Selective thinning to enhance soil biodiversity in artificial black pine stands – what happens to mushroom fruiting?

As a man-induced disturbance of forest ecosystems, thinning may affect biodiversity and other related ecological functions including fungal dynamics. In this context, a multidisciplinary EU-Life project was established in 2014 to evaluate the application of selective thinning in two Pinus nigra plantations areas of the Apennines (Monte Amiata and Pratomagno, Tuscany, Italy). Selective thinning had the aim to improve stands stability and growth rates, taking also into account the various components of soil biodiversity (flora, fungi, mesofauna, nematodes, microarthropods and bacteria). Here we present mushroom fruiting patterns previous to treatment in 2014 and the effect following the application of forest management (selective thinning and traditional thinning from below) in 2018. Boxplots were used to graphically represent intra and inter annual variations in species richness and abundance, while Principal Coordinates Analyses and multi-response permutation procedures based on Bray-Curtis dissimilarity matrix were applied to evaluate turnover in species composition before the management and after 4 years. A significant reduction of fungal richness and abundance after 4 years thinning impact was lacking in both study areas, testifying a certain degree of resistance and/or resilience of mushroom fruiting to forest management-related anthropogenic disturbance. Considering each study site separately, Monte Amiata and Pratomagno did not show one uniform trend but differed significantly in their response to management: while in Pratomagno relevant inter-annual differences were present only in a few cases, an underlining significant variation both for species richness and abundance was registered in Monte Amiata for all treatment types among years (inter-annual variation) but not within each year (intra-annual variation). Only in Pratomagno turnover in species composition in selective thinning differed somewhat from the traditional treatment in 2018, showing that a process is underlying but still potentially masked by other variables. Due to the nature of macrofungi, a longer study period (more than 4 years post treatment impact) as well as the application of a more intense forest management, could be necessary to highlight and disentangle any possible trends in fungal fruiting in artificial stands.