Open Access
Metatranscriptomics sheds light on the links between the functional traits of fungal guilds and ecological processes in forest soil ecosystems
(Blackwell Scientific Publications Ltd, 2023) Auer, Lucas; Buée, Marc; Fauchery, Laure; Lombard, Vincent; Barry, Kerrie; Clum, Alicia; Copeland, Alex; Daum, Chris; LaButti, Kurt; Singan, Vasanth; Yoshinaga, Yuko; Martineau, Christine; Castillo Martínez, Federico; Alfaro Sánchez, Manuel; Imbert Rodríguez, Bosco; Ramírez Nasto, Lucía; Castanera Andrés, Raúl; Pisabarro de Lucas, Gerardo; Finlay, Roger; Lindahl, Björn D.; Olson, Ake; Séguin, Armand; Kohler, Annegret; Henrissat, Bernard; Grigoriev, Igor V.; Martin, Francis; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura; Institute for Multidisciplinary Research in Applied Biology - IMAB
Soil fungi belonging to different functional guilds, such as saprotrophs, pathogens, and mycorrhizal symbionts, play key roles in forest ecosystems. To date, no study has compared the actual gene expression of these guilds in different forest soils. We used metatranscriptomics to study the competition for organic resources by these fungal groups in boreal, temperate, and Mediterranean forest soils. Using a dedicated mRNA annotation pipeline combined with the JGI MycoCosm database, we compared the transcripts of these three fungal guilds, targeting enzymes involved in C- and N mobilization from plant and microbial cell walls. Genes encoding enzymes involved in the degradation of plant cell walls were expressed at a higher level in saprotrophic fungi than in ectomycorrhizal and pathogenic fungi. However, ectomycorrhizal and saprotrophic fungi showed similarly high expression levels of genes encoding enzymes involved in fungal cell wall degradation. Transcripts for N-related transporters were more highly expressed in ectomycorrhizal fungi than in other groups. We showed that ectomycorrhizal and saprotrophic fungi compete for N in soil organic matter, suggesting that their interactions could decelerate C cycling. Metatranscriptomics provides a unique tool to test controversial ecological hypotheses and to better understand the underlying ecological processes involved in soil functioning and carbon stabilization.
Open Access
CO2 fertilization plays a minor role in long-term carbon accumulation patterns in temperate pine forests in the southwestern Pyrenees
(Elsevier, 2019) Lo, Yueh-Hsin; Blanco Vaca, Juan Antonio; González de Andrés, Ester; Imbert Rodríguez, Bosco; Castillo Martínez, Federico; Institute for Multidisciplinary Research in Applied Biology - IMAB
Isolating the long-term fertilization effect of CO 2 from other climate- and site-related effects on tree growth has been proven a challenging task. To isolate long-term effects of [CO2] on water use efficiency at ecosystem level, we used the FORECAST Climate forest model, calibrated for Scots pine (Pinus sylvestris L.) forests in the southwestern Pyrenees, growing at a Mediterranean montane site and at a continental subalpine site. Future climate scenarios (RCP 4.5 and RCP 8.5) were generated using a battery of six climate models to estimate daily values of temperature and precipitation in a 90-year series. A factorial experiment was designed to disentangle the importance on C pools of three growing limiting factors (nitrogen limitation, climate (temperature + precipitation) limitation and atmospheric CO 2 concentration). The relative importance of each factor was quantified by comparing the scenario with the limitation of each individual factor turned on with the non-limitation scenario. Positive CO 2 fertilization due to improvement in water use efficiency was detected by the model, but its quantitative impact improving tree growth was minimum: its average increase in ecosystem C pools ranged from 0.3 to 0.9%. At the site with cooler climate conditions (continental), the main limitation for tree growth was climate. Such limitation will be reduced under climate change and the ecosystem will store more carbon. At the site with milder climate conditions (Mediterranean), N availability was the main limiting factor albeit modulated by water availability. Such limitation could be reduced under climate change as N cycling could accelerate (higher litterfall production and decomposition rates) but also increase if droughts become more frequent and severe. In addition, the magnitude of the uncertainty related to climate model selection was much more important than CO 2 fertilization, indicating that atmospheric processes are more important than tree physiological processes when defining how much carbon could be gained (or lost) in forests under climate change. In conclusion, due to the small changes in forest C pools caused by variation of atmospheric CO 2 concentrations compared to changes caused by other growth limiting factors (nutrients, climate), reducing uncertainty related to climate projections seems a more efficient way to reduce uncertainty in tree growth projections than increasing forest model complexity.
Open Access
¿Puede haber carrascales en el sur de Navarra? Una aproximación mediante la modelización de distribución de especies
(Asociación Española de Ecología Terrestre, 2013) Peralta de Andrés, Francisco Javier; Zepeda Peña, Norma Angélica; Imbert Rodríguez, Bosco; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
De acuerdo con algunos mapas de vegetación potencial diversos factores climáticos y edáficos limitan el hábitat disponible para los bosques de carrasca (Quercus rotundifolia) en el sur de Navarra (NE de España). Este es un territorio con un intenso y antiguo uso agrícola y ganadero, lo que dificulta valorar si son las variables ambientales o factores antrópicos los que hacen que sean muy escasos los carrascales existentes. Para tratar de responder a la cuestión de si este territorio es adecuado para el desarrollo de carrascales, se construyen modelos de distribución de la carrasca con Maxent y modelos lineales generalizados (GLM), se comparan con mapas de vegetación potencial y con otros modelos generados para esta especie en el conjunto de la península ibérica. Las variables empleadas para construir los modelos son precipitación media de agosto, continentalidad, temperatura media de las máximas de enero, radiación de enero, pendiente y desarrollo del suelo; todas fueron significativas en el GLM. En Maxent la variable con mayor contribución al modelo fue la precipitación de agosto. Los distintos modelos y mapas difieren sobre todo en los límites nordeste y sur de distribución de los carrascales. Los modelos construidos en este trabajo y los ya existentes sugieren que las variables ambientales consideradas no limitan el desarrollo de carrascales, al menos en algunas zonas del tercio meridional de Navarra, no contempladas en los mapas de vegetación potencial tradicionales.
Open Access
Environment and density-dependency explain the fine-scale aggregation of tree recruits before and after thinning in a mixed forest of Southern Europe
(PeerJ, 2022) Rodríguez Pérez, Javier; Peralta de Andrés, Francisco Javier; Imbert Rodríguez, Bosco; Zientziak; Institute for Multidisciplinary Research in Applied Biology - IMAB; Ciencias
Thinning in forest management primarily reduces the density of trees and alters the patchiness and spatial complexity of environmental factors and individual interactions between plant recruits. At fine spatial scales, little is known about the relative weight of ecological processes affecting tree regeneration before and after thinning events. Here we studied the density and aggregation of tree recruits in fully-mapped plots located in mixed forests in Northern Iberian Peninsula (Southern Europe) for over four years, which comprises one year before and three years after a thinning event. We applied spatial point-pattern analyses to examine (a) the aggregation of recruits, and their association with trees and (b) the relative effect of both environmental (i.e., the patchiness of the local environment) and density-dependent factors (i.e., the aggregation of trees and/or recruits) to predict the density, aggregation, and survival of recruits. We found, in thinning plots, that recruits were less dense, their aggregation pattern was more heterogeneous, were distributed randomly in respect of trees and their survival was almost unaffected by the tree proximity. By contrast, recruits in control plots were denser, were only aggregated at distances lower than 1.0 m, were closer to trees, and such closer distance to trees affected negatively in their survival. Independently of the treatment, the aggregation of recruits was chiefly determined by the density-dependent factors at less than 1.0 m and environmental factors at distances beyond that proximity. Overall, our results suggest that thinning affected the aggregation of recruits at two spatial scales: (a) by favoring the tree-recruit and recruit-recruit facilitation at less than 1.0 m and (b) by modifying spatial heterogeneity of the environment at distances beyond that proximity.
Open Access
Tree-to-tree competition in mixed European beech-Scots pine forests has different impacts on growth and water-use efficiency depending on site condition.
(Wiley, 2018) González de Andrés, Ester; Camarero, Jesús Julio; Blanco Vaca, Juan Antonio; Imbert Rodríguez, Bosco; Lo, Yueh-Hsin; Sangüesa Barreda, G.; Castillo Martínez, Federico; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Mixed conifer-hardwood forests can be more productive than pure forests and they are increasingly considered as ecosystems that could provide adaptation strategies in the face of global change. However, the combined effects of tree-to-tree competition, rising atmospheric CO2 concentrations and climate on such mixtures remain poorly characterized and understood.2. To fill this research gap, we reconstructed 34-year series (1980-2013) of growth (basal area increment, BAI) and intrinsic water-use efficiency (iWUE) of Scots pine (Pinus sylvestris L.)-European beech (Fagus sylvatica L.) mixed stands at two climati-cally contrasting sites located in the southwestern Pyrenees. We also gathered data on tree-to-tree competition and climate variables in order to test the hypotheses that (1) radial growth will be greater when exposed to inter- than to intraspecific competition, that is, when species complementarity occurs and (2) enhanced iWUE could be linked to improved stem radial growth.3. Growth of both species was reduced when intraspecific competition increased. Species complementarity was linked to improved growth of Scots pine at the continental site, while competition overrode any complementarity advantage at the drought-prone Mediterranean site. Beech growth did not show any significant response to pine admixture likely due to shade tolerance and the highly competitive nature of this species. Increasing interspecific competition drove recent iWUE changes, which increased in Scots pine but decreased in European beech. The iWUE enhancement did not involve any growth improvement in Scots pine. However, the positive BAIiWUE relationship found for beech suggests an enhanced beech growth in drought-prone sites due to improved water use.4. Synthesis. Complementarity may enhance growth in mixed forests. However, water scarcity can constrict light-related complementarity for shade intolerant species (Scots pine) in drought-prone sites. Basal area increment-intrinsic water-use efficiency relationships were negative for Scots pine and positive for European beech. These contrasting behaviours have got implications for coping with the expected increasing drought events in Scots pine-European beech mixtures located near ecological limit of the two species. Complementarity effects between tree species should be considered to avoid overestimating the degree of future carbon uptake by mixed conifer¿broadleaf forests.
Open Access
El ecólogo en su laberinto
(Asociación Española de Ecología Terrestre, 2008) García-Fayos, P.; Bonet, F.J.; Valladares, Fernando; Traveset Vilagines, Anna; Pausas, J.G.; Imbert Rodríguez, Bosco; Lloret, F; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
El presente artículo pretende ser una contribución al debate sobre el papel de los ecólogos en la sociedad. El mismo es producto de la reflexión a partir de discusiones mantenidas a finales de junio de 2007 en Farrera y enero de 2008 en Barcelona, bajo el auspicio de GLOBIMED, una red que reúne a casi 30 científicos españoles del campo de la ecología de los sistemas terrestres (http://www.globimed.net/).
Open Access
Land use change effects on carbon and nitrogen stocks in the Pyrenees during the last 150 years: a modelling approach
(Elsevier, 2015) Lo, Yueh-Hsin; Blanco Vaca, Juan Antonio; Canals Tresserras, Rosa María; González de Andrés, Ester; San Emeterio Garciandía, Leticia; Imbert Rodríguez, Bosco; Castillo Martínez, Federico; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
In the southern Pyrenees, human population and therefore land uses have changed from forests to pastures, then crops, and back to pastures and secondary forests during the last two centuries. To understand what such rapid land use changes have meant for carbon (C) and nitrogen (N) stocks, we used data from two forest sites in the western Pyrenees, combined with regional data on pastures and crop production (potato, cereal), to calibrate the ecosystem-level model FORECAST. Then, we simulated 150-year of land use for each site, emulating historical changes. Our estimates show that the conversion from forests into pastures and crops created C and N deficits (378-427 Mg C ha-1, 4.0-4.6 Mg N ha-1) from which these sites are still recovering. The main ecological process behind the creation of these deficits was the loss of the ecological legacy of soil organic matter (SOM) created by the forest, particularly during conversion to farming. Pastures were able to reverse, stop or at least slow down the loss of such legacy. In conclusion, our work shows the deep impact of historical land use in ecosystem attributes, both in magnitude of removed C and N stocks and in duration of such impact. Also, the usefulness of ecological modelling in absence of historical data to estimate such changes is showcased, providing a framework for potential C and N stocks to be reached by climate change mitigation measures such as forest restoration.
Open Access
Invertebrate community of Scots pine coarse woody debris in the Southwestern Pyrenees under different thinning intensities and tree species
(MDPI, 2021) Herrera Álvarez, Ximena; Blanco Vaca, Juan Antonio; Imbert Rodríguez, Bosco; Álvarez, Willin; Rivadeneira Barba, Gabriela; Zientziak; Institute for Multidisciplinary Research in Applied Biology - IMAB; Ciencias
Background and Objectives: The forest in the Southwestern Pyrenees Mountains (Northern Spain) is mainly composed of pure Pinus sylvestris L. or a mix of P. sylvestris and Fagus sylvatica L. The most common forest management technique to harvest pine is the application of forest thinning with different intensities. It promotes a change in the forest composition and structure. Taking into consideration this region as a site specific research about this topic, we aimed to understand the CWD invertebrate composition response to different thinning intensities and canopy type of these tree species. Materials and Methods: CWD samples were collected belonging to intermediate and advanced decay classes, approximately 10 cm long and 5 cm in diameter. Using a design of three thinning intensities (0%, 20%, and 40% of basal area removed), with three replications per treatment (nine plots in total), four samples were taken per plot (two per canopy type) to reach 36 samples in total. Meso- and macrofauna were extracted from CWD samples with Berlese– Tullgren funnels, and individuals were counted and identified. Results: Most of the taxonomic groups belonged to mesofauna, mainly to Acari and Collembola orders. On the other hand, the macrofauna represented a minimum percentage of the community composition. Our results indicated that although thinning intensities did not significantly affect the invertebrate community, canopy type and CWD water content influenced significantly. It is imperative to consider in forest management the responses of canopy type and thinning intensities in CWD water content, this disturbance could also slow down the organic matter decomposition process in the soil, thus affecting in the long term the natural cycle of nutrients.
Open Access
Simulando la interacción entre la densidad inicial y los flujos de agua y nutrientes para comprender el desarrollo de rodales mixtos de Pinus sylvestris y Fagus sylvatica bajo cambio climático
(Asociación Española de Ecología Terrestre, 2017) Candel Pérez, David; Blanco Vaca, Juan Antonio; González de Andrés, Ester; Lo, Yueh-Hsin; Imbert Rodríguez, Bosco; Castillo Martínez, Federico; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
La gestión de bosques mixtos se ha convertido en una estrategia de adaptación para reducir los riesgos relacionados con el cambio climático. A su vez, los modelos ecológicos pueden ser una herramienta útil para el estudio del crecimiento y la productividad de dichas masas. En este trabajo se presenta una evaluación de la capacidad del modelo híbrido “FORECAST Climate” de simular el estrés hídrico y la productividad en bosques mixtos de pino silvestre y haya en Navarra (norte de España) y su interacción con distintos niveles de densidad de regenerado. En el estudio se incluyeron tres escenarios climáticos para comprobar la capacidad del modelo para simular los flujos de agua bajo condiciones de cambio climático. Las estimaciones del modelo tanto de estrés hídrico como de acumulación de biomasa se mostraron sensibles a la reducción en la densidad de regeneración inicial. Los resultados indicaron que el modelo muestra la suficiente capacidad para simular los efectos de la competencia entre especies en la mortalidad de árboles en bosques mixtos y estimar variables relacionadas con los flujos hídricos. Por un lado, los efectos más significativos de la densidad del rodal sobre la disponibilidad hídrica aparecen durante la primera etapa de desarrollo, mientras que, por otro, el estrés hídrico es mayor en el caso del haya, aunque la reducción de la competencia podría compensar dicho aumento. Las implicaciones de este trabajo para la gestión adaptativa de bosques mixtos sugieren el actual control de la densidad para que los efectos acumulativos sean significativos en próximas décadas.
Open Access
Influence of thinning intensity and canopy type on Scots pine stand and growth dynamics in a mixed managed forest
(Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria (INIA), 2016) Primicia Alvarez, Irantzu; Artázcoz, Rubén; Imbert Rodríguez, Bosco; Puertas, Fernando; Traver, Carmen; Castillo Martínez, Federico; Ciencias del Medio Natural; Natura Ingurunearen Zientziak
Aim of the study: We analysed the effects of thinning intensity and canopy type on Scots pine growth and stand dynamics in a mixed Scots pine-beech forest. Area of the study: Western Pyrenees. Material and methods: Three thinning intensities were applied in 1999 (0, 20 and 30% basal area removed) and 2009 (0, 20 and 40%) on 9 plots. Within each plot, pure pine and mixed pine-beech patches are distinguished. All pine trees were inventoried in 1999, 2009 and 2014. The effects of treatments on the tree and stand structure variables (density, basal area, stand and tree volume), on the periodic annual increment in basal area and stand and tree volume, and on mortality rates, were analysed using linear mixed effects models. Main Results: The enhancement of tree growth was mainly noticeable after the second thinning. Growth rates following thinning were similar or higher in the moderate than in the severe thinning. Periodic stand volume annual increments were higher in the thinned than in the unthinned plots, but no differences were observed between the thinned treatments. We observed an increase in the differences of the Tree volume annual increment between canopy types (mixed < pure) over time in the unthinned plots, as beech crowns developed. Research highlights: Moderate thinning is suggested as an appropriate forest practice at early pine age in these mixed forests, since it produced higher tree growth rates than the severe thinning and it counteracted the negative effect of beech on pine growth observed in the unthinned plots.