Black truffle winter production depends on Mediterranean summer precipitation

Abstract

The unprecedented price inflation of Black truffles, recently exceeding 5000 Euro kg −1 (in Zurich), is a combined result of increasing global demands and decreasing Mediterranean harvests. Since the effects of long-term irrigation and climate variation on symbiotic fungus-host interaction and the development of belowground microbes are poorly understood, the establishment and maintenance of truffle plantations remains a risky venture. Using 49 years of continuous harvest and climate data from Spain, France and Italy, we demonstrate how truffle production rates, between November and March, significantly rely on previous June-August precipitation totals, whereas too much autumnal rainfall affects the subsequent winter harvest negatively. Despite a complex climate-host-fungus relationship, our findings show that southern European truffle yields can be predicted at highest probability (r=0.78, t-stat=5.645, prob=0.000 01). Moreover, we demonstrate the reliability of national truffle inventories since 1970, and question the timing and dose of many of the currently operating irrigation systems. Finally, our results suggest that Black truffle mycorrhizal colonization of host fine roots, the sexualisation of mycelium, and the formation of peridium are strongly controlled by natural summer rainfall. Recognising the drought-vulnerability of southern Europe's rapidly growing truffle sector, we encourage a stronger liaison between farmers, politicians and scientists to maintain ecological and economic sustainability under predicted climate change in the Mediterranean basin.

The crop of desert truffle depends on agroclimatic parameters during two key annual periods

“…H. almeriense is a summer deciduous plant but if the conditions are not sufficiently dry, the plant does not lose its leaves, which could eventually result in plant death (Morte et al 2010). Therefore, in general, climatic parameters, particularly drought conditions in summer, are not critical for desert truffle, contrary to what happens in other close species such as black truffle (Le Tacon et al 1982Büntgen et al 2012Büntgen et al , 2019Baragatti et al 2019). This could be due to the different fruiting seasons and to the difference in the phenology of the host plants, since H. almeriense is a summer deciduous plant, while Quercus species are perennial or winter deciduous plants.…”

Predicted climate change will increase the truffle cultivation potential in central Europe

“…Under predicted climate change scenarios, the temperature increase in the Czech Republic will accelerate evapotranspiration, leading to an elevated risk of agricultural drought 59 , which may critically affect truffle cultivation as well 60 . However, with up to 15 years temporal offset between plantation establishment and truffle harvest 51 , irrigation may help to overcome the constraints natural summer precipitation totals will have on truffle growth 61 .…”

Edible mycorrhizal fungi of the world: What is their role in forest sustainability, food security, biocultural conservation and climate change?

“…(ii) Climate change has dramatically impacted the rainfall patterns or the proliferation of some forest plagues and diseases mainly in stressed trees, and, as a consequence, a number of species, including matsutake, and truffles have declined (Borunda, 2019;Büntgen et al, 2019;Faier, 2011;Guo et al, 2017 (iv) Non-sustainable harvest techniques have dramatically reduced the natural production of many EMF world-wide (Borunda, 2019;Büntgen et al, 2019;Ehlers & Hobby, 2010;Mortimer et al, 2012). Therefore, environmental education of the native gatherers by scientists with the support of local governments or NGO`s needs urgent attention.…”

“… A big challenge is to boost the establishment of successful EMF orchards around the world (Guerin‐Laguette, 2021); Climate change has dramatically impacted the rainfall patterns or the proliferation of some forest plagues and diseases mainly in stressed trees, and, as a consequence, a number of species, including matsutake, and truffles have declined (Borunda, 2019; Büntgen et al., 2019; Faier, 2011; Guo et al, 2017). Therefore, a priority is the development and application of forest management techniques, including cultivation, to enhance EMF production, which has been named mycosylviculture (see Box 1); Actions to mitigate climate change, including successful reforestations using EMF as bio‐inoculants of native trees, constitute an urgent need (for example in Mexico more than 130 combinations of native trees and EMF have been tested, using inoculation techniques which are simple, efficient and have a low cost).…”

“…Therefore, a priority is the development and application of forest management techniques, including cultivation, to enhance EMF production, which has been named mycosylviculture (see Box 1); Actions to mitigate climate change, including successful reforestations using EMF as bio‐inoculants of native trees, constitute an urgent need (for example in Mexico more than 130 combinations of native trees and EMF have been tested, using inoculation techniques which are simple, efficient and have a low cost). With the use of these techniques, a conspicuous enhancement of plant growth, nutrient contents, physiological quality and survival of planted seedlings under field conditions have previously been demonstrated (Pérez‐Moreno, Martínez‐Reyes, Hernández‐Santiago, & Ortíz‐Lopez, 2020); Non‐sustainable harvest techniques have dramatically reduced the natural production of many EMF world‐wide (Borunda, 2019; Büntgen et al., 2019; Ehlers & Hobby, 2010; Mortimer et al., 2012). Therefore, environmental education of the native gatherers by scientists with the support of local governments or NGO`s needs urgent attention.…”