Much of mainland Southeast Asia's primary forest has been converted into secondary vegetation types in the past several decades. In the Lower Mekong Subregion, nearly 100 million ha of forest were significantly altered or removed, with depletion in terms of areal percent most severe in Thailand and Vietnam. Timber extraction and conversion of forestland to agriculture are the two principal causes of forest degradation in the region. Logged sites are often later occupied by migrant homesteaders. The current regional focus of logging has shifted to Laos, Cambodia and Myanmar. Secondary forests, despite their frequently degraded status, continue to play direct and supportive roles with respect to socioeconomic development. Widespread removal of primary forests has made secondary forests the principal source of supplemental livelihood products for millions of poor rural households. Given the critical role of forests in supporting sustainable development, regional governments and a range of non government, research and donor organisations are exploring, developing and supporting strategies for reforestation and natural forest regeneration. There is growing acknowledgement that governments on their own are inadequately equipped to achieve sustainable forest managements, and new policies delegate greater decision making authority and forest management responsibility to local communities. Most of the area which policies now envision giving over to community based sustainable management is secondary forest.