Relaciones de poder y servicios del ecosistema

7 páginas.- Presentación elaborada para las III Jornadas IPErinas, celebradas el 11 de diciembre de 2014.Peer reviewe

Drought impacts on tree growth of two pine species along an altitudinal gradient and their use as early-warning signals of potential shifts in tree species distributions.

Mediterranean pine forests are at risk of experiencing a decline in tree growth in response to climatewarming if rising temperatures amplify drought stress. In mountain areas, tree growth could be enhancedin temperature-limited high elevations, whilst it might decline at water-constrained low elevations.Species differential responses could, however, modulate the impact of drought on forests along altitudinalgradients. To test for evidence of species differential drought impacts along an altitudinal gradient, westudied the growth responses of two Iberian pine species (Pinus sylvestris and Pinus nigra) subjected toMediterranean conditions in Eastern Spain. We analysed the stability of growth (basal area increment)responses to climate and drought during the 1950&-2014 period by using resistance and resilience indices.Pinus sylvestris growth was enhanced by warm spring temperatures, while Pinus nigra growth wasimproved by a positive spring water balance. Pinus sylvestris growth decreased temporally at the lowerend of its altitudinal range, whereas Pinus nigra growth decreased at the upper end. Pinus sylvestris exhibitedlow growth stability at its low-elevation limit. Pinus nigra resistance also decreased along its altitudinalrange, but this effect was compensated by a high resilience. In mixed stands the results werecontrasting, with Pinus sylvestris (at the lower altitudinal range) being more vulnerable to droughtinducedgrowth decline than Pinus nigra (at the upper altitudinal range).Ministerio de Economía y Competitivida

Papel de los factores bióticos y las sequías en el decaimiento del bosque: aportaciones desde la dendroecología

[ES] El aumento de la mortalidad y la pérdida de vitalidad de los bosques son procesos que afectan a diversas especies de árboles y biomas. Estos fenómenos de decaimiento forestal se han asociado a la interacción de múltiples factores relacionados con el cambio global, como el aumento de las sequías o la mayor incidencia de factores bióticos que generan estrés. Sin embargo, el papel que juegan estos organismos en el decaimiento del bosque en relación a la sequía no está del todo comprendido. En este trabajo caracterizamos retrospectivamente los efectos que ejercen dichos organismos sobre el crecimiento radial de árboles estresados por sequía utilizando dendrocronología. El efecto combinado del muérdago y las sequías reducen el crecimiento del pino silvestre y aumentan la defoliación, siendo estos efectos más evidentes en el ápice del árbol. La procesionaria induce pérdidas de crecimiento en pino laricio, pero en general se observa una recuperación dos años después. No encontramos un papel determinante de los hongos patógenos de raíz en el decaimiento del abeto. Finalmente, pinos carrasco muertos que presentaban ataques de insectos perforadores mostraron patrones de crecimiento similares a pinos vivos. Este estudio nos permite caracterizar algunos de los complejos y múltiples efectos de diferentes factores bióticos de estrés sobre el crecimiento y la vulnerabilidad de los bosques susceptibles a los efectos negativos de las sequías.[EN] Increasing mortality and decline of forests are affecting several tree species and biomes. These events of forest decline have been related to the interaction of several global change elements, like the increase in drought stress or a higher incidence of biotic stress factors. However, the roles played by biotic stressors have been scarcely explored as related to drought stress. In this paper we retrospectively characterize the effects of these organisms on radial growth of trees already stressed by drought using dendrochronology. The combined effect of mistletoe and droughts reduce tree growth in Scots pine and increase defoliation, being these effects more noticeable in the apex. The pine processionary moth induces growth losses in the affected stands of black pine, but they usually recover two years after the outbreak. We did not find a determinate role of root pathogens on silver fir dieback. Finally, dead Aleppo pine trees infested by bark beetles showed similar growth patterns than living pine trees. This study allows characterizing some of the complex and multiple effects of different biotic stressors on growth and vulnerability of forests subjected to the negative effects exerted by droughts.Este estudio ha sido financiado por los proyectos CGL2007- 66066-C04-02/BOS, CGL2008-04847-C02-01, CGL2011-26654 (MINECO), 387/2011 (Organismo Autónomo de Parques Nacionales) y PROCLIM (La Caixa-Gobierno de Aragón). Agradecemos la revisión realizada por dos revisores anónimos de una versión previa del texto. También queremos agradecer la ayuda prestada por todos los miembros del Laboratorio de Sanidad Forestal de Mora de Rubielos (Gobierno de Aragón), a todo el personal del Parque Nacional de Ordesa y Monte Perdido, al servicio de parques y jardines del Ayuntamiento de Zaragoza (Montserrat Hernández y José Bellosta), y a todos los APNs que nos han ayudado en las numerosas jornadas de campo. Finalmente, agradecemos a nuestros compañeros del IPE (CSIC) J.D. Galván y A.Q. Alla por su ayuda en los muestreos y la discusión de las ideas presentadas.Peer Reviewe

The performance of Mediterranean subshrubs depends more on microsite than on regional climate conditions

[EN] Question: To what extent do small-scale biotic interactions and local variations determine the spatial pattern and plant performance of three Mediterranean subshrubs growing under contrasting climatic conditions? Location: Three sites subjected to climatically contrasting conditions in Aragón (Javalambre, cold site; Bernués, mesic site; Monegros, xeric site), NE Spain. Methods: The three species studied wereHormathophylla spinosa,Ononis fruticosa and Linum suffruticosum in the cold, mesic and xeric sites, respectively. Two transects (100 9 5 m) were located in each site, one in the upper part and another in the north-oriented slope of a hill. All adult individuals located within each transect of each species were tagged, spatially located and their size measured (height and crown diameter).We also estimated visually the cover of other woody species around each subshrub individual to study inter-specific interactions. We estimated the age of all subshrub individuals by counting annual rings in basal wood sections. To investigate the spatial patterns and plant performance of the three species we used spatial point pattern analyses and structural equation modelling. Results: The density of individuals and the spatial pattern of the species varied greatly among and within sites.H. spinosaandL. suffruticosumshowed higher variability in density among transects and a more aggregated spatial pattern than O. fruticosa. Similarly, the three subshrubs presented different architecture and performed differently in the two transects studied for each species. All three species presented higher growth rates in the upper part of the hill than in the north-oriented slope. Inter-specific interactions were more important than intraspecific ones in determining the performance of the three subshrubs, and were more intense in the case of H. spinosa and L. suffruticosum than in the case of O. fruticosa. Conclusions: Our results demonstrate that the spatial patterns of the three species studied varied within sites as a function of local environmental conditions. Moreover, plant–plant interactions can play an important role in explaining subshrub spatial patterns and performance in Mediterranean ecosystems. Inter- and intra-specific interactions acting at local scales should be considered for understanding the responses of Mediterranean subshrubs to regional climate.Antonio Gazol is supported by the ERMOS programme (co-funded by Marie Curie Actions) Grant nr. 14. This work was supported by the research project CGL2008- 04847-C02-01/BOS financed by the Spanish Commission of Science and Technology and FEDER. J.J.C. acknowledges the support of ARAID. We thank G. Sangu¨esa-Barreda and H. A. Chaparro for their brave help in the field and C. Sancho for advice on histological analyses. We also thank J. Price for revising the English in previous versions of this manuscript.Peer Reviewe

Mediterranean dwarf shrubs and coexisting trees present different radial-growth synchronies and responses to climate

[EN] Due to their diversity and dominance in environmentally harsh sites, Mediterranean dwarf shrubs are a valuable tool to understand the consequences of climatic variability on radial growth in woody plants. We evaluate the dendrochronological potential of three Mediterranean dwarf shrubs versus three coexisting tree species inhabiting cold- (Hormathophylla spinosa vs. Pinus sylvestris), mesic- (Ononis fruticosa vs. Abies alba), and xeric sites (Linum suffruticosum vs. Pinus halepensis). Cross-sectional wood sections of the three shrub species and cores in the case of trees were visually cross-dated and ring-widths were measured and converted into residual growth indices. We used linear mixed-effects models to assess how growth indices respond to local factors and climatic variables. The radial growth of the three dwarf shrub species was more asynchronous, i. e., ring-width series differed among conspecific individuals, than that of coexisting tree species. Growth asynchrony was higher for H. spinosa than for O. fruticosa and L. suffruticosum. Similarly, the ring-width series of O. fruticosa and L. suffruticosum was strongly correlated with that of coexisting tree species, while growth series of H. spinosa and P. sylvestris was not related at all. The growth of the three dwarf shrub species was influenced by the regional climatic conditions, but to a lesser degree than coexisting tree species. The highest responsiveness of growth to climate was observed in Mediterranean dwarf shrubs from xeric sites. However, local conditions are also major drivers of growth in Mediterranean dwarf shrubs as indicated by the stronger asynchrony in ring formation of these species as compared with coexisting trees, particularly in cold sites. © 2012 Springer Science+Business Media B.V.Antonio Gazol is supported by the ERMOS programme (co-founded by Marie Curie Actions), Grant number 14. This work has been supported by research projects CGL2008-04847-C02-01/BOS and CGL2011-26654 financed by the Spanish Commission of Science and Technology and FEDER. J. Julio Camarero acknowledges the support of ARAID. We thank G. Sanguesa and H. A. Chaparro for their brave help in the field, and M.C. Sancho for her advice in the laboratoryPeer Reviewe

La biodiversidad es inversamente proporcional al tamaño del país

12 páginas.- Presentación elaborada para las III Jornadas IPErinas, celebradas el 11 de diciembre de 2014.Peer reviewe

Attributing forest responses to global-change drivers: Limited evidence of a CO2-fertilization effect in Iberian pine growth

© 2015 John Wiley & Sons Ltd. Aim: Forest responses to global-change drivers such as rising atmospheric CO2 concentrations (Ca), warming temperatures and increased aridification will depend on tree species and site characteristics. We aim to determine if rising Ca enhances growth of coexisting pine species along broad ecological gradients in a drought-prone area. Location: Iberian Range, Spain. Methods: We sampled 557 trees of five pine species encompassing a wide climatic gradient and measured their radial growth. We used nonlinear flexible statistics (generalized additive mixed models) to characterize growth trends and relate them to Ca, temperature and water balance. Results: The sites most responsive to the growing-season water balance were dominated by Pinus pinaster and Pinus nigra at low elevations, whereas those most responsive to temperatures were high-elevation Pinus sylvestris and Pinus uncinata stands. From 1950 onwards, most sites and species showed decreasing radial growth trends. Growth trends were coherent with a CO2-related fertilization effect only in one P. sylvestris site. Main conclusions: We found little evidence of growth stimulation of Iberian pine forests due to rising Ca. The results indicated that any positive effect of a Ca-induced growth increase was unlikely to reverse or cancel out the drought-driven trends of reduced growth in most Mediterranean pine forests. Further assessments of CO2-fertilization effects on forest growth should be carried out in sites where climatic stressors such as drought do not override the effects of rising Ca on forest growth.We thank the referees for improving a previous version of the manuscript. We are particularly indebted to all the support provided by the people from the “Laboratorio de Sanidad Forestal” (Mora de Rubielos, Aragón Government), particularly Rodolfo Hernández, Juan Manuel Gil, Miguel Ros, Víctor Pérez Fortea and Araceli Órtiz. We also thank Melissa Hoffer and Justin Waito for their help with laboratory work. Antonio Gazol is supported by a Postdoctoral grant from MINECO (Contrato Formacion Postdoctoral MINECO – FPDI 2013–16600). This study was supported by projects CGL2011–26654 (Spanish Ministry of Economy and Competitiveness), 387/2011 and 1032S/2013 (Spanish Ministry of Agriculture and Environment, OAPN, Spain). The research was also partly funded by the Canada Research Chair Program and a NSERC discovery grant to J.C. Tardif. We are also indebted to all people who helped us sampling in the field. We thank AEMET, CRU and ESRL-NOAA for providing climatic and CO2 data.Peer Reviewe

Disparate effects of global-change drivers on mountain conifer forests: Warming-induced growth enhancement in young trees vs. CO2 fertilization in old trees from wet sites

Theory predicts that the postindustrial rise in the concentration of CO2 in the atmosphere (ca) should enhance tree growth either through a direct fertilization effect or indirectly by improving water use efficiency in dry areas. However, this hypothesis has received little support in cold-limited and subalpine forests where positive growth responses to either rising ca or warmer temperatures are still under debate. In this study, we address this issue by analyzing an extensive dendrochronological network of high-elevation Pinus uncinata forests in Spain (28 sites, 544 trees) encompassing the whole biogeographical extent of the species. We determine if the basal area increment (BAI) trends are linked to climate warming and increased ca by focusing on region- and age-dependent responses. The largest improvement in BAI over the past six centuries occurred during the last 150 years affecting young trees and being driven by recent warming. Indeed, most studied regions and age classes presented BAI patterns mainly controlled by temperature trends, while growing-season precipitation was only relevant in the driest sites. Growth enhancement was linked to rising ca in mature (151-300 year-old trees) and old-mature trees (301-450 year-old trees) from the wettest sites only. This finding implies that any potential fertilization effect of elevated ca on forest growth is contingent on tree features that vary with ontogeny and it depends on site conditions (for instance water availability). Furthermore, we found widespread growth decline in drought-prone sites probably indicating that the rise in ca did not compensate for the reduction in water availability. Thus, warming-triggered drought stress may become a more important direct driver of growth than rising ca in similar subalpine forests. We argue that broad approaches in biogeographical and temporal terms are required to adequately evaluate any effect of rising ca on forest growth. © 2014 John Wiley & Sons Ltd.This study was supported by projects 012/2008 and 387/2011 (OAPN, Spain) and by ARAID (JJC) and a JAE-CSIC grant (JDG). We also acknowledge projects which contributed to build this dataset (FoRmat EU ENV4-CT97-0641, AMB95-0160 and CGL2011-26654). We are indebted to all people who helped us in the field. We thank the ESRL-NOAA for providing CO2 data to the public and the scientific community.Peer Reviewe

Past logging, drought and pathogens interact and contribute to forest dieback

Forest dieback is one of the most widespread responses to global-change drivers, such as climate warming-related drought stress and the spread of pathogens. Although both climatic and biotic stressors have been studied separately, much less is known on how drought and pathogens interact and induce dieback, particularly in formerly used forests. We determine the roles played by each of those drivers as factors causing recent dieback in three Pyrenean silver fir stands: a managed site subjected to past logging and two unmanaged sites not logged for the past 50 years. The age, size, recent competition, and basal-area increment (BAI) trends of non-declining and declining trees, and the presence of fungal pathogens were investigated. Growth patterns at yearly to decadal time scales were compared to distinguish the roles and interactions played by the different stressors. In the managed site, declining trees displayed low growth already before logging (1950-1970s). In both unmanaged sites, declining and non-declining trees displayed divergent growth patterns after extreme droughts, indicating that dieback was triggered by severe water deficit. We did not find indications that fungal pathogens are the primary drivers of dieback, since a low proportion of declining trees were infested by primary pathogens (10%). However, trees with the primary fungal pathogen Heterobasidion showed lower BAI than non-declining trees. On the other hand, the secondary fungal pathogen Amylostereum was isolated from a higher number of trees than expected by chance. These findings highlight the importance of legacies, such as the past use in driving recent forest dieback. Past forest use could predispose to dieback by selecting slow-growing trees and thus, making some them more vulnerable to drought and fungal pathogens. © 2015 Elsevier B.V.This study was supported by projects 387/2011 (OAPN, Spanish Ministry of Environment) and CGL2011-26654 (Spanish Ministry of Economy), and by EU COST Strees (FP1106) and Sensfor (ES1203) projects. We sincerely thank C. Rodriguez-García and the personnel of “Ordesa and Monte Perdido” National Park for their help in the field. We thank CRU and AEMET for providing climatic data.Peer Reviewe

Data from: Different taxonomic and functional indices complement the understanding of herb-layer community assembly patterns in a southern-limit temperate forest

The efficient conservation of vulnerable ecosystems in the face of global change requires a complete understanding of how plant communities respond to various environmental factors. We aim to demonstrate that a combined use of different approaches, traits, and indices representing each of the taxonomic and functional characteristics of plant communities will give complementary information on the factors driving vegetation assembly patterns. We analyzed variation across an environmental gradient in taxonomic and functional composition, richness, and diversity of the herb-layer of a temperate beech-oak forest that was located in northern Spain. We measured species cover and four functional traits: leaf dry matter content (LDMC), specific leaf area (SLA), leaf size, and plant height. We found that light is the most limiting resource influencing herb-layer vegetation. Taxonomic changes in richness are followed by equivalent functional changes in the diversity of leaf size but by opposite responses in the richness of SLA. Each functional index is related to different environmental factors even within a single trait (particularly for LDMC and leaf size). To conclude, each characteristic of a plant community is influenced by different and even contrasting factors or processes. Combining different approaches, traits, and indices simultaneously will help us understand how plant communities work.Funding provided by: Fundación Caja Navarra, Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100006671, Award Number: 10833 (Program "Tú Eliges, Tú Decides"). Funding provided by: Universidad de Navarra, Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100004435, Award Number: project "Biodiversity Data Analytics and Environmental Quality". Funding provided by: Universidad de Navarra, Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100004435, Award Number: project "Red de Observatorios de la Biodiversidad de Navarra (ROBIN)". Funding provided by: Departamento de Educación, Gobierno de Navarra, Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100003425, Award Number: Ayudas predoctorales para la realización de programas de doctorado de interés para Navarra; Plan de Formación y de I + D 2018. Funding provided by: Ministerio Español de Ciencia e Innovación, Crossref Funder Registry ID: Award Number: RyC2020-030647-I. Funding provided by: Consejo Superior de Investigaciones Científicas, Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100003339, Award Number: PIE-20223AT003. Funding provided by: Ministerio Español de Ciencia e Innovación, Crossref Funder Registry ID: Award Number: FJC2020-042954-I. Funding provided by: EU "NextGenerationEU/PRTR", Crossref Funder Registry ID: Award Number: FJC2020-042954-I.Peer reviewe