Assessment of the Benefits from Improvement of Low-yielding Asian White Birch Forest

Six sample plots(0.04hm~2),including three sample plots of Dahurian Larch(Larix gmelini)(stand improvement) and Asian White Birch(Betula platyphylla)(control),were set up in Dahurian Larch plantation generated in 1991-1992 and the reserved Asian White Birch forest separately in Jiaodaomu Forest Farm of Genhe Forestry Bureau.The Dahurian Larch plantation was established in the strip clear-cutting White Birch forest.Based on the survey of primary stand description factors and the results of analytical woods(one plant per plot),assessment was done on the efficiency of low-yielding Asian White Birch forest improvement in quality,outrun,economics and ecology.It was shown that mean diameter at breast height,mean height and standing crop in the 30-year stand after improvement by regeneration were four times,equal approximately to and eleven times as much as that in the unimproved stand,respectively.Therefore,the timber's quality,economic and ecological benefits were enhanced obviously in the improved stand.