7TimoneyKP, RobinsonAL. Old growth white Spruce and Balsam poplar forests of the peace rive lowland , Woo buffalo national park, Canada: development , structure and dlverslty[J]. Forest ecology and management, 1996, 81:17 - 19.
8Vellak K, Paal J. Diversity of bryophyte vegetation in some forest type in Estonia: a comparison of old undamaged forests[ J ]. Biodiversity and Conservation, 1999 (8) : 1595 - 1620.
