Instituto Universitario de Investigación en Gestión Forestal SostenibleIUGFShttps://uvadoc.uva.es/handle/10324/74922024-03-19T08:49:45Z2024-03-19T08:49:45ZSubstrate optimization for shiitake (Lentinula edodes (Berk.) Pegler) mushroom production in EthiopiaDesisa, BuzayehuMuleta, DiribaDejene, TatekJida, MulissaGoshu, AbaynehMartín Pinto, Pablohttps://uvadoc.uva.es/handle/10324/665712024-03-08T20:00:59Z2023-01-01T00:00:00ZEdible mushrooms are seen as a way of increasing dietary diversity and achieving food security in Ethiopia. The aim of this study was to develop substrates using locally available agro-industrial by-products and animal manures to enhance the production of Shiitake (Lentinula edodes) mushrooms in Ethiopia. The hypothesis was L. edodes mushroom production on seven different substrates: 100% sugarcane bagasse (S1), 80% sugarcane bagasse, 20% cow dung (S2), horse manure (S3), chicken manure (S4), cottonseed hulls (S5), sugarcane filter cake (S6), and sugarcane trash (S7). Mushroom yield and biological efficiency were significantly affected by substrate type (p < 0.05). A significantly higher yield (434.33 g/500 g of substrate) and biological efficiency (86.83%) were obtained using substrate S4 while lower yield (120.33 g/500 g) and biological efficiency (24.33%) were obtained using substrate S7 than when using other substrates. The largest first flush of mushrooms was obtained on S4, and five flushes were produced on this substrate. S4 also had the highest biological efficiency, the highest nitrogen content, and the lowest C:N. Chicken manure is rich in nitrogen, magnesium, calcium, and potassium, which are crucial for Shiitake mushroom growth. Thus, substrate S4 would be a viable option for cultivating Shiitake mushrooms, particularly in regions where chicken manure is readily available. Substrate S2 also provided high yields and rapid fructification and would be a suitable alternative for Shiitake mushroom cultivation.
2023-01-01T00:00:00ZTree Growth Response to Low-Intensity Prescribed Burning in Pinus nigra Stands: Effects of Burn Season and Fire SeverityMartin-Benito, DarioRodríguez de Rivera, ÓscarHernando, CarmenGuijarro, MercedesMadrigal, JavierEspinosa Prieto, Juncalhttps://uvadoc.uva.es/handle/10324/652802024-01-30T20:03:39Z2021-01-01T00:00:00ZThe study of the short-term post-burn tree growth in a mixed stand of Pinus nigra and Pinus pinaster and in a pure stand of P. nigra in the Cuenca Mountains (Spain) will enable us to determine the disturbance of prescribed burning conducted in two seasons. Dendrochronological methods and mixed modelling were used to investigate whether tree growth responses are influ-enced by stand and tree characteristics, fire season and fire severity variables. The findings revealed that prescribed burning scarcely affected tree growth. The type of stand (mixed or pure) was not critical for tree growth. The individual tree characteristics were significant factors in all the scenarios studied. The inclusion of some fire severity variables for the first time in tree growth models showed that the maximum scorch height determined a main part of the variability of tree growth. The time during which the temperature was above 60 °C in the cambium region and temperature was above 300 °C in the bark surface were only significant factors after spring burnings. The litterfall one year after the prescribed burning was not a significant factor in any of the models. Overall, the findings confirm the characteristic resistance of P. nigra to surface fires and favor the potential application of prescribed burning programs for this species in the Mediterranean Basin.
2021-01-01T00:00:00ZEmpirical Modelling of Stem Cambium Heating Caused by Prescribed Burning in Mediterranean Pine ForestMadrigal, JavierRodríguez de Rivera, ÓscarCarrillo, CristinaGuijarro, MercedesHernando, CarmenVega, José A.Martín Pinto, PabloMolina, Juan R.Fernández, CristinaEspinosa Prieto, Juncalhttps://uvadoc.uva.es/handle/10324/649452024-03-07T13:42:12Z2023-01-01T00:00:00ZLittle is known about the interactions between the variables involved in the post-fire response of Mediterranean pine species to prescribed burning (PB). Thus, it is essential to develop an empirical model in order to assess the influence of tree and stand attributes, burn season, and fire severity on the probability of stem cambium damage occurring. Prescribed burnings were conducted in different seasons and areas covering a wide climatic and ecological range. Potential explanatory variables were measured. A random effects hurdle model framework was used to evaluate the temperature duration above 60 °C as a proxy for stem cambium damage at tree scale. The results showed significant differences in cambium damage between the PB seasons. Pinus nigra was more resistant than other pine species. Bark thickness was critical for protecting cambium. Volume of crown scorch, percentage of stem scorch, and maximum outer bark temperature were directly related to temperature duration above 60 °C in the cambium. Prescribed burning conducted under tree canopy in Mediterranean pine species generally results in a low level of cambium damage. Empirical models could help managers to predict the effects of PB and thus select the most suitable prescriptions
2023-01-01T00:00:00ZFire-severity mitigation by prescribed burning assessed from fire-treatment encounters in maritime pine standsPalheiro, PedroLoureiro, CarlosAscoli, DavideEsposito, AssuntaFernandes, Paulo M.Espinosa Prieto, Juncalhttps://uvadoc.uva.es/handle/10324/648802024-01-23T20:06:22Z2019-01-01T00:00:00ZMaritime pine (Pinus pinaster Ait.) stands are prone to high-intensity fire. Fuel treatments lessen potential fire behaviour and severity, but evidence of their effectiveness when tested by wildfire is extremely scarce in Europe. We assess the longevity of prescribed burning in maritime pine plantations in decreasing fire severity. Heights of crown scorch and stem-bark char were measured in treated and untreated adjacent areas after fire-treatment encounters in Portugal, Italy, and Australia. Treatment effect was quantified as the log-transformed ratio between prescribed-burned and untreated fire-severity data. Linear mixed modelling indicated that for typical wildfire conditions, the effect of prescribed burning in crown scorch height lasts 2–6 years. The persistence of prescribed burning benefits is higher for fire control operations than for fire-severity mitigation. Regression tree analysis of data from one wildfire highlighted the roles of wind direction, topography, and stand height in explaining variability in fire severity. A 4-year interval between prescribed burning treatments in maritime pine stands is recommended in general, depending on site quality and stand age and structure. Improved fuel-consumption prescriptions and monitoring procedures are advisable to foster prescribed-burning effectiveness and its evaluation.
2019-01-01T00:00:00ZFungal diversity and community composition responses to the reintroduction of fire in a non-managed Mediterranean shrubland ecosystemEspinosa Prieto, JuncalDejene, TatekGuijarro, MercedesCerdá, XimMadrigal, JavierMartín Pinto, Pablohttps://uvadoc.uva.es/handle/10324/647362024-01-18T20:02:01Z2023-01-01T00:00:00ZBackground
More than a decade of fire suppression has changed the structure of fire-adapted shrubland ecosystems in Spain's National Parks, which are now at extreme risk of uncontrolled wildfires. Prescribed burning can mitigate the risk of wildfires by reducing the fuel load but prescribed burning may also alter the soil properties and reduce microbial and fungal activity, causing changes in the availability of nutrients deep in the soil layer. Although fungal communities are a vital part of post-fire restoration, some fire effects remain unclear. To examine the short-term effects of prescribed burning on soil fungal communities in Doñana Biological Reserve (SW Spain), we collected soil samples pre-burn and 1 day, 6 and 12 months post-burn from burned plots to perform physicochemical and metabarcode DNA analyses.
Results
Prescribed burning had no significant effect on the total fungal operational taxonomic unit richness and abundance. However, changes in soil pH, nitrogen and potassium content post-burn affected fungal community composition. Small non-significant changes in pH and phosphorous affected the composition of ectomycorrhizal fungi.
Conclusions
The ectomycorrhizal fungal community appears to be resilient to the effects of low-to moderate-intensity fires and saprotrophic taxa may benefit from this kind of fire. This finding revealed that prescribed burning is a potentially valuable management tool for reducing fire hazards in shrublands that has little effect on the total richness and abundance of fungal communities.
2023-01-01T00:00:00ZShort-term effects of prescribed burning on litterfall biomass in mixed stands of Pinus nigra and Pinus pinaster and pure stands of Pinus nigra in the Cuenca Mountains (Central-Eastern Spain)Espinosa Prieto, JuncalMadrigal, J.De La Cruz, A.C.Guijarro, M.Jimenez, E.Hernando, C.https://uvadoc.uva.es/handle/10324/647102024-01-18T20:02:00Z2018-01-01T00:00:00ZFire severity, defined as the magnitude of fire effects in an ecosystem, is a key factor to consider in planning management strategies for protecting forests against fire. Although prescribed burning has been used as a fuel reduction tool in forest ecosystems, it is quite limited in the Mediterranean region. Furthermore, little is known about how tree crowns are affected by prescribed underburning aimed at reducing fire severity in conifer stands. As part of an ongoing study to assess the effects of prescribed burning on the tree canopy, litterfall is currently being monitored in a network of experimental plots located in mixed (Pinus nigra and Pinus pinaster) and pure (P. nigra) conifer stands in the Cuenca Mountains (Castilla La Mancha, Spain). A total of 12 study plots (30 m × 30 m) were established in a completely randomized experimental design to determine the effect of burning, with 2 treatments: no burning (control) and burning (i.e. with three replicate plots for each treatment and site). Burning was conducted in May 2016. In each plot, 8 litterfall collectors were installed at regular intervals, according to international protocols (ICP Forests), and all biomass falling into the collectors is being monitored monthly. The specific objective of this study is to assess how prescribed burning affects the rate of generation of foliar and non-foliar litterfall biomass due to the fire. In addition, the Leaf Area Index was estimated before burning and one year later to verify possible changes in the structure of the stands. This information could be used to help minimize the negative impacts of prescribed underburning on litterfall. To our knowledge, this study represents the first attempt to evaluate the effect of prescribed burning on litterfall biomass in Europe.
2018-01-01T00:00:00ZWhat is the most suitable height range of ALS point cloud and LiDAR metric for understorey analysis? A study case in a mixed deciduous forest, Pokupsko basin, CroatiaMartín García, SarayBalenović, IvanJurjević, LukaLizarralde, IñigoBuján, SandraAlonso Ponce, Rafaelhttps://uvadoc.uva.es/handle/10324/631472023-11-22T20:00:41Z2022-01-01T00:00:00ZUnderstorey evaluation is essential in wildlife habitat management, biomass storage and wildfire suppression, among other areas. The lack of a standardised methodology in the field measurements, and in their subsequent analysis, forces researchers to look for procedures that effectively extract understorey data to make management decisions corresponding to actual stand conditions. In this sense, when analysing the understorey characteristics from LiDAR data, it is very usual to ask: “what value should we set the understorey height range to?” It is also usual to answer by setting a numeric value on the basis of previous research. Against that background, this research aims to identify the optimal height to canopy base (HCB) filter–LiDAR metric relationship for estimating understorey height (UH) and understorey cover (UC) using LiDAR data in the Pokupsko Basin lowland forest complex (Croatia). First, several HCB values per plot were obtained from field data (measured HCBi—HCBM-i, where i ϵ (minimum, maximum, mean, percentiles)), and then they were modelled based on LiDAR metrics (estimated HCBi—HCBE-i). These thresholds, measured and estimated HCBi per plot, were used as point cloud filters to estimate understorey parameters directly on the point cloud located under the canopy layer. In this way, it was possible to predict the UH with errors (RMSE) between 0.90 and 2.50 m and the UC with errors (RMSE) between 8.8 and 18.6 in cover percentage. Finally, the sensitivity analysis showed the HCB filter (the upper threshold to select the understorey LiDAR points) is the most important factor affecting the UH estimates, while this factor and the LiDAR metric are the most important factors affecting the UC estimates.
2022-01-01T00:00:00ZRelationships between rhizosphere microbiota and forest health conditions in Pinus pinaster stands at the Iberian PeninsulaMorales Rodríguez, CarmenMartín García, JorgeRuiz Gómez, Francisco JPoveda Arias, JorgeDíez Casero, Julio Javierhttps://uvadoc.uva.es/handle/10324/625782023-11-02T20:01:19Z2024-01-01T00:00:00ZMaritime pine (Pinus pinaster) is a Mediterranean forest tree species of great ecological importance within the European Union and the Iberian Peninsula in particular, whose presence is seriously threatened by forest decline. Knowledge of the diversity, abundance, and functionality of rhizospheric microorganisms can provide important information in the design of new strategies for sustainable forest management against forest decline. In this work, rhizospheric samples were collected from representative pine forests in the region of Castilla y León (North-western Spain) (in 10 municipalities of 5 different provinces), analyzing different physicochemical parameters and bacterial and fungal biodiversity (by metabarcoding). In addition, different variables of tree health and climatic conditions were analyzed. The main phylum of microorganisms found in the rhizosphere of P. pinaster were the Ascomycota (54.5 %) and Acidobacteria (16.4 %) in fungi and bacteria, respectively. A clear relationship was found between the presence/absence of certain bacterial and fungal groups (taxonomic and functional) and the presence/absence of healthy/sick trees. Specifically, the fungal genus Umbelopsis and the bacterial genus Paenibacillus were thought as possible control agents of decline, as their presence was related to the absence of disease. Understanding the relationships between rhizosphere microbiota and forest health parameters in Pinus pinaster can be only achieved by exploring the complex ‘ecosystem microbiome’ and its functioning using focused, integrative microbiological and ecological research performed across multiple habitats.
2024-01-01T00:00:00ZLet us give voice to local farmers: Preferences for farm-based strategies to enhance human–elephant coexistence in AfricaMontero Botey, MaríaSoliño Millán, MarioPerea, RamónMartínez Jauregui, Maríahttps://uvadoc.uva.es/handle/10324/619672023-10-11T19:00:45Z2022-01-01T00:00:00ZSimple Summary: Local communities living on the edge of protected areas often experience negative impacts on their livelihoods due to wildlife. These situations threaten support for long-term conservation of wildlife and wild habitats so a key for conservation sustainability should be based on implementing socially accepted and economically sustainable mitigation practices. For successful design and implementation of mitigation strategies, it is vital to engage local communities and understand their preferences and previous experiences. In this study, we present a choice experiment as a tool to analyze local farmer preferences for the most common farm-based solutions to reduce African elephant crop damage. Results show that there are significant differences among responses triggered by farmers’ previous experience with elephants and socioeconomic situation, with a marked spatial distribution among respondents. This methodology, based on a choice modeling approach considering the differential availability of resources and previous experience with elephants or other wildlife, is highly applicable, with small changes in other areas where wildlife competes with local communities for resources. This approach also represents a suitable instrument for identifying stakeholders’ preferences in each specific context.; Local communities surrounding wildlife corridors and natural reserves often face challenges related to human–wildlife coexistence. To mitigate the challenges and ensure the long-term conservation of wildlife, it is important to engage local communities in the design of conservation strategies. By conducting 480 face-to-face interviews in 30 villages along and adjacent to the Selous-Niassa Wildlife Corridor (Tanzania), we quantified farmers’ preferences for farm-based measures to mitigate African elephant damage using choice experiments. Results show that farmers considered no action the least preferred option, revealing that they are open to trying different measures. The most preferred management strategy matched with the preferences of wildlife rangers in the area, suggesting low concern about the potential conflicts between stakeholders. However, a latent class model suggests that there are significant differences among responses triggered by farmers’ previous experience with elephants, the intensity of the elephant damage, and the socioeconomic situation of the farmer. Results show a marked spatial distribution among respondents, highlighting the benefits of zone management as conflicts were found to be highly context dependent. Understanding the human dimension of conservation is essential for the successful planification and implementation of conservation strategies. Therefore, the development and broad utilization of methodologies to gather specific context information should be encouraged.
2022-01-01T00:00:00ZFrass from yellow mealworm (Tenebrio molitor) as plant fertilizer and defense priming agentBlakstad, Jakob IrgensStrimbeck, RichardPoveda Arias, JorgeBones, Atle MagnarKissen, Ralphhttps://uvadoc.uva.es/handle/10324/618702023-10-03T19:03:16Z2023-01-01T00:00:00ZWorld population growth requires the development of a sustainable agriculture that allows feeding all the inhabitants of the planet, while reducing the use of agrochemicals. Currently, the insect farming industry for food and feed production is developing exponentially throughout the world; also producing insect frass with a potential utilization within agriculture and greenhouse industry. In the case of the yellow mealworm (Tenebrio molitor), few studies have been developed so far on the use of frass as a fertilizer, and there are none on its ability to activate plant defenses. By applying 2% sterilized mealworm frass to tomato we found a significant increase in its growth, demonstrating that the microbiota might not play a key role in its fertilizing capacity. In addition, the application of frass to sunflowers under different situations of nutritional deficit allowed us to determine what specific nutrients this fertilizer may be providing to the plant, finding a possible deficiency in the supply of N, but with sufficient amounts of P, K, Ca, and S. With respect to the induction of defenses, mealworm insect frass did not induce local root defenses in a root callose deposition assay in Arabidopsis thaliana under our experimental conditions. However, it activated systemic defenses in Arabidopsis thaliana by inducing defense genes in the absence of pathogen, further enhanced by infection with the necrotrophic fungus Botrytis cinerea. Therefore, mealworm frass could be a good fertilizer resource and plant defense inducer to support development of sustainable agriculture.
2023-01-01T00:00:00ZCarbon accumulation over 70 years of old-field succession driven by live biomass in a Mediterranean continental environmentVelázquez Martín, EduardoTurrión Nieves, María BelénBravo Oviedo, Felipehttps://uvadoc.uva.es/handle/10324/616112023-09-18T19:00:53Z2023-01-01T00:00:00ZForest expansion in abandoned agricultural lands entails the fixation of atmospheric CO2 in the live biomass, the soil as well as in other ecosystem compartments, and in turn, has strong implications for C budgets and the design of actions to mitigate climate change all over the world. However, changes in C stocks in these compartments are still poorly understood. We assessed the main patterns and drivers of C accumulation over spontaneous colonization of abandoned agricultural lands, considering the above- and below-ground biomass (AGB and BGB, respectively), the woody debris (WD), the litter and the surface soil (SS; 0–6 cm depth), in an area of Central-North Spain. To attain this objective, we established a chronosequence of 30 plots (0.0625 ha) located in agricultural lands abandoned in 1956–1977, 1977–2005 and 2005–2017, in four different forest types. We found that the AGB and the SS accounted for the major proportion of the total C stock, but the BGB was also relatively important. Carbon stocks in all these major compartments increased linearly with the age of tree colonization. But C in the SS did not significantly differ among plots abandoned in the three periods considered and showed decreasing rates of change from youngest (i.e. those in plots abandoned in 2005–2017) to oldest (i.e. those in plots abandoned in 1956–1977) stands. Carbon accumulation was mainly driven by adult stem density and age of tree colonization in the AGB and the BGB, and by the total nitrogen content in the SS. Our findings indicate that, in these new forests, C accumulation in the live biomass is still ongoing and proceeds relatively fast and at an increasing rate, which points toward a clear potential for atmospheric CO2 fixation over the next few decades. This process, however, proceeds more slowly and shows signals of an apparent deceleration in the SS. The C stock in the surface soil is, in fact, largely disconnected from that of live biomass and varies depending on pre-abandonment land-use differences among the study sites.
2023-01-01T00:00:00ZComparison of physical-based models to measure forest resilience to fire as a function of burn severityFernández Guisuraga, José ManuelSuarez Seoane, SusanaQuintano Pastor, María del CarmenFernández Manso, AlfonsoCalvo, Leonorhttps://uvadoc.uva.es/handle/10324/615842023-09-15T19:00:38Z2022-01-01T00:00:00ZWe aimed to compare the potential of physical-based models (radiative transfer and pixel unmixing models) for evaluating the short-term resilience to fire of several shrubland communities as a function of their regenerative strategy and burn severity. The study site was located within the perimeter of a wildfire that occurred in summer 2017 in the northwestern Iberian Peninsula. A pre- and post-fire time series of Sentinel-2 satellite imagery was acquired to estimate fractional vegetation cover (FVC) from the (i) PROSAIL-D radiative transfer model inversion using the random forest algorithm, and (ii) multiple endmember spectral mixture analysis (MESMA). The FVC retrieval was validated throughout the time series by means of field data stratified by plant community type (i.e., regenerative strategy). The inversion of PROSAIL-D featured the highest overall fit for the entire time series (R2 > 0.75), followed by MESMA (R2 > 0.64). We estimated the resilience of shrubland communities in terms of FVC recovery using an impact-normalized resilience index and a linear model. High burn severity negatively influenced the short-term resilience of shrublands dominated by facultative seeder species. In contrast, shrublands dominated by resprouters reached pre-fire FVC values regardless of burn severity.
2022-01-01T00:00:00ZForgotten giants: Robust climate signal in pollarded treesOlano Mendoza, José MiguelGarcía López, M.A.Sangüesa Barreda, GabrielCoca, M.E.García Hidalgo, MiguelHoudas, Hermine JosephineRozas Ortiz, Vicente FernandoHernández Alonso, Héctorhttps://uvadoc.uva.es/handle/10324/613002023-09-01T19:01:06Z2023-01-01T00:00:00ZTree ring records are among the most valuable resources to create high-resolution climate reconstructions. Most climate reconstructions are based on old trees growing in inaccessible mountainous areas with low human activity. Therefore, reconstruction of climate conditions in lowlands is usually based on data from distant mountains. Albeit old trees can be common in humanized areas, they are not used for climate reconstructions. Pollarding was a common traditional management in Europe that enabled trees to maintain great vitality for periods exceeding the longevity of unmanaged trees. We evaluate the potential of pollarded deciduous oaks to record past climate signal. We sampled four pollarded woodlands in Central Spain under continental Mediterranean climate. We hypothesized that pollarded trees have a strong response to water availability during current period without pollarding management, but also in the period under traditional management if pruning was asynchronous among trees. Moreover, we hypothesized that if climate is a regional driver of oak secondary growth, chronologies from different woodlands will be correlated. Pollard oaks age exceeded 500 years with a strong response to Standardized Precipitation-Evapotranspiration Index (SPEI) from 9 to 11 months. Climate signal was exceptionally high in three of the sites (r2 = 0.443–0.655) during low management period (1962–2022). The largest fraction of this climate signal (≈70 %) could be retrieved during the traditional management period (1902–1961) in the three sites where pollarding was asynchronous. Chronologies were significantly correlated since the 19th century for all the studied period, highlighting a shared climate forcing. We identified critical points to optimize pollard tree sampling schema. Our results show the enormous potential of pollarded woodlands to reconstruct hydroclimate conditions in the Mediterranean with a fine spatial grain. Studying pollarded trees is an urgent task, since the temporal window to retrieve the valuable information in pollarded trees is closing as these giants collapse and their wood rots.
2023-01-01T00:00:00ZWater use efficiency and climate legacies dominate beech growth at its rear edgeOlano Mendoza, José MiguelSangüesa Barreda, GabrielGarcía López, M.A.García Hidalgo, MiguelRozas Ortiz, Vicente FernandoGarcía-Cervigón Morales, Ana IsabelDelgado HuertasHernández Alonso, Héctorhttps://uvadoc.uva.es/handle/10324/612652023-08-31T19:01:45Z2023-01-01T00:00:00ZRear-edge tree populations are experiencing a combination of higher temperatures and more intense droughts that might push individuals beyond their tolerance limits. This trend towards rising atmospheric [CO2] is concurrent with an increase in intrinsic water use efficiency (iWUE), which theoretically enhances photosynthesis and decrease evapotranspiration rates, consequently improving tree resistance to drought. However, it remains unclear whether iWUE is favouring tree growth under current climate conditions, particularly when climate and iWUE legacy effects are simultaneously considered.
We evaluated this question with an extensive sampling along Iberian rear-edge (dry) populations comprising four mountain ranges and two distinct altitudes. We simultaneously examined the effects of climate and iWUE on secondary growth using annually resolved basal area increments (BAIs) for the period 1901–2017. We used linear mixed models including second-order autocorrelation and 1-year legacy effects of iWUE and summer drought.
BAI and iWUE increased across the studied period. iWUE increase was driven by changes in atmospheric CO2 concentration and water availability during the growing season. Climate and iWUE exerted direct and lagged effects on beech growth. Water availability during growing season was the main driver of tree growth, combining direct and indirect effects through its impact on iWUE. Legacy effects of water availability and iWUE were more important than growing season conditions. The net effect of iWUE shifted when lagged effects were considered, resulting in a net negative impact on tree growth.
Synthesis: Our results reveal that climate and iWUE legacy effects must be considered to assess the net iWUE effect on secondary growth. Considering lagged effects, the current increase in iWUE is constraining tree growth. Modelling efforts of tree growth response to climate warming should include climate and iWUE legacy effects to adequately assess terrestrial ecosystem carbon balance.
2023-01-01T00:00:00ZEvaluation and validation of forest models: Insight from Mediterranean and scots pine models in SpainVázquez Veloso, AitorPando Fernández, ValentínOrdoñez, C.Bravo Oviedo, Felipehttps://uvadoc.uva.es/handle/10324/612232023-08-30T19:05:24Z2023-01-01T00:00:00ZForest models predict tree and stand evolution under different scenarios, thereby supporting decision-making in forest management. Models are complex structures composed of sub-models that estimate forest variables at tree and stand levels. Prediction accuracy has generally been evaluated independently of the model. Integrated sub-models make forest models easier to use and provide predictions for growth, survival, ingrowth and many other tree and stand variables with reduced effort. However, while individual submodel validation is widely practiced and normally done by each author individually, joint model validation remains less explored. This study deploys a useful methodology for evaluating and validating models. After comparing observed and predicted data, several case studies were then proposed to improve the accuracy of the joint model. We used the IBERO model, data from the Spanish National Forest Inventory and the SIMANFOR simulator platform. The accuracy of growth submodels was improved by calibrating their equations, though accuracy was not improved in survival and ingrowth submodels.
2023-01-01T00:00:00ZDrops in needle production are early-warning signals of drought-triggered dieback in scots pineSangüesa Barreda, GabrielGazol, AntonioCamarero, J. Juliohttps://uvadoc.uva.es/handle/10324/605412023-07-26T19:01:05Z2023-01-01T00:00:00ZUnderstanding the mechanisms of drought-induced forest dieback and tree mortality is a priority for predicting forest responses to climate change. However, long-term information on drought impacts on crown dynamics and how it relates to tree water and carbon economy is still lacking. Comparing declining and non-declining Scots pines at the same site, we quantified primary and secondary growth and intrinsic water-use efficiency (WUEi). Further, we reconstructed the needle production and the annual total number of needles using the Needle Trace Method. Here, we reconstructed the apical needles through the assessment of 2460 longitudinal sections. We fitted partial least squares regression models to assess climate influence on primary and secondary growth and needle dynamics, and then linear mixed models using climate covariates and discerning between health status in the 1975–2016 period. Finally, we analyzed drought legacy effects applying a Bayesian hierarchical framework. We detected the highest differences between health tree classes in the annual total number of needles during the warm-dry 1980s. Declining trees responded more negatively to climate than non-declining conspecifics and showed a higher variability of drought legacy effects. We found significant drought legacy effects in the annual total number of needles up to 3 years after a drought. The warm, dry 1980s, that preceded the dieback, showed the highest δ13C values since the 1970s. Declining trees showed higher WUEi than non-declining trees from the 2000s onwards. Our study sheds light on the major role of needle dynamics in dieback episodes and illustrates how past drops in needle production may be interpreted as early warnings of drought-induced dieback in Scots pine.
2023-01-01T00:00:00Z