The relationship between biodiversity and ecosystem functioning (BEF) has been rarely addressed in the fungal kingdom despite their ecological and socioeconomic importance. While species-rich plant communities usually exhibit higher productivity ratios, analogous mechanisms in macrofungal communities remain largely unknown to date. In this contribution, we shed light on how the species number-productivity relationship is modulated by forest management in fungal sporocarp communities. In Pinus uncinata stands, we surveyed both sporocarp productivity and species number across 9 control plots and 9 plots subjected to different intensities of basal area removal between 2020 and 2024. Main outcomes revealed changes in species number-productivity relationship for ECM, while saprotrophic exhibited a linear response in all cases, reflecting a disruption in sporocarp production after forest management activities. These changes could be explained by carbon acquisition strategies and phenological cues within the season. This study highlights the understudied BEF relationship in macrofungal fructification, emphasizing the importance of how diversity-functioning relationships could change under disturbances with direct implications for ecosystem resilience and sustainable forest management.

Pine forests represent globally distributed conifers growing in a wide range of habitats within the Mediterranean basin. One example are the high-altitude mountain pine (Pinus uncinata) forests in the Pyrenees, which stand out for their high fungal sporocarps richness. Nevertheless, studies on the effects of forest management on sporocarps diversity in mountain pine forests have been lacking, despite their importance for optimizing multiple-use forestry practices. To address this gap, we analysed the impact of different thinning intensities on fungal sporocarp diversity and composition in P. uncinata stands in the Pyrenees. The experimental design involved a BACI approach used to compare annual sporocarp diversity and composition five years before and three years after the thinning intervention in 18 permanent plots (9 thinned and 9 control). The results indicated an absence of a thinning effect in the lighter thinning intensities (< 25 % of basal area removal) for the sporocarp richness, while negative effects emerged steadily when increasing the thinning intensity until a clear negative effect reported when removing more than 70 % of the basal area. Sporocarp evenness and Shannon index revealed a negative effect due to forest thinning, with a dominance of some species that can cope with the new stand conditions. The ECM sporocarp composition was mainly affected by interannual variability, while the saprotrophic sporocarp composition was mainly driven by site conditions. However, in both guilds, we detected a reduction of the sporocarps fructification in the higher thinning intensities. Our results indicate that lighter thinning intensities do not compromise fungal diversity conservation. Finally, forest management practices that balance timber production and fungal diversity could create opportunities to enhance the ecological, social and economic value of these forest stands, which have historically been managed exclusively for timber purposes.

Background and aimsPine-oak mixed forests are characteristic of the Mediterranean landscape. Understanding which types of plant-soil feedbacks (PSFs) operate in these communities and how such PSFs could be altered by severe summer droughts is needed in the face of current climate change.MethodsWe conducted a fully reciprocal PSF experiment using eight Mediterranean pine and oak species. Seedlings were grown under controlled conditions in substrate containing sterilised soil and a small amount of soil collected under congeneric or heterogeneric mature trees. Half of the seedlings were subjected to a severe drought during the second growing season.ResultsDifferences in plant biomass and responses to drought were linked to fungal communities in the rhizosphere. Negative PSFs were detected amongst pines and oaks. Pine and oak seedlings grew better in heterogeneric soil than in congeneric soil. Fitness differences correlated with a higher relative abundance of growth-promoting ectomycorrhizal fungi (EMF) in heterogeneric soils. Under severe drought, no differences in seedling biomass, seedling survival or stomatal conductance were observed between seedlings growing in heterogeneric or congeneric soil.ConclusionSeedlings grew better in heterogeneric soils which suggests that Mediterranean pine-oak mixtures could be maintained by negative PSFs. Severe drought could decrease the strength of the negative PSFs, implying that tree diversity in Mediterranean forests could decline in a drier climate.

Background and aimSoil fungal communities can vary in their abundance and diversity between host tree species, but also between genotypes within the same host tree species. However, there are conflicting results on the role of host tree genetics in shaping soil fungal communities and how silvicultural treatments can influence their dynamics.MethodsWe investigated whether genetic variation among 20 populations representing five ecotypes of Pinus halepensis, the most widespread tree species in the Mediterranean basin, affects their soil fungal community, before and after a thinning treatment. Seedlings from these 20 populations were planted in 1996 in a common garden experiment (eastern Spain) under uniform climatic and soil conditions. In October 2019, a 50% thinning treatment was carried out and soil samples were collected immediately before and one year after thinning.ResultsBefore thinning, no significant differences in soil fungal composition were observed between ecotypes. However, saprotrophic richness increased significantly in three ecotypes and saprotrophic diversity in one ecotype one year after thinning. Conversely, the ectomycorrhizal fungal community diversity and composition of the five ecotypes showed non-significant changes following thinning.ConclusionOur results suggest that genetic differentiation in the host tree plays a minor role in shaping the ectomycorrhizal and saprotrophic communities of Mediterranean Aleppo pine forests. Furthermore, the contrasting response of the ectomycorrhizal and saprotrophic communities to thinning treatment highlights the resilience of ectomycorrhizal communities to short-term disturbances such as thinning, while emphasizing the ability of the saprotrophic communities to exploit newly available resources.

Wild macrofungal species are important non-wood forest products in Mediterranean forests, where their ability to release and disperse spores is crucial for completing their life cycle. However, the ecological drivers behind fruitbody production and fungal spore dispersal and deposition remain poorly understood. Here, we assessed the effect of silvicultural management, topography, and weather on macrofungal fruitbody and deposited spore community composition and diversity in a subalpine Mediterranean pine-dominated forest by sampling deposited spores and fungal fruitbodies in 9 paired plots (thinned vs. control) across a 300-m altitudinal gradient from September to November 2021. Spore trap filters were analyzed through ITS2 metabarcoding, while the collected fruitbodies were visually identified. Our results showed that weather fluctuations accounted for the greatest proportion of variance in spore composition for both ectomycorrhizal (15 %) and saprotrophic species (15 %). In contrast, weather explained only a small portion of variance for fruitbodies (2.6 % for the ectomycorrhizal and 0.6 % for the saprotrophic species). Interestingly, topography explained a larger amount of variance for saprotrophic spores and fruitbodies (4.67 % and 1.51 %, respectively) compared to the ectomycorrhizal groups (0.7 % and <0.1 %, respectively), highlighting the spatial dependency of saprotrophic fungi. Contrary to expectations, forest thinning intensity accounted for a non-significant part of the variance for both fruitbodies and spores. Our findings demonstrate the significant role of weather and topography in shaping fungal spore dispersion and fruitbody production in Mediterranean forests, with implications for fungal reproduction strategies and forest management.

Clear-cutting is a common silvicultural practice. Although temporal changes in the soil fungal community after clear-cutting have been widely investigated, little is known about stand-level variations in the spatial distribution of soil fungi, particularly at the clear-cut edge. We performed spatial soil sampling in three clear-cuts (0.5 ha), edge habitats, and surrounding forests 8 years after clear-cutting to examine the impact of clear-cutting on the soil fungal community (diversity, composition, guilds, and biomass) and soil properties in a managed Pinus sylvestris forest in northern Spain. Our analyses showed small differences in the composition of the soil fungal community between edge, forest, and clear-cut zones, with <4 % of the species strictly associated with one or two zones. The richness, diversity, and evenness of the fungal community in the edge zone was not significantly different to that in the forest or clear-cut zones, although the clear-cut core had approximately a third fewer ectomycorrhizal species than the edge or the forest. Saprotrophic fungi were widespread across the clear-cut-forest gradient. Soil fungal biomass varied significantly between zones, ranging from 4 to 5 mg g(-1) dry soil in the forest and at the forest edge to 1.7 mg g(-1) dry soil in the clear-cut area. Soil organic matter, pH, nitrogen, and phosphorus did not differ significantly between edge, forest, and clear-cutting zones and were not significantly related to the fungal community composition. Overall, our study showed that small-scale clear-cut treatments are optimal to guarantee, in the medium-term, soil fungal communities within harvested areas and at the forest edge that are comparable to soil fungal communities in the forest, even though the amount of fungal biomass in the clear-cut zone is lower than at the forest edge or in the forest.

Wildfire risk has been exacerbated across Europe by climate change favoring more damaging and severe wildfire events. This evolving wildfire risk context interacts with a broad landscape of EU policies including those on nature conservation, forestry, bioeconomy or climate and energy, all of which may increase or reduce fire hazard and the level of exposure and vulnerability of the values at risk. Coherently addressed, policies may support wildfire disaster risk management synergistically while reducing potential dysfunctions. This research conducts a content analysis of EU policies and initiatives under the European Green Deal with respect to integrated wildfire risk management and related nature-based solutions. The results show that a consistent EU policy framework to address wildfire risk reduction in a synergic way exists, with no major conflicts in the policy design. Nevertheless, better guidance on fire-smart land management practices and the conceptualization of wildfire-related nature-based solutions may enhance a more coherent policy implementation. Additional suggestions around the legal status of wildfire protection and ‘whole of government’ governance frameworks are discussed. Notably, within the laws, policies and initiatives analyzed, the beneficial side of fire addressed by integrated fire management is either missing or not explicitly mentioned, although it is considered in policy-related supporting guidelines.

In Mediterranean forests, many species of fungi produce fruiting bodies every autumn, some of which are of great social and economic interest as NTFPs. In addition, these fungi are an essential part of the biodiversity network that ensures the proper functioning of natural ecosystems and that is currently in check due to global change. Therefore, understanding the biogeographic patterns of species-specific fungal productivity is fundamental to anticipate possible changes in the socioeconomic value of our forests and to understand the role they play in the functioning of ecosystems in terms of mitigation and adaptation to climate change. In this study we estimate the future impact of climate change (in Catalonia region, between 2023 and 2100) on five fungal species with high socioeconomic interest in a broad bioclimatic gradient representative of the Mediterranean basin using high resolution at the landscape scale. To achieve this, we use predictive models based on machine learning algorithms and a fungal database resulting from the sampling of more than 100 permanent sampling plots over 20 years. We estimate that current and future productivity patterns differ among species, under different climate change scenarios and bioclimatic regions. Our results suggest that optimal productivity areas may be shifted to higher elevations, making those species with higher productivity at higher elevations the most affected by climate change. This would mean that some species with high socioeconomic value, such as Lactarius deliciosus and Boletus edulis, could be negatively affected in their total productivity in the study area. This study highlights the need to anticipate the potential effects of climate change on fungal productivity and in particular on high socioeconomic value species and to develop management policies oriented to maintain the important role of fungi in natural ecosystems.

The ectomycorrhizal fungi Tuber melanosporum Vittad. and Tuber aestivum Vittad. produce highly valuable truffles, but little is known about the soil fungal communities associated with these truffle species in places where they co-occur. Here, we compared soil fungal communities present in wild and planted truffle sites, in which T. melanosporum and T. aestivum coexist, in Mediterranean and temperate regions over three sampling seasons spanning from 2018 to 2019. We showed that soil fungal community composition and ectomycorrhizal species composition are driven by habitat type rather than climate regions. Also, we observed the influence of soil pH, organic matter content and C:N ratio structuring total and ectomycorrhizal fungal assemblages. Soil fungal communities in wild sites revealed more compositional variability than those of plantations. Greater soil fungal diversity was found in temperate compared to Mediterranean sites when considering all fungal guilds. Ectomycorrhizal diversity was significantly higher in wild sites compared to plantations. Greater mould abundance at wild sites than those on plantation was observed while tree species and seasonal effects were not significant predictors in fungal community structure. Our results suggested a strong influence of both ecosystem age and management on the fungal taxa composition in truffle habitats.

Forest dynamics are driven by micro-disturbances leading to gap formation. Root rot pathogens can cause mortality to adult trees, which die forming gaps. However, little is known about the biotic and abiotic factors that govern gap creation and expansion such as tree infection or drought resilience, and what are the consequences for nutrient cycling and soil microbiota. We studied the dynamics of gaps created by Heterobasidion abietinum in mountain silver fir (Abies alba) forests from the Spanish Central Pyrenees. Tree-ring width information was used to evaluate growth patterns of trees located within and at the edge of gaps and under closed canopy conditions. We analysed soil nutrient content and microbial structure at different positions with respect to the gap. Soil fungal community was also characterized by sequencing the ITS2 region. Gaps created by H. abietinum ranged 582-1072 m2 and gathered large amounts of standing and laying dead wood biomass amounting to up to 500 m3 ha-1 of coarse woody debris. This indicates that tree mortality had been occurring over decades, and it was preceded by a long-term growth decline and impaired drought resilience. Root rot affected trees beyond the current limit of the gaps leading to growth decline, preventing canopy closure and allowing the release of suppressed trees within the gap. Gap formation did neither affect soil fertility nor fungal and bacterial biomass and diversity, but long-distance ectomycorrhizal fungi were more abundant within gaps. Synthesis. Root rot pathogens play key ecological roles in forest dynamics at fine spatial scale. Heterobasidion abietinum infection, and its interaction with drought, creates and expands gaps by killing large trees and preventing surrounding trees from closing the gap. The survival of mycorrhizal networks to gap formation suggests little disruption of soil fungal communities. Root rot pathogens play key ecological roles in forest dynamics at fine spatial scale. Heterobasidion abietinum infection, and its interaction with drought, creates and expands gaps by killing large trees and preventing surrounding trees from closing the gap. The survival of mycorrhizal networks to gap formation suggests little disruption of soil fungal communities.image

Pinus uncinata, a species inhabiting the tree line of western Mediterranean countries, forms forests that exhibit one of the highest fungal productivity values among pine forests, providing various ecosystem services. Due to its specific geographical distribution, populations are predicted to shift upward and experience spatial reduction due to global warming. Recognizing the pivotal role of forest fungi in ecosystem functioning and in the bioeconomy of rural areas, ensuring that forest management supports fungal productivity and promotes the delivery of this ecosystem service, is essential. Therefore, our objectives were i) to describe the effect of forest management on fungal productivity and ii) to investigate the interaction between weather, forest management and fungal productivity. Here, we use as a case example a P. uncinata forest located on the Spanish Pyrenees. We collected sporocarps in a multiplot before-after-control-impact experiment established in 2015, consisting of 9 paired permanent inventory plots (a total of 18 plots: 9 control and 9 thinned) of 100 m2 each. Furthermore, each plot was weekly surveyed during the summer and autumn fruiting seasons from 2015 to 2022 to collect all epigeous sporocarps. Principal outcomes demonstrated that lower thinning intensities maintain sporocarp yields, medium thinning intensity could enhance sporocarp fruiting, while high thinning caused a reduction in sporocarp productivity together with an increased sensitivity to adverse weather conditions. With this, it appears that ecosystem services such as timber and mycological production can coexist at lighter forest thinning intensities.

Understanding soil dynamics and nutrient cycling is crucial for the sustainable management of Japanese forests covering 70 % of the national land area. These forests are dominated by tree species with contrasting traits, influencing soil dynamics differently. We investigated how changes in soil characteristics across different forest stands shift in composition and functioning of fungal communities. Four different forest stands dominated by two different mycorrhizal types were selected: Fagus crenata and Larix kaempferi, representing ectomycorrhizal (ECM) types, and Cryptomeria japonica and Robinia pseudoacacia, representing arbuscular mycorrhizal (AM) types. In total, 62 composite topsoil samples from two depths were analyzed for their physicochemical properties and fungal communities were profiled by DNA sequencing. Ectomycorrhizal fungi dominated soils of Fagus crenata and Larix kaempferi forests, while fungal saprotrophs were more abundant in Cryptomeria japonica and Robinia pseudoacacia forests. Forest stand type rather than soil depth determined the composition and structure of soil fungal communities. Soil pH was positively correlated with abundances of saprotrophic fungi (P < 0.05) and negatively with ECM fungi. Soil C:N ratio was positively correlated, and nitrate was negatively correlated with relative abundances of root -associated fungi, primarily ECM fungi. No links between C nor N stocks with fungal guilds were found across the dataset. Observed links between soil C:N ratio and relative abundances of rootassociated fungi and saprotrophs stress the importance of these guilds for influencing nutrient cycling economy across contrasting forest types. The lack of correlation between fungal communities and soil C and N stocks suggests distinct mechanisms driving stocks in these soils.

Understorey vegetation plays a key role in Mediterranean forest ecosystem functioning. However, we still lack a thorough understanding of the patterns and drivers of understorey composition and diversity. As a result, understoreys are often ignored during assessments of forest functioning under climate change. Here we studied the effect of silvicultural management, topography, soil fungal community composition and soil physical and chemical properties on understorey community composition and diversity. The plant cover and number of individuals of understorey perennial plants, shrubs and non-dominant trees was recorded on 24 plots (paired: control-thinned) in a Mediterranean pine-dominated mountainous area in Northeast Spain. The study area represented a broad thinning intensity gradient (from 0 to 70 % in removed stand basal area) along a 400-m altitudinal range (from 609 m to 1013 m). Our results showed that thinning intensity and topography explained the greatest proportion of the total variance in the understorey species composition, i.e., 18 % and 16 %, respectively. Interestingly, the effects of the silvicultural treatments were significant only when considering the altitudinal effect, so that, the main impacts of thinning on the understorey community composition occurred at low altitudes (between 609 m and 870 m). Moreover, we found a significant decrease in both richness and abundance of understorey species in both the control and thinned plots with increasing altitude, with thinned plots being significantly richer in species compared to the control plots. The difference in the understorey community sensitivity to forest thinning along the altitudinal gradient suggests changes in factors that limit plant growth. Low elevation plots were restrained by light availability while high altitudes plots limited by winter freezing temperature.

Pinus uncinata is a species frequently growing in the tree line limit of southwestern European subalpine ecosystems, hosting fungal communities that provide relevant ecosystem services. Despite the high importance of these forests for conservation, limited prior research has analysed the sporocarp fruiting patterns. This study aims at filling this gap in knowledge by describing interannual changes in sporocarp productivity, diversity, and community composition over 5 years and identifying possible relationships with the main weather and soil physicochemical characteristics. The studied P. uncinata stands had an average annual total sporocarp productivity of 21.60 kg ha1yr  1 in dry weight, hosting a total of 255 species with productivity-dominant ectomycorrhizal families such as Russulaceae and Tricholomataceae that occurred mostly from mid-August to end September. In contrast, saprotrophs showed more stable productivity values from mid-August to end of November with average annual sporocarp productivity of 1.76 kg ha1yr  1 in dry weight but exhibited higher fungal richness values from the start of October until the end of November. Fungal productivity and species richness were mostly influenced by weather conditions while soil physicochemical properties had implications in shaping the sporocarp community composition. This study quantifies the interannual fungal fruiting pattern of the understudied fungal communities and underlines the importance of climatic variables in shaping fungal fruiting patterns within a climate change context. In addition, this work is also of special relevance since P. uncinata ecosystems represent the tree line limit, which makes this species and its associated fungal communities especially sensitive to the potential impacts of global warming.

Aim of study: The local ecological knowledge shared in rural communities shapes their norms for using their nearby open-access natural resources. We suggest a method to analyse this form of cognitive social capital with an application to a mushroom picking permit. Area of study: Poblet forest in Catalonia (NE Spain). Material and methods: We applied semi-structured questionnaires to pickers in four municipalities and to the governing body of the protected area. Our methodology assesses cognitive social capital combining three instruments: (i) inter-quartile ratio indexes for community cohesion, (ii) pair-wise comparisons across social groups: pickers and decision-makers (DM), and (iii) correlations for mental models linking perceived ecological, social and economic challenges with foreseen solutions. Main results: Analogous perceptions between DM and local pickers were found in most mushroom-related problems, which align with most picking permit design features. The perceived dissimilar behaviour between local and foreign pickers, the need for forest tending –addressing the wildfire risk–, and trash left in the forest are shared among pickers and DM. Moreover, some mental models of the DM showed statistically consistence. At the individual picker level, mushroom eco-literacy relates to family learning and proximity to DM, while links between pickers and DM correlate with increased forest profitability expectations. Research highlights: Strong convergence in cognitive indicators aggregated at the town level indicate a single hermeneutic community among local pickers, which seems to underlie the large permit acceptance but did not explain the differential permit uptake –thus, structural social capital emerges as complementary predictor.

There is growing concern that changing climate and disturbance regimes are and will result in widespread forest regeneration failure, and thus, there is an increasing need for developing management and adaptation strategies to promote regeneration under climate change. Maritime pine (Pinus pinaster), an ecologically and economically relevant tree species inside and outside its natural range, will likely face such difficulties as drought is the main cause of seedling mortality in this species. Understanding the interactions between silviculture and climate conditions is therefore crucial to inform sound adaptive forest management. However, the evidence on how forest thinning may contribute to enhanced regeneration remains divided and not fully understood, especially in the context of climate change. Hence, the general goal of this study was to evaluate the effect of thinning as a forest management strategy to promote the natural regeneration of P. pinaster stands in Mediterranean areas, and to understand how climatic, edaphic and topographic factors influence the effectiveness of this silvicultural practice. This was done by comparing 13 pairs of thinned and control plots along a thinning intensity gradient (23-69 % in stand basal area) in northeastern Iberian Peninsula and by measuring early-stage regeneration dynamics, namely the density, survival and growth of seedlings for 5 consecutive years. Thinning had a strong positive effect on the establishment and survival of P. pinaster seedlings as well as a weak positive effect on early primary and secondary growth. Not only was the number of seedlings and survival in thinned plots considerably higher than in control plots (15.0 +/- 2.5 vs 1.5 +/- 0.5 seedlings per plot; 23 +/- 4 % vs 0.7 +/- 0.3 % survival) but both seedling density and survival increased with increasing thinning intensity (3-fold and 5-fold, respectively), which matches the light-demanding nature of this species. Such a positive effect of thinning was further modulated by climatic and soil conditions. Overall, the advantage conferred by thinning to seedling establishment and survival was stronger under drier and warmer conditions, which suggests that thinning is particularly beneficial in alleviating competition in water-limited forest ecosystems. Considering that the Mediterranean region is predicted to become warmer and drier under global warming, our findings indicate that thinning will likely become an increasingly important management strategy to ensure the natural regeneration, adaptation and resilience of pine forests in the face of climate change.

The forest-based sector plays a significant role in supporting Europe on its pathway towards a more integrated and bio-based circular economy. Beyond the supply of timber, forest ecosystems offer a wide range of products and services beneficial to human wellbeing. Non-wood forest products (NWFPs) play an integral role in provisioning forest ecosystem services and constitute a huge portfolio of species from various taxonomic kingdoms. As diverse as the resources themselves is the list of end-products that may be derived from raw non-wood materials. Multiple value-chains of NWFPs provide benefits to actors across all stages of the supply chain. Forest management has not yet directed full attention towards NWFPs, since timber production remains the main management objective, although multi-purpose management is recognised as a key principle of the sector's sustainability paradigm. Lack of knowledge of the socio-economic relevance of NWFPs for European societies and diverse property rights frameworks increase the complexity in forest-based decision making additionally. In this study, the future potential of 38 NWFPs for diversifying the forest bioeconomy is investigated by means of multi-criteria analysis, including stakeholder interaction and expert involvement. The results for six case studies in different biogeographical zones in Europe indicate the latent opportunities NWFPs provide to forest owners who are willing to focus their management on the joint production of wood and non-wood resources as well as their value networks. This study intends to unravel perspectives for forest owners in particular, as they often represent principal decision makers in forest ecosystem management, act as main suppliers of NWFP raw materials, and thus can be understood as key stakeholders in a forest bioeconomy. Even though regional perspectives differ, due to varying socio-economic and ecological environments, there is huge potential to strengthen the economic viability of rural areas. Furthermore, sustainable co-production may foster the ecological integrity of forest ecosystems across Europe. Results show that wild mushrooms constitute the most widespread opportunity to increase additional income from forest management, but the most promising NWFPs can be found in the tree product, understorey plant and animal origin categories.

Tree phenology is sensitive to climate warming and changes in seasonal precipitation. Long xylogenesis records are scarce, thus limiting our ability to analyse how radial growth responds to climate variability. Alternatively, process-based growth models can be used to simulate intra-annual growth dynamics and to better understand why growth bimodality varies along temperature and precipitation gradients. We used the Vaganov-Shashkin (VS) growth model to analyse the main climatic drivers of growth bimodality in eight trees and shrubs conifers (four pines and four junipers) across Spain. We selected eleven sites with different continentality degree and spring/autumn precipitation ratios since we expected to find pronounced bimodal growth in less continental sites with spring and autumn precipitation peaks. The VS model successfully simulated annual growth rates at all sites as a function of daily temperature and soil moisture data. Bimodal growth patterns clustered into less continental sites showing low spring/autumn precipitation ratios. This finding agrees with observed climate-growth associations showing that growth was enhanced by wet-cool winter-to-spring conditions, but also by wet autumn conditions in the most bimodal sites. We observed a stronger growth bimodality in pines compared to junipers. We discuss the spatial variability of climate drivers in bimodality growth pattern and how increasing continentality and shifts in seasonal precipitation could affect growth patterns. Bimodality could be an advantageous response to overcome summer drought in Mediterranean forests. The ability of some species to reactivate growth during autumn might determine their capacity to withstand increasing summer aridity.

Mycorrhizal fungi can help plants to cope with drought, but research on the fungal communities that are more resistant to drought or alleviate drought stress of trees is still scarce. In this study, we investigated effects of drought on soil fungal communities and explored potential fungal traits related to drought resistance under greenhouse conditions. We manipulated water availability in pine seedlings belonging to three Spanish Pinus pinaster populations from geographical areas subjected to contrasting summer drought. A set of plant ecophysiological traits were quantified and soil fungi was quantified and profiled using ergosterol and Pacific Biosciences sequencing. Abundance of ectomycorrhizal (ECM) fungi in plants subjected to drought was lower than in well-watered plants. Most ECM taxa in plants surviving drought had long exploration types and were taxa typically forming rhizomorphs and hydrophobic mycelia. By contrast, ECM taxa in well-watered plants had wider range of distinct exploration types. No differences in fungal communities were found among P. pinaster populations. No associations between ECM fungi and plant ecophysiological traits were found, but significant interactions between drought treatments and belowground plant biomass were found for the relative abundances of ECM fungi, particularly ECM with long exploration types. Plants subjected to drought may benefit by associating to ECM taxa previously shown to transport water efficiently.