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

Date
2017-12
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : Stellenbosch University
Abstract
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.
AFRIKAANSE OPSOMMING: Die Cryptosepalum bos is 'n belangrike deel van die ekostelsel in die Mwinilunga-distrik van die Noordwes Provinsie van Zambië. Hierdie bos-tipe beslaan slegs 3 tot 5% van die grondgebied van Zambië, maar dit kom wydverspreid voor op plaaslike vlak (alhoewel dit nie baie akkuraat gedokumenteer is nie). Dit dek groot dele in beide Mwinilunga en Solwezi distrikte in die Noordwes Provinsie asook dele van die Westelike Provinsie met verdere uitbreiding tot in die grensgebiede van Angola. Die bepaling van koolstofinhoud van die bos is tans 'n noodsaaklike komponent vir die verkryging van koolstofkrediete in ontluikende markte. Die belangrikste koolstofkrediet mark in Zambië is UNREDD+ (Verenigde Nasies se vermindering van emissies deur ontbossing en bos aftakeling) onder die Verenigde Nasies se raamwerkkonvensie oor klimaatsverandering (UNFCCC). Die bepaling van koolstof steun op die akkurate voorspelling van biomassa deur die gebruik van toepaslike allometriese modelle wat nie geredelik beskikbaar is nie. Die doel van hierdie studie was om bogrondse allometriese modelle te ontwikkel wat groeiplek- en spesie-spesifiek is vir die Cryptosepalum bos in die Mwinilunga Distrik. Data is versamel van een groeiplek genaamd Kalemalema in die Chiwoma gebied. Dit dek 'n wye verskeidenheid van boomgroottes in terme van DBH (deursnee op borshoogte) en boomhoogtes (van 6.2 tot 58.9 cm en 4.0 tot 22.3 m, onderskeidelik). Bogrondse biomassa modelle is ontwikkel uit destruktiewe monsters van 22 Cryptosepalum bome. Modelpassings het getoon dat groot dele van die variasie in biomassa (R2 = 57%) verklaar kan word deur DBH en hoogte. Die insluiting van die hoogte in die model het die hoeveelheid variasie in biomassa wat verklaar kan word in die model verhoog van 44 tot 57%. Daar word dus aanbeveel dat hoogte ook gebruik word as 'n onafhanklike veranderlike in die model. Die mees gepaste spesie-spesifieke model is: Totale bogrondse biomassas: ln (B)= β0 *(exp((β1*ln (DBH) + (β2* ln (Hoogte)))) (Waar: β0 = 1.10349147; β1 = 1,1157; β2 = 0,01479). Deur hierdie model is die hoeveelheid biomassa vir hierdie bostipe geskat op 395.5 Mg ha-1 en koolstofinhoud op 197.8 Mg C ha-1. Deur die toepassing van die bogrondse : ondergrondse biomassa verhouding van 1 : 0.37, kan die ondergrondse biomassa geskat word op 146.7 Mg ha-1; dus ekwivalent aan 73.4 Mg C ha-1 in wortelbiomassa. Hierdie resultaat vergelyk gunstig met ander studies vir tropiese immergroen woude in Afrika, en kan daarom gebruik word vir die skatting van biomassa en koolstof vir die Cryptosepalum bos in Mwinilunga Distrik onder die UNREDD+ voorskrifte in Zambië.
Description
Thesis (MScFor)--Stellenbosch University, 2017.
Keywords
Biomass, UCTD, Carbon sequestration, Cryptosepalum forests, Forest ecology -- Zambia, Allometry
Citation