Topography modulates climate sensitivity of multidecadal trends of holm oak decline

Forest decline events have increased worldwide over the last decades, being holm oak one of the tree species with the most worrying trends across Europe. Previous research identified drought and soil pathogens as the main causes behind holm oak decline. However, despite tree health loss is a multifactorial phenomenon where abiotic and biotic factors interact in time and space, there are some abiotic factors whose influence has been commonly overlooked. Here, we evaluate how land use (forests versus savannas), topography, and climate extremes jointly relate to spatiotemporal patterns of holm oak defoliation over almost three decades (1987-2014) in Spain, where holm oak represents the 25% of the national forested area. We found an increasing defoliation trend in 119 of the total 134 holm oak plots evaluated, being this increase rate significantly higher in forests compared to savannas. Moreover, we have detected that the interaction between topography and summer drought can explain trends of holm oak decline across the Mediterranean region. While a higher occurrence of dry summers increases defoliation trends in complex terrains where forests dominate, an inverse relationship was found at flatter terrains where savannas are located. Our results contribute to growing evidence of the influence of local topography, tightly linked to potential soil water availability, on forest functioning, as it can shape forest vulnerability against climate extremes. The present work could assist the identification of potential tree decline hotspots over the Mediterranean region. Moreover, our findings suggest that forest adaptive management will be key to guarantee the health and future stability of Mediterranean oak ecosystems, especially in the topographically more complex areas where tree vulnerability to climate extremes may be greater.This work was supported by a Juan de la Cierva-Incorporación postdoctoral contract IJC2020-045630-I and the MANAGE4FUTURE project (TED2021-129499A-I00) both funded by MCIN/AEI /10.13039/501100011033 and the European Union NextGenerationEU/PRTR. Ana-Maria Hereş was financed by the REASONING (PNIII-P1-1.1-TE-2019-1099) project through UEFISCDI (link; Romanian Ministry of Education and Research). This research was supported by the BERC 2018-2021 (Basque Government), and BC3 María de Maeztu Excellence Accreditation 2018-2022, Ref.MDM-2017-0714 (Spanish Ministry of Science, Innovation and Universities).defoliationcoppicesdehesasclimatic anomaliestree declinemultidecadal trendsSpainMediterranean forestPublishe

Complex effects of habitat fragmentation on plant‐soil microbial interactions in Mediterranean Holmoak forests

Póster presentado en el 1st Global Soil Biodiversity Conference (2-5 December 2014 - Dijon, France)The adverse effects of habitat fragmentation on biodiversity have been widely explored; however, little research has been conducted to understand its effects on ecosystem functioning. Effects of forest fragmentation are tightly linked to the surrounding matrix in terms of nutrient inputs and spatial constraints, leading to complex edge effects. Soil ecosystem processes related to carbon cycling are particularly important since soils are the largest carbon pool in terrestrial ecosystems, and habitat fragmentation affects their sink capacity and their vulnerability to global change. Soil organic matter (SOM) decomposition is affected directly by the canopy cover. Thus, the effects of an agricultural matrix could be overridden by the direct effects of canopy rather than by habitat fragmentation itself. In order to evaluate which key factors could be driving SOM decomposition in fragmented landscapes, we analyzed potential enzymatic activities (β-glucosidase, chitinase and phosphatase acid) and field soil respiration in fragmented Mediterranean Holm oak forests. We evaluated if the impact of fragmentation on soil microbial functioning could be explained through its effect on microhabitat characteristics by using structural equation models. Variables measured included biotic (microbial biomass), abiotic (soil moisture, temperature, organic matter, pH, nutrients) and tree structural (stem diameter, canopy projection, leaf area index) characteristics. Tree effects on soil functioning (enzymatic activities) were potentiated by the influence of the agricultural matrix. As expected, trees created a microenvironment where the increment of SOM modified the pH, increasing soil moisture and decreasing temperature, rising the amount of microbial biomass and, therefore, improving the functioning of soil microbial community. Agricultural matrix influence on SOM decomposition was mainly indirect, through its positive effect on tree size. Mediterranean fragmented forests with high influence of agricultural matrix could increase SOM decomposition rates, decreasing soil carbon sink capacity.Peer reviewe

TRY plant trait database – enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.Rest of authors: Decky Junaedi, Robert R. Junker, Eric Justes, Richard Kabzems, Jeffrey Kane, Zdenek Kaplan, Teja Kattenborn, Lyudmila Kavelenova, Elizabeth Kearsley, Anne Kempel, Tanaka Kenzo, Andrew Kerkhoff, Mohammed I. Khalil, Nicole L. Kinlock, Wilm Daniel Kissling, Kaoru Kitajima, Thomas Kitzberger, Rasmus Kjøller, Tamir Klein, Michael Kleyer, Jitka Klimešová, Joice Klipel, Brian Kloeppel, Stefan Klotz, Johannes M. H. Knops, Takashi Kohyama, Fumito Koike, Johannes Kollmann, Benjamin Komac, Kimberly Komatsu, Christian König, Nathan J. B. Kraft, Koen Kramer, Holger Kreft, Ingolf Kühn, Dushan Kumarathunge, Jonas Kuppler, Hiroko Kurokawa, Yoko Kurosawa, Shem Kuyah, Jean-Paul Laclau, Benoit Lafleur, Erik Lallai, Eric Lamb, Andrea Lamprecht, Daniel J. Larkin, Daniel Laughlin, Yoann Le Bagousse-Pinguet, Guerric le Maire, Peter C. le Roux, Elizabeth le Roux, Tali Lee, Frederic Lens, Simon L. Lewis, Barbara Lhotsky, Yuanzhi Li, Xine Li, Jeremy W. Lichstein, Mario Liebergesell, Jun Ying Lim, Yan-Shih Lin, Juan Carlos Linares, Chunjiang Liu, Daijun Liu, Udayangani Liu, Stuart Livingstone, Joan Llusià, Madelon Lohbeck, Álvaro López-García, Gabriela Lopez-Gonzalez, Zdeňka Lososová, Frédérique Louault, Balázs A. Lukács, Petr Lukeš, Yunjian Luo, Michele Lussu, Siyan Ma, Camilla Maciel Rabelo Pereira, Michelle Mack, Vincent Maire, Annikki Mäkelä, Harri Mäkinen, Ana Claudia Mendes Malhado, Azim Mallik, Peter Manning, Stefano Manzoni, Zuleica Marchetti, Luca Marchino, Vinicius Marcilio-Silva, Eric Marcon, Michela Marignani, Lars Markesteijn, Adam Martin, Cristina Martínez-Garza, Jordi Martínez-Vilalta, Tereza Mašková, Kelly Mason, Norman Mason, Tara Joy Massad, Jacynthe Masse, Itay Mayrose, James McCarthy, M. Luke McCormack, Katherine McCulloh, Ian R. McFadden, Brian J. McGill, Mara Y. McPartland, Juliana S. Medeiros, Belinda Medlyn, Pierre Meerts, Zia Mehrabi, Patrick Meir, Felipe P. L. Melo, Maurizio Mencuccini, Céline Meredieu, Julie Messier, Ilona Mészáros, Juha Metsaranta, Sean T. Michaletz, Chrysanthi Michelaki, Svetlana Migalina, Ruben Milla, Jesse E. D. Miller, Vanessa Minden, Ray Ming, Karel Mokany, Angela T. Moles, Attila Molnár V, Jane Molofsky, Martin Molz, Rebecca A. Montgomery, Arnaud Monty, Lenka Moravcová, Alvaro Moreno-Martínez, Marco Moretti, Akira S. Mori, Shigeta Mori, Dave Morris, Jane Morrison, Ladislav Mucina, Sandra Mueller, Christopher D. Muir, Sandra Cristina Müller, François Munoz, Isla H. Myers-Smith, Randall W. Myster, Masahiro Nagano, Shawna Naidu, Ayyappan Narayanan, Balachandran Natesan, Luka Negoita, Andrew S. Nelson, Eike Lena Neuschulz, Jian Ni, Georg Niedrist, Jhon Nieto, Ülo Niinemets, Rachael Nolan, Henning Nottebrock, Yann Nouvellon, Alexander Novakovskiy, The Nutrient Network, Kristin Odden Nystuen, Anthony O'Grady, Kevin O'Hara, Andrew O'Reilly-Nugent, Simon Oakley, Walter Oberhuber, Toshiyuki Ohtsuka, Ricardo Oliveira, Kinga Öllerer, Mark E. Olson, Vladimir Onipchenko, Yusuke Onoda, Renske E. Onstein, Jenny C. Ordonez, Noriyuki Osada, Ivika Ostonen, Gianluigi Ottaviani, Sarah Otto, Gerhard E. Overbeck, Wim A. Ozinga, Anna T. Pahl, C. E. Timothy Paine, Robin J. Pakeman, Aristotelis C. Papageorgiou, Evgeniya Parfionova, Meelis Pärtel, Marco Patacca, Susana Paula, Juraj Paule, Harald Pauli, Juli G. Pausas, Begoña Peco, Josep Penuelas, Antonio Perea, Pablo Luis Peri, Ana Carolina Petisco-Souza, Alessandro Petraglia, Any Mary Petritan, Oliver L. Phillips, Simon Pierce, Valério D. Pillar, Jan Pisek, Alexandr Pomogaybin, Hendrik Poorter, Angelika Portsmuth, Peter Poschlod, Catherine Potvin, Devon Pounds, A. Shafer Powell, Sally A. Power, Andreas Prinzing, Giacomo Puglielli, Petr Pyšek, Valerie Raevel, Anja Rammig, Johannes Ransijn, Courtenay A. Ray, Peter B. Reich, Markus Reichstein, Douglas E. B. Reid, Maxime Réjou-Méchain, Victor Resco de Dios, Sabina Ribeiro, Sarah Richardson, Kersti Riibak, Matthias C. Rillig, Fiamma Riviera, Elisabeth M. R. Robert, Scott Roberts, Bjorn Robroek, Adam Roddy, Arthur Vinicius Rodrigues, Alistair Rogers, Emily Rollinson, Victor Rolo, Christine Römermann, Dina Ronzhina, Christiane Roscher, Julieta A. Rosell, Milena Fermina Rosenfield, Christian Rossi, David B. Roy, Samuel Royer-Tardif, Nadja Rüger, Ricardo Ruiz-Peinado, Sabine B. Rumpf, Graciela M. Rusch, Masahiro Ryo, Lawren Sack, Angela Saldaña, Beatriz Salgado-Negret, Roberto Salguero-Gomez, Ignacio Santa-Regina, Ana Carolina Santacruz-García, Joaquim Santos, Jordi Sardans, Brandon Schamp, Michael Scherer-Lorenzen, Matthias Schleuning, Bernhard Schmid, Marco Schmidt, Sylvain Schmitt, Julio V. Schneider, Simon D. Schowanek, Julian Schrader, Franziska Schrodt, Bernhard Schuldt, Frank Schurr, Galia Selaya Garvizu, Marina Semchenko, Colleen Seymour, Julia C. Sfair, Joanne M. Sharpe, Christine S. Sheppard, Serge Sheremetiev, Satomi Shiodera, Bill Shipley, Tanvir Ahmed Shovon, Alrun Siebenkäs, Carlos Sierra, Vasco Silva, Mateus Silva, Tommaso Sitzia, Henrik Sjöman, Martijn Slot, Nicholas G. Smith, Darwin Sodhi, Pamela Soltis, Douglas Soltis, Ben Somers, Grégory Sonnier, Mia Vedel Sørensen, Enio Egon Sosinski Jr, Nadejda A. Soudzilovskaia, Alexandre F. Souza, Marko Spasojevic, Marta Gaia Sperandii, Amanda B. Stan, James Stegen, Klaus Steinbauer, Jörg G. Stephan, Frank Sterck, Dejan B. Stojanovic, Tanya Strydom, Maria Laura Suarez, Jens-Christian Svenning, Ivana Svitková, Marek Svitok, Miroslav Svoboda, Emily Swaine, Nathan Swenson, Marcelo Tabarelli, Kentaro Takagi, Ulrike Tappeiner, Rubén Tarifa, Simon Tauugourdeau, Cagatay Tavsanoglu, Mariska te Beest, Leho Tedersoo, Nelson Thiffault, Dominik Thom, Evert Thomas, Ken Thompson, Peter E. Thornton, Wilfried Thuiller, Lubomír Tichý, David Tissue, Mark G. Tjoelker, David Yue Phin Tng, Joseph Tobias, Péter Török, Tonantzin Tarin, José M. Torres-Ruiz, Béla Tóthmérész, Martina Treurnicht, Valeria Trivellone, Franck Trolliet, Volodymyr Trotsiuk, James L. Tsakalos, Ioannis Tsiripidis, Niklas Tysklind, Toru Umehara, Vladimir Usoltsev, Matthew Vadeboncoeur, Jamil Vaezi, Fernando Valladares, Jana Vamosi, Peter M. van Bodegom, Michiel van Breugel, Elisa Van Cleemput, Martine van de Weg, Stephni van der Merwe, Fons van der Plas, Masha T. van der Sande, Mark van Kleunen, Koenraad Van Meerbeek, Mark Vanderwel, Kim André Vanselow, Angelica Vårhammar, Laura Varone, Maribel Yesenia Vasquez Valderrama, Kiril Vassilev, Mark Vellend, Erik J. Veneklaas, Hans Verbeeck, Kris Verheyen, Alexander Vibrans, Ima Vieira, Jaime Villacís, Cyrille Violle, Pandi Vivek, Katrin Wagner, Matthew Waldram, Anthony Waldron, Anthony P. Walker, Martyn Waller, Gabriel Walther, Han Wang, Feng Wang, Weiqi Wang, Harry Watkins, James Watkins, Ulrich Weber, James T. Weedon, Liping Wei, Patrick Weigelt, Evan Weiher, Aidan W. Wells, Camilla Wellstein, Elizabeth Wenk, Mark Westoby, Alana Westwood, Philip John White, Mark Whitten, Mathew Williams, Daniel E. Winkler, Klaus Winter, Chevonne Womack, Ian J. Wright, S. Joseph Wright, Justin Wright, Bruno X. Pinho, Fabiano Ximenes, Toshihiro Yamada, Keiko Yamaji, Ruth Yanai, Nikolay Yankov, Benjamin Yguel, Kátia Janaina Zanini, Amy E. Zanne, David Zelený, Yun-Peng Zhao, Jingming Zheng, Ji Zheng, Kasia Ziemińska, Chad R. Zirbel, Georg Zizka, Irié Casimir Zo-Bi, Gerhard Zotz, Christian Wirth.Max Planck Institute for Biogeochemistry; Max Planck Society; German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig; International Programme of Biodiversity Science (DIVERSITAS); International Geosphere-Biosphere Programme (IGBP); Future Earth; French Foundation for Biodiversity Research (FRB); GIS ‘Climat, Environnement et Société'.http://wileyonlinelibrary.com/journal/gcbhj2021Plant Production and Soil Scienc

Walking the line between survival and death

La presente tesis doctoral se centra en el estudio de la mortalidad inducida por la sequía del pino silvestre (Pinus sylvestris L.) en dos sitios, Prades y Arcalís, situados en el noreste de la Península Ibérica, donde ésta extendida especie de árbol boreal alcanza su límite suroccidental (y seco) de distribución. Más precisamente, en esta tesis estudio la relación de la mortalidad del pino silvestre con los eventos de sequía que la precedieron, un fenómeno que se ha comenzado a observar sobre todo después de la década de los 1990, coincidiendo con el aumento de las temperaturas. Al mismo tiempo, en esta tesis comparo diferentes patrones de crecimiento anuales (a partir de los anillos de los árboles) entre los árboles vivos y muertos de pino silvestre, centrándome en las décadas previas a la mortalidad. El propósito de hacerlo es identificar las características que podrían diferenciar árboles vivos y muertos, y que podrían contribuir a la comprensión de los mecanismos que subyacen la mortalidad inducida por la sequía. Las variables estudiadas se refieren al crecimiento (expresado como incremento en área basal), la eficiencia intrínseca del uso del agua (extrapolada a partir de los análisis de 13C en la madera) y varias características anatómicas de la madera (número de traqueidas, tamaño de éstas, etc.). Los resultados de esta tesis muestran una asociación directa entre la mortalidad de pino silvestre y los eventos severos de sequía caracterizados por una baja disponibilidad de agua en verano, en ambas zonas de estudio. Los patrones de crecimiento de los árboles muertos difirieron de los de los sobrevivientes, ya que los pinos silvestres muertos comenzaron a crecer menos que sus vecinos vivos entre 15 y 40 años antes de que ocurriera su muerte. Estas bajas tasas de crecimiento fueron causadas principalmente por una baja producción de traqueidas, lo que apunta hacia depósitos de carbono limitados y/o no disponibles, como lo sugiere también la baja producción de tubos resiníferos que se encontró en los árboles muertos. Otro patrón que diferenciaba los árboles muertos de los vivos fue una conductividad hidráulica baja que estaba vinculada tanto con la producción reducida de traqueidas como al tamaño reducido del lúmen de éstas. En conjunto, los resultados presentados en esta tesis muestran que la mortalidad de pino silvestre en estos dos sitios se caracterizó por una capacidad hidráulica baja y una reducción de la inversión de carbono en el crecimiento y la defensa. Sin embargo, los dos sitios de estudio parecieron tener dos historias diferentes, ya que los árboles vivos y muertos mostraron un crecimiento y un rendimiento hidráulico divergente a largo plazo en Prades, y dicha divergencia era menos acentuada y más reciente en Arcalís. Esta tesis aporta nuevas evidencias que sugieren que si las proyecciones de cambio climático se cumplen los episodios de mortalidad en bosques de pino silvestre continuarán, induciendo cambios en la vegetación dominante en algunas zonas.The present PhD thesis focuses on the study of Scots pine (Pinus sylvestris L.) drought-induced mortality at two sites (Prades and Arcalís) located in the north east of the Iberian Peninsula, where this widespread boreal tree species reaches its south-western (and dry) distribution limit. More precisely, in this thesis I study the association of Scots pine mortality with drought events that predated it, a phenomenon that has started to be observed especially after the 1990s, coinciding with increasing temperatures. At the same time, in this thesis I compare different annual (tree-ring level) patterns between co-occurring living Scots pine trees and dead ones, focusing on the previous to death decades. The purpose of doing so is to identify characteristics that differentiate living and dead trees and could contribute to our understanding of the mechanisms that underlie drought-induced mortality. Studied variables include growth (expressed as basal area increment), intrinsic-water use efficiency (extrapolated from 13C analyses in wood) and several wood anatomical features (number of tracheids, tracheid size, etc.). The results of this thesis show a direct association between Scots pine mortality and severe drought events characterized by low summer water availability at the two study sites. The growth patterns of the dead trees differed from the ones of the surviving ones, as dead Scots pines started to grow less than their living neighbours 15-40 years before their death occurred. This low growth rates were mainly caused by a low tracheid production, thus pointing towards limited and/or unavailable carbon pools as suggested also by the low resin ducts’ production that was found in the dead trees. Now-dead trees were also characterized by low hydraulic conductance, as a result of reduced tracheid production and the small lumen size that characterized their tracheids. Altogether, the results presented in this thesis show that the mortality of Scots pine at these two sites was characterized by a low hydraulic capacity and a reduced investment of carbon into growth and defence. Nevertheless, the two study sites seemed to have two different stories, since living and dead trees showed a long-term divergent growth and hydraulic performance in Prades, whereas this divergence was less accentuated and more recent in Arcalís. This thesis adds to the evidence suggesting that if the projections of more frequent and intense drought events come true, episodes of Scots pine mortality are likely to continue, leading eventually to a shift in the dominant vegetation in some areas

Walking the line between survival and death

La presente tesis doctoral se centra en el estudio de la mortalidad inducida por la sequía del pino silvestre (Pinus sylvestris L.) en dos sitios, Prades y Arcalís, situados en el noreste de la Península Ibérica, donde ésta extendida especie de árbol boreal alcanza su límite suroccidental (y seco) de distribución. Más precisamente, en esta tesis estudio la relación de la mortalidad del pino silvestre con los eventos de sequía que la precedieron, un fenómeno que se ha comenzado a observar sobre todo después de la década de los 1990, coincidiendo con el aumento de las temperaturas. Al mismo tiempo, en esta tesis comparo diferentes patrones de crecimiento anuales (a partir de los anillos de los árboles) entre los árboles vivos y muertos de pino silvestre, centrándome en las décadas previas a la mortalidad. El propósito de hacerlo es identificar las características que podrían diferenciar árboles vivos y muertos, y que podrían contribuir a la comprensión de los mecanismos que subyacen la mortalidad inducida por la sequía. Las variables estudiadas se refieren al crecimiento (expresado como incremento en área basal), la eficiencia intrínseca del uso del agua (extrapolada a partir de los análisis de 13C en la madera) y varias características anatómicas de la madera (número de traqueidas, tamaño de éstas, etc.). Los resultados de esta tesis muestran una asociación directa entre la mortalidad de pino silvestre y los eventos severos de sequía caracterizados por una baja disponibilidad de agua en verano, en ambas zonas de estudio. Los patrones de crecimiento de los árboles muertos difirieron de los de los sobrevivientes, ya que los pinos silvestres muertos comenzaron a crecer menos que sus vecinos vivos entre 15 y 40 años antes de que ocurriera su muerte. Estas bajas tasas de crecimiento fueron causadas principalmente por una baja producción de traqueidas, lo que apunta hacia depósitos de carbono limitados y/o no disponibles, como lo sugiere también la baja producción de tubos resiníferos que se encontró en los árboles muertos. Otro patrón que diferenciaba los árboles muertos de los vivos fue una conductividad hidráulica baja que estaba vinculada tanto con la producción reducida de traqueidas como al tamaño reducido del lúmen de éstas. En conjunto, los resultados presentados en esta tesis muestran que la mortalidad de pino silvestre en estos dos sitios se caracterizó por una capacidad hidráulica baja y una reducción de la inversión de carbono en el crecimiento y la defensa. Sin embargo, los dos sitios de estudio parecieron tener dos historias diferentes, ya que los árboles vivos y muertos mostraron un crecimiento y un rendimiento hidráulico divergente a largo plazo en Prades, y dicha divergencia era menos acentuada y más reciente en Arcalís. Esta tesis aporta nuevas evidencias que sugieren que si las proyecciones de cambio climático se cumplen los episodios de mortalidad en bosques de pino silvestre continuarán, induciendo cambios en la vegetación dominante en algunas zonas.The present PhD thesis focuses on the study of Scots pine (Pinus sylvestris L.) drought-induced mortality at two sites (Prades and Arcalís) located in the north east of the Iberian Peninsula, where this widespread boreal tree species reaches its south-western (and dry) distribution limit. More precisely, in this thesis I study the association of Scots pine mortality with drought events that predated it, a phenomenon that has started to be observed especially after the 1990s, coinciding with increasing temperatures. At the same time, in this thesis I compare different annual (tree-ring level) patterns between co-occurring living Scots pine trees and dead ones, focusing on the previous to death decades. The purpose of doing so is to identify characteristics that differentiate living and dead trees and could contribute to our understanding of the mechanisms that underlie drought-induced mortality. Studied variables include growth (expressed as basal area increment), intrinsic-water use efficiency (extrapolated from 13C analyses in wood) and several wood anatomical features (number of tracheids, tracheid size, etc.). The results of this thesis show a direct association between Scots pine mortality and severe drought events characterized by low summer water availability at the two study sites. The growth patterns of the dead trees differed from the ones of the surviving ones, as dead Scots pines started to grow less than their living neighbours 15-40 years before their death occurred. This low growth rates were mainly caused by a low tracheid production, thus pointing towards limited and/or unavailable carbon pools as suggested also by the low resin ducts' production that was found in the dead trees. Now-dead trees were also characterized by low hydraulic conductance, as a result of reduced tracheid production and the small lumen size that characterized their tracheids. Altogether, the results presented in this thesis show that the mortality of Scots pine at these two sites was characterized by a low hydraulic capacity and a reduced investment of carbon into growth and defence. Nevertheless, the two study sites seemed to have two different stories, since living and dead trees showed a long-term divergent growth and hydraulic performance in Prades, whereas this divergence was less accentuated and more recent in Arcalís. This thesis adds to the evidence suggesting that if the projections of more frequent and intense drought events come true, episodes of Scots pine mortality are likely to continue, leading eventually to a shift in the dominant vegetation in some areas

Red de observación de decaimiento del encinar

Web temática.-- Propósito: divulgativo.-- Estado del proyecto: activo.-- Fecha de la consulta: 14-01-2021..Contiene una app para dispositivos móviles.[ES] La Red de observación de decaimiento del encinar se engloba dentro de las actividades del proyecto VEroNICA (Vulnerability of Mediterranean Holm-Oak forests to Climate Change: Mechanisms and impact of historical management on ecosystem services). VEroNICA abordará las causas y mecanismos causantes de la pérdida de salud de encinares peninsulares. El estudio, además, permitirá valorar el efecto del manejo histórico sobre la vulnerabilidad de los encinares a las sequías y evaluará el efecto del decaimiento sobre servicios ecosistémicos clave asociados.[PT] A rede de observação dos azinhais está incluída nas actividades do projecto VEroNICA (Vulnerability of Mediterranean Holm-Oak forests to Climate Change: Mechanisms and impact of historical management on ecosystem services). VEroNICA abordará as causas e os mecanismos subjacentes à perda de vigor das azinheiras da Península Ibérica. O estudo também permitirá avaliar o efeito do uso do solo histórico na vulnerabilidade da azinheira à seca, e o efeito do seu declínio nos principais serviços de ecossistemas associados.Ministerio de Economía y Competitividad ;CSIC - Museo Nacional de Ciencias NaturalesHome.-- ¿Qué es el decaimiento forestal?.-- ¿Cómo puedes ayudar?.-- Resultados observados.-- Sobre nosotros.-- ContactPeer reviewe

A synthesis of radial growth patterns preceding tree mortality

Tree mortality is a key factor influencing forest functions and dynamics, but our understanding of the mechanisms leading to mortality and the associated changes in tree growth rates are still limited. We compiled a new pan-continental tree-ring width database from sites where both dead and living trees were sampled (2970 dead and 4224 living trees from 190 sites, including 36 species), and compared early and recent growth rates between trees that died and those that survived a given mortality event. We observed a decrease in radial growth before death in ca. 84% of the mortality events. The extent and duration of these reductions were highly variable (1–100 years in 96% of events) due to the complex interactions among study species and the source(s) of mortality. Strong and long-lasting declines were found for gymnosperms, shade- and drought-tolerant species, and trees that died from competition. Angiosperms and trees that died due to biotic attacks (especially bark-beetles) typically showed relatively small and short-term growth reductions. Our analysis did not highlight any universal trade-off between early growth and tree longevity within a species, although this result may also reflect high variability in sampling design among sites. The intersite and interspecific variability in growth patterns before mortality provides valuable information on the nature of the mortality process, which is consistent with our understanding of the physiological mechanisms leading to mortality. Abrupt changes in growth immediately before death can be associated with generalized hydraulic failure and/or bark-beetle attack, while long-term decrease in growth may be associated with a gradual decline in hydraulic performance coupled with depletion in carbon reserves. Our results imply that growth-based mortality algorithms may be a powerful tool for predicting gymnosperm mortality induced by chronic stress, but not necessarily so for angiosperms and in case of intense drought or bark-beetle outbreaks

A synthesis of radial growth patterns preceding tree mortality

Altres ajuts: this study generated from the COST Action STReESS (FP1106) financially supported by the EU Framework Programme for Research and Innovation HORIZON 2020. And the EU Project FEDER 0087 TRANSHABITAT and LIFE12 ENV/FI/000409Tree mortality is a key factor influencing forest functions and dynamics, but our understanding of the mechanisms leading to mortality and the associated changes in tree growth rates are still limited. We compiled a new pan-continental tree-ring width database from sites where both dead and living trees were sampled (2970 dead and 4224 living trees from 190 sites, including 36 species), and compared early and recent growth rates between trees that died and those that survived a given mortality event. We observed a decrease in radial growth before death in ca. 84% of the mortality events. The extent and duration of these reductions were highly variable (1-100 years in 96% of events) due to the complex interactions among study species and the source(s) of mortality. Strong and long-lasting declines were found for gymnosperms, shade- and drought-tolerant species, and trees that died from competition. Angiosperms and trees that died due to biotic attacks (especially bark-beetles) typically showed relatively small and short-term growth reductions. Our analysis did not highlight any universal trade-off between early growth and tree longevity within a species, although this result may also reflect high variability in sampling design among sites. The intersite and interspecific variability in growth patterns before mortality provides valuable information on the nature of the mortality process, which is consistent with our understanding of the physiological mechanisms leading to mortality. Abrupt changes in growth immediately before death can be associated with generalized hydraulic failure and/or bark-beetle attack, while long-term decrease in growth may be associated with a gradual decline in hydraulic performance coupled with depletion in carbon reserves. Our results imply that growth-based mortality algorithms may be a powerful tool for predicting gymnosperm mortality induced by chronic stress, but not necessarily so for angiosperms and in case of intense drought or bark-beetle outbreaks