What micro-environmental factors affect Suillus luteus fuctification in Ponderosa pine afforestations in Patagonia?.

BARROETAVEÑA C.

Córdoba, España

Conferencia; 1º World Conference on the Conservation and Sustainable Use of Wild Fungi.; 2007

Junta de Andalucía, Consejería de medio ambiente

The objective of this study was to determine the biotic and abiotic micro-environmental factors, and their interrelationships, that enhance high fruit body productivity of Suillus luteus (Slippery jack) in certain patches. The study site was a pure 17-18 years old, first rotation, ponderosa pine plantation with sandy loam soil, located close to Esquel City, Chubut, Argentina. Twelve plots with and 12 with out fructifications were randomly selected to make different measurements. Crown cover (CROWN), percentage of herbs + small-shrubs cover (HERB) and species composition were recorded, along with percentage of duff cover (DUFFC), percentage of naked soil (NAKED), duff depth (TDUFFD), gravimetric water (SOILH), soil texture and chemistry variables (pH, organic matter (OM), Nitrogen , Phosphorus, S-SO4 and exchangeable cations including Ca, Mg, K and Na.  Multiple logistic regressions were used to select variables that explain presence or absence of fructifications, and a principal component analysis to further analyze the relationship between shrubs cover and fructification. The occurrence of fructifications was associated with a group of highly correlated variables (high HERB, OM and SOILH and low CROWN, DUFFC and TDUFFD), all determined by the irregular tree spatial patron in plantation that impacts the quantity of light and water reaching the soil. Those variables related with soil texture and chemistry, with the exception of OM, did not play a determinant role. The principal component analysis showed that plots with fructification presented higher Acaena ovalifolia and Poa sp. cover, and high NAKED, and that plots without fructification presented higher CROWN and TDUFFD. Pruning and thinning previous to complete canopy closure would maintain light and water reaching the soil, preventing duff accumulation by stimulating decomposition. If S. luteus fruitbodies will be included as an intermediate product to be obtained from plantations, silvicultural treatments, specifically thinning moments, should be adjusted.