East Spain Research Articles

The economic and environmental impact of fire preventive strategies in the Mediterranean region

Fire behaviour in the Mediterranean region has been altered by climate change. In the last decade, not only has the occurrence of fires increased but also their virulence. This is primarily due to higher temperatures and the decrease in the rainfall, which have made forest ecosystems less able to withstand fires. It has also been observed that most wildfires are related directly or indirectly with human actions, and they usually occur in wildland-urban interface (WUI) areas. The current research focuses on the economic quantification of the benefits that fire preventive strategies could generate, demonstrating that it is worth it to invest in this kind of measures for both the environment and the society. This study shows the results of a pioneering project, called GUARDIAN, which is applied in a WUI area located at the east of Spain, with the aim of preventing and combating wildfires that could put at risk the life of 15,000 inhabitants while preserving the Natural Park of Túria and La Vallesa (Valencia-Spain). GUARDIAN is a multifaceted project that integrates recycled water, advanced technology, and ecological enhancements to create a more fire-resilient environment while educating and preparing the local community for fire-related challenges. The results of the current research intend to give a value to those benefits of the project that usually have not a market value and are difficult to measure, and due to that fact, they are not usually considered in the cost-benefit analysis. The methodology applied allows to compare in economic terms the environmental benefits of fire preventive measures implemented in the GUARDIAN project with the costs incurred by the measures developed. The environmental area protected by the project results in a value that ranges between €338,035,481 to €485,384,281. Accordingly, the methodology and results of this study are of great interest to public administrations, encouraging the implementation of fire preventive strategies.

Long-term effects of combining reclaimed and freshwater on mandarin tree performance

The current scenario of water scarcity leads to a seek for new irrigation strategies that maintain agricultural productivity while reducing the pressure on freshwater resources, especially in the Mediterranean region, which has a structural deficit of water sources. In this study, the effects of irrigation with water from different origins were assessed over six consecutive years in soil salinity indicators, tree physiology and yield of mandarin trees in south east Spain. The following treatments were considered: i) freshwater from the “Tagus-Segura” water-transfer canal (TW or Control); ii) reclaimed water from a wastewater-treatment plant (RW); iii) irrigation with TW, except in stage II of fruit development when RW was used (TWc); and iv) irrigation with RW except in stage II when TW was used (RWc). Soil salinity indicators increased in all treatments with respect to Control, except for TWc in winter. However, this increase only led to reductions in net photosynthesis and stomatal conductance in the RW treatment, while gas exchange parameters of trees from TWc and RWc were not negatively affected. Tree vegetative growth was only affected in the long-term, with trees from the RWc treatment having greater canopies. Yield was increased in the TWc and RWc treatments by 23.1 % and 29.5 %, respectively; while it was reduced by 23.5 % in RW when compared to TW. Likewise, differences among treatments in fruit quality traits were also detected. Our results suggest that combining water from different sources could be a viable alternative for irrigating mandarin trees under semiarid conditions with savings of approximately 50 % of fresh water, although the sustainability of soil health should be ensured. In addition, further research is needed to adapt these strategies to other species and cultivar-rootstock combinations.

Fire and postfire compressive strength of recycled aggregate concrete made with ceramic stoneware

This study investigated the possibilities of reusing ceramic stoneware (CS) waste, a particular type of tiles ceramic waste (TCW), provided by a treatment plant in Castellon (east Spain), as recycled aggregate in structural concrete, and its influence on concrete behaviour when exposed to elevated temperatures (200 °C, 400 °C, 600 °C, 800 °C; compressive strength determined in hot and after air and water cooling). Although all samples exhibited similar strength values at room temperature, their thermal conductivity reduced with increasing CS contents. Strength values progressively dropped with rising temperatures, with the highest results recorded in hot, followed by air and, finally, by water cooling. Smaller differences between the strength registered in hot and after cooling were generally recorded in the recycled aggregate concretes (RAC) than in the reference sample. The concrete prepared with 100 vol% CS gravel was the only one to generally provide better residual strength after air-cooling than in hot.

Does bird life-history influence the prevalence of ticks? A citizen science study in North East Spain

After mosquitoes, ticks are among the most important vector of pathogens of concern for animal and public health, but unless mosquitoes ticks remain attached to their hosts for long time periods providing an opportunity to analyse their role in the dispersal and dynamics of different zoonotic pathogens. Given their interest in public health it is important to understand which factors affect their incidence in different hosts and to stablish effective surveillance programs to determine the risk of transmission and spill-over of zoonotic pathogens. Taking benefit of a large network of volunteer ornithologists, we analysed the life-history traits associated to the presence of ticks using information of 620,609 individuals of 231 avian species. Bird phylogeny, locality and year explained a large amount of variance in tick prevalence. Non-colonial species non breeding in grasslands and non-spending the non-breeding season as gregarious groups or isolated individuals (e.g. thrushes, quails and finches) had the higher prevalence of ticks and appear as good candidates for zoonosis surveillance programs based on the analyses of ticks collected from wild birds. Ringers underestimated tick prevalence but can be considered as an important source of information of ticks for public and animal health surveillance programs if properly trained for the detection and collection of the different tick development phases.

The Origin of Spanish Durum Wheat and Olive Tree Landraces Based on Genetic Structure Analysis and Historical Records

In this study, the origin of Spanish durum wheat and olive tree landrace collections (preserved in seed banks and ex situ field collections, respectively) was traced throughout different studies on genetic structure analysis of different landrace collections and historical records of plant material circulation of these two crops in the south and east of Spain (the main cultivation areas). Although there were several groups of Spanish durum wheat landraces, they did not cluster geographically and likely came from intense grain circulation within the country and abroad (due to a high seeding rate of about 100 kg/ha and an unstable production) from the 15 to 19th centuries (especially the Maghreb and Sicily). However, Spanish olive tree landraces experienced lower genetic circulation over time and space due to the longevity of the species and the large size of the reproductive material. They can be clearly divided into two groups: those from the south, of Maghrebi origin, which most likely originated during the Islamic expansion of the 8–15th centuries, and those from the east, arriving most likely during Roman times from Italy. The genetic circularity levels of the plant material of these two crops are different.

Optimizing planning and operation of renewable energy communities with genetic algorithms

Renewable Energy Communities (REC) have the potential to become a key agent for the energy transition. Since consumers have different consumption patterns depending on their habits, their grouping allows for a better use of the resource. REC provide both economic and environmental benefits. However, its potential drastically diminishes when grouping of prosumers and energy al- location is performed improperly, as the energy generated ends up not being consumed. Given the importance of extracting the maximum potential of REC, this study presents a tool to assist in both the planning and the operation phases. We present a combinatorial optimization method for participant selection and a multi-objective (MO) optimization of solar energy allocation. Specific Ge- netic Algorithms (GA) were developed including problem-specific approaches for reducing the search space, encoding, techniques for space ordering, fitness functions, special operators to replace duplicate individuals and decoding for equality constraints. The performance of the novel solution approach was exper- imentally proved with an electrical solar installation and electricity consumers from Northern east Spain. The results show that the developed tool achieves energy sharing in REC with low solar energy excess, high self-consumption and high avoided CO2 emissions while assuring low payback periods for all partic- ipants. This tool will be essential to increase revenues of REC schemes and boost their beneficial environmental impact.

Influence of Native S. cerevisiae Strains on the Final Characteristics of “Pago” Garnacha Wines from East Spain

This work studies the variability of the Saccharomyces cerevisiae present during the spontaneous fermentation of Garnacha grapes’ musts from a “Pago” winery from the east of Spain. The parameters used to select yeast are those related to growth, fermentative behaviour, and the influence on the wine’s aroma and polyphenolic composition. Yeast identification was performed by ITS analysis and typed by Hinfl mDNA restriction profile analysis. Growth and metabolic characteristics of the isolates were determined by laboratory-scale fermentations of sterile Garnacha must, and the composition of the polyphenolic and the volatile compounds, and the sensory attributes of the small-scale produced red wines were determined. Ten S. cerevisiae strains were isolated and characterized. Overall, strain 22H quickly grew, produced wines with moderate ethanol concentrations and low volatile acidity, and obtained the highest colour and aroma scores, plus a high score for sensory attributes.

Phthalate metabolites in loggerhead marine turtles (Caretta caretta) from the Mediterranean Sea (East Spain region)

The exposure of marine reptiles to phthalates has received considerable attention due to the ubiquitous occurrence of these contaminants in the marine environment. The occurrence of phthalate metabolites is established in human populations and marine mammals, but data is scarce for marine reptiles. In this study, concentrations of 18 phthalate metabolites were determined in liver samples from 79 loggerhead marine turtle (Caretta caretta) samples collected between 2016 and 2021 in the limits of the Valencian Community (East Spain). For this purpose, the phthalate metabolites were purified from the livers by solid phase extraction and were quantified by UPLC-MS/MS. Fifteen phthalate metabolites were detected in the samples. Monoethyl phthalate (mEP), monomethyl phthalate (mMP), mono-n-butyl phthalate (mBP), phthalic acid (PA) and mono-n-hexyl phthalate (mHxP) were the most abundant metabolites, accounting for detection rates >85%. The highest median concentrations were found for PA (24.2 ng/g dry weight, d.w.) and mHxP (20.3 ng/g d.w.) followed by mMP (12.0 ng/g d.w.), mEP (5.76 ng/g d.w.) and mBP (4.26 ng/g d.w.). The sum of the medians of these five phthalate metabolites (Σ5PhMet) indicated that concentrations were higher for turtles during year 2020, while a negative association was found between [Σ5PhMet] and the turtle size. To our knowledge, this is the first study on the biomonitoring of 18 phthalate metabolites in loggerhead marine turtles, and results show that western Mediterranean loggerhead turtles are usually exposed to these contaminants.

Opportunistic vegetation in quarry soil restoration from semiarid South East Spain: Pines and spontaneous species

AbstractThe objective of our study was to undestand the effect of two organic amendments on three planted autochthonous species in two substrates mulched with pine chips 6 years after starting an experimental restoration in a quarry for cement production in semiarid SE Spain. But because this kind of mulch contained pine cones and pine seedlings appeared after the first year of the restoration, new objectives were added to the initial one: to check if organic amendments influenced pine growth among planted vegetation and if there were competition between planted and non‐planted species. Essential soil parameters, plant cover and diversity and pine growth were measured and statistically processed with correlation analyses, ANOVA and detrended correspondence analysis. Six years after restoration, organic amendments contributed significantly to explain the differences on the tested variables. The combined effects of the two substrates and the two organic amendments effectively enhanced soil properties recovery, but they also facilitated the establishment and entry of new species in addition to planted vegetation, driving a differential plant development. Planted vegetation cover and total plant cover from amended plots were double that of control plots. The number of pines, as well as their coverage, depended on the interaction between amendment type and substrate. Organic amendments favoured opportunistic species which, despite competing with those planted, helped to control soil erosion and enhanced pedogenesis. Pine chips used as mulch and derived pine seedlings, despite not entering the experimental design, might have some potential in the restoration of these particular degraded semiarid environments.

Assessment of the interactions between cetaceans and fisheries at the south of the Cetacean Migration Corridor and neighboring waters (Western Mediterranean)

The Cetacean Migration Corridor is an important marine protected area for cetacean species in the Western Mediterranean, and part of its waters constitute the main fishing grounds for the Valencia region (East Spain) fishing fleet. Here we aim to assess the interactions between all active fisheries operating in the waters of the Valencia region and the cetacean species inhabiting this area. A total of 282 face-to-face interviews (51.37% of the total fleet) to fishers were held on 20 ports at the study area to gather information about cetacean by-catch and all types of interactions between fisheries and cetaceans. The interviewed bottom trawlers (n= 148 boats) reported a monthly by-catch rate (C) of 0.01 dolphins per vessel. Bottom trawling vessels operating at neritic zones only reported by-catch of common bottlenose dolphin (C= 0.009), while those fishing at oceanic zones by-caught striped dolphin (C= 0.006) and common bottlenose dolphin (C= 0.003). The interviewed artisanal fishers (n = 114 boats), the second most important fishery in the study area, only reported one dolphin by-catch event, but 90 of these boats communicated continued negative interactions with the common bottlenose dolphin, causing gear damage and catch take. The interviewed vessels gave an estimation of their annual economic loss produced by this interaction (mean ± SD: 2,998.10 ± 2095.02 € per boat). Other fisheries operating in the Valencia region were purse-seiners (n= 15 boats) and pelagic longlines, a fishery that has almost disappeared in the study area (n= 5 boats). The first one had the highest estimated dolphin by-catch rate (C= 0.04) and mainly interacted with common bottlenose dolphin, but also with striped dolphin. The information gathered from interviews was complimented with long-term stranding data (1990–2020). Despite the fact that only 7.80% of all recorded stranded cetaceans showed fisheries interaction signs, 26.72% of the common bottlenose dolphins recorded showed evidence of this interaction, thus confirming that it is the cetacean species most affected by fisheries in the area. Records of stranded striped dolphin (6.45%) also showed evidence of fisheries interaction. Based on both dolphin by-catch and gear damage, management plans are needed in the area to ensure cetacean conservation and also fisheries sustainability in waters inside and around marine protected areas at the Spain’s Mediterranean.

Determination of the Best Planting Season for the Protected Cultivation of Papaya

Papaya is a tropical crop increasingly cultivated in the greenhouses of subtropical regions such as South East Spain, where the determination of the best planting season is important to ensure a stable fruit production and quality during the year. In this work, we studied plant growth, yield, and fruit quality, comparing spring and autumn planting seasons in ‘Intenzza’ cultivar. The results showed that planting in spring favors plant growth, leading to an earlier entry into production. Total yield and fruit quality were similar in both planting seasons, although the spring cycle provided higher profits due to greater commercial yield and lower discards. Our results confirm that adverse environmental conditions affect the crop in a similar way regardless of the planting season, so different growing cycles are not very useful for filling the production gaps and fighting against seasonality in our region, unless unfavorable climate conditions are avoided inside the greenhouse.

Current status and first detection of Xylosandrus germanus (Coleoptera: Curculionidae: Scolytinae) in live trees in the Iberian Peninsula

AbstractThe black stem borer Xylosandrus germanus (Blandford, 1894) (Coleoptera: Curculionidae: Scolytinae) is a species native to Eastern Asia that has invaded 24 countries worldwide, including 21 European countries, the USA, Canada and New Zealand. On the Iberian Peninsula it was recorded for the first time in traps placed in the Basque Country (Northern Spain) in 2003, but its host plants were unknown. In the present work, three populations of X. germanus are recorded in the east of Spain in Girona, Tarragona and Valencia provinces (Automomous Community of Catalonia, and Valencia, respectively). Specimens were collected in traps and on host plants, showing a wider distribution range now including the east and north‐east of the Iberian Peninsula. Infested carob trees (Ceratonia siliqua) were found in agricultural and urban green areas in Tarragona. Ceratonia siliqua is therefore reported here as a new host of X. germanus.

Physiological and Biochemical Responses to Water Stress and Salinity of the Invasive Moth Plant, Araujia sericifera Brot., during Seed Germination and Vegetative Growth

Araujia sericifera is an invasive plant with an increasing presence in South East Spain, where it produces damage to native trees and shrubs and citric orchards. As the climatic conditions in the study area are becoming harsher due to the climate change, the stress tolerance of this species has been studied during germination and vegetative growth. Growth parameters, photosynthetic pigments, ion accumulation, and antioxidant mechanisms were analysed in plants that were subjected to water deficit and salt stress. Seed germination was reduced by salinity but 50% of the seeds still germinated at 50 mM NaCl. The ungerminated seeds did not lose their germination capacity as shown in ‘recovery’ germination assays in distilled water. Germination was less affected by osmotic stress that was induced by polyethylene glycol (PEG), and germination velocity increased in the recovery treatments after exposure to NaCl or PEG. Plant growth was practically unaffected by 150 mM NaCl but inhibited by higher NaCl concentrations or severe drought stress. Nevertheless, all the plants survived throughout the experiment, even under high salinity (600 mM NaCl). A. sericifera relative stress tolerance relies, at least to some extent, on effective antioxidant mechanisms that are based on flavonoid biosynthesis and the activation of antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, and glutathione reductase.

Analytical fault tree and diagnostic aids for the preservation of historical steel truss bridges

Historical steel bridges represent an important construction typology integrating the constructive heritage of the past century that needs to be preserved. Exposure to fatigue phenomenon, aging, improper design or execution, extreme events, and other aggressive environmental agents can seriously compromise the conservation and performance of these structures as some recent catastrophic collapses have shown (Mississippi River bridge, Minneapolis, Minnesota 2007; Kinzua Bridge State Park, Pennsylvania 2003).In this context, the diagnostic of historical steel bridges becomes of basic importance to identify and implement maintenance, monitoring and conservation strategies. Fault Trees are useful tools for practitioners that provide a complete overview of possible failures. In the related literature, this instrument is mainly applied with approaches that are based on previous experience or failures detected in similar structures, and so the Fault Tree can only provide qualitative support.This paper proposes a new method to achieve an “Analytical” Bridge Fault Tree linking the technician’s experience and the numerical simulations of different fault scenarios. The latter are achieved by a numerical model able to consider fatigue failure and different concurring causes in the analysis (e.g., and aggressive phenomena, corrosion, defects, lack of maintenance). The proposed approach was applied to a historical railway steel truss bridge located in the East of Spain (Valencia Region) in order to show its applicability and potential.

Microdebris in three Spanish Mediterranean beaches located at a sporadic loggerhead turtles’ (Caretta caretta) nesting area

We studied microdebris in three western Mediterranean beaches in East Spain. One of them is urban, while the other two are located in a protected environment. Moreover, one of them is used as hatchery for loggerhead turtles’ (Caretta caretta) sporadic nesting activity. Here, we discuss the amount and type of microdebris in the area in different seasons, as well as at the surface and at 40 cm depth, were loggerhead turtles lay their nests. Total mean ± SD in July was 5.66 ± 3.66 MPs/kg at surface and 12.15 ± 7.76 MPs/kg at depth; while in November values were 6.45 ± 4.42 MPs/kg at surface and 5.51 ± 3.14 MPs/kg at depth. There were no significant differences among beaches, months, depths nor protection regime. Polymers found were, by descent order, polyethylene, rubber, latex, polypropylene and ethylene vinyl alcohol; which are mainly used in consumer goods, tires and food packaging. Overall, microdebris in these beaches are not among the highest in the Mediterranean and do not seem to threaten turtles’ reproductive success, although more detailed studies are needed to determine potential effect on embryonic developmental processes.

Polyphasic Analysis of Isolates from Kiwifruit Reveal New Genetic Lineages of Pseudomonas syringae pv. actinidifoliorum Look-Alike

Currently, kiwifruit cultivation arouses great economic interest in the agricultural sector in several countries of the European Union due to high consumer demand and good results achieved in terms of production potential and fruit quality. One of the main bacterial species that cause yield losses in kiwifruit plants is Pseudomonas syringae. Diseases such as bacterial canker, caused by pathovar (pv.) actinidiae; floral bud necrosis caused by pv. syringae and leaf spots caused by pv. actinidifoliorum (Pfm) are clear examples. Between 2014 and 2017, in the main kiwifruit producing areas in the north and east of Spain, several surveys were carried out in search of these pathogens. Analyses realized from symptomatic and asymptomatic plants of Actinidiadeliciosa revealed the existence of new bacterial isolates close to Pfm. These new isolates werelow virulence pathogens similar to Pfm but belonging to a new group of P. syringae that affected the leaves of A. chinensis var. deliciosa. This study focused on the characterization and classification of these new isolates by a polyphasic approach in order to provide more information for understanding how the different populations of P.syringae affecting kiwifruit. They had the phenotypic characteristics of Pfm but by molecular approaches, they constituted a supported genetic lineage closely-related to Pfm independent of the five lineages described so far. This work revealed the great diversity found in P. syringae species affecting kiwifruit plants and supports the hypothesis that Pfm is a low virulence pathogen which is long established in Europe.

Consequences of COVID-19 pandemic over acute bronchiolitis hospitalizations in the center and east of Spain

IntroductionNon-pharmaceutical interventions that have been implemented in southern hemisphere countries because of COVID-19 pandemic declaration in March 2020, have evidenced some unexpected changes in the way of spreading of many other viruses. This study as a part of ECEALHBA’s Project, reports the consequences of COVID-19 pandemic over 2020–2021 bronchiolitis epidemic period in the Central and Eastern regions of Spain. MethodMulticenter, observational, descriptive and ambispective study of admitted infants with the diagnosis of bronchiolitis in 16 Spanish hospitals involved in the investigation project. Five epidemic periods previous to COVID-19 pandemic, from 2015 to 2020, were compared with the current one, 2020–2021, in both a qualitative and quantitative manner. ResultsTotal of 4643 infants were admitted to the participating hospitals along the study period. Pandemic season hospital admissions for bronchiolitis were 94.1% lower than in pre-pandemic period. December and January were peak months for bronchiolitis admissions during pre-pandemic period, but September was the peak month during pandemic year. There was a progressive decrease of admissions from this moment until the end of the follow-up, in April 2021. Rhinovirus has been the commonest etiology for bronchiolitis in 2020–2021 epidemic period of bronchiolitis. ConclusionsSome of the non-pharmaceutical interventions initiated because of COVID-19 pandemic are probably related to the dramatic decrease of bronchiolitis cases in 2020–2021 season. It would be rewarding to purpose novel research to clarify how these simple interventions can be useful, close to vaccines and antiviral drugs, to achieve the goal of avoiding the spread of respiratory viruses in pediatric population.

Medicinal Plants in Traditional Herbal Wines and Liquors in the East of Spain and the Balearic Islands.

Homemade herbal preparations from the East of Spain are the witness of traditional medicine inherited from the ancient complex formulas of herbal teas and medicinal wines. In this study, we document the use of traditional alcoholic beverages, identify their ingredients, almost exclusively botanical, record the local medicinal uses of these mixtures, and discuss patterns of distribution of this knowledge in regions of eastern Spain, the Balearic Islands and Andorra. We determine marker species and relevant patterns of herbal formulas in the different regions of the territory. Homemade liquors and liqueurs are consumed for their digestive and tonic-restorative properties but they also play in some cases an important social role. The elderly remember other medicinal uses such as aperitif, emmenagogue, or antidiarrheal, for some of the most popular preparations. The herbal liqueur formulas include predominantly Lamiaceae, Asteraceae, Rosaceae, Rutaceae, and Apiaceae species. Herbs (58%), fruits (28%), and mixtures of both (12%) are ingredients of liquors and wines, being the aerial parts the most frequent in terms of species (30%) and records (49%). Dictamnus hispanicus, Santolina villosa, Salvia blancoana subsp. mariolensis, Rosmarinus officinalis, Thymus vulgaris, and Clinopodium serpyllifolium subsp. fruticosum are the species most frequently used. Others species used to a lesser extent as Polygonatum odoratum, Thymus moroderi, and Saxifraga longifolia are restricted to locally homemade preparations because their collection and uses require special knowledge of the rare or endemic flora. Sustainability of these practices is strongly limited by the overall loss of local traditional knowledge and by the limited availability of most of the wild species; some of them are endangered or threatened mainly by the loss of their natural habitats. Cultivation and domestication are a promising alternative to collecting from wild populations. The cultivation of Thymus moroderi in the province of Alicante and Polygonatum odoratum in the province of Teruel are good examples. There is a notable decrease in the complexity of the formulas registered throughout the nearly 15 years of the study. This is interpreted as a consequence of a loss of knowledge, less accessibility to wild resources, and changes in traditions and preferences.

Thinning decreased soil respiration differently in two dryland Mediterranean forests with contrasted soil temperature and humidity regimes

The effects of a thinning treatment on soil respiration (Rs) were analysed in two dryland forest types with a Mediterranean climate in east Spain: a dry subhumid holm oak forest (Quercus ilex subsp. ballota) in La Hunde; a semiarid postfire regenerated Aleppo pine (Pinus halepensis) forest in Sierra Calderona. Two twin plots were established at each site: one was thinned and the other was the control. Rs, soil humidity and temperature were measured regularly in the field at nine points per plot distributed into three blocks along the slope for 3 years at HU and for 2 years at CA after forest treatment. Soil heterotrophic activity was measured in laboratory on soil samples obtained bimonthly from December 2012 to June 2013 at the HU site. Seasonal Rs distribution gave low values in winter, began to increase in spring before lowering as soil dried in summer. This scenario indicates that with a semiarid climate, soil respiration is controlled by both soil humidity and soil temperature. Throughout the study period, the mean Rs value in the HU C plot was 13% higher than at HU T, and was 26% higher at CA C than the corresponding CA T plot value, being the differences significantly higher in control plots during active growing periods. Soil microclimatic variables explain the biggest proportion of variability for Rs: soil temperature explained 24.1% of total variability for Rs in the dry subhumid forest; soil humidity accounted for 24.6% of total variability for Rs in the semiarid forest. As Mediterranean climates are characterised by wide interannual variability, Rs showed considerable variability over the years, which can mask the effect caused by thinning treatment.

Species climatic niche explains post-fire regeneration of Aleppo pine (Pinus halepensis Mill.) under compounded effects of fire and drought in east Spain

Fire and drought are two major agents that shape Mediterranean ecosystems, but their interacting effects on forest resilience have not been yet fully addressed. We used Pinus halepensis to investigate how compound fire-drought regimes determine the success of post-fire regeneration. We measured the density of P.halepensis newly established individuals following fire in forty-three sites along the Spanish east coast, the wetter region of the species distribution. The climatic niche of P.halepensis was characterized by considering their populations across its Spanish distribution range. We used yearly values (1979–2013 period) of accumulated precipitation, mean temperature and the warmest quarter values of these two variables to generate the climatic space or climatic niche occupied by the species. Kernel density estimates were then applied to determine the niche centroid, which would correspond to the species’ climatic optimum within its Spanish distribution range. Then, we computed the pre- and post-fire climatic deviations of each sampling site as the difference between site-specific climate conditions respect to the species niche centroid, and assessed their relationship with the success of post-fire regeneration. We found highly variable patterns of post-fire regeneration density of P.halepensis over the studied sites, ranging from 7 to 42,822 tree pines ha−1. Generalized linear models indicated a positive relationship between fire severity and the density of P.halepensis regeneration. Positive temperature deviations - warm conditions - before fire were positively related to pine regeneration. This effect increases under higher fire severity. By contrast, warm temperatures after fire showed a negative effect on the density of pine trees. Positive precipitation deviations - wet conditions - after fire enhanced pine regeneration, while precipitation before fire did not had any significant effect. Though P.halepensis is considered a species adapted to fire and drought, the interaction between these two disturbances can alter the success of its post-fire recovery patterns limiting the species’ resilience in the future.