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- Carbon density in boreal forests responds non-linearly to temperature: an example from the Greater Khingan Mountains, northeast ChinaPublication . Liu, Yang; Trancoso, Ralph; Ma, Qin; Ciais, Philippe; GouvĂȘa, Lidiane; Yue, Chaofang; Assis, Jorge; Blanco, Juan A.Boreal forests play a crucial role in the global carbon (C) cycle and in climate stabilization. To better predict global C budgets, it is important to accurately estimate the size of forest C pools, and to identify the factors affecting them. We used national forest inventory data for the Greater Khingan Mountains, northeast China from 1999 to 2018 and 149 additional field plots to estimate C storage and its changes in forest vegetation, excluding C stored in soils, and to calculate the total C density in forest ecosystems. From 1999 to 2018, the vegetation C storage and density increased by 92.22 Tg and 4.30 Mg C ha-1, respectively, while the mean C sink was 4.61 Tg C yr-1. Carbon storage and density showed the same pattern, with the largest stocks in trees, followed by herbs, shrubs, and then litter. Mean C density was higher in mature forests than in young forests. The maximum C density was recorded in Populus davidiana forests, and was 2.2-times larger than in Betula davurica forests (the minimum). The mean (& PLUSMN; standard error) total C density of forest ecosystems was 111.3 & PLUSMN; 2.9 Mg C ha-1, including C stored in soils. Mean annual temperature (MAT) controlled total C density, as MAT had positive effects when it was lower than the temperature of the inflection point (-2.1 to -4.6 degrees C) and negative effects when it was above the inflection point. The rate of change in the total C density depended on the quantile points of the conditional distribution of total C density. Natural and anthropogenic disturbances had weaker effects on C density than temperature and precipitation. In conclusion, our results indicate that there might be a temperatureinduced pervasive decrease in C storage and an increase in tree mortality across Eastern Asian boreal forests with future climate warming.
- Global impacts of projected climate changes on the extent and aboveground biomass of mangrove forestsPublication . GouvĂȘa, Lidiane; A, SerrĂŁo; Cavanaugh, Kyle; Gurgel, Carlos F. D.; Horta, Paulo A.; Assis, JorgeAim: Over the past 50 years, anthropogenic activities have led to the disappearance of approximately one-third of the world's mangrove forests and their associated ecosystem services. The synergetic combined effect of projected climate change is likely to further impact mangroves in the years to come, whether by range expansions associated with warming at higher latitudes or large-scale diebacks linked to severe droughts. We provide an estimate of future changes in the extent and aboveground biomass (AGB) of mangrove forests at global scales by considering contrasting Representative Concentration Pathway scenarios (decade 2090-2100 under RCP 2.6 in line with the Paris Agreement expectations, and RCP 8.5 of higher emissions). Location: Global. Methods: Boosted regression trees fitted occurrence and AGB of mangroves against high-resolution biologically meaningful data on air temperature, precipitation, wave energy, slope and distance to river Deltas. Results: On the global scale, models produced for present-day conditions retrieved high accuracy scores and estimated a total area of 12,780,356 ha and overall biomass of 2.29 Pg, in line with previous estimates. Model projections showed poleward shifts along temperate regions, which translated into comparable gains in total area, regardless of the RCP scenario (area change RCP 2.6: 17.29%; RCP 8.5: 15.77%). However, biomass changes were dependent on the emission scenario considered, remaining stable or even increasing under RCP 2.6, or undergoing severe losses across tropical regions under RCP 8.5 (overall biomass change RCP 2.6: 12.97%; RCP 8.5: -11.51%). Such losses were particularly aggravated in countries located in the Tropical Atlantic and Eastern Pacific, and the Western and Eastern Indo-Pacific regions (regions with losses above similar to 20% in overall biomass). Conclusions: Our global estimates highlight the potential effect of future climate changes on mangrove forests and how broad compliance with the Paris Agreement may counteract severe trajectories of loss. The projections made, also provided at the country level, serve as new baselines to evaluate changes in mangrove carbon sequestration and ecosystem services, strongly supporting policy-making and management directives, as well as to guide restoration actions considering potential future changes in niche availability.
- Effects of ocean warming and pollution on Sargassum forestsPublication . Peres, LetĂcia M. Costa; GouvĂȘa, Lidiane; Hayden, Juliana; Burle, Giulia; Bastos, Eduardo; Carneiro, Alessandra; Horta, Paulo A.The combined effects of climate change and ocean pollution have resulted in a noteworthy decline of canopyforming species, impacting marine biodiversity and ecosystem functioning significantly. In this context, Sargassum cymosum, which is widely distributed along the southwestern Atlantic Ocean, serves as an excellent model among canopy-forming species to investigate these impacts on populations in different regions and environmental conditions. Here, we evaluate the ecophysiological responses of two populations of S. cymosum, from Florianopolis (warm-temperate province; WTP) and Fernando de Noronha (tropical province, TP), through of interaction of temperatures and nutrient concentrations, representing marine heatwaves and acute pollution levels. Our findings revealed a decrease in biomass in both populations, highlighting the significance of nutrient enrichment as an anthropogenic filter that might potentially inhibit the expansion of the populations from tropical regions and temperature for WTP ones. These stressors directly impacted the physiological performance of S. cymosum populations, including relative growth rates, photosynthesis, chlorophylls, carotenoids and phenolic compound levels. Although there was an increase in both parameters for the TP population, a significant loss of biomass was observed, with growth rates reaching -1.5% per day. Our results highlight the need for urgent actions to manage the eutrophication process due to its negative association with global warming, which can enhance the impacts and preclude the settlement and survival of Sargassum in warm-temperate areas considering the observed and predicted tropicalization process.
- BioâORACLE v3.0. pushing marine data layers to the CMIP6 earth system models of climate change researchPublication . Assis, Jorge; FernĂĄndez Bejarano, Salvador JesĂșs; Salazar, VinĂcius W.; Schepers, Lennert; GouvĂȘa, Lidiane; Fragkopoulou, Eliza; Leclercq, Frederic; Vanhoorne, Bart; Tyberghein, Lennert; Serrao, Ester; Verbruggen, Heroen; De Clerck, OlivierMotivation: Impacts of climate change on marine biodiversity are often projected with species distribution modelling using standardized data layers representing physical, chemical and biological conditions of the global ocean. Yet, the available data layers (1) have not been updated to incorporate data of the Sixth Phase of the Coupled Model Intercomparison Project (CMIP6), which comprise the Shared Socioeconomic Pathway (SSP) scenarios; (2) consider a limited number of Earth System Models (ESMs), and (3) miss important variables expected to influence future biodiversity distributions. These limitations might undermine biodiversity impact assessments, by failing to integrate them within the context of the most up-to-date climate change projections, raising the uncertainty in estimates and misinterpreting the exposure of biodiversity to extreme conditions. Here, we provide a significant update of Bio-ORACLE, extending biologically relevant data layers from present-day conditions to the end of the 21st century Shared Socioeconomic Pathway scenarios based on a multi-model ensemble with data from CMIP6. Alongside, we provide R and Python packages for seamless integration in modelling workflows. The data layers aim to enhance the understanding of the potential impacts of climate change on biodiversity and to support well-informed research, conservation and management. Main Types of Variable Contained: Surface and benthic layers for, chlorophyll-a, diffuse attenuation coefficient, dissolved iron, dissolved oxygen, nitrate, ocean temperature, pH, phosphate, photosynthetic active radiation, total phytoplankton, total cloud fraction, salinity, silicate, sea-water direction, sea-water velocity, topographic slope, topographic aspect, terrain ruggedness index, topographic position index and bathymetry, and surface layers for air temperature, mixed layer depth, sea-ice cover and sea-ice thickness. Spatial Location and Grain: Global at 0.05 degrees resolution. Time Period and GrainDecadal from present-day to the end of the 21st century (2000-2100). Major Taxa and Level of Measurement: Marine biodiversity associated with surface and epibenthic habitats. Software Format: A package of functions developed for Python and R software.
- Phenotypic plasticity in sargassum forests may not counteract projected biomass losses along a broad latitudinal gradientPublication . GouvĂȘa, Lidiane; Horta, Paulo A.; Fragkopoulou, Eliza; Gurgel, Carlos F. D.; Peres, Leticia M. C.; Bastos, Eduardo; Ramlov, Fernanda; Burle, Giulia; Koerich, Gabrielle; Martins, Cintia D. L.; Serrao, Ester; Assis, JorgePhenotypic plasticity and local adaptation can adjust individual responses to environmental changes across species' ranges. Studies addressing the implications of such traits have been underrepresented in the marine environment. Sargassum cymosum represents an ideal model to test phenotypic plasticity, as populations along the southwestern Atlantic Ocean display a sharp decrease in abundance toward distributional range limits. We (1) characterized the macroecological environment of S. cymosum across a latitudinal gradient, (2) evaluated potential differences in ecophysiological adjustments (biomass, photosynthetic pigments, phenolic compounds, total soluble sugars and proteins, and carbon-nitrogen-CN-content), and (3) tested for differences in thermal tolerance based on time series analyses produced from the present to contrasting representative concentration pathways scenarios (RCP) of future climate changes. Our results showed distinct macroecological environments, corresponding to tropical and warm temperate conditions, driving biomass and ecophysiological adjustments of S. cymosum. Populations from the two environments displayed contrasting thermal tolerances, with tropical individuals better coping with thermal stress when compared to more temperate ones (lethal temperatures of 33 degrees C vs. 30 degrees C); yet both populations lose biomass in response to increasing thermal stress while increasing secondary metabolites (for example, carotenoids and phenolic compounds) and decrease chlorophyll's content, Fv/Fm, total soluble sugars concentration and CN ratio, owing to oxidative stress. Despite evidence for phenotypic plasticity, significant future losses might occur in both tropical and warm temperate populations, particularly under the no mitigation RCP scenario, also known as the business as usual (that is, 8.5). In this context, broad compliance with the Paris Agreement might counteract projected impacts of climate change, safeguarding Sargassum forests in the years to come.
- Kelp forest diversity under projected endâofâcentury climate changePublication . Assis, Jorge; Fragkopoulou, Eliza; GouvĂȘa, Lidiane; AraĂșjo, Miguel B.; Serrao, EsterAim: Future climate change threatens marine forests across the world, potentially disrupting ecosystem function and services. Nonetheless, the direction and intensity of climate-induced changes in kelp forest biodiversity remain unknown, precluding well-informed conservation and management practices. Location: Global. Methods: We use machine-learning models to forecast global changes in species richness and community composition of 105 kelp forest species under contrasting Shared Socioeconomic Pathway (SSP) scenarios of climate change (decade 2090-2100): one aligned with the Paris Agreement and another of substantially higher emissions. Results: A poleward and depth shift in species distributions is forecasted, translating into similar to 15% less area in the extent of the global biome, coupled with marked regional biodiversity changes. Community composition changes are mostly projected in the Arctic, the Northern Pacific and Atlantic, and Australasia, owing to poleward range expansions and wide low latitude losses. Main Conclusions: By surpassing the Paris Agreement expectations, species reshuffling may simplify and impair ecosystem services in numerous temperate regions of Australasia, Southern Africa, Southern America and the Northern Atlantic, and in the tropical Pacific, where complete species losses were projected without replacement. These estimates, flagging threatened regions and species, as well as refugial areas of population persistence, can now inform conservation, management and restoration practices considering future climate change.
- Range map data of marine ecosystem structuring species under global climate changePublication . GouvĂȘa, Lidiane; Fragkopoulou, Eliza; Legrand, TĂ©rence; Serrao, Ester; Assis, JorgeData on contemporary and future geographical distributions of marine species are crucial for guiding conservation and management policies in face of climate change. However, available distributional patterns have overlooked key ecosystem structuring species, despite their numerous ecological and socioeconomic services. Future range estimates are mostly available for few species at regional scales, and often rely on the outdated Representative Concentration Pathway scenarios of climate change, hindering global biodiversity estimates within the framework of current international climate policies. Here, we provide range maps for 980 marine structuring species of seagrasses, kelps, fucoids, and cold-water corals under present-day conditions (from 2010 to 2020) and future scenarios (from 2090 to 2100) spanning from low carbon emission scenarios aligned with the goals of the Paris Agreement (Shared Socioeconomic Pathway 1-1.9), to higher emissions under reduced mitigation strategies (SSP3-7.0 and SSP5-8.5). These models were developed using state-ofthe-art and advanced machine learning algorithms linking the most comprehensive and quality-controlled datasets of occurrence records with high-resolution, biologically relevant predictor variables. By integrating the best aspects of species distribution modelling over key ecosystem structuring species, our datasets hold the potential to enhance the ability to inform strategic and effective conservation policy, ultimately supporting the resilience of ocean ecosystems.
- Oceanographic connectivity explains the intra-specific diversity of mangrove forests at global scalesPublication . GouvĂȘa, Lidiane; Fragkopoulou, Eliza; Cavanaugh, Kyle; Serrao, Ester; AraĂșjo, Miguel B.; Costello, Mark John; Westergerling, E. H. Taraneh; Assis, JorgeThe distribution of mangrove intra-specific biodiversity can be structured by historical demographic processes that enhance or limit effective population sizes. Oceanographic connectivity (OC) may further structure intra-specific biodiversity by preserving or diluting the genetic signatures of historical changes. Despite its relevance for biogeography and evolution, the role of oceanographic connectivity in structuring the distribution of mangrove's genetic diversity has not been addressed at global scale. Here we ask whether connectivity mediated by ocean currents explains the intra-specific diversity of mangroves. A comprehensive dataset of population genetic differentiation was compiled from the literature. Multigenerational connectivity and population centrality indices were estimated with biophysical modeling coupled with network analyses. The variability explained in genetic differentiation was tested with competitive regression models built upon classical isolation-by-distance (IBD) models considering geographic distance. We show that oceanographic connectivity can explain the genetic differentiation of mangrove populations regardless of the species, region, and genetic marker (significant regression models in 95% of cases, with an average R-square of 0.44 +/- 0.23 and Person's correlation of 0.65 +/- 0.17), systematically improving IBD models. Centrality indices, providing information on important stepping-stone sites between biogeographic regions, were also important in explaining differentiation (R-square improvement of 0.06 +/- 0.07, up to 0.42). We further show that ocean currents produce skewed dispersal kernels for mangroves, highlighting the role of rare long-distance dispersal events responsible for histori- cal settlements. Overall, we demonstrate the role of oceanographic connectivity in structuring mangrove intra-specific diversity. Our findings are critical for mangroves' biogeography and evolution, but also for management strategies considering climate change and genetic biodiversity conservation.
- Unravelling the role of oceanographic connectivity in the distribution of genetic diversity of marine forests at the global scalePublication . Legrand, TĂ©rence; Fragkopoulou, Eliza; GouvĂȘa, Lidiane; Serrao, Ester A.; Assis, Jorge; Vapillon, LaurenAim Genetic diversity of marine forests results from complex interactions of eco-evolutionary processes. Among them, oceanographic connectivity driven by dispersal through water transport is hypothesized to play a pivotal role, yet its relative contribution has not been addressed at the global scale. Here, we test how present-day oceanographic connectivity is correlated with the distribution of genetic diversity of marine forests across the ocean. Location Global. Time period Contemporary. Major taxa studied Marine forests of brown macroalgae (order: Fucales, Ishigeales, Laminariales and Tilopteridales). Methods Through literature review, we compiled a comprehensive dataset of genetic differentiation, encompassing 699 populations of 30 species. A biophysical model coupled with network analyses estimated multigenerational oceanographic connectivity and centrality across the marine forest global distribution. This approach integrated propagule dispersive capacity and long-distance dispersal events. Linear mixed models tested the relative contribution of site-specific processes, connectivity and centrality in explaining genetic differentiation. Results We show that spatiality-dependent eco-evolutionary processes, as described by our models, are prominent drivers of genetic differentiation in marine forests (significant models in 91.43% of the cases with an average R2 of 0.50â±â0.07). Specifically, we reveal that 18.7% of genetic differentiation variance is explicitly induced by predicted contemporary connectivity and centrality. Moreover, we demonstrate that long-distance dispersal is key in connecting populations of species distributed across large water masses and continents. Main conclusions Our findings highlight the role of present-day oceanographic connectivity in shaping the extant distribution of genetic diversity of marine forests on a global scale, with significant implications for biogeography and evolution. This understanding can pave the way for future research aimed at guiding conservation efforts, including the designation of well-connected marine protected areas, which is particularly relevant for sessile ecosystems structuring species such as brown macroalgae.
- Seagrass biodiversity under the latestâgeneration scenarios of projected climate changePublication . GouvĂȘa, Lidiane; Fragkopoulou, Eliza; AraĂșjo, Miguel B.; Serrao, Ester A.; Assis, JorgeAimThe potentially cascading consequences of climate changes on redistribution of habitat-forming species, like seagrasses, remain a major research gap. Empirical demonstrations of local population changes are increasingly reported without a globally integrated predictive framework as a leading testable hypothesis. Therefore, here, we aimed to estimate changes in species richness, community composition, and areas of climatic refugia under future climate scenarios.LocationGlobal scale.Time PeriodPresent-day conditions (from 2010 to 2020) and for three Shared Socioeconomic Pathway (SSP) scenarios of future climate change (from 2090 to 2100).Major Taxa StudiesSeagrasses (plantae).MethodsWe coupled seagrass occurrences with environmental predictors (temperature, salinity, nitrate, wave energy, and ice) in stacked species distribution modelling.ResultsModels estimated a present global extent of 917,169 km2 with high species richness in Temperate Australasia, Indo-Pacific, and Temperate North Pacific. Future projections predicted widespread spatial redistribution, with Arctic expansions, losses in lower latitudes, and deeper vertical ranges, while globally maintaining the area extent occupied worldwide by seagrass species (only 5% of change). Species richness increased poleward under more drastic scenarios (SSP3-7.0 and SSP5-8.5), with losses in tropical zones (30oN to 30oS). Local climatic refugia are retained in all scenarios but decrease under higher emissions. Additionally, even where seagrass species remain, widespread community composition changes were predicted.Main ConclusionsOur findings serve as baselines to inform, anticipate, and mitigate cascading consequences of shifts in seagrass ecosystems that provide essential services for humanity.