DEAD WOOD, FOREST FRAGMENTATION AND ELEVATION INFLUENCES MACROFUNGAL DIVERSITY ON DOWNED COARSE WOODY DEBRIS IN BEECH AND OAK OLD FOREST ECOSYSTEMS FROM NORTHEASTERN ROMANIA

摘要

Coarse woody debris is often highlighted as the most important microhabitat for numerous saproxylic species, including macrofungi. Providing valuable nutrients, stable microclimatic conditions and development space, logs and large branches are considered of great ecological value for macrofungal diversity conservation. Old forests are especially rich in downed coarse dead wood both at quantity and quality level. Unfortunately, these forests are also affected by human interventions, through wood extraction and forest fragmentation. The main objective of this study was to find the factors that best explain the macrofungal diversity on downed coarse woody debris (DCWD). For this, we sampled 21 plots in forests dominated by beech or oak from Northeastern Romania, where we collected data about fungi, forest structure, and dead wood. We completed the variables set with forest fragmentation and topographic indices. In order to find the best models and predictors, we used generalized linear models (GLM). We found 163 taxa, polypores and agarics being the most frequent. The two most important predictors had a positive effect, increasing macrofungal diversity: 2'nd and 3'rd decay stages DCWD volume and elevation while the third one had a hump-shape effect on diversity. In old forests, downed dead wood quality and quantity is a vital component for numerous species of fungi to survive and develop. Elevation is a known proxy of macroclimatic conditions, furthermore creating new rich-resources niches because increasing humidity and taxonomic diversification by conifers occurrence. Patch shape can have divergent effects on fungi, as increasing perimeter is associated from one point on, with human deforestation and accessibility. Overall, we believe that Northeastern Romania's old forests hosts a great lignicolous macrofungal richness, which will be protected through silvicultural practices such as keeping valuable dead wood on site.