This thesis explores issues relating to the application of physiological-process models (???process models???) of forest growth to mixed species, mixed age forests, in particular the coastal blackbutt forests of New South Wales. Using a dataset provided by State Forests of New South Wales (Carter 1994 unpubl.) a numeric description of the forest was developed and stand-level parameters of interest were derived, in particular the plot by plot stemwood volume growth from 1975 to 1999. The amounts of harvested volume, volume that died and volume that grew into the measurement population were identified separately, and several different means of accounting for volume change over time were investigated. A method for quantifying the impact of harvesting and other silvicultural practices on the growth of the forest was developed and programs were written to convert the stand-level summary of the harvest impact into a semi-random selection of trees that would be ???harvested??? from the database under the set of silvicultural assumptions (Dore et al. 1999). A number of process models were investigated and reviewed before selecting one particular model, SUSTAIN (Dewar 1997) for adaption to these forests. This model is a relatively simple process model with a small number of input parameters. The model was adapted so that it could be used to compare the SUSTAIN estimate of growth with the growth of an individual stand of trees in the Kendall Forest Management Area, between Wauchope and Taree on the mid-north coast of NSW. To improve the accuracy of the prediction of growth by SUSTAIN, a method of re-setting the state of the stand to the actual condition at the time of remeasurement was developed. In addition, the SUSTAIN model was extended to enable two separate levels of canopy to be described and grown separately. Ultimately the model was only partially successful in mirroring the growth predicted by the empirical data. Its partial success is attributed primarily to the difficulties associated with correctly determining the allocation parameters used by the model to assign net photosynthate to the roots, foliage and stemwood. The nature of the change in allocation parameters when the forest stand is disturbed by harvest or fire needs further investigation.

The potential of airborne LiDAR technology to quantify forest structure within eucalypt forests has been evaluated with a focus on the understorey stratum. To achieve this, three studies have been undertaken using multiple (4) LiDAR datasets acquired over three test areas located in Wedding Bells State Forest, Coffs Harbour, Australia. Initially, the effects of sensor configuration were evaluated using field measurements collected from three structurally and topographically differing field plots (40 x 90 m areas). Results indicated that canopy height profiles derived from LiDAR data at the plot scale were largely unaffected by a change in platform altitude from 1000 to 3000 m (p &gt 0.05). In addition, the derivation of individual tree attributes was found to be highly sensitive to the density of LiDAR observations whilst higher platform altitudes showed an increased proportion of single returns over forested areas. In the second study, an innovative field based approach was developed to sample the structure of the understorey (horizontally and vertically) for LiDAR validation purposes. Using two separate LiDAR datasets, this research confirmed that mean understorey height and understorey cover can be effectively mapped in areas of low to medium canopy cover whilst no significant relationship (p &gt 0.05) was identified between field and LiDAR estimates of maximum understorey height. In the third study, an optimised LiDAR beam interception model was developed and validated, and then applied to assess the interaction of extrinsic and intrinsic factors of the LiDAR survey. This demonstrated that the probability of beam interception through the forest canopy can be affected by factors both intrinsic (e.g. crown cover) and extrinsic (e.g. scan angle) to the structure of the canopy. Overall, the results of this research indicate that optimising the sensor configuration is important to the derivation of particular forest structural attributes and significantly, there is potential for LiDAR technology to provide quantitative and spatially detailed estimates of key understorey attributes such as mean height and cover.

Lead has a more than three-millennia-long pollution history in Europe. Metal production, burning of coal and use of leaded petrol resulted in a significant pollution of the atmosphere. As a consequence of atmospheric fallout, the Swedish boreal forest is strongly contaminated by airborne lead pollution. High levels of lead in the soil and soil pore water are of concern because the soil fauna, plants and aquatic biota may respond negatively to this toxic element. The fate of the accumulated pool of pollution in the soil is not well known. In this thesis, I determine four variables of importance for increasing our knowledge about the past, present and future lead levels in the boreal forest soil: 1) the pre-pollution atmospheric deposition rate of lead; 2) the upward flux of lead from deeper soil layers to near-surface horizons as a result of plant uptake; 3) the mean residence time of lead in the mor layer (the organic horizon at the surface of forest soils); and 4) the vertical and lateral transport of pollution lead within the mineral soil and to streams. Lead concentration measurements and stable lead isotope analyses were used for distinguishing pollution lead from natural lead in cores from ombrotrophic bogs, forest soil profiles, forest mosses, soil-water and stream-water samples. The results clearly stress that the boreal forest ecosystem is totally dominated by pollution lead. This is proved by low 206Pb/207Pb ratios (mainly between 1.14 and 1.20) in the mor layer, forest plants and stream water, while the local geogenic lead of the mineral soil (C-horizon) has high ratios (> 1.30). The dominance of pollution in the mor layer is caused by high deposition rates of airborne lead pollution, minute transport rates of lead from the mineral soil by forest plants (about 0.02 mg lead m-2 year-1) and a long mean residence time of the deposited lead (~250 years for mature forest). In the pristine pre-pollution environment, lead was a rare element due to low atmospheric deposition rates (0.001 to 0.01 mg m-2 year-1). It is estimated that the present lead inventory in the mor layer is up to 100 times higher than in the pristine environment where ≤ 8 mg m-2 was present in the mor. The levels in this biologically important horizon will decrease at a very slow rate and it will take centuries for the deeper part of the mor layer to fully respond to decreasing atmospheric inputs. In a hypothetic scenario with a ceased atmospheric lead deposition, the pool of pollution lead will ultimately be redistributed to deeper water-saturated soil layers from where a lateral transport to surface waters occurs. In the studied catchment, the export of pollution lead from the soil to the stream is estimated to peak slightly about one thousand years from now.

Thesis (M. Sc.)--York University, 2002. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 155-164). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ71590.

This research focused on the secondary succession of spring flora occurring within pits of windthrows located in the area described as Ginn/ Nixon Woods, an old growth beech-maple forest community that transitions to a mixed mesophytic forest community, approximately 12 miles north of Muncie, IN. More specifically, this research sought to identify the vegetative production capacities of pits as well as determine the extent to which pit microtopography and light influx affect the production of spring flora.In all sixty plots were established--30 test plots within the confines of windthrow pits, and 30 control plots, each one just six feet away from a test plot on undisturbed forest soil. One sampling period occurred in 1993 (just prior to leafing); four sampling periods occurred in 1994 (two prior to leafing and two after leafing). Species presence, density and cover data were used to produce two-dimensional ordinations for examination. Species presence, plot depth, slope, and light data were subjected to the Spearman Rank Order Correlation Test to determine the extent of influence pit microtopography and light influx have on spring flora.Examination of the data clearly showed that disturbed areas known as windthrow pits experience a significant decline in vegetative production--at least for a few years but likely for many years, after the initial disturbance or windthrow occurs. The data also clearly showed that over time windthrow pits eventually recover vegetative production.The recovery of vegetative production in pits was shown to have a positive correlation with plot depth; that is to say, as pit depth decreases, vegetative diversity increases. Standing water in pits, though not recorded statistically, was observed in the field as having a strong negative impact on vegetative recovery. Consequently, the environmental factors that work together to affect the topographical recovery of the pit to an elevation equal to or greater than the surrounding forest floor were found to be critical in the vegetative recovery of pits. This researcher has appropriately termed this recovery process as "elevation equilibrium," since the end result is a pit whose topographical relief has given way to a relatively static elevation equal to adjacent undisturbed areas of the forest floor.Unlike plot depth, the amount of slope in pits did not seem to play a significant role in reducing or encouraging vegetative recovery. Likewise the amount of shade cast on pits prior to leafing, and the size and/or presence of gaps in the canopy after leafing, appeared to have little influence on the recovery of spring flora. When plant diversity data for each test plot was correlated with its slope, pre-leafing light influx and post-leafinglight influx data using the Spearman Rank Order Correlation test, it found no significant relationships between any of the sets of variables. / Department of Natural Resources and Environmental Management

"The pre-settlement distribution and character of Wimmera Buloke woodlands are described based on historical data including early parish plans. It is suggested the open structure of these woodlands was maintained by relatively frequent fire. The floristic composition of the most intact Wimmera Buloke woodland remnants was intensively surveyed. Five floristic communities are described based on computer-based analysis of species presence data. Eight 'pre-settlement Buloke woodland types' are described based on surface soil texture categories and average annual rainfall zones. Native daisies, chenopods and shrubs are components of the understory that differentiate the 'pre-settlement Buloke woodland types'. [...] A series of experiments was undertaken with the aim of determinig the factors responsible for the paucity of Allocasuarina luehmannii regeneration in remnant Wimmera bushland." / Master of Applied Science

"The pre-settlement distribution and character of Wimmera Buloke woodlands are described based on historical data including early parish plans. It is suggested the open structure of these woodlands was maintained by relatively frequent fire. The floristic composition of the most intact Wimmera Buloke woodland remnants was intensively surveyed. Five floristic communities are described based on computer-based analysis of species presence data. Eight 'pre-settlement Buloke woodland types' are described based on surface soil texture categories and average annual rainfall zones. Native daisies, chenopods and shrubs are components of the understory that differentiate the 'pre-settlement Buloke woodland types'. [...] A series of experiments was undertaken with the aim of determinig the factors responsible for the paucity of Allocasuarina luehmannii regeneration in remnant Wimmera bushland." / Master of Applied Science

This thesis explores issues relating to the application of physiological-process models (???process models???) of forest growth to mixed species, mixed age forests, in particular the coastal blackbutt forests of New South Wales. Using a dataset provided by State Forests of New South Wales (Carter 1994 unpubl.) a numeric description of the forest was developed and stand-level parameters of interest were derived, in particular the plot by plot stemwood volume growth from 1975 to 1999. The amounts of harvested volume, volume that died and volume that grew into the measurement population were identified separately, and several different means of accounting for volume change over time were investigated. A method for quantifying the impact of harvesting and other silvicultural practices on the growth of the forest was developed and programs were written to convert the stand-level summary of the harvest impact into a semi-random selection of trees that would be ???harvested??? from the database under the set of silvicultural assumptions (Dore et al. 1999). A number of process models were investigated and reviewed before selecting one particular model, SUSTAIN (Dewar 1997) for adaption to these forests. This model is a relatively simple process model with a small number of input parameters. The model was adapted so that it could be used to compare the SUSTAIN estimate of growth with the growth of an individual stand of trees in the Kendall Forest Management Area, between Wauchope and Taree on the mid-north coast of NSW. To improve the accuracy of the prediction of growth by SUSTAIN, a method of re-setting the state of the stand to the actual condition at the time of remeasurement was developed. In addition, the SUSTAIN model was extended to enable two separate levels of canopy to be described and grown separately. Ultimately the model was only partially successful in mirroring the growth predicted by the empirical data. Its partial success is attributed primarily to the difficulties associated with correctly determining the allocation parameters used by the model to assign net photosynthate to the roots, foliage and stemwood. The nature of the change in allocation parameters when the forest stand is disturbed by harvest or fire needs further investigation.

Thesis (doctoral)--Rijksuniversiteit te Utrecht, 1983. / Vita. Summary, closing, and vita in Dutch. Includes bibliographical references.

Thesis (doctoral)--Universiteit Leiden, 2006. / Includes bibliographical references (p. [91]-99).