Beetle-Killed Trees Host Succession of Fungi

As the sapwood of lodgepole pines attacked by mountain pine beetle dries, it harbours a dynamic mix of fungal species.

This research is the first to document the diversity of fungi infecting red and grey pine trees attacked by mountain pine beetles and several new species of tree fungi were uncovered.

Within the first year of beetle attack, decay fungi were rarely found in pine sampled from Manning Park, Riske Creek, Radium and Cranbrook in British Columbia. Sapwood-staining fungi Ophiostoma clavigerum and O. montium dominated among the seven species of staining fungi encountered.

During the year, sapwood moisture levels dropped from 120-130 percent of oven-dry mass down to 40-80 percent. The following year, during red attack stage, another fungal cohort, basidiomycetous fungi, including decay fungi, become 2 to 3 times more numerous. Meanwhile, staining fungi declined in numbers. Most prevalent is a previously unreported species, Entomocorticium sp. type 2 that does not appear to cause wood decay.

Three years after bark beetle attack, at the grey attack stage, moisture levels in some trees dropped below 18 percent, too low to support the staining fungi, while basidiomycetous fungal populations remained high.