Survey and Reclamation of Saline/Alkaline Scalds in the Uralla/Walcha district of Northern New South Wales

This research project was initiated by the Harhnam and Bozo landcare groups in response to concerns expressed by landholders on the Northern Tablelands of New South Wales about the apparent increase in saline/alkaline scalds in the early 1990s. The aim was to investigate the extent and severity of bare scalds with a view to testing different methods of making them productive again. The project was initiated in 1992 and funded under the National Landcare Program (NLP) program, formerly the National Soil Conservation Program (NSCP). The project concentrated on the districts of Uralla, Wollun and Walcha, an area of approximately 30000 hectares. Two surveys (landholder and field surveys) were carried out initially to gauge the extent of the problem within the study area. A total of 82 saline/alkaline sites were located from the landholder survey, and more detailed information collected from 50 of these in field surveys. The surveys indicated a wide variety of characteristics among the scalds and the general pattern appeared different from the pattern of salinity described for Western Australia and Victoria. Twenty experimental sites were then chosen based on similar site characteristics such as position in the landscape, slope, site characteristics and vegetation and five replications of a control and 4 treatments consisting of ponding, reverse interception drains and the application of gypsum and epsomite were set up. The gypsum and epsomite were applied inside steel rings at the same sites ... This study provides some basic information to assist landholders in the choice of specific treatments for saline/alkaline scalds. Each scald requires its own evaluation of the problems at that site and the best treatment to adopt should be based on the individual scald

Aspects of the Dynamics of Rainforests in North-East Australia

The aims of this study were to show that the structural and floristic features of some tropical rainforests in north-east Australia appear to be largely the result of characteristics of the individual plant species available at each site and the history and nature of disturbance at that site. ... Field observations indicated that gaps created by the death of a canopy level or larger tree were important in rainforest regenerative processes. The role of gaps was more closely examined using a theoretical model and field and glasshouse experiments. ... From a forest management viewpoint, studies of processes associated with regeneration in gaps suggested that there might be important limitations to the maximum growth rates which can be achieved by the restricted silvicultural modification of tropical rainforests. Nevertheless, the development of improved techniques for managing these forests is essential. This goal might be best achieved by continuing to develop an understanding of rainforest dynamics through studies of the regeneration, growth and mortality characteristics of their component species

Eucalypt Re-establishment on the Northern Tablelands of New South Wales

In the 1970s hundreds of thousands, if not millions, of native eucalypt trees died on the Northern Tablelands of New South Wales in a syndrome which came to be called 'New England Dieback'. The magnitude of dieback and a recognition of the value of trees on farms led to a desire by many people for information about eucalypt establishment and it is this desire which sparked the commencement of this project in 1982. The overall aim has been to better understand the mechanisms by which eucalypts common on grazing properties of the Northern Tablelands of N.S.W. regenerate naturally and to use this information to design eucalypt re-establishment strategies for areas affected by tree decline. Emphasis has been placed on: • Flowering and seedfall cycles (phenology) of local native eucalypts of the Northern Tablelands; • Conditions which favour seedling establishment and growth; • Techniques for re-establishment or regeneration of eucalypts on land which has been grazed or cropped in the past. Understanding the nature of eucalypt regeneration and reproductive behaviour is vital if we wish to preserve and re-establish native trees on rural land. This study, therefore is an attempt to increase our knowledge of the mechanisms involved in the maintenance of populations of woodland eucalypts and to provide some techniques for their re-establishment where the numbers of trees have been seriously depleted in the past. Understanding the nature of eucalypt regeneration and reproductive behaviour is vital if we wish to preserve and re-establish native trees on rural land. This study, therefore is an attempt to increase our knowledge of the mechanisms involved in the maintenance of populations of woodland eucalypts and to provide some techniques for their re-establishment where the numbers of trees have been seriously depleted in the past

Reducing seed production using late post-emergence applications of selective herbicides to manage wild oat ('Avena' spp.) populations

'Avena' spp. (wild oats) continue to persist as a major weed of winter cereal crops as most control strategies fail to contain wild oat populations. From a review of literature it was concluded that the primary mechanism for wild oat persistence in Australia was associated with in-crop seed production, not seed dormancy as appeared to be the case for most northern hemisphere wheat growing countries. Late germination and recruitment of wild oat seedlings and incomplete kill of wild oat plants were likely causes of survival and subsequent seed production. It was also concluded from a review of literature that two herbicides, flamprop (and its various analogues of flamprop) and fenoxaprop-p-ethyl, exhibit potential to selectively reduce wild oat seed production if applied late post-emergence in wheat or barley. Time of application appears to be an important factor affecting efficacy of these herbicides

Patterns and Processes in Population Divergence of 'Microlaena stipoides' (Labill.) R. Br.

The distribution of 'Microlaena stipoides' (Labill.) R. Br. on the Northern Tablelands of New South Wales was examined by surveying 101 paddocks on 33 commercial properties. Greater abundance of 'M. stipoides' was observed on the eastern side and the southern half of the Northern Tablelands where rainfall and altitude were higher. Pasture management correlates that were significantly associated with abundant 'M. stipoides' were high tree density, minimum soil disturbance and long period since last cultivation. Greater abundance of 'M. stipoides' was observed in paddocks containing other year-long green perennials, cool season annuals and exotic sown species in addition to warm season perennials and annuals. 'Microlaena stipoides' grew well in association with other perennial grasses found in permanent pastures, such as 'Lolium perenne', 'Damlis glomerata', 'Poa pratensis' and 'Phalaris aquatica', which may indicate the permanency of these species associations

Direct measurement of moisture ingress in PV laminates

This work demonstrates a novel method for the measurement of moisture ingress into PV laminates, by the use of humidity indicator cards encapsulated within the structure. The humidity indicator cards change colour due to moisture exposure, which is quantified by processing images of the samples taken with a camera. To allow the variance of colour to be matched to specific levels of humidity, a detailed calibration was first performed. To achieve this, laminates with the structure [EVA-humidity indicator card-EVA-glass] were stabilised in an environmental chamber at 85ºC at increasing levels of relative humidity. The colour change of the humidity indicator cards corresponding to the relative humidity inside the chamber was then plotted on RGB colour space diagrams. The purpose of this work is the development of a measurement method for the moisture that accumulates at the front side of PV cells, for the experimental verification of simulations of the moisture ingress into PV modules and the better understanding of degradation modes related to corrosion

Plant Strategies in Herbaceous Vegetation in Relation to Soil Disturbance, Fertilization and Sowing on the Northern Tablelands of NSW

This study examined whether the response of herbaceous vegetation to environmental disturbances such as mechanical soil disturbance and fertilization can be predicted from a knowledge of the component species' plant attributes. Some aspects of Grime's (1979) C-S-R model were also tested. The model proposed that the three permutations of low stress and low disturbance, low stress and high disturbance, and high stress and low disturbance are associated with competitive (C), ruderal (R) and stress-tolerant (S) plant strategies, respectively. A completely randomised block experiment with three factors, soil disturbance, fertilization and sowing, was established in an area of moderately grazed temperate grassland on the Northern Tablelands of New South Wales. The site was dominated by the tall, warm season perennial grasses, 'Aristida ramosa' and 'A. warburgii' and its yellow podzolic soil was deficient in phosphorus, nitrogen and sulphur. The study area experiences an annual average rainfall of 914 mm, an annual average maximum temperature of 20.3°C and an annual average minimum temperature of 7.3°C. There were three levels of soil disturbance (none, hand-hoed and rotary-hoed), two levels of fertilization (none and fertilized NPS) and two levels of sowing (none and sown). The sown treatment consisted of hand-sowing the propagules of seven exotic species into the plots. During the experimental period (August 1992 -February 1994), the sown treatment was applied once in August 1992, disturbance was applied annually in August, fertilizer was applied twice a year and the vegetation was sampled in spring (November) and summer (March/February) each year. ... In conclusion, the response of herbaceous vegetation to mechanical soil disturbance and fertilization could be predicted from a knowledge of the component species' plant attributes. Plant attributes relating to plant persistence, biomass partitioning (leaves vs reproduction vs storage), and use of resources (conservative versus liberal) were strongly related to fertilization and soil disturbance. Plant attributes can discriminate between habitats as well as, or better than, floristic data. On a community scale, the influence of historical factors on vegetation response was not removed by the plant attribute approach, although it was somewhat reduced. Thus, the relationships found using this approach were of intermediate generality and are applicable to sites with a similar fertilizer and disturbance history. The greatest support for the C-S-R model was found using the key (4 predictions upheld, 1 inconsistent and 2 rejected). Support for the model was also found by testing its underlying hypotheses (2 predictions upheld, 2 inconsistent and 2 rejected), while the ordination of vegetation samples by the mean Rmax and MI of its component species was unsuccessful (0 predictions upheld, 2 inconsistent and 3 rejected). The present study shows how vegetation models may be viewed as a starting point for research and refinement rather than something that must be either wholly accepted or rejected

Ecology of 'Phyla canescens' (Verbenaceae) in Australia

'Phyla canescens' has invaded large areas of wetland and grassland on floodplains in Australia, particularly the Murray Darling Basin, where 'P. canescens' threatens the sustainability of internationally significant wetlands and the viability of grazing enterprises. The species was introduced into Australia from South America, where it is a common and widespread species of floodplains and waterways, particularly in areas subject to constant grazing, or otherwise continuously disturbed. It has been promoted in Australia and elsewhere as a hardy groundcover for its perceived aesthetic and soil conservation values. 'Phyla canescens' continues to be sold in the horticulture industry, invariably labelled "Phyla nodiflora"; a closely related species with which it is frequently confused. Both species are generally associated with waterways and floodplains and share a prostrate habit, with adventitious roots developing at each node along the numerous, intertwining stolons. Both species form dense mats to the exclusion of other vegetation. While 'P. canescens' has typically smaller features and inhabits more southerly, inland areas with heavy clay soils, the coarser "P. nodiflora" is more common in northern, coastal regions with sandy soils. The general lack of quantitative information on fundamental aspects of the life-history of 'P. canescens' is a substantial impediment to the development of sustainable and ecologically sound management protocols for this species, including biological control, and the communities which it invades. Experiments were devised to help address this information gap, the results of which are presented in this thesis