The history of forestry management on drained areas shows that if a choice of objects and work quality was correct we can receive high silvicultural results. The addition increment of wood after 30 years of drainage fluctuates from 1 to 4 m3/ha per year in dependence on growth sites. Forest drainage promotes to extension of forested areas owing to afforestation of mires. Except a forestry effect the ecological role of forest drainage including biosphere processes are studies. As a result of investigation the connection between a addition increment change and annual carbon loss had been obtained. There was fixed that if the addition increment of wood by drainage reason is 1.25 m3/ha the annual carbon accumulation in ecosystem equal zero, if more - a carbon flow to ecosystem is increased, if less - on the contary.