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Growth responses to fertilizer application of thinned, mid-rotation Pinus radiata stands across a soil water availability gradient in the Boland area of the Western CapeChikumbu, Vavariro 12 1900 (has links)
Thesis (MscFor)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The purpose of the study was to investigate the effect of mid rotation fertilizer application
on leaf area index (LAI), basal area and volume increment in thinned Pinus radiata stands
on the most common soils of the Boland region in the Western Cape.
The study was conducted on a range of sites in the Boland region of MTO Forestry
Company, chosen to reflect the two most common soil types and a water availability
gradient in each soil type. A factorial combination of fertilizer treatments with three levels
each for nitrogen (N) at 0, 100 and 200 kg ha-1 and phosphorus (P) at 0, 50 and 100 kg ha-
1 was used. This design was replicated four times across a gradient of water availability
for each of the two common soil groups, forming a complete trial series. All replications
were laid out in P. radiata stands that had received their mid-rotation thinning prior to
treatment implementation.
LAI, diameter at breast height and height measurements as well as foliar analysis were
determined before the implementation of the study in 2008 and then subsequently at
predetermined intervals in 2009 and 2010. Leaf area index and stem volume increment
were measured in order to evaluate the influence on growth efficiency. LAI was estimated
using the gap fraction method with the use of a ceptometer. Volume increment was
calculated using diameter and height measurements and basal area was calculated by
means of diameter measurements. The abovementioned growth responses were then
used to determine the effect of increased nutrient availability on stand growth.
There were no significant interactions detected between any of the factors, N, P and water
availability class in their effect on LAI, basal area, volume increment and growth efficiency.
LAI increment responded significantly to N and P in the first year but only to P in the second year after treatment. Significant basal area responses to N and P were recorded
in the second but not the first year. This might have been due to the fact that trees had to
re-build their canopies after thinning before a basal area response could be obtained. For
the variables where an analysis of total growth response over the two year period was
done, basal area increment and volume increment significantly responded to the
application of nitrogen but not to phosphorus. Growth efficiency was not significantly
influenced by either nitrogen or phosphorus over the full two year monitoring period.
Water availability class consistently and significantly influenced basal area increment,
volume increment and growth efficiency over the two year period as well as during year
one and year two.
The best responses generally occurred as a result of the additive effects of N and P. The
growth response did not remain the same across the water availability classes. The wetter
sites tended to have greater responses than the drier sites. Although these are still early
results, the growth responses could be attributed to an increase in LAI. Nutrient analysis
through vector analysis indicated that the additional N and P from fertilizer application
were taken up by the trees thereby resulting in greater LAI and increased stem wood
production. / AFRIKAANSE OPSOMMING: Die studie het ten doel gestel om die effek van mid-rotasie bemesting op blaar oppervlak
indeks (BOI), basale oppervlakte- en volume aanwas te ondersoek in gedunde opstande
van Pinus radiata op die mees algemene grondtipes van die Bolandstreek, Wes-Kaapland.
Eksperimente is uitgelê oor 'n reeks van groeiplekke in die Bolandstreek wat gekies is om
'n water beskibaarheidsgradient te verteenwoordig oor elk van die twee mees algemene
grondtipes. 'n Faktoriaal-kombinasie van kunsmisbehandelings met drie vlakke elk van
stikstof [(N) teen 0, 100 en 200 kg ha-1] en fosfor [(P) teen 0, 50 en 100 kg ha-1] is
toegedien. Hierdie ontwerp is vier maal herhaal oor 'n gradient van grondwater
beskikbaarheid, oor elk van die twee mees algemene grondtipes, om sodoende 'n
volledige eksperimentele reeks te vorm. Elke herhaling is uitgelê in 'n P. radiata opstand
wat reeds 'n mid-rotasie dunning ondergaan het voor implementering van die kunsmis
behandelings.
Metings van BOI, deursnee op borshoogte, boomhoogte asook blaarmonsters is geneem
voor implementering in 2008 en daarna met vooraf bepaalde tussenposes in 2009 en
2010. Die BOI en stam volume aanwas is bepaal om die effek van behandelings op groeieffektiwiteit
te evalueer. Die gaping fraksie tegniek is gebruik om BOI te skat met behulp
van 'n sonvlek septometer. Volume aanwas is bereken vanaf deursnee en hoogtemetings
en basale oppervlak aanwas vanaf deursnee-metings. Metings van al bogenoemde
groeireaksies is gebruik om die effek van verhoogde voedingstof beskikbaarheid op
opstandsgroei te evalueer.
Daar was geen betekenisvolle interaksies tussen enige van die faktore N, P of water
beskikbaarheidsklas met betrekking tot reaksies op BOI, basale oppervlak- en volume aanwas of groei-effektiwiteit nie. Die BOI het betekenisvol gereageer op N en P in die
eerste jaar, maar slegs op P in die tweede jaar na behandeling. Basale oppervlakte
aanwas is betekenisvol verbeter deur N en P in die tweede jaar maar nie in die eerste jaar
nie. Dit is waarskynlik as gevolg van die feit dat opstande eers hul kroondak moes herstel
(na dunnings) voordat 'n reaksie in basale oppervlak verkry kon word. Vir die
veranderlikes waar 'n analise van die groeireaksie oor die volle twee jaar
moniteringsperiode gedoen is, het basale oppervlak- en volume aanwas betekenisvol
gereageer op stikstof maar nie op fosfor nie. Groei-effektiwiteit is nie betekenisvol
geaffekteer deur N of P oor die volle twee jaar moniteringsperiode nie. Water
beskikbaarheidsklas het basale oppervlak en volume aanwas asook groei-effektiwiteit
betekenisvol en voortdurend beïnvloed in die eerste en tweede jaar, asook gedurende die
volle twee jaar moniteringsperiode.
Die beste groeireaksie is oor die algemeen verkry waar N en P gesamentlik toegedien is
en waar dus aanvullende reaksies verkry is. Groeireaksies het betekenisvol verskil na
gelang van water beskikbaarheidsklas, met die grootste reaksie op die natste groeiplekke.
Hoewel hierdie vroeë resultate is, kan ons die meganisme van die reaksie primêr toeskryf
aan 'n toename in BOI. Vektor analise van blaar voedingstof vlakke het aangedui dat
addisionele N en P na kunsmis toediening opgeneem is, wat die weg gebaan het vir 'n
toename in BOI en verhoogde volume aanwas.
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Stem form, height and volume models for teak in TanzaniaVan Zyl, Louis 03 1900 (has links)
Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2005. / The aim of this study was to develop a set of models that will allow the determination of
volume for Tectona grandis trees and stands grown in plantation form in Tanzania. As a
secondary objective, models describing tree and dominant stand height were developed.
Total volume and volume ratio models were fitted that respectively predict total tree
volume and merchantable volume. In order to allow the calculation of volume for
different product classes and dimensions, taper models were fitted. All the data were
collected by non-destructive sampling methods using a Barr and Stroud optical
dendrometer. This proved to be an accurate and inexpensive method of collecting data
for developing volume and taper models. Sampling stratification was based on age and
site quality and as wide a range as possible was covered to ensure adequate
representation of all growing sites and ages present in Tanzanian teak plantations. A
total of 2617 individual observations were made from 222 trees at three teak plantations.
Several models were selected from the literature to describe teak volume and shape.
Results indicated that the Schumacher and Hall (1933) volume equation best describes
total volume over and underbark to a fixed upper limit of 7.5 cm. Merchantable volume
to upper stem diameter and height limits were best described by respectively the
Burkhart (1977) volume ratio model and the Cao and Burkhart (1980) modification
thereof. Many of the fitted taper models were unable to adequately describe stem shape
over the whole stem, mainly due to the large range in tree sizes and ages used in model
fitting. The variable form taper model by Perez, Burkhart and Stiff (1990) provided the
best results according to various criteria and is recommended for predicting teak
underbark diameters to various heights and, if only a single model is required, the
merchantable volume.
Top height growth of teak stands was adequately described by the generalized
Schumacher (1939) model with the value of the exponent k estimated from the sample
data. From this a series of anamorphic site index curves were developed. Suitable
height-dbh curves were obtained by a simple linear model and predictions improved by
including stand age and site index as predictor variables.
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The growth response of Eucalyptus grandis x e. camaldulensis to salt stress, ectomycorrhizae and endomycorrhizae double colonisationHengari, Simeon Ngaitungue 03 1900 (has links)
Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2007. / The study was undertaken to determine the potential physiological benefits to plants provided by the double colonisation of host plant roots by endomycorrhizal (AM) and ectomycorrhizal (ECM) fungi, when growing under normal and under salt stress conditions. Plants of the Eucalyptus grandis x E. camaldulensis clone were grown in a sterile soil with 0 and 75 mM NaCl and with or without infection with the fungi Glomus etunicatum (an AM fungus) and Pisolithus tinctorius (an ECM fungus). The Eucalyptus clone formed both ECM and AM in single and double inoculation. The mycorrhizal symbiosis did not provide any nutritional benefits to the hosts. The double colonisation had no effect on plant growth under normal growth conditions while single colonisations of AM and ECM reduced growth. Double colonisation reduced host plant specific leaf mass by 12% and increased total leaf area by 43% compared with the control under these growth conditions. This colonisation also reduced photosynthesis per leaf area by 29% compared with the control. The reduced photosynthesis of the double colonisation did not result in reduced plant growth because these plants may have had a high total plant photosynthesis because of their large total leaf area. The double symbiosis however did not reduce salt stress when host plants were exposed to 75 mM NaCl, while the AM fungus increased plant dry weight by 13% compared to the control. AM and ECM colonisation in the double colonised roots under salt stress was decreased by 18 and 43% compared to that in plants under normal growth. The reduced colonisation may have reduced the fungi’s abilities to be beneficial to the host plant. The double symbiosis is recommended based on the documented positive effects of this symbiosis to plant growth and the considered possible long-term benefits to host plants growing in saline soils.
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Die herwinning van waaisand op Walker Bay-Staatsbos, Hermanus langs die Suidwes-Kaapse kus deur van Ammophila arenaria (L) link gebruik te maakReyneke, P. G. 12 1900 (has links)
Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 1985. / Die ontstaan van waaisand langs die Suidwes-Kaapse kus en die geskiedenis van waaisandherwinning in die gebied word behandel. Die gebruik van Ammophila arenaria (marram) en A. breviligulata tydens die herwinning van waaisand in ander lande word bespreek.
Verskillende metodes kan gebruik word om die resultate van die onderskeie behandelings op die groei van marramgras te bepaal.
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The use of high-resolution satellite imagery in forest inventory : a case of Hans Kanyinga Community Forest - NamibiaKamwi, Jonathan Mutau 12 1900 (has links)
Thesis (MSc (Forest and Wood Science))—University of Stellenbosch, 2007. / The present study investigated double sampling with regression estimators as a quest for efficiency and effectiveness in forest inventory in Namibian woodlands. Auxiliary data used were obtained from Standard QuickBird satellite scenes (phase 1) for Hans Kanyinga Community Forest from October and November 2004 covering an area of 12,107 hectares, amplified with terrestric data (phase 2) of 2002. The relationships between auxiliary and terrestric variables are described and prediction models were constructed. According to the results of the stepwise procedure with the Mallow’s Cp statistic as the selection criteria, photogrammetric stand density and a combination of the photogrammetric crown area with photogrammetric stand density were the best candidates for predicting the stand volume. The resulting volume model explains 56% of the variation. Photogrammetric stand density was found to be highly correlated to the terrestric stand density with the resulting model explaining 81% of the variation. Photogrammetric crown diameter was found to be correlated with the diameter at breast height measured from the plots which were assessed for spatial tree positions, which enabled the derivation of the diameter distribution. The diameter distribution model explains 43% of the variation. In addition, the actual tree positions were determined using the GPS and surveying techniques (polar positions) involving distance and bearings. GPS tree positions showed a considerable shift of up to 8.67 m. However, only the distance measurements of tress from the plot centre using the infield surveying methods were more reliable. Nevertheless, the influences of the tree positional errors are not of high concern for temporary based sample plots which are normally used in Namibian forest inventories. A reduction in inventory cost was found to be 24% i.e. N$25.79 to N$19.67 per hectare. The results of this study are valid for Kavango region or any other region with similar set of physical and climatic conditions, but caution must be exercised in implementing these results elsewhere under different physical and environmental conditions.
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Analysis of the potential socio-economic impact of establishing plantation forestry on rural communities in Sanga District, Niassa province, MozambiqueLandry, Jennifer Ann January 2009 (has links)
Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: This thesis assesses the livelihoods of rural households in a proposed green field forestry
area, located in Sanga District of Niassa province, Mozambique. The livelihood analysis
was used to analyze potential socio-economic impacts of introducing forest plantations to
rural households located within the proposed afforestation area. The study made use of
household interviews, key informant interviews and secondary data. The sustainable
livelihoods framework was used in the research process to develop the household
questionnaire and to identify livelihood strategies. Data was analyzed using 331
household questionnaires collected throughout the proposed afforestation area in various
communities in the study area. Findings from the study indicated that there is minimal
wealth gaps between rural households; but that the introduction of the forestry industry
and the subsequent employment created thereof may result in larger wealth gaps between
wage earning and non-wage earning households. The study further concludes by linking
the potential socio-economic impacts with mitigation recommendations that could be
harmonized with FSC Standard requirements for forestry companies interested in
developing a forest industry in the study area. / AFRIKAANSE OPSOMMING: Hierdie tesis ontleed die lewensbestaan van landelike huishoudings in ‘n voorgestelde
nuwe bosbou area, gelee in die Sanga distrik van die Niassa provinsie, Mosambiek. Die
lewensbestaan ontleding was gebruik om die potensiele sosio-ekonomiese impak van die
vestiging van bosbou plantasies op landelike huishoudings in die voorgestelde bebossings
area te analiseer. Hierdie studie het gebruik gemaak van huishoudelike onderhoude,
sleutel informant onderhoude asook sekondere data. Die volhoubare lewensbestaan
raamwerk was gebruik in die navorsings proses om die huishoudelike onderhoude te
ontwikkel en om die huishoudelike strategiee te identifiseer. Data was geanaliseer van
331 huishoudelike onderhoude afgeneem in verskeie gemeenskappe binne die studie
areas. Bevindinge van die studie het aangetoon dat daar minimale inkomste gapings is
tussen landelike huishoudings, maar met die vestiging van kommersiele bosbou en
geassosieerde werskeppings moontlikhede, mag groter inkomste gapings ontwikkel
tussen huishoudings wat inkostes uit bosbou verdien en huishoudings daarsonder. Verder
het die studie aangetoon dat daar ‚n potensiele sosiale impak is van mense wat na die area
migreer en dat sulke impakte deur FSC sertifisering beheer kan word.
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Livelihood and income generation from the woodcarving trade in the Cape Town area of the Western Cape Province, South AfricaMikolo Yobo, Christian 12 1900 (has links)
Thesis (MScFor) (Forest and Wood Science)--University of Stellenbosch, 2007. / While the contribution of non-timber forest products (NTFPs) in sustaining livelihoods of the poor is gaining global attention, the importance of woodcarving trade in sustaining the livelihoods of the poor people has been poorly researched. A study was conducted in Cape Town area of the Western Province, South Africa to assess the contribution of woodcarving trade to the livelihoods of the traders and the dynamics of the trade, and institutional constraints impacting on the development of the trade. A total of 61 traders in wood carving, as well as municipal authorities and key informants, were interviewed using structured questionnaires; note taking, personal observations, and in-depth interview based open-ended questions.
The findings of the study revealed that the woodcarving trade is a highly male (69%) dominated activity. Most traders were married (55%) and most of the respondents (63%) fell within the active age group of 21-35 years. The wood carving trade was dominated by highly literate people with 66% and 25% having reached secondary and tertiary education, respectively. The study also revealed that “earning a living” represented the single most important factor (70%) that pushed people into the wood carving trade. Most traders (85%) did not own property but for those who owned property, 56% were South Africans followed by Zimbabweans (22%).
The study showed that most of the woodcarving products arriving in the Western Cape come from the SADC region accounting for 78% of the products. Malawi (36%), Zimbabwe (30%) and Kenya (13%) are the main sources of the wooden crafts curio into the Western Cape woodcraft market. The study also found that Dalbergia melanoxylon from Zimbabwe (47%) and Malawi (16%) and Brachylaena huillensis from Kenya (47%) and Afzelia quanzensis from Zimbabwe (27%) represent the most traded wood species.
The wood for carving was mainly accessed through intermediate agents (48%) and on site purchase (43%); and polishing represented the most important process (80%) of value adding compared to painting and shining. Personal cars (38%) and buses (36%) were the main means of transportation used compared to other forms of transport.
It was shown that cost (48%) and customer based price (33%) represented the main pricing methods used by traders. Shop owners had an average income estimated at R 6, 450 and R 2, 692 in good and lean month sales, respectively. In addition, seasonality represented the single most important factor (56%) threatening the woodcarving industry and the livelihood of urban traders compared to factors such as quality of wood product (18%) and scarcity of the resource (10%).
This study found that traders had difficulties accessing physical infrastructures (87%); social assets (50%) and human capital (74%). On the other hand, 62% of the traders did not seem to have problems accessing natural assets. As a livelihood strategy, traders also undertook multiple activities including sale of minor products as well as soliciting extra help from companions and/or hiring extra help during peak seasons.
For the sustainability of the woodcarving trade in the Western Cape, there is a need for sustained, long-term management of wood species used for carving through domestication and use of alternative wood species. In addition, policies should promote: (i) integrated resource use that will ensure maximum utilisation of the wood from a single tree e.g. timber and wood carving, (ii) the culture of association and cooperation among traders, (iii) collaborative mechanisms involving all players from the forest and the tourism sector as well as the traders, (iv) secure traders’ livelihood assets, (v) an environment favourable to business venture’s expansion and growth through micro-finance and micro-credit schemes.
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Genetic variation for growth, wood and fibre properties of Pinus patula families grown on six sites in South Africa.Vermaak, J. A. 03 1900 (has links)
Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2007. / This study evaluates the variation that exists between six sites and between more than
200 Pinus patula families established across the sites for various traits utilised in a tree
improvement programme. The traits utilised were growth at ages five and eight years,
gravimetric densitometry of a sub-sample of the top 100 families at age eight, and microdensitometry
and fibre morphological characteristics as determined by image analysis of
increment cores, extracted from a sub-sample of the top 30 families. Significant
differences were found between locations for growth at ages five and eight, density (both
gravimetric and micro densitometry) and fibre properties. For each of the site
combinations, utilising Type B- genetic correlations, the interaction between families and
locations were evaluated in order to determine which locations could be grouped together
in order to determine the effect various sites will have on the deployment of material.
Significant differences were also found between families for the various traits
investigated, which would indicate that desired trait or trait combinations can be selected
for in a tree improvement programme. Heritability estimates for growth varied across
sites, ranging from 0,32 to 0,57 at five years and 0,34 to 0,59 at eight years for family
heritability. The individual tree estimates ranges from 0,08 to 0,27 at five years and from
0,09 to 0,26 at eight years. The standard errors associated with the heritability estimates
for growth however indicate that the estimates, especially those of the individual trees
should be used with caution. The heritability estimates for density and fibre
morphological characteristics on the family and individual tree level are on a number of
sites very high, although this is associated with large standard errors. Indications were
that the traits can be combined effectively into a multi-trait selection index, since the
phenotypic and genotypic correlations indicated mostly favorable or slight negative
correlations between traits.
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State-community partnership as an option for sustainable management of an Androstachys johnsonii dominated woodland in Mabote District, MozambiqueCuambe, Carla Cristina 12 1900 (has links)
Thesis (MscFor)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: The state owned and managed forest and woodland resources during the colonial and postindependence
periods in Mozambique. However, the centralised government forestry policies
failed to stop the continual loss of natural forest and woodland resources under the state
control. This study is concerned with the sustainability of a cimbirre (Androstachys johnson iidominated)
woodland in a rural part of Mozambique. A. johnsonii trees are the major source
of subsistence and income generation in southern Mozambique. Nevertheless, the exploitation
of the species is running illegally because the diameters used for poles are below the
harvestable diameter limit defined by the forestry legislation.
This study is part of the research activities of a community-based natural resources
management project being implemented in the Mabote District. The study focuses on the four
villages covered by this project funded by the Government of Finland. It intends to develop
guidelines for sustainable management of the woodland which is of a great concern to the
rural woodland-dependent communities. The study examines the socio-economic context of
commercial harvesting of A. johnsonii trees for poles by local communities, as well as the
sustainability of the woodland resources concerned, especially with respect to the setting of
minimum harvestable diameter limits. It is assumed that the current deliberate burning of
cimbirre woodlands to kill the desired species would cease once a sustainable diameter limit
is established. Three methods are used to respond to the objectives of the study, namely: (1)
Semi-structured interviews and group discussions with key informants; (2) Structured
questionnaire surveys submitted to households randomly selected within the four villages
being studied; and (3) Forest resource assessment.
The literature review documents the theoretical issues of sustainable management of natural
resources and forest in particular, both past and present. It indicates that a state-community
partnership should be considered for sustainable management of the area. It is also valid for
communal areas in Mozambique in general, where the government legally controls forest
resources.
The implementation of the structural adjustment programme that Mozambique currently
pursues, allied to the retrenchments in the gold mining industry in South Africa and the
abolishment of recruitment of Mozambican labourers in the South African mining industry,
have transformed the traditional forms of rural livelihoods. These measures provide rather
large incentives for private interests to exploit poles for commercial purposes. Findings of this
study based on the forest resource assessment provide an ecological basis for allowing
harvesting of juvenile trees of A. johnsonii for poles by local communities, because the
current level of harvesting trees does not lead to woodland degradation. Besides, the
centralised policies that governed the allocation of forest resources both in colonial and postindependent
Mozambique have transformed traditional authorities. This has led to a confusion
of roles and conflicting power in forest management.
Key words: Community involvement, deforestation, sustainable natural forest management. / AFRIKAANSE OPSOMMING: Gedurende die koloniale en post-onafhanklike periode in Mosambiek is die woude en bosland
hulpbronne deur die staat beheer en besit. Dié gesentraliseerde regeringsbeleide het egter nie
die voortdurende verlies aan natuurlike hulpbronne onder staatsbeheer gestop nie. Hierdie
studie handle oor die volhoubaarheid van 'n cimbirre (Androstachys johnson ii-dominated)
inheemse bos in 'n landelike deel van Mosambiek. A. johnsonii bome is die hoofbron van
bestaan en inkomstegenerering in die suidelike deel van Mosambiek. Nogtans word dié
spesie onwettiglik uitgebuit omdat die deursnee vir pale onder die oesbare minimum deursnee
is, soos bepaal deur bosbouwetgewing.
Dié studie vorm deel van die navorsingsaktiwiteite van 'n gemeenskapsbeheerde, natuurlike
hulpbron bestuursprojek wat tans geïmplementeer word in die Mabote Distrik. Die fokus van
dié studie is vier dorpies wat gedek word deur die projek. Die doelwit is om riglyne te
ontwikkel vir die volhoubare bestuur van die bosgebied wat 'n groot bron van bekommernis is
vir die landelike gemeenskappe wat van die bos afhanklik is. Die studie ondersoek die sosioekonomiese
konteks vir die kommersiële oes van A. johnsonii bome vir pale deur die
plaaslike gemeenskappe, sowel as die volhoubaarheid van die bosebied se hulpbronne hier
betrokke, veral met die oog op die bepaling van 'n minimum deursnee beperking vir
oesdoeleindes. Dit word aanvaar dat die huidige doelbewuste brand van cimbirre boslande,
om die gewenste spesies dood te maak, beeïndig sal word as 'n volhoubare deursnee limiet
vasgestel word. Dit sal gedoen word met behulp van insette deur die afhanklike
gemeenskappe. Drie metodes is gebruik om die doelwitte van die studie te behaal; (1) Semigestruktureerde
onderhoude en groepbesprekings met kerninformante; (2) Getruktureerde
vraelys opname wat aan lukraak geselekteerde huishoudings binne die vier dorpies (wat deel
maak van studie) gegee is; en (3) Hulpbronwaardering in die bos.
Die literatuurstudie dokumenteer die teoretiese kwessies oor die volhoubare bestuur van
natuurlike hulpbronne en dan spesifiek woude, beide in die verlede en in die huidige situasie.
Die gevolgtrekking is dat 'n staatgemeenskapsvennootskap oorweeg moet word vir die
volhoubare bestuur van die area. Dit geld ook in die algemeen vir die kommunale areas in
Mosambiek, waar die regering wettiglik woudhulpbronne beheer.
Die implementering van strukturele aanpassings programme tans in Mosambiek, asook die
afdankings in die goudmynindustrie in Suid-Afrika en die beeïndiging aan die werwing van
Mosambiekse arbeiders deur Suid-Afrika, het tradisionele vorms van landelike broodwinning
getransformeer. Dit lei weer tot die misbruik van pale vir kommersiële doeleindes, deur die
privaat sektor. Bevindings uit dié studie, gebaseer op die woudhulpbron waarderings, verskaf
'n ekologiese basis vir die oes van jong A. johnsonii bome vir pale deur die plaaslike
gemeenskappe, want die huidige vlak van oes van dié bome lei nie tot boslandagteruitgang
nie. Boonop het die gesentraliseerde beleide wat die toekenning van woudhulpbronne beheer,
in beide 'n koloniale Mosambiek en 'n post-onafhanklike Mosambiek, tradisionele
gesagsstrukture getransformeer. Dit het gelei tot 'n verwarring in rolle en 'n konflik in mag in
inheemse bosbestuur.
Key words: Deforestasie, gemeenskapsbetrokkenheid, volhoubare natuurlike bosbestuur.
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An investigation into the feasibility of forest inventory by means of stereo satellite imagery employing digital photogrammetry technologyVogt, Holger K. H January 2000 (has links)
Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The aim of the study was to extract elevation information (such as tree height) from
stereo satellite imagery (IRS-I C), to scrutinise the performance of the DTM (Digital
Terrain Model) tools as provided by the LH (LeicalHelava) Systems' softcopy
system, and subsequently to perform a feasibility study on the application of a
practically viable forest inventory design.
A softcopy photogrammetry workstation (LH Systems DPW 770), IRS-I C stereo
panchromatic satellite imagery, and digital aerial photography at a scale of 1:30000
(scanned at 15 micrometers) was used. The study was conducted over various sites in
the Sabie area (province of Mpumalanga) in South Africa, where extensive man made
forests with pine and eucalypts are to be found. The extraction of stand parameters
such as tree height was performed manually, semi-automatically, and automatically.
In addition, the compartment area was determined using a GIS tool. The Digital
Surface Models (DSM), representing the canopy structure of the stands, was extracted
from the IRS-I C imagery and validated through a comparison of the resulting
contours with the corresponding contours generated by aerial photogrammetric
methods.
Due to the coarse spatial resolution of the IRS-IC imagery (5m) and the suboptimal
BIH (BaselHeight) ratio (0.57), only objects featuring a height exceeding 20m could
be manually measured with confidence. Furthermore, only the edges of the
compartments proved to be suitable for the determination of tree heights (i.e. with a
sufficiently large parallax difference and image contrast).
The manual determination of tree heights in the IRS-I C imagery yielded accuracies of
about 95% compared to the height values of the aerial photographs and the ground
data. The application of image enhancement techniques had severe effects on the
accuracy of the IRS-IC stereo model, resulting in deviations of about -57m from the
'true' value. It was observed that image matching was only a problem where features changed their appearance (e.g. clearfelled or burnt areas) during the acquisition period
of the stereo pair of the satellite imagery.
LH Systems' Adaptive Automatic Terrain Extraction (AATE) tool performed very
well for the creation of digital terrain and surface models when using digital aerial
photography with a high scanning rate. In contrast, the automatic creation of canopy
surface models from various forest compartments did not yield any useful results
when applied to IRS-l C imagery. AATE could not model the canopy structure
properly. The coarse spatial resolution of the satellite imagery in conjunction with the
sparse post spacing (20m) and matching errors are most likely to be responsible for
this poor performance.
Two-phase sampling and the Hugershoff method were chosen for automatically
derived height values to be evaluated for possible application in forest inventory.
Unfortunately, neither for the determination of the regression estimator for the first
method, nor for the calculation of timber volume after application of the Hugershoff
method could any useful result be obtained. This is mostly due to the fact that image
matching errors and blunders (resulting in tree heights of -885m) were not properly
accounted for in the terrain extraction software. However, the outcomes for the
manual measurement of tree heights performed on the satellite imagery show that
under optimal conditions accuracies can be achieved similar to those for the height
determination in small scale aerial photographs, but at lower cost. The obtained height
values can then be used for the calculation of timber volume according to Eichhorn's
law.
Keywords: AATE, blunders, digital photogrammetry, DPW770, forest inventory,
Hugershoff IRS-l C, matching error, remote sensing, satellite
imagery, two-phase sampling / AFRIKAANSE OPSOMMING: N GANGBAARHEIDSTIIDIE VIR BOSINVENTARIS MET BEHULP VAN
STEREO SATELLIETBEELDE MET GEBRUIK VAN SAGTEKOPIE
FOTOGRAMMETRIESETEGNOLOGIE: Die doel van hierdie studie was om elevasie inligting (soos boomhoogtes) uit stereo
satellietbeelde (IRS-I C) te ontrek, en die DTM (Digitale Terrein Modelle) funksies van
die LH Systems se sagtekopie sisteem te evalueer en 'n ondersoek in te stel na praktiese
toepassing van die tegnologie in bosvoorraadopname.
'n Sagtekopie fotogrammetriese werkstasie (LH Systems DPW 770), IRS-I C stereo
panchromatiese satellietwaarneming en digitale lugfotografie is gebruik. Die studie is
uitgevoer oor verskeie areas in die Sabie omgewing (Mpumalanga, Suid-Afrika), waar
daar ekstensiewe mensgemaakte woude voorkom met denne en Eucalyptus soorte. Die
ekstraksie van opstandparameters soos boomhoogte is uitgevoer met die hand, as ook met
semi-outomatiese en outomatiese metodes. Die digitale oppervlakmodelle (wat die
kroondakstrukture van die opstande voorstel) was vanaf die IRS-I C beelde onttrek en
gevalideer deur vergelyking van die resulterende kontoere met die korresponderende
kontoere wat deur lugfotogrammetriese metodes gegenereer is. As gevolg van die
growwe ruimtelike resolusie van die IRS-IC waarneming (Sm) en die suboptimale BIH
verhouding (0.57) kan slegs voorwerpe met 'n hoogte van meer as 20m met vertroue met
die hand gemeet word. Slegs die rande van die vakke is bruikbaar vir die berekening van
boomhoogtes (d.w. s. met 'n voldoende paralaksverskil en 'n sterk beeldkontras ).
Boomhoogtes wat met die hand bepaal is vanaf IRS-I C beelde is 95% akkuraat in
vergelyking met die hoogtewaardes verkry vanaf die lugfoto's en die veldmetings. Die
toepassing van beeldverbeteringstegnieke het duidelike invloede op die akkuraatheid van
die IRS-IC stereomodel met afwykings van ongeveer -57m vanaf die "werklike"
waardes. Daar is ook waargeneem dat beeldooreenstemming slegs 'n probleem is waar
terreinvorme se voorkoms verander het (weens afkappings of brande) gedurende die
verkrygingsperiode waarin die stereo paar van die satellietbeelde verkry is. LH Systems se Aanpassende Outomatiese Terrein Onttrekkings (Adaptive Automatic
Terrain Extraction - AATE) instrument het goed gevaar tydens die gebruik van digitale
lugfotografie met Inhoë skanderingstempo.
In kontras hiermee het die outomatiese skepping van kroondakoppervlakmodelle van
verskeie plantasievakke geen nuttige resultate gelewer wanneer dit op IRS-I C beelde
toegepas is nie. Die growwe ruimtelike resolusie van die satellietbeelde tesame met die
wye paalspasïering (20m) en passingsfoute is waarskynlik vir hierdie swak resultate
verantwoordelik.
Twee-fase proefueming en die Hugershoff metode was gebruik vir die bepaling van
outomaties afgeleide hoogtewaardes vir evaluering van moonlike toepassing in
bosvoorraadopnames. Geen bruikbare resultate kon verkry word vir die vasstelling van
die regressieskatter vir die eersgenoemde metode of vir die berekening van die
houtvolume volgens die Hugershoff metode nie. Dit is meestal as gevolg van beeld--
ooreenkomsfoute en flaters, (wat tot boomhoogtes van -885m gelei het) wat nie
voldoende in ag geneem word in die terreinekstraksie sagteware nie. Die resultate vir die
handgemete ('manual') boomhoogtebepaling wat uitgevoer is op die satellietbeelde (op
die sagtekopie werkstasie DPW 770), toon dat akkuraathede soortgelyk aan daardie vir
hoogte bepaal op klein-skaal lugfotos onder optimale toestande verkry kan word, maar
goedkoper. Die hoogtewaardes wat verkry is kan gebruik word vir die berekening van
houtvolume volgens die wet van Eichhorn.
Sleutelwoorde: AATE, afstandswaarneming, bosvoorraadopnames, digitale
fotogrammetrie, DPW770, flaters, Hugershoff, IRS-! C, satellietbeelde,
twee-fase proefueming
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