Stand dynamics during a 12-year period in a second-growth stand in a cool temperate forest in northern Japan

In 1981 and 1993, trees over 2m high were measured and mapped to clarify stand dynamics in two permanent plots of 0.1 ha in a secondary, cool temperate, mixed broadleaf/conifer forest after logging in the Tomakomai Experiment Forest, central Hokkaido, northern Japan. The species could be placed in two groups according to the change in basal area and density, and annual height growth: Quercus mongolica var. grosseserrata, Phellodendron amurense, Prunus sargentii and Tilia japonica (Group I: GI) showed episodic regeneration and/or fast height growth; Acer mono, Acer palmatum var. matsumuae and Sorbus alnifolia (Group II: GII) showed continuous regeneration and/or slow height growth. The age distribution of stems over 10 cm in d.b.h. suggests synchronous regeneration of GI and GII species. Vertical stratification was promoted during the 12-year period by the difference in annual height growth between the two species groups. Additional tree censuses in both remnant old-growth stands and second-growth stands after large scale blowdowns demonstrated that Q. mongolica var. grosseserrata is most dominant in stands varying in the stages of development. Disturbance history and successional trends in dominant species implied that stand-devastating disturbances were responsible for the regeneration of Q. mongolica var. grosseserrata in the study forest.