Modeling above-ground biomass of selected tree species within a Mistbelt forest in KwaZulu Natal

Pienaar, Louis Otto (2016-03)

Thesis (MScFor)--Stellenbosch University, 2016.

Thesis

ENGLISH ABSTRACT: The objective of this study was to develop species-specific allometric models for selected natural forest species within a forest forming part of the Southern Mistbelt Forest Group, close to the town of Richmond in KwaZulu Natal. The objective was met by determining the tree dimensions (diameter at breast height (DBH) and tree height) of the forest. The collected variables were used and the most dominant species in terms of their basal area coverage: Xymalos monospora and Celtis africana were selected for biomass modeling. The allometric models were developed from a two-step stratified sampling approach. Population dimensions were determined from sample plots, where-after trees were sampled for biomass representing the collected dimensions. The dry mass of the sampled components were used in a regression modeling approach to develop a set of species-specific and combined species linear models. The best models were selected based on goodness-of-fit model evaluation criteria (GOF) and parsimony principles and a two-step upscaling process was used to upscale samples to tree level and from tree to stand level. DBH and basic density were significant predictors of total above-ground biomass (AGB) and diameter as single predictor produced consistently good results. Diameter was used throughout the upscaling process to determine the biomass per ha. The estimated AGB for X. monospora, C. africana and all the species were 62.98, 93.56 and 230.86 Mg haˉ¹ respectively. Estimated AGB for all species compared well with results from other biomass studies. Future research can investigate remote sensing applications in combination with the field sampling to estimate forest biomass more cost effectively over larger areas.

AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om spesie-spesifieke allometric modelle vir geselekteerde natuurlike woudspesies te ontwikkel in 'n woud wat deel vorm van die Suidelike Misbelt woudgroep, naby die dorp Richmond in KwaZulu-Natal. Die doel was bereik deur die bepaling van die boom dimensies (deursnee op die bors hoogte en boomhoogte) van die woud en deur gebruik te maak van die versamelde veranderlikes, is die mees dominante spesies in terme van hul basale area dekking: Xymalos monospora en Celtis africana gekies vir modellering. Die allometriese modelle is ontwikkel uit 'n twee-stap gestratifiseerde steekproefneming benadering. Bevolkings dimensies is bepaal van die monster erwe, waar-na ‘n steekproef van die bome verteenwoordigend van die versamelde dimensies bemonster is vir biomassa bepaling. Die droë massa van die monster komponente is in 'n regressie modelerings benadering tot 'n stel van spesie-spesifieke en gekombineerde spesies lineêre modelle ontwikkel. Die beste modelle is gekies op grond van beste model evalueringskriteria en model spaarsamigheidsbeginsels en 'n twee-stap opskaling is gebruik om monsters op te skaal tot boom vlak en van boom tot vlak staan. Deursnee op borshoogte en basiese digtheid was beduidende voorspellers van die totale bogrondse biomassa en deursnee as enkele voorspeller het konsekwent goeie resultate gelewer. Deursnee is dwarsdeur die opskalings proses gebruik om die biomassa per ha te bepaal. Die beraamde totale bogrondse biomassa vir X. monospora, C. africana en al die spesies tesame was 62.98, 93.56 en 230.86 Mg haˉ¹ onderskeidelik. Beraamde totale bogrondse biomassa vir alle spesies het goed vergelyk met die resultate van ander biomassa studies. Toekomstige navorsing kan afstandswaarnemings tegnieke in kombinasie met die veld steekproefneming ondersoek om biomassa meer koste-effektief oor groter gebiede te bepaal.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/98459
This item appears in the following collections: