An international research team under the lead of Ulf Büntgen and Simon Egli from the Swiss Federal Research Institute WSL, has for the first time linked a continuous decline of the Périgord truffle (Tuber melanosporum) with long-term Mediterranean summer drying. Their ecological findings at the interface of climatology, dendrochronology and mycology were published online November 27th 2012 in "Nature Climate Change."
Comparison of annual truffle harvests from the most important production regions in northeastern Spain (Aragon), southern France (Périgord), and northern Italy (Piedmont and Umbria) with meteorological observations since the 1970s reveals a significant relationship between summer climate and the subsequent winter truffle yield. At the same time was the team able to detect a distinct association between the Périgord black truffle, clearly ranging among the world's most exclusive delicacies, and the annual tree rings of its symbiotic host vegetation. Above average rainfall together with lower temperatures between June and August not only enhance oak growth but also stimulate truffle fruiting from November-February. Warm and dry summers, however, negatively affect the productivity and functioning of Mediterranean forest ecosystems.
A Swiss future for Périgord truffles?
Considering a variety of climate models, the researches predict incessant Mediterranean summer drying until the end of the 21st century, associated with a continuation of fading Spanish, French and Italian truffle harvests. At the time, the team emphasizes that the observed impacts of global climate change are particularly severe across the Mediterranean Basin, whereas forest ecosystems north of the Alpine arc still benefit from slightly warmer but not drier conditions, and may even transform into more suitable habitats for both, natural and cultivated truffles.
This outlook coincides with recent evidence of a general fungi increase in Switzerland, together with the unexpectedly rich occurrence of Burgundy truffles (Tuber aestivum) in southern Germany. Hence, truffle cultivation in more temperate Central European environments north of the Alps will likely become more important under projected climate change -- economically and ecologically.
Causes for the continuous decline in truffle production during the past 40 years were so far not known. This knowledge gap not only resulted in local uncertainty within the traditional Spanish (Aragón and Catalonia), French (Périgord), and Italian (Piedmont and Umbria) production regions, but also triggered a global prize inflation of this exclusive delicacy. With a price of up to 2,000€/kg the Périgord truffle ranges among the world's most expensive gourmet foods. A better understanding of growth-climate interactions of truffles is of high scientific and direct economic interest. The course of future truffle harvests will likely affect the economy of rural Mediterranean areas.
Materials provided by Swiss Federal Institute for Forest, Snow and Landscape Research WSL. Note: Content may be edited for style and length.
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