This thesis examines the application of the heat pulse velocity technique (HPV) to plantation-grown Eucalyptus grandis in the Eastern Transvaal, South Africa. The work addresses the application of the technique per se and is ultimately focused on improving the prediction of the hydrological impact of afforestation, to assist in the equitable management of South Africa's limited water resources. The verification of the HPV technique on E. grandis against the cut-tree method showed that the technique accurately reflected the water uptake in four three-year-old trees and a sixteen-year-old tree. It was found that accurate measurement of wound size and probe separation was essential for accurate water use estimates. The optimal probe allocation strategy for accurate measurements of transpiration in individual trees and stands of trees was examined. Stratifying the depths of implanted probes resulted in greater precision and repeatability in the HPV-derived estimates of sap flow in E. grandis. Given a limitation in the number of probes available to estimate stand transpiration, the results showed that sampling many individuals with a low sampling intensity (few probes per tree), rather than sampling few individuals intensively, improved the estimate of stand transpiration. An examination of the influence of tree age and season on transpiration rates showed that the transpiration rate per unit leaf area of E. grandis declined with age. Also, transpiration rates were higher in summer than under equivalent conditions of evaporative demand in winter. A seasonal change in the response of transpiration to VPD was implicated as the primary cause of this shift. A number of models were derived to predict transpiration from E. grandis. The variables vapour pressure deficit (VPO) and photosynthetically active radiation (PAR) were found to account for a large proportion of the observed variation in transpiration from the age sequence of trees studied. The models developed are applicable to trees of varying age, but are valid only for conditions where minimal soil water stress is experienced. The derived models were tested against two sets of independent data. This confirmed that a simple linear multiple regression adequately describes the relationship between transpiration and the two driving meteorological variables, PAR and VPO, in E. grandis. The application of a selection of the developed models on a sample data set from Sabie showed that transpiration from a three-year-old stand of E. grandis in summer may be more than double that for a sixteen-year-old stand under the same conditions. Simulated results also showed that transpiration in summer was about 25 to 50% higher than that from the same stand during winter conditions. Simulated transpiration rates from the young E. grandis stands were high, suggesting that further validation of the estimated rates is required before the models are applied. It is concluded that the HPV method is an ideal technique to estimate water use in E. grandis trees. The models developed represent a major advancement on previous models used to predict the hydrological impact of afforestation on mountain catchments. / Thesis-(Ph.D.)-University of Natal, Durban, 1994.

The prospect of integrating transgenic eucalypts with conventional breeding programmes is of value to the Plantation Forestry and Forest Products Industries. However, significant progress in this regard has still to be reported, one constraint is the lack of appropriate high yielding regeneration culture methods for clonal material. Such was the main aim of the present study. The strategy was to develop a suitable protocol using in vitro shoots of an E. grandis x E. urophy/la clone (GU185) and thereafter to test its applicability to other clones. Explants from greenhouseestablished cuttings provided the in vitro shoots, which were multiplied via axillary bud proliferation either on semi-solid medium or using a RIT A system. To determine the best conditions for callus and shoot regeneration, parameters such as vessels (petri dishes and tubes) and types and levels of plant growth regulators were tested. The best callus production (100%) and shoot regeneration (78.9 - 100% callus with shoots) for GU185 occurred on MS, 30 g rl sucrose, 4 g rl Gelrite, 5 mg rl IAA and 0.25 mg rl BAP. Parameters tested to identify the most suitable explants for indirect organogenesis were the age of parent plants, different systems to generate in vitro shoots, elongation status of explants, 1 sI and 2nd generation in vitro shoots and the use of hyperhydric shoots. Of these, the most suitable explants for indirect organogenesis were shoots from axillary bud multiplication of 3-month-old parent plants using the semi-solid system (33 shoots/dish). Up to 90% rooting was achieved on 1f4 MS (Murashige and Skoog, 1962), 15 g rl sucrose, 0.1 mg rl biotin, 0.1 mg rl calcium pantothenate, 4 g rl Gelrite and mA. The highest rooting was obtained when regenerated shoots were first multiplied and then placed on medium without plant growth regulators for one week, before transfer to root induction medium containing 0.1 - 0.5 mg rl mA. Acclimatization success was 95% when rooted shoots were placed in pots with a rooting mix (2 perlite: 1 coir) enclosed in plastic bags and the humidity was gradually reduced over four weeks. The developed indirect organogenesis protocol appeared to have a broad general application, although the tested clones exhibited a genotype-dependent response, with GU180, GUI77 and TAG31 producing fewer shoots (9, 6 and 7 shoots/dish) than ZG14 and GU185 (24 and 18 shoots/dish). Similarly high levels of rooting were obtained for TAG3l (93.8%) and ZG14 (90%) and for hardening-off (90.7% for TAG31 and 91.4% for ZG14). / Thesis (M.Sc.)-University of KwaZulu-Natal, 2004.

There is growing interest in airborne lidar for forest carbon accounting and precision forestry purposes. Airborne lidar systems offer a cost-effective, versatile, operationally flexible and robust sampling tool for forest managers. The objective of this study was to develop and test lidar canopy surface enhancement and segmentation processes for estimating dominant above-ground biomass (DAB) in a harvested eucalypt forest on the Central Coast of New South Wales (Australia). The Crown Infill, Trim and Smooth (CITS) process, incorporating a series of filters, algorithms, and selective multi-stage smoothing, was used to enhance lidar canopy surfaces prior to segmentation. Canopy segmentation was achieved using a vertical crown template approach termed the Spatially and Morphologically Isolated Crest (SMIC) process. SMIC delineates dominant tree crowns by detecting elevated crown crests within a 3D lidar canopy surface. Consolidated crown units constitute the basic sampling, analysis and reporting units for wall-to-wall forest inventory. The performance, sensitivity and limitations of these procedures were evaluated using a combination of simulated forest models and actual lidar forest data. Automated crown polygons were used as a sampling template to extract dominant tree height values which were converted to DAB estimates via height-to-biomass relationships derived from field survey and on-site destructive sampling. Results were compared with field based tree height and biomass estimates. Compared against a manually derived crown map from a 2ha field plot, canopy segmentation results revealed a producer???s accuracy of 76% and overall accuracy of 67%. Results indicated a trend toward greater crown splitting (fragmentation) as trees increase in age, height, stem diameter and crown size. Extracted dominant tree height values were highly correlated with ground survey height estimates (r2 0.95 for precision survey and r2 0.69 for standard survey). There was also no significant difference between SMIC and manual crown height estimates. SMIC units overestimated ground-based DAB by 5%; this increased to 36% with the inclusion of segmentation errors. However, SMIC estimation of total plot above-ground biomass (AGB) was within 9% of the ground-based estimate. Results are encouraging considering the mixed-species, multi-aged composition of the forest, and the combined effects of SMIC segmentation and lidar height errors.

Eucalyptus pellita is a commercially important plantation hardwood species for the humid tropics of north Queensland. This species is favoured by both small-scale growers for use in mixed species woodlots targeting low-volume high-value sawn timber, and also by industrial forest companies growing monocultures for integrated pulp – sawn timber regimes. This study investigated whether mixed-species designs can increase the growth of this tropical eucalypt when compared to monocultures.A replacement series experiment with monocultures of Eucalyptus pellita (E) and Acacia peregrina (A) and mixtures in various proportions (75E:25A, 50E:50A, 25E:75A) was used to examine questions about growth and productivity. The trial was located on the Atherton Tablelands of north Queensland, Australia. High mortality in the establishment phase due to repeated damage by tropical cyclones altered the trial design. Effects of experimental designs on tree growth were estimated using a linear mixed effects model with restricted maximum likelihood analysis (REML). Volume growth of individual eucalypt trees were positively affected by the presence of acacia trees at age five years and this effect generally increased with time up to age 10 years. However, the stand volume and basal area increased with increasing proportions of E. pellita, due to its larger individual tree size. Conventional analysis did not offer convincing support for mixed-species designs. Preliminary individual-based modelling using a modified Hegyi competition index offered a solution and an equation that indicates acacias have positive ecological interactions (facilitation or competitive reduction), and definitely do not cause competition like E. pellita. These results suggest that significantly increased growth rates could be achieved with mixed-species designs over E. pellita monocultures. This statistical methodology could enable a better 4 understanding of species interactions in similarly altered experiments, or undesigned mixed-species plantations.The effects of trees on soils are highly variable and highly site and species specific. That trees can change soil chemistry over time is well established. The soil chemical properties under the eucalypt: acacia experiment were compared to several potential baseline data sources: the reference description of this soil type; those measured at 7 months after planting; and with those of soils under two adjacent vegetation types (forest and pasture) when the experiment was aged 9 years. At 9 years after planting soil total nitrogen increased with increasing proportion of acacias in the treatment. The mean total N under the acacia monoculture was significantly higher (P = 0.041) than that of either the eucalypt monoculture, or the surrounding pasture. The proportion of acacia in the treatment was positively linearly correlated with soil total N (r2 = 0.46; P = 0.018). Soils under the eucalypt monocultures were more similar to those under pasture for a range of soil chemical properties, compared with soils under treatments containing acacias. Results from this site show that the two species alter the soil chemistry in different ways. It is possible that the increased total N under the acacias could be facilitating the growth of the E. pellita, however without n-fixation analysis or tissue sampling it is not possible to confirm that the eucalypt is using the N. Similar cause and effect (or ‘supply and use’) questions also remain for soil pH and available phosphorus changes with increasing acacia in treatment. This study also demonstrates the difficulty in monitoring changes in soil properties over long cycles of forest plantations.The photosynthetic response to light was assessed in the stratified canopy of the mixed species field trial of the eucalypt: acacia experiment, and among commonly planted taxa of E. pellita in glasshouse pot trials. In the field trial photosynthetic capacity of fully5 expanded sun and shade leaves of both species was measured. E. pellita has a wide natural distribution with considerable variation in morphology and growth within the species, with several provenances commonly planted in north Queensland. Photosynthetic capacity and leaf nutrient content of three of these taxa (two from northern occurrences and one from southern occurrences of E. pellita) were measured on two occasions in glasshouse pot trials. A non rectangular hyperbolic function was used to describe the light response curves, and analysis of variance was used to determine differences in the biologically relevant curve parameters between treatments. In the field trial sun and shade leaves of E. pellita produced similar light saturated photosynthetic rates, and experienced little competition for light from the acacia crowns. In contrast there was significant variation in the photosynthetic response between acacia sun and shade leaves. In the glasshouse trials, differences in leaf and petiole morphology were observed, which were coupled with differences in leaf nutrient content and highly significant variation in light saturated photosynthetic rate between the three taxa. This study characterised the light response of E. pellita and suggests that differences in physiological responses to resource availability should be expected among taxa within this species, which may be important for forest productivity models which endeavour to predict tree growth and resource use.An empirical model of growth of E. pellita from a designed monocultures vs. mixedspecies experiment has been used to explore system behaviour rather than predict production of this species from specific forests. This approach has allowed examination of the effect of plantation design on competition, soil nutrient pool change with time and physiological responses to light; leading to a greater understanding of why mixtures can lead to greater productivity than monocultures.

Eucalyptus pellita is a commercially important plantation hardwood species for the humid tropics of north Queensland. This species is favoured by both small-scale growers for use in mixed species woodlots targeting low-volume high-value sawn timber, and also by industrial forest companies growing monocultures for integrated pulp – sawn timber regimes. This study investigated whether mixed-species designs can increase the growth of this tropical eucalypt when compared to monocultures.A replacement series experiment with monocultures of Eucalyptus pellita (E) and Acacia peregrina (A) and mixtures in various proportions (75E:25A, 50E:50A, 25E:75A) was used to examine questions about growth and productivity. The trial was located on the Atherton Tablelands of north Queensland, Australia. High mortality in the establishment phase due to repeated damage by tropical cyclones altered the trial design. Effects of experimental designs on tree growth were estimated using a linear mixed effects model with restricted maximum likelihood analysis (REML). Volume growth of individual eucalypt trees were positively affected by the presence of acacia trees at age five years and this effect generally increased with time up to age 10 years. However, the stand volume and basal area increased with increasing proportions of E. pellita, due to its larger individual tree size. Conventional analysis did not offer convincing support for mixed-species designs. Preliminary individual-based modelling using a modified Hegyi competition index offered a solution and an equation that indicates acacias have positive ecological interactions (facilitation or competitive reduction), and definitely do not cause competition like E. pellita. These results suggest that significantly increased growth rates could be achieved with mixed-species designs over E. pellita monocultures. This statistical methodology could enable a better 4 understanding of species interactions in similarly altered experiments, or undesigned mixed-species plantations.The effects of trees on soils are highly variable and highly site and species specific. That trees can change soil chemistry over time is well established. The soil chemical properties under the eucalypt: acacia experiment were compared to several potential baseline data sources: the reference description of this soil type; those measured at 7 months after planting; and with those of soils under two adjacent vegetation types (forest and pasture) when the experiment was aged 9 years. At 9 years after planting soil total nitrogen increased with increasing proportion of acacias in the treatment. The mean total N under the acacia monoculture was significantly higher (P = 0.041) than that of either the eucalypt monoculture, or the surrounding pasture. The proportion of acacia in the treatment was positively linearly correlated with soil total N (r2 = 0.46; P = 0.018). Soils under the eucalypt monocultures were more similar to those under pasture for a range of soil chemical properties, compared with soils under treatments containing acacias. Results from this site show that the two species alter the soil chemistry in different ways. It is possible that the increased total N under the acacias could be facilitating the growth of the E. pellita, however without n-fixation analysis or tissue sampling it is not possible to confirm that the eucalypt is using the N. Similar cause and effect (or ‘supply and use’) questions also remain for soil pH and available phosphorus changes with increasing acacia in treatment. This study also demonstrates the difficulty in monitoring changes in soil properties over long cycles of forest plantations.The photosynthetic response to light was assessed in the stratified canopy of the mixed species field trial of the eucalypt: acacia experiment, and among commonly planted taxa of E. pellita in glasshouse pot trials. In the field trial photosynthetic capacity of fully5 expanded sun and shade leaves of both species was measured. E. pellita has a wide natural distribution with considerable variation in morphology and growth within the species, with several provenances commonly planted in north Queensland. Photosynthetic capacity and leaf nutrient content of three of these taxa (two from northern occurrences and one from southern occurrences of E. pellita) were measured on two occasions in glasshouse pot trials. A non rectangular hyperbolic function was used to describe the light response curves, and analysis of variance was used to determine differences in the biologically relevant curve parameters between treatments. In the field trial sun and shade leaves of E. pellita produced similar light saturated photosynthetic rates, and experienced little competition for light from the acacia crowns. In contrast there was significant variation in the photosynthetic response between acacia sun and shade leaves. In the glasshouse trials, differences in leaf and petiole morphology were observed, which were coupled with differences in leaf nutrient content and highly significant variation in light saturated photosynthetic rate between the three taxa. This study characterised the light response of E. pellita and suggests that differences in physiological responses to resource availability should be expected among taxa within this species, which may be important for forest productivity models which endeavour to predict tree growth and resource use.An empirical model of growth of E. pellita from a designed monocultures vs. mixedspecies experiment has been used to explore system behaviour rather than predict production of this species from specific forests. This approach has allowed examination of the effect of plantation design on competition, soil nutrient pool change with time and physiological responses to light; leading to a greater understanding of why mixtures can lead to greater productivity than monocultures.

Tall tuart (Eucalyptus gomphocephala) trees are a defining element of the landscape of Perth and the coastal plain to the north and south. However, with the health of some tuart stands deteriorating, most notably at Yalgorup south of Perth, concerns are heightening that the already fragmented tuart ecosystem will continue to contract, leaving a cultural and ecological scar in the landscape. Like many other eucalypt ecosystems, tuart woodlands have had a long association with fire and are believed to have been frequently burnt by the Aborigines prior to European settlement. Today, fragmentation and European land management practices have led to a lower frequency of fire across most remaining woodlands, but also episodes of intense fire at shorter intervals in some areas. Individual fire events as well as fire regimes have the potential to shape the structure, composition and extent of ecosystems, and eucalypt ecosystems are no different. Thus, the impact of fire and fire regimes on tuart health and regeneration was investigated in this study. A survey of the woodlands at Yalgorup revealed tuart decline was present across a range of sites with contrasting fire histories. Tuart health was poorest at the longest unburnt site (35 years) and the site burnt by frequent wildfire (three fires in 13 years), suggesting these extreme fire regimes had played a role in the decline. Nevertheless, low ratings of tree health at sites burnt approximately once per decade, point to factors other than fire playing a role in the decline of tuart at Yalgorup. The tuart populations at Yalgorup were dominated by individuals in larger size-classes and there was a significant negative relationship between tree size and the probability of tree mortality. In one stand in Yalgorup National Park, 38 % of the tuart saplings/trees had died. It follows that the regeneration and development of tuart seedlings into adults will need to occur within the next one to two decades if these woodlands are to persist. Seedling counts confirmed that tuart regeneration was virtually absent in unburnt areas, as is common with eucalypt species. Interpretations of size-class distributions suggested controlled burning contributed little to recruitment, whereas in areas subject to wildfire outside Yalgorup, tuart had regenerated in abundance such that size-class distributions were skewed towards the smaller size-classes. A repeat survey of plots established in 1976 supported anecdotal reports that the mid-storey tree peppermint (Agonis flexuosa) was increasing in density and height in Yalgorup. The skew towards the smallest size-class within peppermint populations at Yalgorup and the presence of seedlings ( > 200 seedlings ha-1) within areas not recently burnt (at least four years since fire) brought into focus the differing mode of regeneration for this species in comparison to tuart. In further contrast to tuart, mature peppermints were in good health with no dead trees reported in the population surveys. A possible role for competition in tuart decline was highlighted by significant negative correlation between peppermint density and tuart health. Together, these results suggest that a general drift from tuart woodland to peppermint forest appears entrenched. Comparative studies of the bark thickness, fire response and resprouting behaviour of tuart and peppermint illustrated the capacity of individuals of both species to persist with recurrent fire. As adults or juveniles, tuart and peppermint resprouted following complete canopy scorch, and often from crown branches: an ability not uncommon for co-occurring tree species and shrubs in this environment. Survival was between 75 and 100 % for fully-scorched tuarts in size-classes ranging from small saplings to trees across six sites. From the small sample of peppermints available for comparison, seedlings and small saplings appeared to be more vulnerable to mortality by fire; only 45 % of individuals with a diameter at breast height ¡Ü 1 cm survived following complete canopy scorch from a controlled burn. With thicker bark, a reliance on stem epicormic buds rather than a lignotuber for resprouting and a greater capacity for height growth, the fire resistance and post-fire recovery of tuart would be expected to differ from that for peppermint. Opportunities for managers to exploit these differences in their burning prescriptions so as to address the drift from tuart to peppermint dominance were outlined. In addition, results indicating a positive response in canopy condition for tuarts with < 10 % canopy scorch following a controlled burn imply that tuart vigour may benefit more immediately from fire. But, observations also revealed that spikes in intensity within controlled burns can damage large unhealthy trees and thereby accelerate the decline process. Thus, the application of fire to declining tuart stands needs to be conducted skillfully. Patterns of growth and survival for tuart and peppermint seedlings were linked to the contrasting ability of the species to establish at burnt and unburnt sites. The purported importance of ashbeds in tuart establishment was demonstrated; at the end of summer (February) at a recently burnt site (Golden Bay), the mean height of tuart seedlings on ashbeds was three times that for those off ashbeds, and the survival rate on and off the ashbeds was 35 % and 15 %, respectively. Therefore, while important, tuart seedlings were not dependent on ashbeds in this instance. The hardy nature of peppermint seedlings when compared to tuart was illustrated when the species were planted in an unburnt area of tuart-peppermint woodland at Yalgorup; nine months after planting, 38 % of the peppermint seedlings survived while only 9 % of the tuart survived. Most of the mortality was linked with the summer-drought period and it was suspected that peppermint seedlings were more drought tolerant. A complementary glasshouse experiment showed that tuart had a greater shoot:root ratio than peppermint, which may be one factor in the greater sensitivity of this species to drought. Further, this experiment revealed that with an increase in nutrient supply, the proportional increment in rooting depth for tuart (1.6 times) was significantly greater than for peppermint (0.3 times). An increased availability of nutrients in ashbeds following fire, particularly for phosphorous, was measured within tuart woodland. Therefore, it was inferred that the availability of nutrients was a critical factor increasing the growth, rooting depth and consequently the greater survival of tuarts on ashbeds. Overall, tuart was concluded to share the Competitor strategy (after Grime) in common with many other eucalypts: rapid growth and the attainment of a large size. On the other hand, peppermint exhibits some of the traits of the Stress Tolerator strategy (after Grime): low minimum resource requirements for growth and survival. The consequence of the increasing cover of peppermint on tuart establishment was explored in field experiments with planted tuart seedlings. No significant impact on seedling growth or survival was observed. There was a declining trend in the seedling growth rates under the high compared to the low peppermint density treatments as the second summer of the experiment was approached, although a statistical difference could not be shown. Peppermint density also had no significant influence on damage to the seedlings from insect attack or the foliar pathogen Mycosphaerella cryptica. Overall, insects and M. cryptica had only an incidental impact on the seedlings: the mean level of canopy damage per affected seedling was < 10 % for either of these two damage agents. Soil type, specifically whether growth occurred on an ashbed was demonstrated to be the most important factor in tuart growth and survival in the 18 months following planting. Although survival was superior on ashbeds (88 %), mean survival was > 50 % in unburnt soil 18 months after planting indicating the potential for restorative plantings to occur in some woodlands between fires. Tuart decline, and the role of altered fire regimes in the decline is complex and further avenues of research were emphasized. Nevertheless, the findings of this and other studies are sufficient to enable purposeful actions to conserve and restore tuart woodlands; recommendations regarding the application of fire with a view to these goals are presented in the final discussion.

Thesis (Ph.D.) -- University of Adelaide, Dept. of Entomology, 1980.

Thesis (Ph.D.)--University of Melbourne, Dept. of Zoology, 1978. / Typescript (photocopy). Includes bibliographical references.

Thesis (Ph.D.)--Murdoch University, 2003. / Thesis submitted to the Division of Arts. Bibliography: p. 273-289.

Thesis (Ph.D.)--Murdoch University, 2004. / Thesis submitted to the Division of Science and Engineering. Bibliography: p. 214-231.