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A sampling study of branching characteristics towards obtaining more efficiency for tree selection in breeding trialsGwebu, Simosabo Bhekinkhosi 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: A total of 125 trees covering a range of tree diameters were selected from a progeny trial
of open pollinated progenies of Pinus patuia for studies on trait assessments and
evaluation for branching characteristics. The trees comprised 25 families with each
family having five trees. The trial was 36 months old and was located in a relatively high
yielding site in Block B at Usutu in Swaziland. The height, diameter, the number of
branches and the number of whorls of each tree were recorded. In addition to these
objective assessments on individual trees, trees were given scores for branch size, branch
angle, stem straightness and crown coarseness. For the detailed branch evaluation study,
trees were marked at 20% and 50% of the total tree height and the section between this
range was used. On this section the internode length, the internode diameter, the branch
diameter and the branch angle were measured. It was observed that the objective
assessments correlated strongly with the scoring (subjective) and it was further
recommended that a closer look is needed to consider the prospects of employing
subjective assessments as a means of reducing costs incurred during objective trait
assessments. The branch sampling study revealed that there were prospects of assessing
fewer branches on a tree as opposed to assessing all the branches, which could be a major
contributor to the high costs in tree breeding. All three methods used to explore this
prospect showed some reasonable agreement with each other in this regard. The best
sample is to measure all branches in whorl one and two above 20% tree height followed
by sampling four branches, two from the first whorl and two from the second whorl.
There is a slight difference in these two samples as determined by the coefficents of determination. The study recommends that four branches can be used in the assessment
of the branch angle and the branch diameter on the trees when one considered the cost
elements. / AFRIKAANSE OPSOMMING: In 'n ondersoek na die evaluering van tak-eienskappe van Pinus patuIa is 125
bome in 'n oop-bestuifde nageslags-proef geselekteer. Hierdie bome is gekies met
groottes wat strek oor 'n wye verskeidenheid van borshoogtedeursnee. Die ondersoek het
25 families ingesluit met elke familie wat uit 5 bome bestaan. Die proef is 36 maande
oud en is gevestig in'n hoë produksiearea van Blok B, Usutu, in Swaziland. Die hoogte,
borshoogtedeurnee, aantal takke en die hoeveelheid takkranse is gemeet en bepaal by elk
van die 125 bome. Verder is punte toegeken vir takgrootte, takhoek, graad van
stamkromming en kroon grofheid. In die gedetailleerde tak-evaluasie is slegs die
stamseksie tussen 200!o en 50% van die totale boomhoogte gebruik. Op hierdie seksie
van die boomstam is die internodale afstand, die internodale deursnee, die takdeursnee en
die tak-hoek gemeet. Uit die gegewens wat versamel is, het dit geblyk dat daar sterk
korrelasie tussen die objektiewe evaluasie en die subjektiewe evaluasie (met gebruik van
kwalitatiewe eienskappe op 'n tellingbasis) verkry is. Hieruit word aanbeveel dat meer
aandag aan subjektiewe evaluasie (as vereenvoudigde evaluasieprosedure) bestee word
om kostes te besnoei. Die gedetailleerde tak-evaluasiestudie het aangedui dat die gebruik
van slegs 'n paar takke, in teenstelling met al die takke op die boom, voordelig kan wees
om verdere kostes van evaluasie te bespaar. Die beste monster is om al die takke in die
eerste twee takkranse bo 20% boomhoogte te meet. Daarnaas is die beste monster die
eerste twee grootste takke in die eerste en tweede takkranse. Die gebruik van hierdie
kleiner monsters vir evaluering het in sekere opsigte nog beter voorspellings gelewer as
in die gevalle waar al die takke in die eerste takkrans gebruik is. Die studie b aan dat In
betroubare monster van vier takke (twee uit elke takkrans bo 20% boomhoogte) geneem
kan word om die boom se takeienskappe te be-oordeel.
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Factors affecting the successful deployment of Pinus patula as rooted cuttings.Mitchell, Richard Glen. January 2005 (has links)
Summary:
The future mass propagation of elite families of Pinus patula by cuttings is a realistic
method of deployment if the short-term performance of cuttings and seedlings are
confirmed at harvesting. This will impact significantly on the future outlook of forestry in
South Africa as softwood yields are improved substantially through the introduction of
material of high genetic value in commercial plantings. This, however, will require
significant changes in future silviculture and other management practices as foresters and
plantation staff learn to regenerate, maintain, and schedule the harvesting of cutting
stands according to a different set of demands as a result of the change in plant type.
Contrary to operational experience, cutting survival was similar to seedling survival in all
field studies. This indicates that factors other than those that were studied and reported
on, such as planting techniques, may be contributing to mortality. Also, due to the
different root structure of cuttings they may be more fragile. The similar survival
observed in these trials, therefore, may have been due to the close supervision given to
the planting operations by the research staff. Although survival was similar, both plant
types survived unacceptably poorly in the majority of studies with an average stocking of
approximately 50% at one year. It is therefore anticipated that commercial stands will
require several blanking operations in order to achieve an acceptable stocking in excess
of 85% by the following planting season. The reduction in expected profitability as a
result of blanking costs, delayed establishment, and the loss of improved genetic plant
material, indicates that this is an area that still requires further research irrespective of
what plant type is being planted.
The pathogen, Fusarium circinatum, was commonly isolated from the planting stock
before and after planting in two studies. Due to its virulent nature, it was assumed that
mortality on the trees on which F. circinatum was isolated was principally due to this
pathogen. At planting all plants were observed to be healthy and free of disease
indicating that this pathogen maybe carried from the nursery to the field in a cryptic form,
either inside or outside the plant tissue , which results in the death of the newly planted
tree. In two field studies, where F. circinatum was commonly isolated, the application of
Benomyl fungicide and to some extent the biological control agent Trichoderma
harzianum at planting appeared to improve survival although this improvement was not
significant. Laboratory studies, designed to determine alternatives to Benomyl fungicide,
indicated that three fungicides (Octave, Folicur and Tilt), three sterilants (Sporekill®,
Prasin®and Citex®) , as well as a biological control agent (T.harzianum), were all highly
successful in controlling F. circinatum colony growth in vitro. It is recommended that
these products undergo nursery testing , where the plant material is inoculated with F.
circinatum spores, in order to test their efficacy and possible phytotoxicity in vivo before
commercial application.
Post-planting survival was also affected by site climate . Greater temperature extremes, as
well as lower humidity and less rainfall resulted in poor survival. Plant dimension at
planting was found to interact with site quality where it was a significant factor on a poor
quality site. Optimal cutting dimensions at planting was a root collar diameter of 2.8 - 3.2
mm, and a stem height greater than 7 cm at planting for cuttings produced in cavities
90 ml in volume. Optimal seedling dimensions at planting were a root collar diameter of
1.8 - 2 mm, and a stem height of 10 - 15 cm for seedlings produced in cavities 80 ml in
volume.
In a separate study, plant morphological criteria influenced medium-term growth, where
greater root mass and thicker cutting root collar diameters at planting improved field
growth performance for seven years after planting. A greater root mass at planting was
achieved by raising cuttings in containers that could support greater medium volume.
From the study it was concluded that cuttings should be raised for an approximate period
of 9 months in container cavities no smaller than 80 ml in volume and possess an oven-dry
root mass of 0.3 - 0.5 g at planting. In addition to similar survival, the cuttings in this
study grew either similarly to, or in some cases out-performed, the seedlings that were
used as a control.
Several other published studies indicate that hedge maturation poses the greatest threat to
the success of softwood cutting deployment. This is especially true in clonal forestry and
methods to maintain juvenility, such as cold storage of shoots and cryopreservation,
require further research before clonal plantations of P. patula can be realised. In the
studies carried out on family hedges in this report, the effect of donor hedge maturation
was found to influence nursery management practice and the characteristics of rooted
cuttings. The nursery data indicates that rooting efficiency, root system quality, and stem
size and form, all decline with increasing hedge age particularly from two years after the
date of sowing. A decline in root system quality was particularly apparent and was
observed prior to a decline in rooting efficiency. If field trials indicate poorer
performance from older hedges , it may be necessary to determine whether the causes are
purely ontogenetic, morphological, or both before drawing final conclusions about hedge
longevity. Until such results are known, it is recommended that P. patula cuttings should
be propagated from seedling donors maintained as hedges , approximately 15 cm high, for
a period not more than three years from the date of sowing. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
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A method for three-dimensional stem analysis and its application in a study on the occurrence of resin pockets in Pinus patulaLerm, Frederik Johannes 03 1900 (has links)
Thesis (MScFor)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Information on the external shape and internal properties of a tree such as the branch
structure, tree ring widths and formation, and defects such as resin pockets is important for
many forest –and wood science researchers as well as for the forest and wood processing
industries. Resin pockets are internal defects associated with some softwood species, and are
undesirable in some wood applications such as furniture and veneer. A tool that is often used in
research to obtain this information is the Computed Tomography scanner. The high cost of the
scanner, as well as the cost of transporting logs to the scanner, limits the application range of
this equipment. An alternative, lower cost method would be beneficial for many researchers
interested in tree shape and macroscopic internal tree characteristics. The objectives of this
study were to:
- Design, construct and test a mobile system that can be used in field to obtain a
three‐dimensional model of a log or tree stem indicating selected macroscopic
internal characteristics and,
- Interpret results to explain the occurrence and causes of resin pockets in Pinus
patula from the Mpumalanga escarpment, South Africa.
A system for dissecting and measuring trees in field was designed, constructed and tested. The
metal frame was used to cut a stationary, fixed log into discs and obtain digital images of crosssections
along the stem axis. The frame was capable of processing logs with maximum
dimensions of 3 m in length and 45 cm in diameter. Software was developed to convert the
digital images into three‐dimensional models of logs and trees to demonstrate properties such
as the external shape of the trees, branch structure and pith location. Properties such as ring
width were measured from the images obtained.
The study was conducted in the Mpumalanga escarpment to obtain three‐dimensional models
of Pinus patula trees and to establish the reason for formation of resin pockets in these trees. Four 3 m logs from twenty‐four trees from three compartments were dissected and digitally
reconstructed into three‐dimensional models.
A total of 61 cross sections with resin pockets were identified from the 2750 cross cut images
taken 20 cm apart along the longitudinal axis of the log. It was not possible to accept or reject
conclusively any of the existing hypotheses for the cause of resin pocket formation. The
formation of Type 2 resin pockets was most probably due to felling damage during thinning
operations. It seems likely that wind damage and possibly insects might be responsible for the
formation of Type 1 resin pockets. / AFRIKAANSE OPSOMMING: Kennis in verband met die interne eienskappe van ‘n boom soos takeienskappe, jaarringwydte
en vorm, en harsholtes is belangrik vir sommige bos ‐en houtkundige navorsers. Die toerusting
wat huidiglik algemeen gebruik word om inligting van hierdie aard te bekom is ‘n CT skandeerder.
Die metode is egter duur as gevolg van hoë kapitale koste van die toerusting
sowel as die vervoerkoste van stompe na die CT‐fasiliteit. ‘n Meer ekonomiese alternatief sal vir
baie navorsers van waarde wees. Harsholtes in hout lei tot afgradering van hout en fineer.
Die doel van die studie was twee‐sydig:
- Om ‘n stelsel te ontwerp en bou wat ‘n drie‐dimensionele model van ‘n boom kan
skep wat sommige makroskopiese, interne eienskappe weergee, en
- Om die voorkoms en oorsaak van harsholtes in Pinus Patula van die Mpumalanga
platorand te ondersoek.
‘n Raam is ontwerp en vervaardig wat in die plantasie gebruik word. Die raam kan stompe van
tot drie meter lengte met ‘n maksimale diameter van 45 cm hanteer. Die raam is gebruik om
snitte deur die stompe te maak, ‘n afstandmeting tot by die gesaagde oppervlak word deur ‘n
lasermeter geneem en ‘n kamera neem ‘n foto. Sagteware word dan gebruik vir die uitkenning
van sekere dele in elke beeld sowel as die samestelling van ‘n drie‐dimensionele model.
Data‐insameling met die raam is in Mpumalanga gedoen. Die raam is in die tydperk getoets en
het goed gefunksioneer. Vier stompe elk vanaf vier‐en‐twintig bome vanuit drie afsonderlike
kompartemente is verwerk op die raam en volledige drie‐dimensionele modelle geskep vir
hierdie bome insluitend hul eksterne vorm, takeienskappe en pitvorm (“pith location”). Ongeveer 2750 foto’s van dwarssnitte is tydens data‐insameling geneem. Net 61 van die foto’s
het harsholtes bevat. Geen definitiewe oorsaak van harsholtes kon bepaal word nie. Tipe 2
harsholtes word waarskynlik as gevolg van skade tydens uitdunning van bome gevorm. Wind en
insekte lyk na die mees waarskynlike oorsake van Tipe 1 harsholtes.
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The effect of irregular stand structures on growth, wood quality and its mitigation in operational harvest planning of Pinus patula standsAckerman, Simon Alexander 12 1900 (has links)
Thesis (MScFor)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The practice of combining row and selective thinning in commercial pine plantation silviculture carries the risk of unwanted irregularities in tree distribution within the stand. This situation is aggravated with poor tree selection during marking. The potential consequences of poor tree selection are gaps created along row removals, which are necessary for access to harvesting operations. These gaps lead to spatially asymmetric growing space among adjacent trees.
The effect of irregular stand structures on tree morphology and growth are investigated in this study, and are based on two stands of Pinus patula, (Schiede ex Schlechtendal et Cham.) in Langeni plantation, South Africa. This study focuses on two aspects. Firstly, a comparison between trees grown in all-sided and one-sided spatial competition situations in order to assess if there are differences in growth and selected quality parameters. Secondly, the mitigation of irregular structures using a simulation based study on changing the planting geometry in order to investigate the effect on harvesting in terms of stand impact, simulated harvesting productivity and harvesting system costs.
Results showed that trees grown in an irregular competitive status have significantly larger crown diameters, crown lengths, longer and thicker branches, disproportionately one sided crown growth and a reduction in space-use efficiency. Simulations indicated that changing planting geometry from the current 2.7m x 2.7m to 2.3m x 3.1m and 2.4m x 3m would result in up to a 20% reduction of machine trail length and fewer rows being removed for machine access. The simulation of harvesting thinnings showed that various planting geometry alternatives increased harvesting productivity by 10% to 20% and reduced overall thinning harvesting cost by up to 11%.
This study successfully investigated the factors that potentially negatively affect saw timber quality and volume production of the stand at final felling. It also illustrated the applicability of simulation methods for testing harvesting scenarios and developing economically viable alternatives. / AFRIKAANSE OPSOMMING: Die praktiese kombinasie van ryuitdunning en seleksiedunning in kommersiële denneplantasies dra die risiko van ongewensde onreelmatighede in die verspreiding van bome in die opstand. Hierdie situasie word vererger deur swak boomseleksie tydens die merk van dunnings. Die potensiële gevolge van swak boomseleksie is die ontstaan van onreelmatige gapings tussen boomkrone, veral langs die rydunnings, wat nodig is vir toegang tydens die ontginning van die hout. Dit lei daartoe dat die bome langs die dunningsrye asimmetriese ruimtes het om in te groei.
Die effek van onreelmatige opstandstrukture op boom-morfologie en -groei word in hierdie studie ondersoek in twee Pinus patula, (Schiede ex Schlechtendal et Cham.) vakke te Langeni plantasie, Suid-afrika. In die studie word daar gefokus op twee aspekte. Eerstens word bome wat onder toestande van eweredige ruimetlike kompetisie groei vergelyk met die wat onder toestande van eensydige ruimtelike kompetisie groei om sodoende vas te stel of daar verskille is in die groeipatroon aan die hand van geselekteerde gehalteparameters. Tweedens word daar gefokus op die verbetering van onreelmatige opstandstrukture deur gebruik te maak van ’n simulasie-gebasseerde studie om veranderinge in die aanplantingsgeometrie te ondersoek met die doel om die effek van plantspasieering op ontginningsimpakte, gesimuleerde ontginningsproduktiwiteit en -sisteem koste te bepaal.
Die resultate het getoon dat bome wat onder toestande van onreelmatige spasieering en kompetisie groei krone met groter deursnee asook langer lengtes ontwikkel, langer en dikker takke het, disproporsionele, eensydige kroongroei en ’n reduksie in ruimte-gebruik toon, wat die groeidoeltreffendheid nadelig beinvloed. Simulasies met betrekking tot die verandering in boomaanplantgeometrie vanaf die huidige 2.7m x 2.7m na 2.3m x 3.1m en 2.4m x 3m het gedui op ’n reduksie van 20% in die masjienpadafstand en na minder rye wat uitgehaal moes word om die toegang van masjiene moontlik te maak. Die simulasie van die ontginning van dunnings het getoon dat verskillende aanplantgeometriealternatiewe die ontginningsproduktiwiteit met 10% tot 20% verbeter het, en die algehele dunningsoeskoste met tot 11% verminder het.
In hierdie studie is die faktore, wat die gehalte van saaghoutkwaliteit en volume tydens die finale oes van die plantasie potensieel negatief mag beinvloed, suksesvol ondersoek. Dit illustreer ook die geskiktheid van simulasietoepassings vir die toets van ontginningsalternatiewe en die ontwikkelling van meer ekonomies voordelige praktyke .
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