The effects of wood decay type on the growth of bryophyte gametophytes

Deadwood is an important habitat for bryophytes in boreal and subalpine forests. The type of decay in wood (white, brown, and soft rot) caused by fungal colonizers has been revealed to affect bryophyte communities. However, little is known about the effects of decay type on the growth of bryophytes. We tested the effect of wood decay type on gametophyte growth for two common bryophyte species, Scapania bolanderi Austin and Pleurozium schreberi (Brid.) Mitt., which dominate the logs in subalpine coniferous forest on Mt. Ontake, in central Honshu, Japan. We used pot culture experiments in an open-sky nursery field. After eight months of cultivation, the growth of S. bolanderi was larger on brown rot wood than white rot wood, but the growth of P. schreberi was not. Mixed cultures of the two species also showed greater growth on brown rot wood. However, growth of S. bolanderi was significantly smaller than P. schreberi in mixed culture. These results suggest that brown rot wood enhances growth of S. bolanderi, but growth may be reduced under competition from P. schreberi. The results are in agreement with the field observation that brown rot wood has a positive association with S. bolanderi coverage on deadwood.