeke J., Venturoli F., Verheye H.M., Vianna M., Vieira R.P., Vrška T., Quang Vu C., Van Vu L., Waide R.B., Waldock C., Watts D., Webb S., Wesołowski T., White E.P., Widdicombe C.E., Wilgers D., Williams R., Williams S.B., Williamson M., Willig M.R., Willis T.J., Wipf S., Woods K.D., Woehler E.J., Zawada K., Zettler M.L. (2018) BioTIME: A database of biodiversity time series for the Anthropocene. Global Ecology and Biogeography. 27: 760-786.EnllaçDoi: 10.1111/geb.12729
Motivation: The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene. Main types of variables included: The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record. Spatial location and grain: BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2). Time period and grain: BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year. Major taxa and level of measurement: BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates. Software format:.csv and.SQL. © 2018 The Authors. Global Ecology and Biogeography Published by John Wiley & Sons Ltd
Garnier E., Vile D., Roumet C., Lavorel S., Grigulis K., Navas M.-L., Lloret F. (2018) Inter- and intra-specific trait shifts among sites differing in drought conditions at the north western edge of the Mediterranean Region. Flora: Morphology, Distribution, Functional Ecology of Plants. : 0-0.EnllaçDoi: 10.1016/j.flora.2018.07.009
Identifying consistent and predictable associations between traits and environment is one of the oldest quest of ecology. Yet, there are few formal and robust quantification of such associations, which seriously impedes our capacity to predict how ecological systems respond to global changes, including climate. This study was designed to assess how differences in environmental conditions affect plant form and function in a wide array of species. Twelve traits were measured on 40 species in three Mediterranean sites differing in drought conditions. Some species being common among sites, 78 species belonging to four major Raunkiær life form categories were studied. These traits correspond to: (i) plant size: vegetative and maximum plant height, (ii) seed mass, (iii) leaf morpho-anatomical traits: leaf area, specific leaf area, dry matter content and thickness, (iv) leaf chemical composition: mass based nitrogen, phosphorus and carbon contents, and carbon isotopic fraction. On average, there was a shift in the phenotypic space towards more resource conservative and taller species in the drier sites. These changes were not always consistent for hemicryptophytes and chamaephytes on the one hand, and for phanerophytes on the other hand. This is interpreted as different species responding to different aspects of complex changes in environmental factors. Intraspecific trait variation differed among species, and was lower than interspecific variation. Changes in site-average trait values were therefore mostly driven by species turnover among sites. The traits selected do not respond strongly to the differences in environmental conditions however, resulting in a moderate shift in the phenotypic space between sites. We argue that traits more directly related to plant water economy should be considered for an improved description of plant phenotypic response to the environmental factors at stake. The implications for the prediction of plant responses to climate changes likely to occur in the Mediterranean Region are discussed. © 2018
Hartmann, H., Moura, C.F., Anderegg, W.R.L., Ruehr, N.K., Salmon, Y., Allen, C.D., Arndt, S.K., Breshears, D.D., Davi, H., Galbraith, D., Ruthrof, K.X., Wunder, J., Adams, H.D., Bloemen, J., Cailleret, M., Cobb, R., Gessler, A., Grams, T.E.E., Jansen, S., Kautz, M., Lloret, F., O'Brien, M. (2018) Research frontiers for improving our understanding of drought-induced tree and forest mortality. New Phytologist. 218: 15-28.EnllaçDoi: 10.1111/nph.15048
Lloret F., Kitzberger T. (2018) Historical and event-based bioclimatic suitability predicts regional forest vulnerability to compound effects of severe drought and bark beetle infestation. Global Change Biology. 24: 1952-1964.EnllaçDoi: 10.1111/gcb.14039
Vulnerability to climate change, and particularly to climate extreme events, is expected to vary across species ranges. Thus, we need tools to standardize the variability in regional climatic legacy and extreme climate across populations and species. Extreme climate events (e.g., droughts) can erode populations close to the limits of species' climatic tolerance. Populations in climatic-core locations may also become vulnerable because they have developed a greater demand for resources (i.e., water) that cannot be enough satisfied during the periods of scarcity. These mechanisms can become exacerbated in tree populations when combined with antagonistic biotic interactions, such as insect infestation. We used climatic suitability indices derived from Species Distribution Models (SDMs) to standardize the climatic conditions experienced across Pinus edulis populations in southwestern North America, during a historical period (1972–2000) and during an extreme event (2001–2007), when the compound effect of hot drought and bark beetle infestation caused widespread die-off and mortality. Pinus edulis climatic suitability diminished dramatically during the die-off period, with remarkable variation between years. P. edulis die-off occurred mainly not just in sites that experienced lower climatic suitability during the drought but also where climatic suitability was higher during the historical period. The combined effect of historically high climatic suitability and a marked decrease in the climatic suitability during the drought best explained the range-wide mortality. Lagged effects of climatic suitability loss in previous years and co-occurrence of Juniperus monosperma also explained P. edulis die-off in particular years. Overall, the study shows that past climatic legacy, likely determining acclimation, together with competitive interactions plays a major role in responses to extreme drought. It also provides a new approach to standardize the magnitude of climatic variability across populations using SDMs, improving our capacity to predict population's or species' vulnerability to climatic change. © 2018 John Wiley & Sons Ltd
Lloret F., Sapes G., Rosas T., Galiano L., Saura-Mas S., Sala A., Martínez-Vilalta J. (2018) Non-structural carbohydrate dynamics associated with drought-induced die-off in woody species of a shrubland community. Annals of Botany. 121: 1383-1396.EnllaçDoi: 10.1093/aob/mcy039
Background and Aims The relationship between plant carbon economy and drought responses of co-occurring woody species can be assessed by comparing carbohydrate (C) dynamics following drought and rain periods, relating these dynamics to species' functional traits. We studied nine woody species coexisting in a continental Mediterranean shrubland that experienced severe drought effects followed by rain. Methods We measured total non-structural carbohydrates (NSC) and soluble sugars (SS) in roots and stems during drought and after an autumn rain pulse in plants exhibiting leaf loss and in undefoliated ones. We explored whether their dynamics were related to foliage recovery and functional traits (height [H], specific leaf area [SLA], wood density [WD]). Key Results During drought, NSC concentrations were overall lower in stems and roots of plants experiencing leaf loss, while SS decreases were smaller. Roots had higher NSC concentrations than stems. After the rain, NSC concentrations continued to decrease, while SS increased. Green foliage recovered after rain, particularly in plants previously experiencing higher leaf loss, independently of NSC concentrations during drought. Species with lower WD tended to have more SS during drought and lower SS increases after rain. In low-WD species, plants with severe leaf loss had lower NSC relative to undefoliated ones. No significant relationship was found between H or SLA and C content or dynamics. Conclusions Our community-level study reveals that, while responses were species-specific, C stocks overall diminished in plants affected by prolonged drought and did not increase after a pulse of seasonal rain. Dynamics were faster for SS than NSC. We found limited depletion of SS, consistent with their role in basal metabolic, transport and signalling functions. In a scenario of increased drought under climate change, NSC stocks in woody plants are expected to decrease differentially in coexisting species, with potential implications for their adaptive abilities and community dynamics. © The Author(s) 2018.
Pérez Navarro M.Á., Sapes G., Batllori E., Serra-Diaz J.M., Esteve M.A., Lloret F. (2018) Climatic Suitability Derived from Species Distribution Models Captures Community Responses to an Extreme Drought Episode. Ecosystems. : 1-14.EnllaçDoi: 10.1007/s10021-018-0254-0
The differential responses of co-occurring species in rich communities to climate change—particularly to drought episodes—have been fairly unexplored. Species distribution models (SDMs) are used to assess changes in species suitability under environmental shifts, but whether they can portray population and community responses is largely undetermined, especially in relation to extreme events. Here we studied a shrubland community in SE Spain because this region constitutes an ecotone between the Mediterranean biome and subtropical arid areas, and it has recently suffered its driest hydrological year on record. We used four different modeling algorithms (Mahalanobis distance, GAM, BRT, and MAXENT) to estimate species’ climatic suitability before (1950–2000) and during the extreme drought. For each SDM, we related species’ climatic suitability with their remaining green canopy as a proxy for species resistance to drought. We consistently found a positive correlation between remaining green canopy and species’ climatic suitability before the event. This relationship supports the hypothesis of a higher vulnerability of populations living closer to their species’ limits of aridity tolerance. Contrastingly, climatic suitability during the drought did not correlate with remaining green canopy, likely because the exceptional episode led to almost zero suitability values. Overall, our approach highlights climatic niche modeling as a robust approach to standardizing and comparing the behavior of different co-occurring species facing strong climatic fluctuations. Although many processes contribute to resistance to climatic extremes, the results confirm the relevance of populations’ position in the species’ climatic niche for explaining sensitivity to climate change. © 2018 Springer Science+Business Media, LLC, part of Springer Nature
Stuart-Haëntjens E., De Boeck H.J., Lemoine N.P., Mänd P., Kröel-Dulay G., Schmidt I.K., Jentsch A., Stampfli A., Anderegg W.R.L., Bahn M., Kreyling J., Wohlgemuth T., Lloret F., Classen A.T., Gough C.M., Smith M.D. (2018) Mean annual precipitation predicts primary production resistance and resilience to extreme drought. Science of the Total Environment. 636: 360-366.EnllaçDoi: 10.1016/j.scitotenv.2018.04.290
Extreme drought is increasing in frequency and intensity in many regions globally, with uncertain consequences for the resistance and resilience of ecosystem functions, including primary production. Primary production resistance, the capacity to withstand change during extreme drought, and resilience, the degree to which production recovers, vary among and within ecosystem types, obscuring generalized patterns of ecological stability. Theory and many observations suggest forest production is more resistant but less resilient than grassland production to extreme drought; however, studies of production sensitivity to precipitation variability indicate that the processes controlling resistance and resilience may be influenced more by mean annual precipitation (MAP) than ecosystem type. Here, we conducted a global meta-analysis to investigate primary production resistance and resilience to extreme drought in 64 forests and grasslands across a broad MAP gradient. We found resistance to extreme drought was predicted by MAP; however, grasslands (positive) and forests (negative) exhibited opposing resilience relationships with MAP. Our findings indicate that common plant physiological mechanisms may determine grassland and forest resistance to extreme drought, whereas differences among plant residents in turnover time, plant architecture, and drought adaptive strategies likely underlie divergent resilience patterns. The low resistance and resilience of dry grasslands suggests that these ecosystems are the most vulnerable to extreme drought – a vulnerability that is expected to compound as extreme drought frequency increases in the future. © 2018
Suarez M.L., Lloret F. (2018) Self-replacement after small-scale partial crown dieback in austral Nothofagus dombeyi forests affected by an extreme drought. Canadian Journal of Forest Research. 48: 412-420.EnllaçDoi: 10.1139/cjfr-2017-0305
The spectrum of structural response in drought-induced mortality (degree of partial crown mortality) could play a key role in pervasive changes in plant composition, as individual openings could reset self-replacement dynamics or trigger shifts in vegetation. Here we capture the community pattern 17 years after a drought episode over a range of canopy responses in Nothofagus dombeyi forests. We applied a widespread demographic approach to address evidence of species shifts vs. self-replacement and to relate partial dieback to understory structure and composition. Assuming that the outcome of growth release of the understory components can be observed 17 years after canopy loss, this study reveals evidence of self-replacement in N. dombeyi forests heavily affected by drought. Alternatively, when the co-dominant species A. chilensis is widely present in the understory and large gaps are opened, a compositional shift may be possible, with a potential change in forest functionality. Individual partial openings do not favor more shrubby communities or a shift toward a new community. Thus, partial crown dieback contributes to self-replacement mechanisms by hampering strong growth release in understory shrubs, as evident in plots with high mortality, and by facilitating the growth of dominant tree species. © 2018, Canadian Science Publishing. All rights reserved.
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