Estimating carbon sequestered in the cryptosepalum forest in Mwinilunga district of North-western Province, Zambia

[摘要] ENGLISH ABSTRACT: Cryptosepalum forests are an important part of the forest ecosystem in Mwinilunga district of the North–western Province, Zambia. Though they occupy only 3-5 % of the national total land area, their distribution at the local level, despite not being documented, is high. Cryptosepalum forests cover large areas in both the Mwinilunga and Solwezi districts in the North-western Province and parts of the Western Province, extending in to the border areas of Angola.The estimation of carbon in the forest is currently an essential component in the implementation of emergent carbon credit market initiatives. The most important carbon credit market in Zambia is the United Nations Reducing Emissions from Deforestation and forest Degradation (UNREDD+) under the United Nations Framework Convention on Climate Change (UNFCCC, 1998). This necessitates the use of appropriate allometric models for accurate biomass prediction which are not readily available. The aim of this study was to develop site/species specific above–ground allometric models for the Cryptosepalum forests in the Mwinilunga district. The data was collected from one site namely Kalemalema in the Chiwoma area. It covers a wide range of tree sizes in terms of DBH and height i.e. 6.2–58.9 cm and 4.0–22.3 m, respectively. Above– ground biomass models were developed from 22 destructively sampled Cryptosepalum trees. The model fitting showed that large parts of the biomass variation (R2 = 57 %) were explained by DBH and height. The inclusion of height increased the explanation of biomass variation from 44 to 57%. Therefore, it is recommended that height should be used as an additional independent variable. The species-specific model with the best fit is: Total Above-ground Biomass = ln (B) = β0 * (exp ((β1 * ln (DBH)) + (β2 * ln (Ht)))) (Where: β0 = 1.10349147; β1 = 1.1157; β2 = 0.01479). When applying this model, biomass and carbon quantities for this forest type was estimated at 395.5 Mg ha-1 and 197.8 Mg C ha-1, respectively. When applying the root-to-shoot ratio of 1: 0.37, the Below–ground Biomass was estimated at 146.7 Mg ha-1; resulting in an equivalent of 73.4 Mg C ha-1 as Below-ground Carbon. This result compares favourably with the other studies for tropical evergreen forests in Africa. Therefore, it can be applied in the estimation of biomass and carbon for the Cryptosepalum forests in the Mwinilunga district under the UNREDD+ mechanism in Zambia.

[发布机构] Stellenbosch University