No description available.

This thesis describes a series of laboratory and field experiments that quantify the population dynamics of the heather beetle (Lochmaea suturalis Thomson), in relation to temperature and its host plant heather (Calluna vulgaris (L. ) Hull). The sex ratio, fecundity, egg laying threshold temperature, emergence threshold temperature, life stage development periods, and life stage mortalities were investigated. It was shown that the life stages were significantly dependent on temperature, whilst it was shown that there was no significant relationship between larval growth and Calluna vulgaris plants sourced from the study sites. The results of the population dynamics experiments were incorporated into a temperature driven, cohort based, and daily looped, stochastic population dynamics computer model. The temperature component of the model was derived from temperature data collected from nine moorland sites, at different altitudes, where there was shown to be a significant relationship between temperature and altitude. The population dynamics model was run for a fifty year period with a population of I million beetles at seven temperature regimes and five different altitudes. The model predicted that as daily mean temperatures rose, so there was a greater chance of increasing populations and that as altitude increases, so the chance of increasing populations decreases. At a predicted daily mean temperature rise of 2-3'C there was evidence of considerable population increases at lower altitudes, and with a daily mean temperature rise of 4-6'C the beetle population exhibited persistent, large, fluctuating populations in the region of three to sixty fold increases at all modelled altitudes over a number of years. An uncertainty and sensitivity analysis of the model was undertaken utilising a Latin Hypercube Swnpling regime, where it was shown that fecundity, egg mortality and pupal mortality were the most important life history variables in i contributing to the model output imprecision. The thesis discussesth eser esults in the light of predicted climate change and their use as an aid to moorland and heathland managers.

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No description available.

Thesis, M.Sc.--University of Adelaide.

During the late 19th and early 20th centuries, extensive logging reduced the forests of red spruce (Picea rubens) by nearly 99% through portions of West Virginia. In the wake of this disturbance, red spruce has begun regenerating on the ridge and mountaintop areas of Canaan Valley, West Virginia, where heath and grassland communities have both persisted in natural barrens and expanded into formerly forested areas. To understand abiotic and biotic conditions guiding the advance of the red spruce stand, I conducted a broad-scale assessment of thirty-one demographics plots spread across two sites (north Cabin Mountain and Bear Rocks/Dolly Sods), and a more focused assessment of red spruce species associations within thirty-two paired plots at Cabin Mountain. At the 15m x 15m demographics plots, I conducted a count of all P. rubens present, measured specimen height, DBH or diameter at ground level (DGL) for specimens < 1.37m tall, and assessed the relative percent cover of rock, shrub, herbaceous, and tree cover. These data, along with additional abiotic components derived from a DEM, formed the basis of my assessment using a generalized linear mixed model (GLMM) to identify the most significant biophysical variables related to P. rubens count. In the paired plots, I used the relative interactions index (RII) to compare the total cover of each present non-graminoid vascular species and the grouped cover types Rock, Graminoid, Lichen, Litter, and Moss in one 45cm-radius plot with a < 1.37m P. rubens specimen, and one paired 45cm-radius plot in open heath. The significance of differences in total cover were assessed with the Wilcoxon test and Tukey HSD. The GLMM identified percent rock cover and distance from the nearest P. rubens stand to be important correlates of P. rubens count at the demographic plots. Graminoid cover was found to be higher in P. rubens 45cm-radius plots than in paired heath plots, and Vaccinium angustifolium cover was found to be concentrated in 45cm radius plots beyond the first 15cm from the P. rubens stem. These findings reinforce a complex interplay between both the biotic and abiotic characteristics of a microsite and the successful germination and regeneration of a red spruce seedling in the heathland. / Master of Science / During the late 19th and early 20th centuries, extensive logging reduced the forests of red spruce (Picea rubens) by nearly 99% through portions of West Virginia. In the wake of this disturbance, red spruce has begun regenerating on the ridge and mountaintop areas of Canaan Valley, West Virginia, where heath and grassland communities have both persisted in natural barrens and expanded into formerly forested areas. To understand the necessary abiotic and biotic conditions guiding the advance of the red spruce stand, I conducted a broad-scale assessment of thirty-one demographics plots spread across two sites (north Cabin Mountain and Bear Rocks/Dolly Sods), and a more focused assessment of red spruce species associations within thirty-two paired plots at Cabin Mountain. At the 15m x 15m demographics plots, I measured and counted all red spruce present. I collected landscape and community data on each plot using field surveys and a digital elevation model (DEM) to the variables most associated with a higher count of red spruce in each plot. In the 45cm-radius paired plots, I used simple mathematical comparisons to identify positive and negative interactions between red spruce shorter than breast height (1.37m) and different types of cover, including heathland species such as Vaccinium angustifolium (lowbush blueberry), rock, graminoid, and moss. Modeling indicated that rock cover, and distance between the plot and the nearest stand of red spruce, were found to be the most significant variable affecting the count of red spruce at each plot, with increased rock cover and shorter stand distance both associated with higher numbers of spruce. In the paired plots, there was slightly higher graminoid cover associated with the tree than with the open heath plot, and V. angustifolium was more concentrated beyond 15cm from each red spruce specimen. These findings suggest that rock cover is important for tree regeneration both the biotic and abiotic characteristics of a microsite and the successful germination and regeneration of a tree seedling in heathlands.

of the thesis Heathlands are an unique semi-natural element of European landscape, which historically evolved under continuous man land-use pressure. In conditions of our country, this biotope is relatively rare in occurrence and small in area. In the former military training zone Brdy, Protected landscape area nowadays, there are heathlands of great extent developed due to deforestration and history of fires and mechanical disturbances of the soil surface and vegetation, which used to accompany military trainings. After the termination of military use of the locality, there is a risk of gradual degradation of the biotope caused by tree encroachment, litter accumulation which inhibits generative regeneration of the heath, and degeneration of the heath itself. This thesis aism to entangle influence of the fire on the heathland vegetation in the area with special attention given to vitality and structure of heath stands. The fieldwork was focused on the dynamics and species composition of the vegetation, including bryophytes and lichens, separately on the long-term scale (up to 80 years) and the short-term scale (permanent plots in the recently burnt vegetation). Experimental part of the thesis tested germination of the seeds from Brdy area under the conditions of fire and with presence of different...

The vegetation of the Sydney Basin, Australia, is highly flammable and subject to a wide range of fire regimes. Sclerophyllous shrubs and sedges are common and in some vegetation types up to 70 % of fuel consumed during a fire can be live. Research into fire behaviour and fuel dynamics has been minimal. To address this issue this thesis investigated the principal factor affecting the ease of ignition and rate of combustion of individual fuel particles and fuel beds in bushfires: dead fine fuel moisture (FFM). Two common Sydney Basin vegetation types, eucalypt woodland and heathland, each with a history of problematic fire management, were measured in the field for diurnal fluctuations in FFM following rain, under conditions similar to when prescribed burns are conducted. The FFM components of current operational fire behaviour models were found to be inadequate for predictions of FFM and fire behaviour under these conditions. The equilibrium moisture content (EMC) of five fuel types from the field site was investigated in a laboratory study. An existing function describing EMC as a function of temperature and relative humidity was evaluated and found to be very accurate for these fuels. Two FFM predictive models incorporating this function were evaluated on the field data and the laboratory results were shown to be applicable to the estimation of FFM in the field. One model gave very accurate predictions of FFM below fibre saturation point, but its accuracy was reduced when screen level conditions were used instead of those measured at fuel level. A recent process-based model that accounts for rainfall showed promise for predicting when fuel is < 25 % FFM. Systematic problems with the radiation budget of this model reduced the accuracy of predictions and further refinement is required. Live fine fuel moisture content (LFMC) of common heathland shrubs and sedge was investigated over two years and found to be both seasonal and influenced by phenology. LFMC minima occurred in late winter and spring (August to October), and maxima were in summer (December to February) when new growth was recorded. The dominant near-surface fuel in mature heath was sedge. It was found to have little seasonal variation in its??? percentage dead but the percentage dead maxima occured at the same time as the LFMC minima of shrubs and sedge in both years. Simple instantaneous models for duff moisture content in woodland and heathland and LFMC and the percentage dead sedge in heathland were developed. The information gained by this study will form the basis for future development of fuel moisture models for prescribed burning guidelines and fire spread models specific to the vegetation communities of the Sydney Basin.

The vegetation of the Sydney Basin, Australia, is highly flammable and subject to a wide range of fire regimes. Sclerophyllous shrubs and sedges are common and in some vegetation types up to 70 % of fuel consumed during a fire can be live. Research into fire behaviour and fuel dynamics has been minimal. To address this issue this thesis investigated the principal factor affecting the ease of ignition and rate of combustion of individual fuel particles and fuel beds in bushfires: dead fine fuel moisture (FFM). Two common Sydney Basin vegetation types, eucalypt woodland and heathland, each with a history of problematic fire management, were measured in the field for diurnal fluctuations in FFM following rain, under conditions similar to when prescribed burns are conducted. The FFM components of current operational fire behaviour models were found to be inadequate for predictions of FFM and fire behaviour under these conditions. The equilibrium moisture content (EMC) of five fuel types from the field site was investigated in a laboratory study. An existing function describing EMC as a function of temperature and relative humidity was evaluated and found to be very accurate for these fuels. Two FFM predictive models incorporating this function were evaluated on the field data and the laboratory results were shown to be applicable to the estimation of FFM in the field. One model gave very accurate predictions of FFM below fibre saturation point, but its accuracy was reduced when screen level conditions were used instead of those measured at fuel level. A recent process-based model that accounts for rainfall showed promise for predicting when fuel is < 25 % FFM. Systematic problems with the radiation budget of this model reduced the accuracy of predictions and further refinement is required. Live fine fuel moisture content (LFMC) of common heathland shrubs and sedge was investigated over two years and found to be both seasonal and influenced by phenology. LFMC minima occurred in late winter and spring (August to October), and maxima were in summer (December to February) when new growth was recorded. The dominant near-surface fuel in mature heath was sedge. It was found to have little seasonal variation in its??? percentage dead but the percentage dead maxima occured at the same time as the LFMC minima of shrubs and sedge in both years. Simple instantaneous models for duff moisture content in woodland and heathland and LFMC and the percentage dead sedge in heathland were developed. The information gained by this study will form the basis for future development of fuel moisture models for prescribed burning guidelines and fire spread models specific to the vegetation communities of the Sydney Basin.

No description available.