Literatura científica selecionada sobre o tema "Sclerophyll"

An increase (percentage dry weight) in both lignin and cellulose (with a greater proportion of cellulose than lignin being formed) is associated with a decrease in the concentration of phosphorus (and of other related elements) per unit dry weight in the leaves of sunlit overstorey species, of both sclerophyll and savannah communities in the mediterranean climate of southern Australia. Simultaneously, crude protein decreases. Leaves become increasingly sclerophyllous (with a higher Sclerophyll Index), with lower crude protein (cytoplasm) per unit dry weight; thicker leaves with lower leaf specific area result. The degree of sclerophylly per unit foliar phosphorus content is a little higher in understorey species which are partially shaded by the overstorey canopy.

Wet sclerophyll forest (also called tall open forest) is unique to Australia, being dominated by tall trees of the genus Eucalyptus (Myrtaceae). In this paper, we refer to the wet sclerophyll forest in north-east Queensland as tropical wet sclerophyll forest. Tropical wet sclerophyll forest is a threatened ecosystem which is maintained by fire. Our study describes the community, relative abundance and trophic structure of birds using the tropical wet sclerophyll forest. We surveyed the birds and recorded 100 taxa, of which = 29% (n = 29) are endemic to north-east Queensland. The community is comprised predominantly of insect-eaters (58% of the species) and nectar-feeders (26%), along with smaller guilds of fruit-eaters (11%) and seed-eaters (5%). Despite comprising only a small geographic area (82 800 ha), tropical wet sclerophyll forest supports a high diversity of birds. We believe it is essential that the tropical wet sclerophyll forest be conserved and managed to maintain the full range of its biodiversity. Because the tropical wet sclerophyll forest is fire-adapted and fire-dependent, the use of prescribed fire as a modern management tool is imperative. Unless fire has a central role in managing tropical wet sclerophyll forest, then this forest type and its dependent species will cease to exist.

Data from 152 plots (0·8 ha) and 659 small quadrats (0·04 ha) were used to assess rooting activity by feral pigs in forest communities in north Queensland. Study sites spanned the rainforest–sclerophyll-forest gradient along the western margin of the wet tropics region. Detailed floristic, physiognomic and edaphic data were recorded for each plot and used to develop a predictive model of pig activity in these habitats. The most striking result was that rooting activity varied markedly among different forest types. Wet sclerophyll forests consistently had the greatest area disturbed, followed by mesic and dry sclerophyll forests. Both rainforest and rainforest-invaded sclerophyll forests had relatively low activity levels. There were some differences in rooting activity among different geographic regions, but few effects of local topography, soil type or proximity to water. A mathematical model was developed to predict the ecological associations of pig rooting activity, using generalised linear modeling. Pig rooting was associated with certain attributes of wet sclerophyll forests and with slopes and ridge tops, but the model had limited effectiveness, with fitted values explaining 16% of the actual variation in rooting activity. This may have resulted because microhabitat preferences of pigs varied among different forest types and seasons. We suggest that pigs could be consuming fungal fruit-bodies in sclerophyll forests, and if so they may compete for food with some native, mycophagous mammals.

Replicated sampling regimes were used to assess the numbers of Rattus fuscipes in cool temperate rainforests and dry sclerophyll forests, on Gloucester Tops, N.S.W. R. fuscipes was significantly more abundant in the rainforest habitat than in the sclerophyll habitat, and this result was consistent under a number of different sampling regimes. Numbers changed significantly between April 1978 and March 1980, but the patterns of change were similar in each habitat. Fire and logging contributed to the spatial and temporal heterogeneity of the Gloucester Tops, and the cool temperate rainforests appeared to be more protected from disturbance than the dry sclerophyll forests. The cool temperate rainforests may be important refuges for populations of R. fuscipes, and may provide recruits for areas of sclerophyll forest the populations of which have been reduced by logging or fire.

Vegetation maps were prepared from aerial photographs taken in 1943?45 and 1991?92 of three, widely separated areas of sclerophyll forest adjacent to the western edge of rainforest on granitic soils in north Queensland. Nine types of sclerophyll communities could be discerned from aerial photos and characterized by field measurement. Two types of Wet Sclerophyll Forest (WSFa and b) were separated on the species of tree composing the tallest stratum and these were subdivided according to whether the ground layer was dominated by grass or young rainforest. A related type showed large, residual Eucalyptus grandis emergent from mature rainforest. Closed canopy sclerophyll forest with no emergents (SF), sclerophyll woodland and Acaciaforest were also discerned. WSF was defined as having more than 30 per cent of the closed crown cover contributed by trees more than 35 m tall. During the 50-year study period rainforest invaded 70 per cent of WSFa (tallest stratum dominated by E. grandis), which principally occurs as a narrow strip along the rainforest margin, and 57 per cent of the adjacent WSFb (tallest stratum composed of mixed species). Grass would be quickly excluded from invaded areas and thereafter they would only burn under extreme atmospheric conditions. Because sclerophyll trees are unable to regenerate in shade and usually require fire to provide the appropriate conditions, a long-term transition to rainforest may ensue. The final stages of this transition were observed in areas that exhibited full-stature rainforest with large, relictual E. grandis emergents in 1943, but had disappeared by 1992. The initial cause of this vegetation transition is a fire-free period of sufficient length for rainforest tree seedlings to establish and suppress the grass layer. It is not known whether these vegetation changes represent a trend, possibly caused by a change a century ago from fire management by Aboriginal people to management for the cattle industry, or whether it is a temporary phase in the fire-induced, dynamic relationship between rainforest and sclerophyll vegetation. The current loss of WSF probably endangers the survival of a range of genetically endemic biota. Most groups are poorly known but the marsupial Yellowbellied Glider Petaurus australis reginae is totally dependent upon WSF and a number of vertebrates would probably go locally extinct if WSF is replaced by rainforest. WSF is the wettest part of the sclerophyll communities and probably acts as a refuge in times of unusual aridity. To maintain the WSF habitat, fire management is clearly indicated, but the intensity of fire required to reverse the advance of rainforest may be socially unacceptable to instigate or impossible to control if it occurs by accident.

The effects of burning on in situ extractable nitrogen (NH+4-N+NO-3-N) and net Nmineralisation following scheduled fuel reduction burns in repeatedly burnt dry and wet sclerophyll forest sites in south-east Queensland were assessed. In addition, soil organic matter composition in the wet sclerophyll site was assessed by 13C NMR spectroscopy. The results showed that at the dry sclerophyll site, extractable N and net N mineralisation for 1 year were largely unaffected by burning, while at the wet sclerophyll site, these parameters decreased. 13C NMR analysis of soil samples from the wet sclerophyll site revealed that there was a significant reduction in the proportion of O-alkyl (alkoxy/carbohydrate) C with increasing burning frequency. Statistically significant effects on the other chemical shift regions were not detected. The ratio of alkyl C to O-alkyl C, a proposed index of organic matter decomposition, increased with increasing burning frequency. A high ratio of alkyl C to O-alkyl C suggests low amounts of carbohydrates relative to waxes and cutins, which could in turn lead to slower mineralisation. The findings are in accord with this hypothesis. There were significant linear relationships between cumulative N mineralisation for 1 year and the proportions of alkyl C and O-alkyl C, and the ratio of alkyl C/O-alkyl C. Thus, in addition to reductions in substrate quantity (low organic C and total N for burnt soils), there was also an alteration of substrate quality as revealed by 13C NMR spectroscopy which is reflected in low N mineralisation.

Marbled Frogmouths are rare, cryptic, shy, nocturnal birds restricted primarily to rainforest and wet sclerophyll forest. Two sub-species are recognized in two isolated areas on the east Australian coast. A stronghold for the southern subspecies (Plumed Frogmouth) occurs in the Conondale Ranges. This area has been subject to forestry practices for the past 100 years. Because of public concerns and a perceived need to undertake planning and management to assist in conserving the species, a study was undertaken to assess its population status. Radio-tracked adults associated primarily with rainforest and wet sclerophyll along drainage lines, although gullies containing rainforest species within dry sclerophyll were also utilized. Taped playback of Plumed Frogmouth calls revealed a distribution within core habitat (rainforest and wet sclerophyll) across the Conondale Ranges. Individuals radio-tracked in the Conoodale Ranges occupied home ranges from 5 to 18 ha. Estimates of the combined home ranges of pairs ranged from 12 to 19 ha. Home range overlap between pairs was minimal. An assessment of the area of currently suitable core habitat (14 508 ha) within the Conondale Range forested area suggests that conservatively, 755 pairs currently exist; if potential future habitat (i.e., regenerating) of 1 954 ha is taken into consideration, this figure will rise to 857 pairs. If use of dry sclerophyll by birds is also taken into account then these estimates may be as high as 858 and 974 pairs respectively. There is currently no reliable estimate of the amount of suitable habitat, which is not occupied by Plumed Frogmouths or of habitat only occupied by single unpaired birds or non-breeding pairs. Future research should aim to redress this lack of information which could severely reduce any estimates of the numbers of breeding pairs.

Impacts on the understorey vegetation of a range of silvicultural alternatives to clearfelling in lowland Eucalyptus obliqua wet forest were studied over a decade in the Warra silvicultural systems trial in southern Tasmania. The treatments were clearfell with understorey islands, patchfell, stripfell, dispersed retention, aggregated retention, and single-tree/small-group selection. High intensity burning, low intensity burning and no burning were variously applied as part of these treatments. Three understorey types were studied, including one wet sclerophyll community and two rainforest communities. Wherever burning occurred across the research trial, the regenerating vegetation was floristically wet sclerophyll with an incipient composition consistent with that of the pre-harvest wet sclerophyll community. Sites previously occupied by rainforest understoreys retained occasional rainforest elements, but the regeneration was overwhelmingly sclerophyll in nature. There were no consistent differences in the floristic composition of the regenerating vegetation, after burning or harvesting disturbance, that could be attributed to the silvicultural system. However, field observations and the results of a related, subsequent study suggest that, in designing silvicultural trials similar to the present one, close attention should be paid to the size of quadrats in relation to the level at which disturbance impacts are operating. The response of the vegetation at edges created by the treatments, and in the undisturbed forest beyond, supports the finding that edge effects on the vascular flora extend for less than 10 m into the undisturbed forest.

Chytrids are common microfungi in soils, but their distribution and diversity in Australian soils is poorly described. In this study we analyzed chytrid distribution and diversity in soils from four collection sites representing a subtropical rain forest, wet sclerophyll forest, dry sclerophyll forest, and open heath, using a defined and reproducible sampling protocol. The greatest number of chytrid species was observed from dry sclerophyll forest soils, while the least number of species occurred in the open heath soils, although each soil sample of the open heath harbored more species per sample. Differences in patterns of distribution of chytrid species were statistically significant between subtropical rain forest and open heath. Patterns in other habitats differed but could not be verified statistically to be significant at the 5% level. Observed differences in chytrid distribution, diversity, and freqency indicate that their ecological strategies may be in response to environmental cues such as specific edaphic conditions and substrate availability, and their capacity to respond to the environment.Key words: Chytridiomycota, frequency, habitat, sampling.

The roosting and foraging ecology of the golden-tipped bat (Kerivoula papuensis) was studied by radio-tracking on the south coast of New South Wales. Despite a previous scarcity of records, 16 bats were harp-trapped during spring and summer, of which 11 were radio-tracked. Roost types (n = 33 roosts over 48 roost days) were the suspended nests of yellow-throated scrubwrens (Sericornis citreogularis) (50%), nests of brown gerygone (Gerygone mouki) (27%), beneath hanging moss on tree trunks (21%) and in foliage (2%). All roosts were located in rainforest and close to creek lines (mean = 6 m). Yellow-throated scrubwren nests were more common in rainforest on small, first- and second-order streams (4.6 nests km–1 – 5.2 km searched) than on larger, third-order streams (1.1 nests km–1 – 2.7 km searched). Colonies were small (<10 bats) and usually comprised a mix of sexes. Maternity roosts in summer were located in both yellow-throated scrubwren nests (n = 8) and brown gerygone nests (n = 3). Foraging bats were recorded flying a maximum of 2.1 km and were regularly recorded (43% of monitored time) on upper slopes away from rainforest. Plots (5 × 5 m) were used to compare prey densities (small web-building spiders) between rainforest and sclerophyll forest and different topographies (creeks, riparian vegetation and upper slopes). Although spider numbers were patchy, upper-slope sclerophyll forest supported the greatest number of spiders, the number being significantly greater in upper-sclerophyll forest than in sclerophyll creeks and rainforest on upper slopes. A forward step-wise multiple regression showed that spider numbers per plot were positively related to the density of understorey stems. Management implications from this research are that riparian rainforest provides the key roosting habitat for K. papuensis. Recent management prescriptions in New South Wales' forests available for logging have correctly targeted the protection of this environment. However, the extent of foraging in sclerophyll forest on upper slopes was previously unknown. Attention needs to be given to management actions that maintain a mosaic of dense patches of understorey on upper slopes, where the numbers of web-building spiders are high. Further research is required to determine the effectiveness of using buffered protection zones within logged areas for K. papuensis.

This project evaluated the impact of myrtle rust, a fungal pathogen that threatens the persistence of one of Australia’s most iconic plant families Myrtaceae. Five tree species were studied in a wet sclerophyll forest in the Tallebudgera Valley and showed a decreasing survival probability over time. This mortality led to an increase in canopy gap fraction—a surrogate measure for light availability; although no significant difference was found in plant composition below living and dead trees. After just four years of infection forest structure is changing which is increasing light and could lead to an increase in weeds.

In this thesis I present and test a methodology for developing a stand scale index of structural complexity. If properly designed such an index can act as a summary variable for a larger set of stand structural attributes, providing a means of ranking stands in terms of their structural complexity, and by association, their biodiversity and vegetation condition. This type of index can also facilitate the use of alternative policy instruments for biodiversity conservation, such as mitigation banking, auctions and offsets, that rely on a common currency – the index value – that can be compared or traded between sites. My intention was to establish a clear and documentable methodology for developing a stand scale index of structural complexity, and to test this methodology using data from real stands.¶ As a starting point, I reviewed the literature concerning forest and woodland structure and found there was no clear definition of stand structural complexity, or definitive suite of structural attributes for characterising it. To address this issue, I defined stand structural complexity as a combined measure of the number of different structural attributes present in a stand, and the relative abundance of each of these attributes. This was analogous to approaches that have quantified diversity in terms of the abundance and richness of elements. It was also concluded from the review, that stand structural complexity should be viewed as a relative, rather than absolute concept, because the potential levels of different structural attributes are bound within certain limits determined by the inherent characteristics of the site in question, and the biota of the particular community will have evolved to reflect this range of variation. This implied that vegetation communities with naturally simple structures should have the potential to achieve high scores on an index of structural complexity.¶ I proposed the following five-stage methodology for developing an index of stand structural complexity: 1. Establish a comprehensive suite of stand structural attributes as a starting point for developing the index, by reviewing studies in which there is an established relationship between elements of biodiversity and structural attributes. 2. Develop a measurement system for quantifying the different attributes included in the comprehensive suite. 3. Use this measurement system to collect data from a representative set of stands across the range of vegetation condition (highly modified to unmodified) and developmental stages (regrowth to oldgrowth) occurring in the vegetation communities in which the index is intended to operate. 4. Identify a core set of structural attributes from an analysis of these data. 5. Combine the core attributes in a simple additive index, in which attributes are scored relative to their observed levels in each vegetation community.¶ Stage one of this methodology was addressed by reviewing a representative sample of the literature concerning fauna habitat relationships in temperate Australian forests and woodlands. This review identified fifty-five studies in south-east and south-west Australia, in which the presence or abundance of different fauna were significantly (p<0.05) associated with vegetation structural attributes. The majority of these studies concerned bird, arboreal mammal, and ground mammal habitat requirements, with relatively fewer studies addressing the habitat requirements of reptiles, invertebrates, bats or amphibians. Thirty four key structural attributes were identified from these fifty-five studies, by grouping similar attributes, and then representing each group with a single generic attribute. This set, in combination with structural attributes identified in the earlier review, provided the basis for developing an operational set of stand level attributes for the collection of data from study sites.¶ To address stages two and three of the methodology, data were collected from one woodland community –Yellow Box-Red Gum (E. melliodora-E. Blakelyi ) – and two dry sclerophyll forest communities – Broadleaved Peppermint-Brittle Gum (E. dives-E. mannifera ), Scribbly Gum-Red Stringybark (E. rossii E. macrorhyncha ) – in a 15,000 km2 study area in the South eastern Highlands Bioregion of Australia. A representative set of 48 sites was established within this study area, by identifying 24 strata, on the basis of the three vegetation communities, two catchments, two levels of rainfall and two levels of condition, and then locating two sites (replicates) within each stratum. At each site, three plots were systematically established, to provide an unbiased estimate of stand level means for 75 different structural attributes.¶ I applied a three-stage analysis to identify a core set of attributes from these data. The first stage – a preliminary analysis – indicated that the 48 study sites represented a broad range of condition, and that the two dry sclerophyll communities could be treated as a single community, which was structurally distinct from the woodland community. In the second stage of the analysis, thirteen core attributes were dentified using the criteria that a core attribute should:¶ 1. Be either, evenly or approximately normally distributed amongst study sites; 2. Distinguish between woodland and dry sclerophyll communities; 3. Function as a surrogate for other attributes; 4. Be efficient to measure in the field. The core attributes were: Vegetation cover <0.5m Vegetation cover 0.5-6.0m; Perennial species richness; Lifeform richness; Stand basal area of live trees; Quadratic mean diameter of live stems; ln(number of regenerating stems per ha+1); ln(number of hollow bearing trees per ha+1);ln(number of dead trees per ha+1);sqrt(number of live stems per ha >40cm dbh); sqrt(total log length per ha); sqrt(total largelog length per ha); Litter dry weight per ha. This analysis also demonstrated that the thirteen core attributes could be modelled as continuous variables, and that these variables were indicative of the scale at which the different attributes operated.¶ In the third and final stage of the analysis, Principal Components Analysis was used to test for redundancy amongst the core attributes. Although this analysis highlighted six groupings, within which attributes were correlated to some degree, these relationships were not considered sufficiently robust to justify reducing the number of core attributes.¶ The thirteen core attributes were combined in a simple additive index, in which, each attribute accounted for 10 points in a total index value of 130. Attributes were rescaled as a score from 0-10, using equations that modelled attribute score as a function of the raw attribute data. This maintained a high correlation (r > 0.97, p< 0.0001) between attribute scores and the original attribute data. Sensitivity analysis indicated that the index was not sensitive to attribute weightings, and on this basis attributes carried equal weight. In this form my index was straightforward to apply, and approximately normally distributed amongst study sites.¶ I demonstrated the practical application of the index in a user-friendly spreadsheet, designed to allow landowners and managers to assess the condition of their vegetation, and to identify management options. This spreadsheet calculated an index score from field data, and then used this score to rank the site relative to a set of reference sites. This added a regional context to the operation of the index, and is a potentially useful tool for identifying sites of high conservation value, or for identifying sites where management actions have maintained vegetation quality. The spreadsheet also incorporated the option of calculating an index score using a subset of attributes, and provided a measure of the uncertainty associated with this score.¶ I compared the proposed index with five prominent indices used to quantify vegetation condition or habitat value in temperate Australian ecosystems. These were: Newsome and Catling’s (1979) Habitat Complexity Score, Watson et al.’s (2001) Habitat Complexity Score, the Site Condition Score component of the Habitat Hectares Index of Parkes et al. (2003), the Vegetation Condition Score component of the Biodiversity Benefits Index of Oliver and Parkes (2003), and the Vegetation Condition Score component of the BioMetric Assessment Tool of Gibbons et al. (2004). I found that my index differentiated between study sites better than each of these indices. However, resource and time constraints precluded the use of a new and independent data set for this testing, so that the superior performance of my index must be interpreted cautiously.¶ As a group, the five indices I tested contained attributes describing compositional diversity, coarse woody debris, regeneration, large trees and hollow trees – these were attributes that I also identified as core ones. However, unlike these indices, I quantified weeds indirectly through their effect on indigenous plant diversity, I included the contribution of non-indigenous species to vegetation cover and did not apply a discount to this contribution, I limited the direct assessment of regeneration to long-lived overstorey species, I used stand basal area as a surrogate for canopy cover, I quantified litter in terms of biomass (dry weight) rather than cover, and I included the additional attributes of quadratic mean diameter and the number of dead trees.¶ I also concluded that Parkes et al. (2003), Oliver and Parkes (2003), and Gibbons et al. (2004), misapplied the concept of benchmarking, by characterising attributes in terms of a benchmark range or average level. This ignored processes that underpin variation at the stand level, such as the increased development of some attributes at particular successional stages, and the fact that attributes can respond differently to disturbance agents. It also produced indices that were not particularly sensitive to the differences in attribute levels occurring between stands. I suggested that a more appropriate application of benchmarking would be at the overarching level of stand structural complexity, using a metric such as the index developed in this thesis. These benchmarks could reflect observed levels of structural complexity in unmodified natural stands at different successional stages, or thresholds for structural complexity at which a wide range of biota are present, and would define useful goals for guiding on-ground management.

An examination was undertaken of the literature and restoration cases for 4 major Australian vegetation types (sclerophyll; rainforest; grassland; and wetland) to explore the proposition that ecological resilience may govern recovery after anthropogenic damage, and/or provide a fundamental guide and measure of success for ecological restoration. Also, primary data were collected from highly degraded sites (5 sclerophyll, 3 rainforest, and 4 grassy sites) to assess recovery after restoration treatment. These were supplemented with questionnaire data from practitioners working at a wider range of rainforest and sclerophyll sites, and reports from practitioners working on grassland and wetland sites. In all 4 vegetation types, species generally fell into two main groups : longer-lived 'resprouters' and shorter-lived 'obligate seeders'. But different resilience models were identified for the 4 vegetation types. The sclerophyll type exhibited higher in situ resilience but lower migratory resilience than the rainforest type, which was facilitated by flying frugivore dispersal to perch trees. Self-perpetuation was more tightly coupled with disturbance in the sclerophyll, grassland and wetland types than rainforest; and therefore 'designed disturbance' played a more obvious role in enhancing recovery within these types, than in rainforest. Results suggest that resilience (as both an ecosystem property and a theoretical concept) is fundamental to the practice of ecological restoration. Some prediction of resilience potential of particular degraded sites (and prediction of the degree and type of restoration subsidy needed) can be based on knowledge of : individual species' recovery mechanisms; resilience models for individual vegetation-types; and the site's colonisation potential and impact history
Doctor of Philosophy (PhD)

Thesis (MSc)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: The Mountain Fynbos biome, a division of the Cape Floristic Region (CFR), is home to round-leafed Buchu [Agathosma betulina (Berg.) Pillans], one of South Africa’s best-known endangered herbal medicinal plants. Agathosma betulina is renowned as a traditional additive to brandy or tea, which is used for the treatment of a myriad of ailments. In its natural habitat, A. betulina thrives on mountain slopes in acid and highly leached gravelly soils, with a low base saturation and low concentrations of organic matter. To adapt to such adverse conditions, these plants have formed mutualistic symbioses with arbuscular mycorrhizal (AM) fungi. In this study, the effect of indigenous AM taxa on the physiology of A. betulina is investigated. In addition, the AM taxa responsible for these physiological responses in the plant were identified using morphological and molecular techniques. Agathosma betulina was grown under glasshouse conditions in its native rhizosphere soil containing a mixed population of AM fungi. Control plants, grown in the absence of AM fungi, were included in the experimentation. In a time-course study, relative growth rate (RGR), phosphorus (P)-uptake, P utilization cost, and carbon (C)-economy of the AM symbiosis were calculated. The data showed that the initial stages of growth were characterized by a progressive increase in AM colonization. This resulted in an enhanced P-uptake in relation to non-AM plants once the symbiosis was established. Consequently, the lower P utilization cost in AM plants indicated that these plants were more efficient in acquiring P than non-AM plants. When colonization levels peaked, AM plants had consistently higher growth respiration. This indicated that the symbiosis was resulting in a C-cost to the host plant, characterized by a lower RGR in AM plants compared to non-AM plants. Arbuscular mycorrhizal colonization decreased with increasing plant age that coincided with a decline in P-uptake and growth respiration, along with increases in RGR to a level equal to non-AM plants. Consequently, the AM benefit was only observed during the initial stages of growth. In order to identify the AM fungi in planta, morphological and molecular techniques were employed, which indicated colonization by AM fungi belonging to the genera Acaulospora and Glomus. Phylogenetic analyses of a dataset containing aligned 5.8S ribosomal RNA gene sequences from all families within the Glomeromycota, including sequences obtained during the study, supported the above mentioned identification.
AFRIKAANSE OPSOMMING: Die Fynbos bergbioom, ‘n onderafdeling van die Kaapse Floristiese Streek, huisves rondeblaar Boegoe [Agathosma betulina (Berg.) Pillans], een van Suid Afrika se bekendste bedreigde medisinale plante. Agathosma betulina is bekend vir sy gebruik as tinktuur vir die behandeling van verskeie kwale. Die plant kom voor in bergagtige streke, in suur en mineraal-arm grond, met ‘n lae organiese inhoud. Gevolglik, om aan te pas by hierdie ongunstige kondisies, vorm die plante simbiotiese assosiasies met blaasagtige, struikvormige mikorrisa (BSM). In die huidige studie is die effek van hierdie BSM op die fisiologie van A. betulina ondersoek. Die identiteit van die BSM is ook gevolglik met morfologiese en molekulêre identifikasie tegnieke bepaal. Agathosma betulina plante is onder glashuis kondisies in hul natuurlike grond gekweek, wat ‘n natuurlike populasie van BSM bevat het. Kontroles is ook in die eksperiment ingesluit en hierdie stel plante is met geen BSM geïnokuleer nie. Gevolglik is die relatiewe groeitempo, fosfor opname, fosfor verbuikerskoste asook die koolstof ekonomie van die plante bereken. Die data het getoon dat die eerste groeifase gekarakteriseer is deur toenames in BSM kolonisasie vlakke. Dit het tot ‘n hoër fosfor opname in BSM geïnokuleerde plante gelei. Die laer fosfor verbuikerskoste gedurende hierdie fase het aangedui dat die plante wat geïnokuleer is met BSM oor beter meganismes beskik het om fosfor uit die grond te bekom. Toe BSM kolonisasie vlakke gepiek het, was groei respirasie hoër in BSM geïnokuleerde plante as in die kontroles. Dit het aangedui dat die BSM kolonisasie van plante tot hoër koolstof kostes vir hierdie plante gelei het, wat weerspieël is in die laer groeitempo van die BSM geïnokuleerde plante. Die BSM kolonisasie vlakke het gedaal met toenemende ouderdom van hul gasheer plante, wat gekarakteriseer is deur ‘n laer opname van fosfor en laer groei respirasie, tesame met ‘n toename in relatiewe groeitempo tot vlakke soortgelyk aan die van die kontrole plante. Die BSM voordele vir die plant is dus net gedurende die eerste groeifase waargeneem. Die BSM wat verantwoordelik is vir hierdie fisiologiese veranderinge is gevolglik geïdentifiseer met behulp van morfologiese en molekulêre tegnieke en dit is gevind dat BSM wat behoort tot die genera Acaulospora en Glomus binne hierdie plante voorkom. Filogenetiese analise gegrond op opgelynde 5.8S ribosomale RNA geen volgordes afkomstig van al die families binne Glomeromycota asook volgordes gevind in die studie, het die bogenoemde identifikasie gestaaf.

Nearly one fifth of Australia’s continent is covered by forests, including 147.4 million hectares of native forest and 2.0 million hectares of forestry plantations. Australia has about 4 percent of the world’s forests on 5 percent of the world’s land area. Prescribed burning has been extensively applied to manage forest fuels in Australia since the 1960s. It greatly decreases the wildfire hazard, promotes forest regeneration and controls insects and disease. Fire modifies both the above-ground vegetation and below-ground microbial community. Despite the significant role of prescribed burning in nitrogen (N) dynamics, most studies have focused only on the responses of one or several forest components (e.g. vegetation, microbial community or soil nutrients) to fire separately. Few studies have offered an in-depth insight into the relationship between soil N cycling processes and associated functional communities in response to long-term prescribed burning. Denitrification is an important part of forest N cycling. It is a stepwise dissimilative reduction process of nitrate (NO3-) to dinitrogen gas (N2) under anaerobic conditions and the primary pathway of nitrous oxide (N2O) emission from soil. This gaseous product has a global warming potential about 298 times greater than that of carbon dioxide (CO2). The potential environmental implication of denitrification to global warming has drawn increasing scientific attention worldwide. A variety of microbial functional groups participate in the denitrification process and each of them can be measured by targeting one or more specific functional genes.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
Full Text

Thesis (PhD (Microbiology))--University of Stellenbosch, 2010.
Dissertation presented for the degree of Doctor of Philosophy in Microbiology at the University of Stellenbosch.
ENGLISH ABSTRACT: The interaction between a soil yeast, Cryptococcus laurentii and a medicinal plant, Agathosma betulina (Berg.) Pillans (Rutaceae), was studied. Cryptococcus laurentii CAB 578 was isolated from the rhizosphere of wild A. betulina and liquid chromatographytandem mass spectrometry analysis revealed that the yeast was capable of producing polyamines such as cadaverine and spermine. Since the exogenous application of polyamines are known to impact on root growth, these findings supported the results obtained when A. betulina seedlings grown under axenic and low nutrient conditions were inoculated with C. laurentii CAB 578 and cultivated for five months under glasshouse conditions. The presence of the yeast increased root growth by 51%. Using soil dilution plates, it was demonstrated that yeast numbers were greater in the vicinity of the roots than in the bulk soil. Furthermore, fluoromicroscopy, in combination with the fluorescent probes Calcofluor White and Fungolight revealed the presence of metabolic active yeast colonies on the rhizoplane. The first part of the study thus provided evidence for a symbiosis between A. betulina and C. laurentii CAB 578. During the second part of the investigation, the effect of this symbiosis on quantitative elemental distribution in A. betulina roots grown under axenic, nutrient-poor conditions was assessed using micro-particle-induced x-ray emission spectrometry. To aid in the interpretation of heterogeneous elemental distribution patterns, apoplastic barriers and endophytic C. laurentii CAB 578 in root tissues were located using fluorescence microscopy and transmission electron microscopy, respectively. The results showed that the average concentrations of iron, manganese and phosphorus were significantly (P < 0.05) higher within roots of yeast-inoculated plants, compared to control plants. It was shown that the yeast was not a root endophyte and that elemental enrichment in the epi/exodermal-outer cortical tissues correlated with the presence of Casparian bands in the exodermal cells of both treatments. This was the first report describing the role of a soil yeast as a plant nutrient-scavenging microsymbiont. In the final part of the investigation, the effect of C. laurentii CAB 578 on the photosynthetic nitrogen, phosphorus and water-use efficiencies, as well as the carbon economy of A. betulina was studied. Agathosma betulina plants inoculated with C. laurentii CAB 578, as well as controls, were grown under axenic conditions and the following parameters measured: Apparent photon yield, foliar nitrogen and phosphorus concentrations, leaf dark respiration, maximum photosynthetic rate, photosynthetic nitrogen-use efficiency, photosynthetic phosphorus-use efficiency, photosynthetic wateruse efficiency, root construction cost, stomatal conductance, substomatal CO2 and transpiration rate. The data showed that the higher photosynthetic resource-use efficiencies in yeast-inoculated plants were a consequence of higher maximum rates of CO2 assimilation, which was not related to foliar nitrogen and phosphorus content. We hypothesize that photosynthetic stimulation in yeast-inoculated plants was a result of the increased demand for photosynthates of the yeast-root symbiosis. In summary, the study revealed that a symbiosis exists between A. betulina and the soil yeast C. laurentii CAB 578. This interaction has a significant effect on the size of the yeast population as well as on the physiology of the plant.
AFRIKAANSE OPSOMMING: Die interaksie tussen ‘n grondgis, Cryptococcus laurentii, en ‘n medisinale plant, Agathosma betulina (Berg.) Pillans, is ondersoek. Cryptococcus laurentii CAB 578 is vanuit die risosfeer van A. betulina in sy natuurlike omgewing geisoleer en vloeistof chromatografie tandem massa spektrofotometriese analise het bewys dat die gis poliamiene insluitend kadaverien en spermien produseer. Dit is bevind dat die eksogene aanwending van poli-amiene wortelgroei bevorder. Hierdie bevinding staaf die waargenome 51% verhoging in wortelgroei van mikroob-vrye A. betulina saailinge geinokuleer met C. laurentii CAB 578 en gekweek vir vyf maande onder lae nutriënt kondisies in ‘n glashuis. Met gebruik van die grond verdunningsplaat-metode, is dit verder bewys dat gisgetalle hoër was in die teenwoordigheid van wortels as in die omliggende grond. Dit is ook bewys met die gebruik van die fluoressente peilers Calcofluor White en Fungolight, in kombinasie met fluoressensie-mikroskopie, dat metabolies aktiewe giste die wortels se oppervlak gekoloniseer het. Die eerste deel van die studie het dus bewys dat ‘n simbiose tussen A. betulina en C. laurentii CAB 578 bestaan. Tydens die tweede deel van die ondersoek is die effek van C. laurentii CAB 578 op die konsentrasie en verspreiding van elemente binne A. betulina wortels, gekweek onder lae-nutriënt, mikroob-vrye kondisies, bepaal met behulp van mikro-partikel geinduseerde X-straal emissie spektrofotometrie. Om die interpretasie van heterogene verspreidingspatrone van die onderskeie elemente te ondersteun, is daar met behulp van fluoressensie en transmissie-elektron-mikroskopie vir apoplastiese versperrings en endofitiese C. laurentii CAB 578 in die wortelweefsel getoets. Dit is bevind dat die gemiddelde konsentrasie van fosfaat, mangaan en yster beduidend (P < 0.05) hoër was in gis-geinokuleerde plante, as in kontrole plante. Die gis was nie ‘n wortel endofiet nie en elementale verryking in die epi/eksodermale-buitenste korteks weefsels het gekorreleer met Casparian bande in die eksodermale selle van beide behandelings. Hierdie was die eerste verslag wat die rol van ‘n grondgis as ‘n nutriënt-bekommende mikrosimbiont vir plante beskryf het. In die laaste gedeelte van hierdie ondersoek is die effek van C. laurentii CAB 578 op die fotosintetiese fosfaat, stikstof en water-verbruiksdoeltreffendheid, asook die koolstof ekonomie in mikroob-vrye Agathosma betulina plante geinokuleer met C. laurentii CAB 578 asook kontrole plante bestudeer. Die volgende parameters is getoets: Blaar donker respirasie, blaar fosfaat en stikstof konsentrasies, fotosintetiese fosfaatverbruiksdoeltreffendheid, fotosintetiese stikstof-verbruiksdoeltreffendheid, fotosintetiese water-verbruiksdoeltreffendheid, huidmond konduktansie, huidmond CO2 konsentrasie, klaarblyklike foton opbrengs, maksimum fotosintetiese spoed, wortel konstruksie-koste, en transpirasie spoed. Die resultate het getoon dat die hoër maksimum fotosintestiese spoed in gis-geinokuleerde plante gelei het tot ‘n hoër fotosintetiese verbruiksdoeltreffendheid van fosfaat, stikstof en water en dat dit nie verband gehou het met blaar fosfaat en stikstof konsentrasies nie. Dit word voorgestel dat die stimulasie van fotosintese in gisgeinokuleerde plante ‘n gevolg is van die verhoogde aanvraag na fotosintaat deur die giswortel simbiose. Om op te som, die bevindings van hierdie studie het bewys dat ‘n simbiose tussen A. betulina en C. laurentii CAB 578 bestaan. Hierdie simbiose het ‘n beduidende effek op die populasie grootte van die gis sowel as die fisiologie van die plant.

1st Topographical Survey Squadron, Royal Australian Engineers, provides deployable geospatial support to the Australian Defence Force. Part of this role is the production of products for use by commanders. These products provide commanders at all levels with mission specific and up to date knowledge of the terrain that he will encounter on the battlespace. Currently 1st Topographical Survey Squadron provides products that contain manmade features, hydrography, slope, surface configuration and vegetation as displayed on current mapping products. They do not provide an accurate portrayal of the effect that vegetation characteristics have on the battlespace. Introducing these types of features will give the commander a greater knowledge of the terrain and environment that he will encounter, and will greatly improve the planning and success of the campaign. This research explored to what extent the accuracy of the terrain analysis products currently produced by 1st Topographical Survey Squadron would increase by adding a more detailed portrayal of vegetation extracted from remote sensing data.

1st Topographical Survey Squadron, Royal Australian Engineers, provides deployable geospatial support to the Australian Defence Force. Part of this role is the production of products for use by commanders. These products provide commanders at all levels with mission specific and up to date knowledge of the terrain that he will encounter on the battlespace. Currently 1st Topographical Survey Squadron provides products that contain manmade features, hydrography, slope, surface configuration and vegetation as displayed on current mapping products. They do not provide an accurate portrayal of the effect that vegetation characteristics have on the battlespace. Introducing these types of features will give the commander a greater knowledge of the terrain and environment that he will encounter, and will greatly improve the planning and success of the campaign. This research explored to what extent the accuracy of the terrain analysis products currently produced by 1st Topographical Survey Squadron would increase by adding a more detailed portrayal of vegetation extracted from remote sensing data.

The Hunter Region, between the Hawkesbury and Manning rivers in eastern New South Wales, hosts a rich diversity of vegetation, with many species found nowhere else. Spanning an area from the coast to the tablelands and slopes, its rainforests, wet and dry sclerophyll forests, woodlands, heathlands, grasslands and swamps are known for their beauty and ecological significance. Flora of the Hunter Region describes 54 endemic trees and large shrubs, combining art and science in a manner rarely seen in botanical identification guides. Species accounts provide information on distribution, habitat, flowering, key diagnostic features and conservation status, along with complete taxonomic descriptions. Each account includes stunning botanical illustrations produced by graduates of the University of Newcastle's Bachelor of Natural History Illustration program. The illustrations depict key diagnostic features and allow complete identification of each species. This publication will be a valuable resource for those interested in the plants of the region, including researchers, environmental consultants, horticulturalists and gardeners, bush walkers, herbaria, and others involved in land management.