Structural Complexity Enhancement increases fungal species richness in northern hardwood forests

Forest management practices directly influence microhabitat characteristics important to the survival of fungi. Because fungal populations perform key ecological processes, there is interest in forestry practices that minimize deleterious effects on their habitats. We investigated the effects on fungal sporocarp diversity of modified uneven-aged forest management practices in northern hardwood ecosystems, including a technique called Structural Complexity Enhancement (SCE). SCE is designed to accelerate late-successional stand development; it was compared against two conventional selection systems (single tree and group) and unmanipulated controls. These were applied in a randomized block design to a mature, multi-aged forest in Vermont, USA. Eight years after treatment, fungal species richness was significantly greater in SCE plots compared to conventional selection harvests and controls (p < 0.001). Seven forest structure variables were tested for their influence on fungal species richness using a Classification and Regression Tree. The results suggested that dead tree and downed log recruitment, as well as maintenance of high levels of aboveground biomass, under SCE had a particularly strong effect on fungal diversity. Our findings show it is possible to increase fungal diversity using forestry practices that enhance stand structural complexity and late-successional forest characteristics.