Estimating growing stock and allowable cut in Lao PDR using data from land use maps and the National Forest Inventory (NFI)
Abstract: Since 1989, the Lao government is implementing a policy on better use of forest resources. In order to get more accurate data for strategic decisions and planning of a sustainable forest management, the government is conducting a national forest inventory (NFI) and a nationwide mapping of land use and forest cover. Both activities provide important information but any of the two sources is not sufficient for calculating growing stock for production forest areas which is an important base for estimating allowable cut. The objective of this study is to investigate the possibility of combining two different types of data, firstly sampling data from the NFI and secondly land use maps based on SPOT satellite imagery, for estimating growing stock in small areas (production areas) and estimating allowable cut on province level. In the study an approach (CNL) has been developed. The CNL approach provides the opportunity of combining the different types of data and it is also tested and evaluated in two production forest areas. In the study, management inventory data has been used as a reference, and government guide-lines for determining, in which area logging can take place. For each area, the CNL provided such information as the average volume per hectare for different land use groups and forest types and the average number of trees per hectare. For current forest the information on crown density and stand structure has been used to improve the estimates. The precision of the estimates has also been calculated. The CNL approach gave slightly higher figures than the reference data (average volume per hectare of Natural High Forest), but the differences can be explained by the time factor (different year of survey) and classification standards. It is concluded that the CNL is feasible for estimating growing stock for areas similar to the two study areas. The areas were about 10,000 hectares each and located in accessible areas (covered by NFI sample plots). Through the CNL approach, it is possible to make use of NFI and map data in combination to calculate the growing stock for areas defined by the data user. This information is one important piece of information needed for estimating the Annual Allowable Cut on, for example, province level.
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