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Recent Water Constraints Mediate the Dominance of Climate and Atmospheric CO2 on Vegetation Growth
China’s vegetation growth has shown a broad increase under climate change and human activities over the past few decades. At the same time, changes in vegetation water demand, terrestrial water availability, and climatic factors are expected to lead to increasing water constraints on vegetation growth. Pictures: @Pixabay Since the Industrial Revolution, climate change and direct human activities have shown a significant impact on water, carbon, and energy exchanges between the land surface and the atmosphere across a large part of the planet. Too much or too little water availability can disrupt normal vegetation growth, both for natural and cultivated plants.
Although recent studies have shown that global vegetation is greening as a result of elevated atmospheric carbon dioxide (CO2) concentrations, nitrogen deposition, climate warming, and changes in land‐use and land‐management at regional and continental scales, this is simultaneously exacerbating water demands on ecosystems to some extent. In addition, global ecosystems are projected to become increasingly vulnerable to droughts associated with climate change in the future. Thus, we are obliged to take into account water constraints on vegetation growth when looking at the current phenomenon of the greening of the Earth.
New paper published in Earth’s Future studies vegetation growth that has taken place in China under climate change and human activities over the past few decades. In this study, authors provide a comprehensive assessment of recent water constraints and their implications for vegetation growth in China between 1982 and 2015. Authors analyse the spatiotemporal patterns of the relationship between vegetation growth and water availability.
According to this study, recent water constraints on vegetation growth were hidden in the overall greening of China. More than half of China’s vegetated areas were regarded as vegetation water deficit regions, with this situation being expected to worsen in the future. “More importantly, our study revealed that climate and atmospheric CO2 had different weights in regulating vegetation growth across water deficit and water surplus regions”, highlights Dr. Yang Song from Institute of Crop Sciences and National Nanfan Research Institute (Sanya), Chinese Academy of Agricultural Sciences, China.
In Further analysis this study shows that climate and atmospheric CO2 have exerted varying levels of importance in regulating vegetation growth across different water constraints. With increasing water constraints, more regions become climate‐dominated and fewer become CO2‐dominated.
“Overall, our findings are important for further understanding land carbon sink under climate change, highlighting the need for explicit consideration of water constraints on sustainable vegetation greening trends. As an indirect climate change impact, water constraints on vegetation growth should be considered by land surface models to reduce uncertainties in terrestrial water and CO2 flux projections. This will help decision‐makers recognize the uncertainty of sustainable vegetation greening trends” concludes Prof Josep Peñuelas, from CREAF-CSIC.
Reference: Song, Y., Penuelas, J., Ciais, P., Wang, S., Zhang, Y., Gentine, P., McCabe, M.F., Wang, L., Li, X., Li, F., Wang, X., Jin, Z., Wu, C., Jin, X. 2024. Recent Water Constraints Mediate the Dominance of Climate and Atmospheric CO2 on Vegetation Growth Across China. Earth’s Future 12(6), e2023EF004395. Doi: 10.1029/2023EF004395.
La Legislatura del no retorn
Des del món científic portem dècades alertant de la gravetat de la crisi ambiental global i de com es va tancant la finestra d’oportunitat per impedir les pitjors conseqüències de la desestabilització climàtica i ecològica del Planeta. Si no articulem accions polítiques que situïn aquest repte al centre de les prioritats del nou govern, ens movem cap al col•lapse de molts sectors productius i cap a unes condicions de vida molt més adverses que les actuals.
Les manifestacions són cada vegada més alarmants. També a Catalunya, amb una sequera que sembla no tenir fi, temporals que s’enduen passejos i platges, morts prematures per onades de calor o la contaminació de l’aire, la pèrdua massiva i creixent de biodiversitat, o la degradació i minva d’un recurs tan essencial com l’aigua.
A nivell econòmic els costos ja ascendeixen als milers de milions d’euros anuals, només al Principat, i les conseqüències socials són preocupants, amb alces insostenibles de preus de productes bàsics, ERTOs d’empreses que no poden mantenir la producció, o les tensions entre sectors i territoris pel que fa al repartiment de l’aigua o la transició energètica.
La crisi climàtica i ecològica tindrà uns costos molt majors si es posposa l’acció
La crisi climàtica i ecològica tindrà uns costos molt majors si es posposa l’acció, que si l’afrontem avui. Només integrant de manera immediata i efectiva l’acció climàtica amb la conservació i ús sostenible de la natura correspondrem a la crida dels panells científics de les Nacions Unides (IPCC i IPBES) a mantenir-nos dins els límits ambientals de seguretat del Planeta.
Davant d’una nova contesa electoral a la Generalitat, hem d’instar amb urgència un full de ruta per la sostenibilitat de Catalunya basat en el consens científic.
És primordial accelerar l’abandonament dels combustibles fòssils; protegir i restaurar la biodiversitat; preservar els recursos hídrics i garantir la qualitat de l’aire; prevenir i reduir els residus de manera creïble i ambiciosa; planificar al màxim nivell i de manera transversal l’adaptació territorial i econòmica al canvi climàtic; garantir la justícia social i intergeneracional en tota aquesta transformació; educar sobre el profund canvi sociocultural que afrontem; i monitoritzar i retre comptes d’aquests punts de manera freqüent.
Està en mans de la societat a través del Govern i el Parlament liderar la inajornable transició ecològica del país
En context d’emergència ambienta la gestió de calamitats serà habitual. Està en mans de la societat a través del Govern i el Parlament liderar la inajornable transició ecològica del país. Però serà imprescindible que els principals sectors econòmics i socials (energia, agroalimentari, turisme, indústria, banca, sindicats…) els facin costat, perquè d’ells en depèn alinear l’economia i l’ocupació amb els diagnòstics de la ciència.
Com a persones dedicades a la ciència, és el nostre deure recalcar que ens apropem perillosament al punt de no retorn i denunciem les onades de desinformació que qüestionen la ciència mateixa com a font d’informació veraç. Per garantir l’estabilitat planetària aquesta és una dècada clau, però comptem amb gran talent humà, capacitat tecnològica, institucions de recerca i innovació, i capital social al servei del país. Aprofitem-ho; mai quatre anys havien estat tan transcendents.
La carta està firmada per Josep Peñuelas (CREAF-CSIC), Pep Canadell (CSIRO), Jaume Terradas (CREAF-UAB), Mar Reguant (ICREA-IAE-CSIC), Lluís Brotons (CREAF-CSIC) i Marta Torres (IDDRI).
Font: La Vanguardia
Monoterpene emissions from vegetation, a ‘thermometer” of plant health
Global vegetation is considerably affected by rising temperatures, for example the emissions of bVOCs, such as monoterpenes will increase with rising temperatures. Mnoterpenes role in the earth’s system extend from communication signals to influencing atmospheric processes. Image: Nature website.Terrestrial vegetation emits biogenic volatile organic compounds (bVOCs), particularly vast amounts of monoterpenes (MT; C10H16), into the atmosphere in response to abiotic drivers such as temperature. MT, in turn, influence ecological interactions and atmospheric chemistry. As global temperatures continue to rise and extreme heat events become more frequent, the temperature sensitivity of forests is emerging as a critical issue for understanding the impacts of climate change on forest ecosystems and atmospheric chemistry. One important aspect of this sensitivity is this emission of bVOCs, such as MT, which will increase with rising temperatures.
In a new paper published in One Earth journal, authors study these greater MT emissions resulting from rising temperatures that can have far-reaching and uncertain consequences for the biosphere, potentially disrupting its delicate balance and feedback mechanisms among ecology, atmospheric chemistry and climate.
Global emissions are usually estimated as a function of temperature with a fixed exponential relationship (β coefficient) across forest ecosystems and environmental conditions. The authors of this new study applied meta-analysis algorithms on 40 years of published monoterpene emission data and showed that the relationship between emissions and temperature is more sensitive and intricate than previously thought. “Considering the entire dataset, our analyses indicate that co-occurring environmental factors modify the temperature sensitivity of the emissions that are primarily related to the specific plant functional type (PFT). Implementing a PFT-dependent β in a biogenic emission model, demonstrated that atmospheric processes are exceptionally dependent on monoterpene emissions which are subject to amplified variations under rising temperatures“, explains Prof. Efstradios Bourtsoukidis, from The Cyprus Institute.
The results obtained in this study, however, suggest that the temperature responses of MT emissions may exhibit dynamic variations throughout the tree’s age. According to the authors should be noted that while a clear relationship between PFT and the β coefficient became evident, the role of the other parameters might have been underappreciated due to the frequently unreported values.
“With newly discovered biogenic MT sources and the challenge of modeling co-occurring environmental drivers on the biosphere, our study highlights the need for more process oriented research of biosphere-atmosphere interactions, particularly in tropical, pan-Arctic, grassland, and agricultural ecosystems. As the effects of climate change intensify, biogenic VOC emissions from global vegetation will play a crucial role in evaluating the health of ecosystems and influencing the atmospheric oxidation capacity, with implications for the chemical composition, aerosols, and climate”, concludes Prof. Josep Peñuelas from CREAF-CSIC.
Bourtsoukidis, E., Pozzer, A., Williams, J., Makowski, D., Penuelas, J., Matthaios, V., Lazoglou, G., Yañez-Serrano, A., Ciais, P., Lelieveld, J., Vrekoussis, M., Daskalakis, M., Sciare, J. 2024. High temperature sensitivity of monoterpene emissions from global vegetation. Communications Earth & Environment 5, 23 (2024). doi: 10.21203/rs.3.rs-2024459/v1.
Las fuentes de regiones con clima mediterráneo están amenazadas por el cambio global, según un estudio en el que participa la UMH y la Global Ecology Unit
Los ecosistemas fontinales ubicados en regiones con clima mediterráneo albergan una extraordinaria diversidad biológica, que incluyen numerosas especies de invertebrados y plantas exclusivas de algunas fuentes. Sin embargo, los cambios en los patrones de temperatura, precipitación y uso del suelo están afectando seriamente la integridad ecológica de estos ecosistemas acuáticos. Esta es una de las principales conclusiones del estudio liderado por el Centro de Investigación Ecológica y Aplicaciones Forestales (CREAF) de Cataluña y en el que ha participado el investigador del Departamento de Biología Aplicada de la Universidad Miguel Hernández (UMH) de Elche José Manuel Zamora, junto con otras 15 instituciones científicas de España, Portugal, Italia y Suiza.
Pie de foto: representación ilustrativa de los microambientes y la biodiversidad acuática y terrestre asociada a una fuente mediterránea de montaña. Fuente: Jordi Corbera.
Según el equipo investigador, las regiones de clima mediterráneo se encuentran entre los ecosistemas más amenazados del mundo, debido principalmente a la reducción de recursos hídricos y a los intensos impactos derivados de la actividad humana. Estas regiones presentan condiciones áridas o semiáridas y generalmente incluyen la cuenca mediterránea, California (EE.UU.), Chile central, la región del Cabo Occidental (Sudáfrica) y el suroeste de Australia. Dadas sus condiciones de aridez (precipitación anual inferior a los 500 mm), las fuentes -o ecosistemas fontinales- de estas regiones albergan una extraordinaria biodiversidad de animales y plantas, aunque hasta la fecha ningún estudio había resaltado su elevado interés ecológico ni su vulnerabilidad frente al cambio global.
El estudio, publicado en la revista Global Change Biology, evalúa cuáles son los factores de origen hidrogeológico, climático, biológico y humano que determinan el funcionamiento de las fuentes mediterráneas, así como las principales amenazas que se ciernen sobre estos ecosistemas acuáticos. Para ello, un equipo multidisciplinar formado por 17 especialistas en los campos de la ecología, limnología, hidrogeología, botánica, zoología y biología de la conservación compilaron toda la información disponible en la literatura científica publicada para proporcionar una síntesis sobre las principales características de las fuentes. Además, los investigadores utilizaron datos sobre fuentes ubicadas en las montañas litorales de Cataluña como caso de estudio para poner de manifiesto el impacto del cambio global sobre la preservación de estos ecosistemas.
Las fuentes constituyen puntos de descarga de un acuífero en un paisaje eminentemente terrestre y, generalmente, aparecen con mayor frecuencia en zonas montañosas con topografía escarpada. La hidrogeología determina enormemente la composición química de las aguas, cuya carga en cationes y aniones está estrechamente relacionada con el tipo de roca que alberga el acuífero y con el tiempo de residencia y tránsito del agua. Pese a sus reducidas dimensiones, las fuentes presentan multitud de microambientes diferentes que forman un mosaico y permiten la coexistencia de un amplio abanico de formas de vida. Por ejemplo, hay especies de invertebrados que se desarrollan exclusivamente en la surgencia del agua donde ni siquiera llega la luz solar, mientras que otras especies prefieren habitar en la cubeta central, o incluso en el entorno húmedo que marca el límite entre el medio acuático y el terrestre.
Las fuentes de regiones mediterráneas aparecen generalmente dispersas en el paisaje y muy aisladas entre sí, propiciando que las especies animales y vegetales estrechamente asociadas a estos ecosistemas tengan pocas opciones de colonizar nuevos ambientes. Este atributo ha motivado que las fuentes mediterráneas presenten un alto número de especies endémicas (exclusivas de una o pocas fuentes). Por ejemplo, se han descrito hasta 18 especies de ácaros de agua (Hydrachnnida) que son endémicos de fuentes italianas, mientras que otras 18 especies de moluscos son endémicas de las fuentes australianas de la cuenca del lago Eyre. Un ejemplo extremo del extraordinario número de endemismos que soportan algunos ecosistemas fontinales se puede encontrar en la Gran Cuenca Artesiana (Australia), donde se han descrito 51 especies de moluscos, 24 de crustáceos y ocho de peces que son endémicas de fuentes ubicadas en esta región. La escasa información disponible sobre flora asociada a fuentes también apunta a que estos ecosistemas mantienen una rica comunidad vegetal, incluyendo numerosas especies de diatomeas (algas microscópicas) y musgos endémicos.
Pese a su elevado valor ecológico, las fuentes del mediterráneo se enfrentan a un amplio abanico de amenazas derivadas de la actividad humana, entre las que se encuentran la reducción en la disponibilidad de recursos hídricos, la sobreexplotación de los acuíferos, la contaminación orgánica e inorgánica (vertidos urbanos y filtraciones agrícolas) y por residuos emergentes (microplásticos y productos sintéticos), la introducción de especies exóticas y el abandono de las prácticas tradicionales. Como caso de estudio, el trabajo cuantifica una reducción del 92% en el caudal de 31 fuentes monitoreadas entre 2013 y 2023 en las montañas litorales de Cataluña, habiéndose secado el 45% de estas fuentes en tan solo una década. Los autores finalizan el trabajo proporcionando una serie de recomendaciones para poner en marcha estrategias coordinadas que garanticen la conservación efectiva de estos ecosistemas amenazados y reclaman la preservación urgente de las fuentes bajo la designación de una figura de protección específica.
Este estudio colaborativo es fruto de unas jornadas de trabajo celebradas en Mataró a mediados de febrero de 2023 y organizadas por el CREAF en el marco del reconocimiento de Excelencia Científica Severo Ochoa. En las jornadas se dieron cita todos los autores del trabajo para poner en común el conocimiento recabado en diferentes campos relacionados con los ecosistemas fontinales y establecer una hoja de ruta para el desarrollo del estudio.
Fuente: Universitas Miguel Hernández. Servicio de Comunicación, Marketing y Atención al Estudiantado
Acceso al artículo: Fernández-Martínez, M., Barquín, J., Bonada, N., Cantonati, M., Churro, C., Corbera, J., Delgado, C., Dulsat-Masvidal, M., García, G., Margalef, O., Pascual, R., Peñuelas, J., Preece, C., Sabater, F., Seiler, H., Zamora-Marín, J.M. & Romero, E. 2024. Mediterranean springs: Keystone ecosystems and biodiversity refugia threatened by global change. Global Change Biology, 30(1):e16997. https://doi.org/10.1111/gcb.16997
Fragmentation and edge effect exacerbate biomass loss in Amazon forests
Long-term tree measurements have shown that forest fragments in Central Amazonia experience a dramatic loss of aboveground tree biomass caused by the mortality of large trees that is not offset by the growth and recruitment of new trees. However, differences in tree allometry caused by edge effects on tree architecture could either lead to additional losses in aboveground biomass. Picture: Freepick (left) EFE (right) The three-dimensional form of trees, or tree architecture, reflects the allocation of photosynthetically fixed carbon within the plants. Tree architecture can be considered a by-product of environmental pressures on plant growth, reproduction and survival. Fine adjustments of the aboveground architecture of trees can minimise competition from neighbouring trees, improve hydraulic conductance, limit transpiration and maximise light capture.
In Amazonian forests, trees vary greatly in size and architecture across species, as a result of evolutionary processes over millions of years. Habitat fragmentation could potentially affect tree architecture and allometry, thus the architecture of Amazonian trees could be affected by disturbances arising from this forest fragmentation.
In a new study published in Nature Communications authors use ground surveys of terrestrial LiDAR in Central Amazonia to explore the influence of forest edge effects on tree architecture and allometry, as well as forest biomass, 40 years after fragmentation.
According to this study, the edges of forest fragments tend to have greater light availability due to the mortality of large trees and lateral light penetrating from the edges. “This may induce changes in tree architecture to optimise the capture and use of light under these new circumstances, including higher vertical and horizontal crown growth that modify branching patterns and crown shape. Higher temperatures and lower water availability in forest edges increase the evaporative demand of the vegetation, and trees can shorten the distances for transporting water and nutrients to minimise hydraulic conductance”, explains Dr. Matheus Henrique Nunes, from University of Helsinki and University of Maryland.
Authors tested two hypotheses, that: (1) both pre-existing trees established before forest fragmentation and trees that colonised the forest fragments had their architectural traits and allometry affected by forest edges, given the higher light availability, higher wind turbulence, the hotter and drier conditions near these forest edges and the high mortality of large trees that may damage their neighbours; and (2) the aboveground biomass of fragmented forests is impacted by edge effects on tree allometry, with potentially significant biome-wide implications.
Models presented in this study demonstrated that edge effects affected architectural traits, but these effects were dependent on when plants were established in the forest fragments. The surviving tall trees in the edges had higher surface area per unit volume of trunks, which demonstrates that edge effects led to thinner trunks. Results also demonstrate that short trees colonising the forest edges had thicker branches and trunks, owing to reduced branch surface area per unit volume and trunk surface area per unit volume, trees were more asymmetrical and had higher path fraction.
Thus, this study finds that young trees colonising the forest fragments have thicker branches and architectural traits that optimise for light capture, which result in 50% more woody volume than their counterparts of similar stem size and height in the forest interior. However, authors observe a disproportionately lower height in some large trees, leading to a 30% decline in their woody volume. Despite the substantial wood production of colonising trees, the lower height of some large trees has resulted in a net loss. “Our findings indicate a strong influence of edge effects on tree architecture and allometry, and uncover an overlooked factor that likely exacerbates carbon losses in fragmented forests”, concludes Prof. Josep Peñuelas, from CSIC-CREAF.
Publication: Nunes, M., Vaz, M., Camargo, J.L., Laurance, W., de Andrade, A., Vicentini, A., Laurance, S., Raumonen, P., Jackson, T., Zuquim, G., Wu, J., Penuelas, J., Chave, J., Maeda, E. 2023. Edge effects on tree architecture exacerbate biomass loss of fragmented Amazonian forests. Nature Communications 8129. Doi: 10.1038/s41467-023-44004.
Prof. Josep Peñuelas Reixach, ‘Alejandro Malaspina’ National Research Award 2023
Prof. Josep Peñuelas Reixach, has received the ‘Alejandro Malaspina’ National Research Award, in the area of Material Resources Sciences and Technologies. He receives the award for his extensive scientific career as an international reference in global change research, as well as his leadership in technological innovation and outreach work in this area.
The National Research Awards recognize the merit of those researchers of Spanish nationality who are carrying out outstanding work in scientific fields of international relevance and who contribute significantly to the advancement of scientific knowledge and the progress of Humanity. There are 10 modalities that correspond to 10 areas of knowledge.
The National Research Awards 2023 are Spain’s most important recognition in the field of scientific research.
Prof Peñuelas has stated to be “very happy to receive this prize, which is the product of the research of our entire group of research”
Leaf-level coordination principles propagate to the ecosystem scale.
Optimality principles and patterns in trait coordination have been widely studied and confirmed at the leaf and plant scale. The question now is whether these coordination principles that apply to the leaf and plant scales can be used to approximate ecosystem-scale coordination among communities and ecosystems. Image: Pixabay/ FreePhotosART Variation in plant traits arises from balancing the costs and benefits of resource-use strategies at the leaf level. The interplay between natural selection and environmental filtering leads to predictable patterns in traits that promote the efficiency of plant processes necessary for growth, survival, and reproduction.
In a recent publication in the journal Nature Communications, researchers explore whether trade-offs and optimality principles in leaf functional traits extend to the ecosystem level. By analyzing a comprehensive dataset from 98 global eddy covariance flux measurement sites and utilizing vegetation data collected in the field and from global plant trait databases, the authors investigate ecosystem-scale analogs to the relationships observed in functional traits.
The leaf economics spectrum, which represents consistent correlations among various leaf traits reflecting a range of plant strategies from conservative to acquisitive, is examined. Additionally, the study explores the global spectrum of plant form and function, which encompasses evolutionary strategies related to plant growth, survival, and reproduction. The researchers also investigate the least-cost hypothesis, which suggests that plants acclimate to minimize carbon costs associated with photosynthesis on a per-leaf-area basis.
The findings of this study indicate that coordination of functional properties is conserved at the ecosystem scale. However, it is important to note that additional processes occur at the ecosystem level compared to the leaf level, emphasizing the significance of scale-emergent properties in understanding and predicting ecosystem behavior. Ulisse Gomarasca from the Max Planck Institute for Biogeochemistry highlights the importance of evaluating ecosystem functional properties for the development of more realistic global dynamic vegetation models, which can reduce uncertainty in climate change projections.
The study provides strong evidence supporting the conservation of the leaf economics spectrum at the ecosystem level. Similarly, the global spectrum of plant form and function and the least-cost hypothesis are observed in whole ecosystems, despite involving secondary mechanisms at the ecosystem scale.
Prof. Josep Penuelas from CSIC-CREAF emphasizes the need for upscaling from leaf or plant to ecosystem-level processes in order to make more accurate predictions about ecosystem responses to global environmental changes. This involves considering whether the coordination observed at the leaf and plant levels is conserved at the ecosystem scale or whether scale-emergent behaviors occur and should be explicitly incorporated into models.
Publication: Gomarasca, U., Migliavacca, M., Kattge, J., Nelson., Niinemets, Ü., Wirth, C., Cescatti, A., Bahn., Nair, R., Acosta, A., Arain, A., Beloiu, M., Black, T., Bruun, H.H., Bucher, F., Buchmann, N., Carrara, A., Byun, C., Conte, A., da Silva, A., Duveiller, G., Fares, S., Ibrom, A., Knohl, A., Komac, B., Limousin, J-M., Lusk, C., Mahecha, M., Martini, D., Minden, V., Montagnani, L., Mori, A., Onoda, Y., Penuelas, J., Poschlod, P., Powell, T., Reich, P., Šigut, L., van Bodegom, P., Walther, S., Wohlfahrt, G., Wright, I., Reichstein, M. 2023. Leaf-level coordination principles propagate to the ecosystem scale. Nature Communications 14:3948. Doi: 10.1038/s41467-023-39572-5.
Decreasing efficiency and slowdown of the increase in terrestrial carbon-sink activity
Anthropogenic fertilization of the Earth with increasing concentrations of atmospheric CO2 and nitrogen in-puts has enhanced plant photosynthesis and carbon sinks of terrestrial ecosystems. Several signals now suggest, however, that this carbon-sink activity is slowing its rate of increase because of limitations of nutrients, water, and heat, among other factors. Image: Pixabay.Current anthropogenic warming, as a result of greenhouse had emission, particularly carbon dioxide (CO2), poses a very high risk to nature and human well-being. Up to now, this risk has been buffered by a key group of other species on the planet, terrestrial plants, which have assimilated almost a third of emissions, helping us avoid a much stronger and faster degree of warming.
In a new paper published in One Earth journal, author raises the question of how long will plants continue to rescue us. According to Prof Josep Penuelas from CSIC-CREAF, several signals suggest that this carbon-sink activity might be decreasing its efficiency and slowing its rate of increase because of limitations of nutrients, water, heat, fires, pollution, and reduced vegetation carbon residence time.
Author highlights that plant production requires many more nutrients than just C and N. Bio-elements such as phosphorus (P), potassium, calcium, magnesium, molybdenum, manganese, and zinc are needed for information and energy production and storage, functional control, catalytic power, physiological processes, and cell homeostasis, i.e., for cell structure and function, and therefore for plant growth. The availability of carbon from rising atmospheric carbon dioxide levels, and of nitrogen from various human-induced inputs to ecosystems, is continuously increasing. However, these increases are not paralleled by a similar increase in all these other bio-elements.
According to the study the limitations for increasing carbon sinks do not end with nutrients; many other limitations are linked to climate change itself, which raises temperatures above the optimum and drives aridification of many regions. With all these conspiring factors, we can thus expect the pace of current carbon sinks to slow because of decreased efficiency.
This scenario calls for a reconsideration of IPCC climate projections toward a possible reduction in the mitigation capacity of the terrestrial biosphere even warmer conditions than currently projected and stronger impacts. “If current models continue to ignore it, they may overestimate carbon sinks, and therefore underestimate climate warming and overestimate mitigation potential”, noted Prof. Penuelas.
Climate change is unfortunately already here and may become stronger if mitigation actions do not fully succeed, so countries should also aim to develop better adaptation strategies. Currently, adaptation strategies are largely fragmented, local, and incremental, with limited evidence of transformational adaptation and negligible evidence of risk reduction outcomes. “As we shift from a fertilization-dominated to a warming-dominated biosphere, we need to diversify our approaches and take action to healing harms already inflicted and avoid worse future ones”, concludes Prof. Penuelas.
Carbon sequestration at risk of destabilization in large regions of the world
Mediterranean scrubland. Source: Joaquim F. P. a Flickr.A study published this week in the renowned journal Nature shows clear signs of destabilizing carbon uptake by land ecosystems in large regions of the world. In particular, the difference between the CO2 taken up and the CO2 released into the atmosphere in these regions increasingly differs across years, with high plant productivity (and high carbon sequestration) in some years and low plant productivity (and low sequestration) in others. The study’s authors warn that such increasing variability indicates a risk of ecosystems becoming destabilized, spiralling away from their current situation and undergoing abrupt changes.
“We have not only detected an increase in variability in these areas, but also an increase in their ‘memory’ — temporal autocorrelation — which indicates that carbon uptake in one year is increasingly positively related to the previous year. A lower carbon uptake in one year is therefore becoming more likely to be followed by an even lower uptake the next year, ” says the study’s lead author, Marcos Fernández, researcher at CREAF and University of Antwerp “These are clear symptoms of a possible destabilization of the major ecosystems affected, something that might entail an abrupt change in the way they work and, in their landscapes,” he continues. “In Mediterranean ecosystems, for example, forests could become scrublands that are unable to turn back into forests in the current climate.”
The study confirms that that the areas most at risk of destabilization have less forest cover and more cropland, are warmer, and have experienced greater rises in temperature variability, which could be related to an increase in extreme weather events, such as heatwaves and cold snaps. These areas include the Mediterranean region, eastern Africa, the west coasts of North and Central America, India and Pakistan, and Southeast Asia.
To carry out the study, the research team worked with global net ecosystem production data for the 1981-2018 period from CAMS and CarboScope, two global atmospheric inversion models. They also used net ecosystem production data from TRENDY, an ensemble of 12 dynamic global vegetation models.
Instability constrains carbon sequestration
The study shows that carbon sequestration capacity has been compromised in the regions with the greatest potential for destabilization in recent years , whereas it has increased in areas where variability has declined, such as the Amazon and parts of central and northern Europe. “In the case of the Amazon, despite carbon having been lost on average over the study period, the losses are smaller and smaller because these systems have actually been increasing their carbon sequestration capacity,” explains CREAF-based CSIC research professor Josep Peñuelas.
“Being able to predict the carbon cycle is vital to combating climate change If their carbon uptake capacity declines, society will need to reduce their carbon emissions faster than is currently assumed” remarks CREAF researcher Jordi Sardans, another of the study’s authors. “While we do not yet know whether such abrupt changes will alter the climate or plants’ carbon sequestration capacity, a possible destabilization of large regions of the biosphere complicates making predictions because it greatly increases variability.”
Tropical forest at Brasil. Source: Toni Arnau (RUIDO photo).
Does greater biodiversity mean more stability?
The study found variability in carbon sequestration to be at its greatest in regions with intermediate biodivesity too.
In ecology, it is always said that the most biodiverse ecosystems, those with the greatest wealth and diversity of species, are the most stable and productive, giving them the highest carbon sequestration capacity. The study put that notion to the test in all the regions under analysis. The researchers found carbon sequestration rates to be highest in regions with intermediate biodiversity values, and lower in places with a very high level of biodiversity, such as the tropics.. According to the authors, this could be due to the positive effect that biodiversity has on decomposition and respiration, offsetting the positive effect of photosynthesis in tropical ecosystems, something that would not happen in other ecosystems. Additionally, and in contrast to what was previously thought, the study found variability in carbon sequestration to be at its greatest in regions with intermediate biodiversity too. Given the global scale of the study, it is very difficult to pinpoint the mechanisms that have given rise to its findings.
Led by CREAFand Antwerp University, the study was carried out by a team including scientists from the Spanish National Research Council CSIC, the University of Barcelona, the University of Paris-Saclay , (France), theInternational Institute for Applied Systems Analysis(Austria), University of Oxford(UK), the Max Planck Institute for Biogeochemistry, (Germany), the University of Exeter (UK), the Canadian Centre for Climate Modelling and Analysis (Canada), the University of Illinois (USA), the National Center for Atmospheric Research (USA), and the National Centre for Atmospheric Science (UK).
Article:
Fernández- Martínez M. Peñuelas J. Chevallier F, Ciais P, Obersteiner M, Rödenbeck C, Sardans J, Vicca S, Yang H, Sitch S, Friedlingstein P, Arora K, Goll D, K.Jain A,.Lombardozzi D, McGuire P, A.Janssens I, Diagnosing destabilization risk in global land carbon sinks. Nature DOI : 10.1038/s41586-023-05725-1 2021-11-17874
Source: https://blog.creaf.cat/en/noticias/carbon-sequestration-risk-destabilization-large-regions-world/
El secuestro de carbono está en riesgo de desestabilizarse en grandes regiones del planeta
Matorral mediterráneo Fuente: Joaquim F. P. a Flickr.Un estudio publicado esta semana en la prestigiosa revista Nature ha detectado signos claros de que el secuestro de carbono está en riesgo de desestabilizarse en grandes regiones del planeta. El estudio demuestra que, en algunas zonas, el secuestro de carbono (la diferencia entre el CO2 que capturan y liberan los ecosistemas a la atmósfera) ha variado mucho en los últimos años, con años con mucha productividad vegetal (mucho secuestro) y años con poca (poco secuestro). Los autores alertan de que esta variabilidad es una señal de que los ecosistemas podrían estar en riesgo de desestabilizarse y entrar en una espiral que les alejase de la situación actual y los llevara a cambios abruptos.
«Por ejemplo, en los ecosistemas mediterráneos, podríamos ver bosques que pasan a ser matorrales sin capacidad de volver a la forma original de bosque», comenta Marcos Fernández, primer autor del estudio, investigador del CREAF y colaborador de la Universidad de Barcelona que estaba en la Universidad de Antwerp en el momento de la investigación, y añade, “en estas zonas también hemos detectado otra señal, un aumento en su “memoria” (autocorrelación temporal), indicando que cada valor está cada vez más positivamente relacionado con lo anterior de modo que si un valor es decreciente, el siguiente será aún más decreciente”.
El estudio confirma que las zonas que más riesgo presentan de desestabilizarse tienen menos bosques, más cultivos, son más cálidas y han sufrido mayores aumentos en la variabilidad de sus temperaturas, lo que podría estar relacionado con un aumento de los episodios de tiempo extremo como oleadas de calor y de frío. En el mapa, estas regiones serían la zona mediterránea, la zona este de África oriental, las costas occidentales de Norte América y Centro Americano, India y Pakistán o el sureste asiático.
Para realizar el estudio el equipo de investigación ha trabajado con los datos globales de producción neta de los ecosistemas para el período 1981-2018 de dos modelos globales de inversión atmosférica (CAMS y CarboScope). También datos de producción limpia de los ecosistemas de un conjunto de 12 modelos dinámicos de vegetación global (TRENDY).
La naturaleza inestable limita el secuestro de carbono
El estudio pone de manifiesto que las regiones con un potencial más elevado de desestabilizarse en los últimos años han visto comprometida su capacidad de secuestrar carbono. Por el contrario, las zonas que han tendido a ser menos variables (Amazonas o regiones del centro y norte de Europa, entre otras) han aumentado su capacidad de secuestrar carbono. «En el caso del Amazonas vemos concretamente que aunque durante el período de estudio, de media, ha perdido carbono, cada vez pierde menos porque el sistema es ahora menos variable que antes», complementa Josep Peñuelas, profesor de investigación del CSIC en el CREAF.
“Poder predecir el ciclo del carbono es clave en la lucha contra el cambio climático. Aunque todavía no sabemos si estos cambios abruptos traerán cambios en el clima o en la capacidad de las plantas de secuestrar carbono, una potencial desestabilización de grandes regiones de la biosfera nos hace las predicciones más difíciles porque aumenta mucho la variabilidad”, comenta Jordi Sardans, también autor e investigador del CREAF.
Bosque tropical en Brasil. Fuente: Toni Arnau (RUIDO photo).¿Los sistemas que tienen más biodiversidad, son más estables?
La máxima variabilidad en el secuestro de carbono también se da en regiones con biodiversidad intermedia.
En ecología siempre se dice que los ecosistemas más biodiversos, con mayor diversidad y riqueza de especies, son más estables y productivos, y por tanto tienen más capacidad de secuestrar carbono. En este estudio se ha querido testear esto en todas las regiones del mundo estudiadas y se ha visto que las tasas más elevadas de secuestro de carbono se dan en regiones con biodiversidad intermedia, mientras que en lugares donde la biodiversidad es muy elevada, como ahora los trópicos, esta capacidad de secuestro de carbono es menor.. Según apuntan los investigadores, esto puede deberse a que el efecto positivo de la biodiversidad sobre la descomposición y respiración de los ecosistemas tropicales podría compensar el efecto positivo sobre la fotosíntesis, lo que no ocurriría en otros ecosistemas. Por otra parte, y en contra de lo que se pensaba, este trabajo también apunta a que la máxima variabilidad en el secuestro de carbono también se da en regiones con biodiversidad intermedia. Dada la escala global de este estudio, entender los mecanismos detrás de estos resultados resulta muy difícil.
El artículo ha estado liderado por el CREAF y la Universitat de Antwerp, Bélgica, ha contado con la colaboración de un equipo con miembros del Consejo Superior de Investigaciones Científicas CSIC, de la Universitat de Barcelona, la Universidad Paris-Saclay, Francia, delInternational Institute for Applied Systems Analysis, Austria, la Universidad de Oxford, Reino Unido, del Max Planck Institute for Biogeochemistry, Alemania, de la Universidad de Exeter, Reino Unido, del Canadian Centre for Climate Modelling and Analysis , Canada, de la Universidad de Illinois, EEUU, del National Center for Atmospheric Research, EEUU y del National Centre for Atmospheric Science, Reino Unido.
Artículo:
Fernández- Martínez M. Peñuelas J. Chevallier F, Ciais P, Obersteiner M, Rödenbeck C, Sardans J, Vicca S, Yang H, Sitch S, Friedlingstein P, Arora K, Goll D, K.Jain A,.Lombardozzi D, McGuire P, A.Janssens I, Diagnosing destabilization risk in global land carbon sinks. Nature DOI : 10.1038/s41586-023-05725-1 2021-11-17874
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