Dynamics of a savanna-forest mosaic in the Australian monsoon tropics inferred from stand structures and historical aerial photography

2005 ◽  
Vol 53 (3) ◽  
pp. 185 ◽  
Author(s):  
Daniel S. Banfai ◽  
David M. J. S. Bowman
Keyword(s):  
Aerial Photography ◽  
Activity Index ◽  
Field Measurements ◽  
Aerial Photographs ◽  
Annual Rainfall ◽  
Australian Monsoon ◽  
Closed Forest ◽  
Fire Activity ◽  
Forest Mosaic ◽  
Ground Truthing

Stratified ground-truthing was undertaken within an area of approximately 30 km2 of tropical savanna across an abrupt sandstone escarpment in the monsoon tropics of Australia. Comparison of aerial photographs from 1941 and 1994 had previously revealed a landscape-wide expansion of closed forest and contraction of grassland patches. Good congruence between field measurements and the vegetation classifications from the 1994 aerial photography supported the authenticity of the vegetation changes. The relative abundance of rainforest and non-rainforest tree species also concurred with mapped vegetation transitions. Changes in individual size classes of rainforest species, which are relatively fire sensitive, were consistent with the primacy of fire in controlling the distribution of the closed-forest formation. Fire scars previously mapped from satellite imagery were used to derive a fire activity index for contrasting vegetation transitions. Savannas that had converted to closed forest had lower fire activity than did stable savannas. Conversely, closed forests that converted to savanna had the highest fire activity index. The landscape-wide expansion of rainforest is associated with the cessation of Aboriginal fire management, possibly in conjunction with elevated CO2 and increasing annual rainfall.

Assessing woody vegetation cover change in north-west Australian savanna using aerial photography

2003 ◽  
Vol 12 (4) ◽  
pp. 359 ◽  
Author(s):  
R. J. Fensham ◽  
R. J. Fairfax
Keyword(s):  
Structural Change ◽  
Aerial Photography ◽  
Vegetation Cover ◽  
Grazing Intensity ◽  
Field Measurements ◽  
Aerial Photographs ◽  
Woody Vegetation ◽  
North West ◽  
Land Type ◽  
Calibration Models

Models to calibrate tree and shrub cover assessed from aerial photography with field measurements were developed for a range of vegetation types in north-western Australia. The models verify previous studies indicating that woody cover can be successfully determined from aerial photography. The calibration models were applied to estimates of woody vegetation cover determined for 279 randomly located sample areas in the Ord–Victoria Rivers region using aerial photography from 1948 to 1950 and 1988 to 1997. Overstorey cover increased from a regional average of 11.5% to 13.5% and understorey cover increased from 1.3% to 2.0%. Downs, Limestone Hills and Alluvia land-types showed the most substantial increases in overstorey cover while overstorey cover in the Limestone plains land-type decreased. Relatively open structured vegetation is most susceptible to thickening. Rainfall records reveal an extreme multi-year rainfall deficit in the study area in the 1930s and relatively wet times in the 1970s and 1980s. Interpretation of a limited set of aerial photographs taken between 1964 and 1972 suggests that most of the increases in cover have occurred since this time. The study highlights the possibility that the average trend of vegetation thickening represents recovery during the relatively wet times after the 1970s. There was no relationship between structural change and a grazing intensity surrogate (distance of sample points to stock watering-points). However, the causes of structural change are undoubtedly multi-factored and the relative contributions of climate, fire and grazing vary for different landscapes and tree species.

Corrigendum to: Assessing woody vegetation cover change in north-west Australian savanna using aerial photography

2004 ◽  
Vol 13 (1) ◽  
pp. 131
Author(s):  
R. J. Fairfax ◽  
R. J. Fensham
Keyword(s):  
Structural Change ◽  
Aerial Photography ◽  
Vegetation Cover ◽  
Grazing Intensity ◽  
Field Measurements ◽  
Aerial Photographs ◽  
Woody Vegetation ◽  
North West ◽  
Land Type ◽  
Calibration Models

Models to calibrate tree and shrub cover assessed from aerial photography with field measurements were developed for a range of vegetation types in north-western Australia. The models verify previous studies indicating that woody cover can be successfully determined from aerial photography. The calibration models were applied to estimates of woody vegetation cover determined for 279 randomly located sample areas in the Ord–Victoria Rivers region using aerial photography from 1948 to 1950 and 1988 to 1997. Overstorey cover increased from a regional average of 11.5% to 13.5% and understorey cover increased from 1.3% to 2.0%. Downs, Limestone Hills and Alluvia land-types showed the most substantial increases in overstorey cover while overstorey cover in the Limestone plains land-type decreased. Relatively open structured vegetation is most susceptible to thickening. Rainfall records reveal an extreme multi-year rainfall deficit in the study area in the 1930s and relatively wet times in the 1970s and 1980s. Interpretation of a limited set of aerial photographs taken between 1964 and 1972 suggests that most of the increases in cover have occurred since this time. The study highlights the possibility that the average trend of vegetation thickening represents recovery during the relatively wet times after the 1970s. There was no relationship between structural change and a grazing intensity surrogate (distance of sample points to stock watering-points). However, the causes of structural change are undoubtedly multi-factored and the relative contributions of climate, fire and grazing vary for different landscapes and tree species.

scholarly journals Laser Scanning and Aerial Photography with UAV in Studying the Structure of Forest-Tundra Stands in the Khibiny Mountains

2021 ◽  
pp. 9-22
Author(s):  
Nail Nisametdinow ◽  
◽  
Pavel Moiseev ◽  
Ivan Vorobiev ◽  
◽  
...  
Keyword(s):  
Aerial Photography ◽  
Laser Scanning ◽  
Field Measurements ◽  
Research Area ◽  
Aerial Photographs ◽  
Projection Area ◽  
Ground Vegetation ◽  
Average Height ◽  
Forest Tundra ◽  
Manual Correction

Studying the structure of stands is a key point in assessing the role of trees in carbon deposition. Information on the spatial structure of ground vegetation at the upper treeline is still insufficiently presented in modern studies. High resolution remote sensing can provide important data to understand the properties and dynamics of vegetation in these conditions. We test the applicability of ground-based mobile laser scanning of the terrain and aerial photography for the rapid and high-precision assessment of the characteristics of tree stands in the forest-tundra ecotone. We obtained canopy height models (CHMs) of the forest and supplemented them with aerial photographs of the research area on the southeastern slope of the Khibiny Mountains. Using CHMs we have delineated boundaries of tree crowns. The height and projection area were determined for each tree. The first characteristic obtained by laser scanning was compared to the heights of the same trees estimated by field measurements. This was done for the purposes of verification. The comparison revealed that laser scanning data allow to set heights closest to field measurements in case the heights are determined by the maximum values of brightness of pixels of CHMs with manual correction of values when outliers are detected (R2 = 0.84). Since manual correction of outliers is time-consuming, we proposed a way to automate the measurements by determining tree heights using the sum of the average value of pixel brightness and the standard deviation multiplied by 2.5 (R2 = = 0.79). We compared the area characteristics of the stands obtained by laser scanning and the unmanned aerial vehicle (UAV) photography. Thus, we obtained detailed information on the spatial location and size of 4424 trees in an area of about 10 ha and compared the results of measuring tree characteristics obtained by different methods. It was also found that with increasing height from 290 to 425 m above sea level on the studied slope, the average height of stands decreases gradually from 4.5–5.0 to 1.1–1.6 m with small fluctuations (0.2–0.4 m), while the density of stands changes from 4620–5860 to 145 m2/ha in a non-linear way.

scholarly journals The excavation of two crop-marks at Huntingtower, Perthshire

1983 ◽  
Vol 112 ◽  
pp. 580-583
Author(s):  
Gordon J Barclay
Keyword(s):  
Aerial Photography ◽  
Aerial Photographs ◽  
Cambridge University ◽  
Unpublished Note ◽  
Ancient Monuments

In the 1940s and 50s Mr Eric Bradley, a flying instructor at Scone, noticed and described a series of crop-marks to the W of Perth during attempts to trace the Roman road, from the Gask Ridge, at its last known point near Dupplin Lake some 8-5 km to the SW of the fort at Bertha. In 1969 Dr J X W P Corcoran admirably summarized the evidence available from Mr Bradley's notes and maps, Cambridge University Committee for Aerial Photography (CUCAP) photographs and RAF vertical photographs in an unpublished note, now in the NMRS. In 1967 a valuable series of aerial photographs of the Huntingtower sites was taken by John Dewar Studios for the Inspectorate of Ancient Monuments. Subsequently RCAHMS has photographed the area resulting in the discovery of further features.

scholarly journals Changing the geometry of basins and water resources of Lakes Gopło and Ostrowskie under the influence of anthropopressure

2014 ◽  
Vol 14 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Piasecki Adam ◽  
Skowron Rajmund
Keyword(s):  
Water Resources ◽  
Surface Area ◽  
Water Cycle ◽  
Field Measurements ◽  
Aerial Photographs ◽  
Maximum Width ◽  
Digital Terrain ◽  
Terrain Models ◽  
Basic Parameters ◽  
Area And Volume

Abstract The paper presents the changes that have occurred in the morphometry of Lakes Gopło and Ostrowskie, which are located in central Poland. The analysis covered the period characterised by increased human interference into the water cycle, which has been taking place continually since the mid-eighteenth century. On the basis of available cartographic materials (aerial photographs, topographic maps, bathymetric charts of the lakes) and the authors’ own field measurements digital terrain models were developed for the immediate environment of the surveyed lakes. These models, in turn, were used for measuring basic parameters characterising the external dimensions of the lakes (surface area, length and maximum width, shoreline length) and their underwater relief (volume, maximum and average depth). In addition, the selected indicators of the shape and form of the lake basins were determined. The results showed a drastic reduction of water resources of the two lakes. The basin of Lake Gopło covers only the deepest parts of the former reservoir, accounting for only 23.3% of the lake before 1772, and 32.5% of its former volume. In the case of Lake Ostrowskie the surface area and volume decreased, respectively, by 23.5% (74.9 ha) and 21.3% (6 695 000 m3). Such large changes in surface area and volume of both lakes have contributed to significant changes in other morphometric parameters and indicators. In particular, significant changes were observed in relation to such morphometric characteristics as length and maximum width, as well as average and maximum depth.

scholarly journals Evaluation of hillslope failure and community adjustment after extreme weather event, Waimarama 26-27 April, 2011

2021 ◽  
Author(s):  
◽  
Albert Edward Frampton
Keyword(s):  
Water Content ◽  
Small Businesses ◽  
Extreme Event ◽  
Extreme Rainfall ◽  
Field Measurements ◽  
Economic Loss ◽  
Laboratory Analysis ◽  
Annual Rainfall ◽  
Financial Loss ◽  
North West

<p>In 2011, Waimarama received 80% of its annual rainfall in 48 hours. This extreme event with a return period of >100 years caused saturated hillslopes to collapse forming 100s of shallow landslides in the Puhokio Valley. This study collected soil samples from 54 exposed slip scarp horizons for laboratory analysis of soil mechanical properties. Field measurements of slip and slope angles, length, width and depth to determine that 23,212m³ of sediment was volume lost, from the 54 landslides. The field and lab measurements were used to generate a coherent understanding of landsliding at Waimarama. Laboratory analysis for liquid limits water content showed a high of 88.5% to a low of 18.8% and plastic limit water content had a high of 51% in the A horizon (organics) and low of 16.1%. Specific gravity also indicated a high reading 1.74 g/cm³ with a low of 1.16 g/cm³. The A horizon was able to tolerate high levels of water content in most tests, while the B horizon was capable of coping with some increase in water content. The C horizon was only able to handle low volumes of water, and was the main initiator of regolith collapse. The laboratory results indicated high saturation levels within the horizons of weak lithology of marine regolith that over caps impervious marine bedrock. The main cause for hillslope collapse and exposure of multiple translational and debris flow landslides was extreme saturation. However, towards the height of the rainfall event a 4.5 magnitude earthquake was recorded with unknown collateral consequences. Most slip locations were found in the aspects of east, south-east, west, and north-west, and on slope angles 15 -25°. The study confirmed previous surveys that regolith depth 80-100cm on impervious sandstone, siltstone/mudstone, when saturated over lengthy wet spells or from extreme precipitation, will collapse. In addition to the physical geographic study a survey was included to record individual and family accounts of the weather phenomenon. A questionnaire was prepared with specific questions that required yes or no answers. These questions dealt with loss of buildings, loss of land, animals, financial loss and recovery, economic loss, insurance and mitigation plans. The most affected were farmers and the next affected were householders while the holiday park was the worst affected of small businesses. Insurance was a significant help in most recoveries. Land rehabilitation was mitigated with new plantings and some aerial sowing, otherwise many slips were left to revegetate naturally. Economic and financial loss was severe for most farmers, due to pasture loss and animal relocation. Extreme rainfall causes slips that affect humans, but they can be mitigated. The Waimarama event is one of many events that can happen countrywide, the results can be a disastrous loss of personal, economic and financial assets, loss of infrastructure, including roading, bridges and communication. These are factors that many people and communities only realise when it happens to them. Mitigation against such events might include adequate insurance and knowledge of what to do, and where to go should an event happen unexpectedly and without warning.</p>

Estimating Pine Density and Competition Condition in Young Pine Plantations Using 35mm Aerial Photography

1989 ◽  
Vol 13 (3) ◽  
pp. 107-112 ◽  
Author(s):  
James L. Smith ◽  
Shepard M. Zedaker ◽  
Richard C. Heer
Keyword(s):  
Decision Making ◽  
Aerial Photography ◽  
Field Work ◽  
Treatment Decisions ◽  
Pine Plantations ◽  
Aerial Photographs ◽  
Prediction System ◽  
Competition Condition ◽  
Competition Control

Abstract A prediction system was developed that estimated pine density and hardwood competition levels in young plantations using simple measurements made on 35mm aerial photographs. The precision of the prediction system was found to be moderate to good. The use of these photo-based modelsin a decision-making situation was examined. Ground-based decisions regarding replanting, spraying for competition control, or no treatment were compared to similar decisions reached strictly from the aerial photographic measurements. Approximately 80% of all decisions agreed, and 90% of theno-treatment decisions agreed. While aerial photographs do not totally eliminate the need for field work, it is clear that photographic information can often produce reliable decisions with reduced field efforts. South. J. Appl. For. 13(3):107-112.

Coastal Studies by Sequential Air Photography

1965 ◽  
Vol 19 (4) ◽  
pp. 372-381 ◽  
Author(s):  
H. L. Cameron
Keyword(s):  
Shallow Water ◽  
Systematic Study ◽  
Aerial Photography ◽  
Aerial Photographs ◽  
Current Action ◽  
Coastal Changes ◽  
Air Photo

With the advent of air photography, many problems of mapping coast lines, such as those caused by surf action and underwater obstructions, were solved, as the vertical air photo shows the exact configuration of the coast and reveals many of the shallow-water obstructions. This paper shows that aerial photographs, obtained at intervals ranging from 2 to 20 years, contain important information on long-term coastal changes, brought about by wave and current action over a period of time. Two examples of such changes, revealed by sequential aerial photography, are given. It is concluded that a program of systematic study of existing photographs and supplementary rephotography would more than justify its cost.

Assessing techniques for estimating the extent of mangroves: topographic maps, aerial photographs and Landsat TM images

2001 ◽  
Vol 52 (5) ◽  
pp. 787 ◽  
Author(s):  
F. J. Manson ◽  
N. R. Loneragan ◽  
I. M. McLeod ◽  
R. A. Kenyon
Keyword(s):  
Thematic Mapper ◽  
Aerial Photographs ◽  
Landsat Thematic Mapper ◽  
Pixel Resolution ◽  
Topographic Data ◽  
Linear Extent ◽  
Cape York ◽  
Ground Truthing ◽  
Remote Sensing Techniques ◽  
Thematic Mapper Imagery

Coastal habitats are critical to the sustained production of many fisheries. It is important, therefore, that fishery managers obtain accurate estimates of the extent of these habitats. This study investigated three methods of estimating the linear extent and area of mangroves (commercially available topographic data, aerial photographs and Landsat Thematic Mapper satellite imagery) in two regions in northern Australia: the Joseph Bonaparte Gulf (in particular, the Berkeley and Lyne Rivers) with typically narrow fringes of mangroves (<50 m wide), and the Embley River on Cape York Peninsula,with much broader mangrove stands (50–1000 m wide). Ground-truthing verified that aerial photographs provided the most accurate estimates of extents of mangroves in all rivers,because of their high spatial resolution (2 m). Landsat Thematic Mapper imagery gave good estimates of the area of habitats, but, because of the 30 m pixel resolution, it underestimated the linear extent in places where the mangrove fringe was narrow. Topographic data gave good estimates of the extent of mangroves where the forests were more extensive and less linear in shape, but were very poor otherwise at this scale. These findings have implications for the use of remote sensing techniques in ecological studies in these regions.

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