Soil parameters explain short-distance variation in production of Tuber aestivum Vittad. in an oak plantation in the central-northern part of the Great Hungarian Plain (Jaszsag region, Hungary)

Abstract

Truffles are ectomycorrhizal fungi of which several species can be commercially produced in man-made plan-tations using trees inoculated with their mycelia. The production in tree plantations is meant to increase the availability of economically valued ascocarps on the market and, in the same time preserve natural habitats from an excessive pressure of truffle hunters, as well as limit the damage that they may face due to the inadequate management of truffle-producing regions. Even though plantations of summer truffle (Tuber aestivum Vittad.) are the most ubiquitous in France and Italy, the Jaszsag region in Hungary has been recently recognized as one of the most productive areas in Europe. Forestry practice in this region often assumes the renovation of autochthonous tree stands by massive sowing of the tree seeds. One of these plantations of oaks (Quercus robur and Q. cerris), spontaneously colonized without artificial inoculation, appeared to produce the highest officially reported amounts of summer truffles in Europe. Therefore, the managing forestry company decided to apply practice that aimed at maintenance of high truffle production. Assuming that climatic and vegetation factors have no impact on ascocarp production within the stand, the plantation provided perfect experimental setup for investigating the influence of very localised soil properties and terrain morphology on truffle abundance. Therefore, in this contribution selected soil properties have been investigated in the entire plantation using specifically designed protocols to characterize the site and find out if the spatial variation in the truffle production can be explained by short-distance differences in soil properties. In the Chernozem soil type that dominated the entire forest stand, soil organic matter (SOM), soluble nitrogen (TN) and properties influenced by SOM and biological activity were positively correlated with high ascocarp production, whereas increased soil aggregate size and clay content was negatively correlated with productivity. The spatial distribution of these parameters appeared strongly related to ascocarp abundance distribution. Chernozem seems to be an ideal type of soil for Tuber aestivum ascocarp production, but terrain morphology and soil properties spatial pattern, which may have been historically influenced by fluvial and aeolian processes, can significantly influence the rate of production. In the case of non wood products such as truffles, forest management will necessarily have to consider the conditions of the soil environment that, influencing the presence of the truffle species, can make their production interesting in terms of income for the forest owner.