La importància del potassi en el creixement dels boscos

El potassi ha estat, en general, un element poc considerat en els estudis ecològics del creixement dels boscos. Partint d'aquest fet, un grup d'investigadors del CREAF a la UAB ha estudiat el paper d'aquest element en el creixement de 2836 parcel·les de boscos catalanes. Així, aquests investigadors han posat de manifest la importància del potassi per aquest tipus d'estudis ecològics i han millorat el coneixement que es tenia dels factors que influeixen en el contingut dels diferents elements, nitrogen i fòsfor a més del potassi, en les fulles i la fusta dels arbres. També han arribat a la conclusió que el contingut de potassi en els arbres està determinat per factors ambientals.El potasio ha sido, en general, un elemento poco considerado en los estudios ecológicos del crecimiento de los bosques. Partiendo de este hecho, un grupo de investigadores del CREAF, en la UAB, ha estudiado el papel de este elemento en el crecimiento de 2836 parcelas de bosques catalanes. Así, estos investigadores han puesto de manifiesto la importancia del potasio para este tipo de estudios ecológicos y han mejorado el conocimiento que se tenía de los factores que influyen en el contenido de los diferentes elementos, nitrógeno y fósforo además del potasio, en las hojas y la madera de los árboles. También han llegado a la conclusión de que el contenido de potasio en los árboles está determinado por factores ambientales.Potassium is generally not considered in ecological studies of forest growth. Based on this, a group of researchers at the CREAF in the UAB has studied the role of this element in the growth of 2836 forests parcels in Catalonia. Thus, these researchers have highlighted the importance of potassium for such ecological studies and improved knowledge of the factors that had influenced the content of these different elements, nitrogen and phosphorus plus potassium, in leaves and wood of trees. They also concluded that potassium content in trees is determined by environmental factors

Soil carbon stocks and their variability across the forests, shrublands and grasslands of peninsular Spain

Accurate estimates of C stocks and fluxes of soil organic carbon (SOC) are needed to assess the impact of climate and land use change on soil C uptake and soil C emissions to the atmosphere. Here, we present an assessment of SOC stocks in forests, shrublands and grasslands of peninsular Spain based on field measurements in more than 900 soil profiles. SOC to a depth of 1 m was modelled as a function of vegetation cover, mean annual temperature, total annual precipitation, elevation and the interaction between temperature and elevation, while latitude and longitude were used to model the correlation structure of the errors. The resulting statistical model was used to estimate SOC in the ∼8 million pixels of the Spanish Forest Map (29.3 × 10⁶ ha). We present what we believe is the most reliable estimation of current SOC in forests, shrublands and grasslands of peninsular Spain thus far, based on the use of spatial modelling, the high number of profiles and the validity and refinement of the data layers employed. Mean concentration of SOC was 8.7 kg m-₂, ranging from 2.3 kg m-₂ in dry Mediterranean areas to 20.4 kg m-₂ in wetter northern locations. This value corresponds to a total stock of 2.544 Tg SOC, which is four times the amount of C estimated to be stored in the biomass of Spanish forests. Climate and vegetation cover were the main variables influencing SOC, with important ecological implications for peninsular Spanish ecosystems in the face of global change. The fact that SOC was positively related to annual precipitation and negatively related to mean annual temperature suggests that future climate change predictions of increased temperature and reduced precipitation may strongly reduce the potential of Spanish soils as C sinks. However, this may be mediated by changes in vegetation cover (e.g. by favouring the development of forests associated to higher SOC values) and exacerbated by perturbations such as fire. The estimations presented here provide a baseline to estimate future changes in soil C stocks and to assess their vulnerability to key global change drivers, and should inform future actions aimed at the conservation and management of C stocks

Béns i serveis que proveeixen els boscos de Catalunya

Investigadors/es del CREAF i la UAB han demostrat que la combinació de múltiples fonts de dades pot ajudar a tenir un coneixement més ampli i detallat dels ecosistemes dels boscos de Catalunya i els serveis i béns que aquests proporcionen, essencials pel benestar de la nostra societat. Els resultats obtinguts permeten desenvolupar millors estratègies de planificació territorial i de gestió de recursos naturals.Investigadores/as del CREAF y de la UAB han demostrado que la combinación de múltiples fuentes de datos puede ayudar a tener un conocimiento más amplio y detallado de los ecosistemas de los bosques de Cataluña y de los servicios y bienes que estos proporcionan, esenciales para el bienestar de nuestra sociedad. Los resultados obtenidos permiten desarrollar mejor estrategias de planificación territorial y de gestión de recursos naturales.A recent study published by CREAF and the UAB shows that the combination of multiple sources of information helps to have a broader and better understanding of the forest ecosystems of Catalonia and the services and goods they provide, which are key for human well-being. The results obtained allow better strategies for land planning and management of natural resources

Estudi del decaïment en Pinus halepensis al Parc de Collserola

Aquest és un treball fet amb l'objectiu general d'intentar determinar les causes més probables del decaïment i mort d'un gran nombre de peus de l'espècie Pinus halepensis a la finca de Can Catà (parc natural de Collserola), després dels aprofitaments forestals que s'hi van fer entre agost i novembre de 2012. Com a punt de partida és planteja comparar els patrons de creixement entre els arbres morts i els vius, en relació a les principals variants climàtiques (pluviometria i temperatura, tant anuals com estacionals). Els resultats de les correlacions entre cadascuna de les variables climàtiques i els BAI fan descartar aquestes hipòtesis al no trobar-se diferències significatives entre els valors referits als arbres morts i els referits als vius. El treball "amplia les hipòtesis de partida" quan, durant el tractament i anàlisis de les mostres, apareixen bastants cores amb taques blaves (que evidencien un atac per fongs blue stain) i la majoria d'aquest cores pertanyen a arbres morts. A partir d'aquest moment també ens interessem per aquest fong i per la seva associació amb el coleòpter Tomicus destruens, (podríem parlar de la coincidència temporal de la gestió forestal amb una plaga d'aquests escolítids). L'associació Tomicus / blue stain està documentada des de 1922 i amb beneficis recíprocs; el fong entra conjuntament amb el escolítid i també aprofita les seves galeries per entrar al càmbium i germinar-hi, i ajuda al Tomicus per mitjà de la dessecació de l'albeca, inhabilitant els processos de resinosi que afecten les larves i els ous de l'escarabat. La coincidència dels símptomes descrits ens diferents articles (en els arbres colonitzats per blue stain), amb els observats en els nostres individus morts; els estudis de com el blue stain bloqueja el flux ascendent d'aigua que puja per l'albeca, produint embolisme als vasos conductors, dessecant la fusta i arribant a produir la mort de l'arbre; les coincidències temporals descrites de la mort dels hostes; el resultat força significatiu del test de la X² per la infecció fúngica... Són arguments que indiquen que probablement van ser aquests fongs els causants directes de la mort dels individus estudiats

A Battery of soil and plant indicators of NBS environmental performance in the context of global change

Nature-based solutions (NBSs) for risk reduction produce environmental effects that must be assessed to evaluate their performance. In a context of climate change and growing concern about the loss of biodiversity, indicators informing about ecosystem complexity, resilience and stability are required. NBS projects hardly ever include environmental monitoring programs and, at best, NBS performance is evaluated based on elementary indicators that provide poor information about ecosystem functions and services. Within the framework of the PHUSICOS (EU, H2020) project, a NBS approach is being applied to reduce the hydrometeorological risks (rock falls and snow avalanches) that threaten a transnational road and a very populated town in the Pyrenees range. In both cases, the planned actions are modifying soil and vegetation structure and functioning as well as the environmental services they provide. Here we present a set of soil and plant indicators designed to be included in the postoperation monitoring plan of both NBS projects. We provide a description and information about the range of values of every indicator measured in the study sites together with indications about analytical methods and sampling calendar. We discuss the trade-offs between monetary cost, expertise requirements and meaningfulness of the indicators

Assessing the distribution of forest ecosystem services in a highly populated Mediterranean region

Altres ajuts: FP7-Marie Curie-COFUND program of the European Commission (Grant 'Clarín' ACA17-02)Forest ecosystems provide a wide range of goods and services to society and host high levels of biodiversity. Nevertheless, forest ecosystem services (ES) are often quantified and assessed using simplified methodologies (e.g., proxy methods based exclusively on Land Use Land Cover maps) that introduce substantial uncertainty in the analysis by ignoring, for instance, the species composition and spatial configuration of the ecosystems studied. In this work we defined and calculated a set of 12 indicators of several ES for the forests of the highly populated region of Catalonia (North-eastern Iberian Peninsula). The indicators combined different sources of information such as forest surveys, ecological model predictions and official statistics, but also included additional land cover information. All ES indicators were aggregated at the municipality level to compare their values and distribution patterns. We assessed spatial trade-offs and synergies among ES, as well as their relationships with a set of socioeconomic, climatic and biodiversity variables using correlation analyses and mixed-effects models. The results suggest a clustering of provisioning and regulating ES in mountainous zones towards the North of the study area. These two types of services showed a high degree of spatial similarity and presented high positive correlations. In contrast, cultural ES showed a more scattered pattern, which included lower elevation areas in the South of the study region. Climatic conditions were the main determinants of the spatial variability in the supply of the different ES, with most indicators being positively associated with precipitation and negatively associated with temperature. In addition, biodiversity (particularly woody species richness) showed positive relations with most of these ES, while socioeconomic variables (such as population density and the percentage employment in agriculture) showed negative associations with most of them. The combination of information from different data sources (including primary data) allowed for a detailed analysis of forest ES, likely removing some of the problems derived from approaches based only on proxy methods. In addition, the use of municipalities as study unit makes results directly relevant to management and planning strategies operating at this scale (e.g., forest management and planning

Reassessing global change research priorities in mediterranean terrestrial ecosystems : how far have we come and where do we go from here?

Aim: Mediterranean terrestrial ecosystems serve as reference laboratories for the investigation of global change because of their transitional climate, the high spatiotemporal variability of their environmental conditions, a rich and unique biodiversity and a wide range of socio-economic conditions. As scientific development and environmental pressures increase, it is increasingly necessary to evaluate recent progress and to challenge research priorities in the face of global change. - Location: Mediterranean terrestrial ecosystems. - Methods: This article revisits the research priorities proposed in a 1998 assessment. - Results: A new set of research priorities is proposed: (1) to establish the role of the landscape mosaic on fire-spread; (2) to further research the combined effect of different drivers on pest expansion; (3) to address the interaction between drivers of global change and recent forest management practices; (4) to obtain more realistic information on the impacts of global change and ecosystem services; (5) to assess forest mortality events associated with climatic extremes; (6) to focus global change research on identifying and managing vulnerable areas; (7) to use the functional traits concept to study resilience after disturbance; (8) to study the relationship between genotypic and phenotypic diversity as a source of forest resilience; (9) to understand the balance between C storage and water resources; (10) to analyse the interplay between landscape-scale processes and biodiversity conservation; (11) to refine models by including interactions between drivers and socio-economic contexts; (12) to understand forest-atmosphere feedbacks; (13) to represent key mechanisms linking plant hydraulics with landscape hydrology. - Main conclusions:(1) The interactive nature of different global change drivers remains poorly understood. (2) There is a critical need for the rapid development of regional- and global-scale models that are more tightly connected with large-scale experiments, data networks and management practice. (3) More attention should be directed to drought-related forest decline and the current relevance of historical land use

Impactes del canvi global sobre els boscos de la Península Ibèrica: estocs, creixement i regeneració

Aquesta tesi analitza els impactes recents del canvi global sobre els boscos de l’Espanya peninsular basant-se en la informació de les parcel·les dels dos darrers inventaris forestals nacionals (IFN2 i IFN3). Es tenen en compte, a la vegada, els efectes complementaris del clima, l’estructura del bosc i altres factors locals. Un estudi d’aquestes característiques –a escala regional amb un important gradient climàtic, en clima mediterrani (on l’aigua és un dels principals factors limitants) i on, d’acord amb les projeccions dels model climàtics, el canvi climàtic pot ser especialment acusat en el futur– fa que aquesta aproximació sigui especialment rellevant per les implicacions que podria tenir en les funcions i serveis ecosistèmics que ofereixen els boscos. Per mitjà de models estadístics apropiats hem analitzar els efectes sobre els estocs i el balanç de carboni (C), els canvis demogràfics i els canvis en la distribució geogràfica de les espècies arbòries. Els principals resultats són: 1) La riquesa estructural és el principal predictor de l’estoc de C per hectàrea amb els valors més elevats en els rodals amb major riquesa estructural. Les variables climàtiques tenen principalment efectes indirectes sobre l’estoc a través de la riquesa estructural i tenen un efecte predictiu directe baix quan es tenen en compte totes les variables predictores a la vegada; 2) Els bosc no pertorbats de l’Espanya peninsular estan acumulant C a una taxa de 1.4 Mg C ha-1 any-1. Les variables estructurals són els principals determinants del creixement del bosc i dels canvis en l’estoc de C. La disponibilitat d’aigua està positivament relacionada amb el creixement i la taxa d’acumulació de C. L’escalfament recent ha reduït el creixement i la taxa d’acumulació de C especialment en les zones més humides; 3) Les elevades taxes de regeneració dels planifolis es pot explicar per la seva major habilitat per mantenir un elevat banc de plançons degut a la seva tolerància a l’ombra. L’abundància de plançons de coníferes i de planifolis està principalment determinat per l’estructura forestal, mentre que els efectes directes de les pertorbacions i el clima han estat més modestos. No s’ha detectat cap efecte de l’escalfament recent i; 4) La majoria d’espècies arbòries de l’Espanya peninsular s’han mogut muntanya amunt capa zones més fresques. Ara bé la major part dels patrons observats, inclosos alguns canvis geogràfics inesperats, s’expliquen per l’estructura forestal. Les principals conclusions són: 1) Els nostres resultats suggereixen que per aconseguir un major estoc de C és necessari promoure una major riquesa estructural gestionant els boscos com a masses irregulars afavorint els planifolis per damunt de les coníferes. 2) L’efecte negatiu de l’escalfament en la taxa d’acumulació de C desapareix si només es tenen en compte els boscos gestionats, emfatitzant el potencial que pot tenir la gestió forestal per mitigar l’efecte negatiu del canvi climàtic; 3) La resposta diferencial de les coníferes i els planifolis al tancament de capçades suggereix un probable increment dels primes a expenses de les segones. Aquesta transició pot tenir lloc més d’hora en els rodals on la dinàmica de tancament de les capçades és més ràpida i; 4) L’abandonament de la gestió forestal i les pertorbacions (p.e., focs) de les darreres dècades ha dut a l’expansió dels planifolis a expenses de les coníferes, degut a la seva major habilitat per fer front als factors biòtics com la competència. No és gens clar que aquesta tendència pugui mantenir-se en el futur degut a l’increment de l’aridesa de les projeccions dels models climàtics, tenint en compte la major habilitat de les coníferes per fer front als esdeveniment climàtics extrems.This Ph D Thesis analyzes the recent impact of global change on forests of Peninsular Spain using the information of the two last national forest inventories (IFN2 and IFN3). It takes into account at the same time the complementary effects of climate, forest structure and other local factors. A study of such characteristics –at a regional scale, with an important climatic gradient, in a Mediterranean climate (where water is one of the main limiting factors) and where, according to the predictions of climatic models, climatic change may be especially important in the future– makes that this approach is especially relevant for the implications that these changes may have on ecosystem services offered by forests. By means of appropriate statistical models I have analyzed the effects of these impacts on stocks and carbon (C) balance, demographic changes and geographical changes in the distribution of tree species. The main results are: 1) The structural richness is the main predictor of stand tree C stock with larger C stocks in structurally richer stands. Climate variables have mainly an indirect effect through structural richness but a smaller direct predictive ability when all predictors are considered.; 2) Undisturbed forests in Peninsular Spain are accumulating C at a rate of 1.4 Mg C ha-1 yr-1. The forest structural variables are the main determinants of forest growth and C stock change. Water availability was positively related to growth and C accumulation. Recent warming has reduced growth rate and C accumulation, especially in wet areas; 3) The higher values of regeneration rate of broadleaves can be explained because of their ability to maintain a higher sapling bank due to their higher shadetolerance. Sapling abundance and regeneration rate were mainly determined by stand structure, both in conifers and broadleaves, whereas the direct effects of disturbances and climate were relative small and there was no detectable effect of recent warming and; 4) The geographic distribution of most tree species in peninsular Spain has moved upwards towards cooler environments. We also show that most of the observed patterns, including some counterintuitive geographic shifts, are explained by forest structure. The main conclusions are: 1) To achieve a greater standing C stock, our results suggest the need for promoting high structural richness by managing for uneven-aged stands and favoring broadleaf over conifer species; 2) Interestingly, the negative effect of warming on forest C accumulation disappears if only managed stands are considered, emphasizing the potential of forest management to mitigate the effects of climate change; 3) The differential response of conifers and broadleaves to canopy closure suggests a likely increment of broadleaves at the expense of conifers. This transition could occur earlier in stands with faster canopy closure dynamics and; 4) Changes in forest management practices (i.e., forest abandonment) and disturbances (e.g., fires) during the last decades have leaded to the expansion of broadleaves over conifers, due to their greater ability to cope with biotic factors such as competition. It is unclear whether this trend will continue under the greater aridness projected by climate models, considering the greater ability of conifers to cope with extreme drought events