Cultivation of truffles in managed orchards has become an important agricultural alternative in rural Mediterranean regions. The declines of wild Tuber melanosporum throughout its natural range, its high market value and the development of nursery and cultivation techniques have encouraged its successful cultivation during the last several decades. We present here the state of the art of black truffle cultivation, habitat requirements of the fungus, cultivation techniques and descriptions of the mycorrhizae of four important Tuber species. Additionally we provide recent research findings with special implications for truffle cultivation and a brief review of truffle culinary products. In the last section we address the developing Truffle Sector in Southwest Turkey. ; This project is co-funded by the European Union and the Republic of Turkey
Over the past 15 years, 3 million hectares of forests have been converted into shrublands or grasslands in the Mediterranean countries of the European Union. Fire and drought are the main drivers underlying this deforestation. Here we present a conceptual framework for the process of fire‐induced deforestation based on the interactive effects of fire and drought across three hierarchical scales: resistance in individuals, resilience in populations, and transitions to a new state. At the individual plant level, we review the traits that confer structural and physiological resistance, as well as allow for resprouting capacity: deforestation can be initiated when established individuals succumb to fire. After individuals perish, the second step toward deforestation requires a limited resilience from the population, that is, a reduced ability of that species to regenerate after fire. If individuals die after fire and the population fails to recover, then a transition to a new state will occur. We document trade‐offs between drought survival and fire survival, as embolism resistance is negatively correlated with fire tolerance in conifers and leaf shedding or drought deciduousness, a process that decreases water consumption at the peak of the dry season, temporally increases crown flammability. Propagule availability and establishment control resilience after mortality, but different hypotheses make contrasting predictions on the drivers of post‐fire establishment. Mycorrhizae play an additional role in modulating the response by favoring recovery through amelioration of the nutritional and water status of resprouts and new germinants. So far, resprouter species such as oaks have provided a buffer against deforestation in forests dominated by obligate seeder trees, when present in high enough density in the understory. While diversifying stands with resprouters is often reported as advantageous for building resilience, important knowledge gaps exist on how floristic composition interacts with stand flammability and on the "resprouter exhaustion syndrome," a condition where pre‐fire drought stress, or short fire return intervals, seriously restrict post‐fire resprouting. Additional attention should be paid to the onset of novel fire environments in previously fire‐free environments, such as high altitude forests, and management actions need to accommodate this complexity to sustain Mediterranean forests under a changing climate. ; Erasmus Mundus Master Course Mediterranean Forestry Natural Resources Management (MEDfOR) Ramón y Cajal fellowship. Grant Number: RYC‐2012‐10970 Spanish Government. Grant Number: AGL2015‐69151‐R
Predicted changes in global climate might negatively affect the soil microbiome and associated ecosystem processes in Mediterranean forests. Forest treatments, such as forest thinning, have been suggested to mitigate climate change impacts on vegetation by reducing competition between trees, thus increasing water availability. Studies addressing the combined effects of climate and forest thinning on belowground fungal communities are still scarce, being fundamental to elaborate adaptive strategies to global warming. The aim of this study was to evaluate the tree density reduction effects on soil fungal communities and their response to inter-annual changes in weather conditions. The temporal dynamics of soil fungal communities in relation to these two drivers (i.e., forest management and weather conditions) were studied from 2009 until 2014 in a set of 12 pairs of thinned and un-thinned plots dominated by Pinus pinaster Ait. Thinning (from 30% up to 70% reduction in stand basal area) was conducted in 2009 and soil fungal community composition was studied during 4 years. Here, we used autumn precipitation and temperature to describe the impact of inter-annual weather changes. We used Pacific Biosciences sequencing of fungal ITS2 amplicons to study fungal communities in soil samples. Forest thinning did not significantly affect fungal community composition nor fungal species richness and diversity, indicating that the soil fungal community is resistant to forest thinning regardless of its intensity. However, fungal species composition changed progressively across years, both at the species level and with regards to functional guilds. These changes in community composition were partly driven by inter-annual variation in precipitation and temperature, with free-living fungi increasing in abundance under wetter conditions, and symbiotic fungi being more prominent under drier and colder conditions. The results indicate that mycorrhizal communities in Mediterranean forest ecosystems can resist forest thinning, if enough trees and functional roots from thinned trees are retained. ; This work was supported by the Spanish Ministry of Economy and Competitivity (MINECO) [grant number AGL2015-66001-C3] and by the Collaborative European project ERANET-INFORMED (PCIN-2014-050). Carles Castaño received the support of the Doctorats Industrials program, funded by the European Union and the European Social Fund. Sergio de-Miguel was supported by the European Union's Horizon 2020 MultiFUNGtionality Marie Skłodowska-Curie [Grant number IF-EF No-655815]. Josu G. Alday was supported by Ramon y Cajal fellowship [Grant number RYC-2016-20528] and José Antonio Bonet benefited from a Serra-Húnter Fellowship provided by the Generalitat of Catalunya. The authors are very grateful to the PNIN of Poblet for its considerable help with the process of installing and maintaining the experimental plots. We thank Liu Bing, Daniel Oliach, Francesc Bolaño, Jordi Margalef, Josep Miró and Jewel Yurkewich for their assistance with sampling the plots and processing the samples. The constructive comments and suggestions of two anonymous reviewers were improved substantially this manuscript.
The Périgord black truffle is an exclusive culinary delicacy, but its Mediterranean harvests have declined, despite cultivation efforts since the 1970s. The role of long-term irrigation, symbiotic fungus-host interaction, and microbial belowground progression remain poorly understood, because generally too short experimental settings miss the necessary degree of real world complexity and reliable information from truffle orchards is limited. Here, we conduct the first dendrochronological and wood anatomical assessment of 295 holm oaks, which have been growing under different irrigation intensities in the world's largest truffle orchard in Spain. The relationships between different climatic variables (monthly temperature means and precipitation totals) and dendro-parameters (ring width, vessel count and vessel size) of the oak hosts are utilized to disentangle direct and indirect drivers of truffle fruit body production. Irrigation at medium - instead of high - intensity is most beneficial for oak growth. Non-irrigated trees reveal overall lower stem increments. Warmer temperatures from February to April and wetter conditions from May to July enhance host vitality and possibly also its interplay with fungi symbionts via increased fine root production and mycorrhizal colonization. Adequately irrigated Mediterranean orchards may counteract some of the drought-induced natural truffle decline, and help stabilizing rural tourism, regional agriculture and global markets. ; Supported by the WSL-internal DITREC project, the Ernst Göhner Foundation, the ClimFun project of the Norwegian RC (No. 225043), the project AGL2012-40035-C03 (Government of Spain), the project Micosylva+ (Interreg IVB SUDOE SOE3/P2/E533), the Government of Castilla y León, ARAID, the project Xilva (CGL2011-26654, Economy and Competitiveness Ministry), as well as the Operational Program of Education for Competitiveness of Ministry of Education, Youth and Sports of the Czech Republic (No. CZ.1.07/2.3.00/20.0248).
