Sunday, 29 May 2016

Habitat indicators for cavity-nesters: The polypore Phellinus pini in pine forests

Volume 66, July 2016, Pages 275–280

  • Department of Zoology, Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise 46, EE-51014 Tartu, Estonia


Drained pine wetlands had a sparse tree-cavity supply and few cavity nesters.
Fruit-bodies of Phellinus pini explained >50% variation in cavity-nester densities.
Snags and tree-cavity counts were less useful as indicators.
Phellinus pini can serve as an indicator and flagship for tree-cavity management.


Foresters and arborists have long used fruit-bodies of heart-rot fungi as signs of advanced live-tree decay, but such usage has not been elaborated for forest conservation. I analysed relationships between a heart-rot fungus, tree-cavity supply, and cavity-nesting bird assemblage in wet hemiboreal Scots pine (Pinus sylvestris) forests in Estonia. The focal species, Phellinus pini, is the main heartwood decayer of live pines; it typically forms fruit-bodies at the stage of advanced decay on old trees. I found that the pine wetlands had few tree-cavities (mostly in snags) and cavity-nesting birds (woodpeckers being almost absent) despite abundant snag supply. Only one fruit-body of P. pini was found on cavity-tree but stand-scale abundance of the fruit-bodies correlated well with cavity-nester densities. Multifactor models indicated that cavity formation, not tree death, was the limiting process for secondary cavity-nesters, and P. pini could indeed be used (in combination with old-pine abundance) for assessing their habitat quality. This fungus could also serve as an educational flagship species to bridge conservation biology and forest pathology, and its fruit-bodies can signal trees to be retained at harvesting in pine forests. The conclusion is that there is hope for developing practical indicators to manage for the hidden decay processes that govern tree-cavity development.

Graphical abstract

Image for unlabelled figure


  • Heart decay fungi;
  • Hole-nesting passerines;
  • Pinus sylvestris;
  • Snag;
  • Tree cavity;
  • Woodpecker