Most of the world's 4030 million ha of forested lands are situated on hilly, mountainous or well-drained upland landscapes where improved drainage is not needed. However, there are millions of hectares of poorly drained forested lands where excessively wet soil conditions limit tree growth and access for harvesting and other management activities. Improved or artificial drainage has been used to improve forest productivity on such lands substantially. Drainage has increased timber growth in natural forests and, applied as a silvicultural practice, enabled harvesting, regeneration and increased production of plantation forests
Skaggs, R.W.;Tian, S.; Chescheir, G.M.; Amatya, D.M.; Youssef, M.A. 2016. Forest drainage. In: Amatya et al. (eds.), Forest Hydrology: Processes, Management and Assessment. CABI Publishers, U.K. 124 - 140 . 17 p.