Panchromatic Aerial Photographs Research Articles

Detecting Vegetation to Open Water Transitions in a Subtropical Wetland Landscape from Historical Panchromatic Aerial Photography and Multispectral Satellite Imagery

Over the last century, direct human modification has been a major driver of coastal wetland degradation, resulting in widespread losses of wetland vegetation and a transition to open water. High-resolution satellite imagery is widely available for monitoring changes in present-day wetlands; however, understanding the rates of wetland vegetation loss over the last century depends on the use of historical panchromatic aerial photographs. In this study, we compared manual image thresholding and an automated machine learning (ML) method in detecting wetland vegetation and open water from historical panchromatic photographs in the Florida Everglades, a subtropical wetland landscape. We compared the same classes delineated in the historical photographs to 2012 multispectral satellite imagery and assessed the accuracy of detecting vegetation loss over a 72 year timescale (1940 to 2012) for a range of minimum mapping units (MMUs). Overall, classification accuracies were >95% across the historical photographs and satellite imagery, regardless of the classification method and MMUs. We detected a 2.3–2.7 ha increase in open water pixels across all change maps (overall accuracies > 95%). Our analysis demonstrated that ML classification methods can be used to delineate wetland vegetation from open water in low-quality, panchromatic aerial photographs and that a combination of images with different resolutions is compatible with change detection. The study also highlights how evaluating a range of MMUs can identify the effect of scale on detection accuracy and change class estimates as well as in determining the most relevant scale of analysis for the process of interest.

Fully convolutional networks for land cover classification from historical panchromatic aerial photographs

Historical aerial photographs provide salient information on the historical state of the landscape. The exploitation of these archives is often limited by accessibility and the time-consuming process of digitizing the analogue copies at a high resolution and processing them with a proper photogrammetric workflow. Furthermore, these data are characterised by limited spectral information since it occurs very often in a single band. Our work presents a first application of deep learning for the extraction of land cover from historical aerial panchromatic photographs of the African cities of Goma, Bukavu and Bujumbura. We evaluate the suitability of deep learning for land cover generation from a challenging dataset of photographs from the 1940s and 1950s that covers large geographical extents and is characterised by radiometric variations between dates and locations. A fully convolutional approach is investigated by considering two network architectures with different strategies of exploiting contextual information: one used atrous convolutional layers without downsampling, whereas the second network has both downsampling and learned upsampling convolutional layers (U-NET). The networks are trained to detect three main classes namely, buildings, high vegetation and a mixed class of bare land and low vegetation class. High overall accuracies of >90% in Goma-Gisenyi and Bukavu, and >85% in Bujumbura are obtained. This work provides a novel methodology that outperforms a baseline standard machine learning classifier for the exploitation of the vast archives of historical aerial photographs that can aid long-term environmental baseline studies. Future work will entail developing domain adaptation strategies in order to make the trained network robust for different image mosaics.

Spatially explicit statistical modeling of random and systematic land cover transitions in the main grassland plain of Nech Sar National Park, Ethiopia

The main grassland plain of Nech Sar National Park (NSNP) is a federally managed protected area in Ethiopia designated to protect endemic and endangered species. However, like other national parks in Ethiopia, the park has experienced significant land cover change over the past few decades. Indeed, the livelihoods of local populations in such developing countries are entirely dependent upon natural resources and, as a result, both direct and indirect anthropogenic pressures have been placed on natural parks. While previous research has looked at land cover change in the region, these studies have not been spatially explicit and, as a result, knowledge gaps in identifying systematic transitions continue to exist. This study seeks to quantify the spatial extent and land cover change trends in NSNP, identify the strong signal transitions, and identify and quantify the location of determinants of change. To this end, the author classifies panchromatic aerial photographs in 1986, multispectral SPOT imagery in 2005, and Sentinel imagery in 2019. The spatial extent and trends of land cover change analysis between these time periods were conducted. The strong signal transitions were systematically identified and quantified. Then, the basic driving forces of the change were identified. The locations of these transitions were also identified and quantified using the spatially explicit statistical model. The analysis revealed that over the past three decades (1986–2019), nearly 52% of the study area experienced clear landscape change, out of which the net change and swap change attributed to 39% and 13%, respectively. The conversion of woody vegetation to grassland (~ 5%), subsequently grassland-to-open-overgrazed land (28.26%), and restoration of woody vegetation (0.76%) and grassland (0.72%) from riverine forest and open-overgrazed land, respectively, were found to be the fully systematic transitions whereas the rest transitions were recorded either partly systematic or random transitions. The location of these most systematic land cover transitions identified through the spatially explicit statistical modeling showed drivers due to biophysical conditions, accessibility, and urban/market expansions, coupled with successive government policies for biodiversity management, geo-politics, demographic, and socioeconomic factors. These findings provide important insights into biodiversity loss, land degradation, and ecosystem disruption. Therefore, the model for predicted probability generally suggests a 0.75 km and 0.72 km buffers which are likely to protect forest and grassland from conversion to grassland and open-overgrazed land, respectively.

Assessment of shoreline alterations using a Digital Shoreline Analysis System: a case study of changes in the Yeşilırmak Delta in northern Turkey from 1953 to 2017.

The aim of our study was to determine the erosion rates and shoreline changes in the Yeşilırmak Delta (Delta) between the oldest available date (1953) before construction of the large-scale dams on the Yeşilırmak River in northern Turkey and 2017. To clearly illustrate the impacts of the dams on the Delta, we investigated the relationship between the dams and shoreline changes. To compute the net shoreline changes and erosion rates over these 64years, we used a Digital Shoreline Analysis System. To digitize the shoreline changes at the mouth of the Yeşilırmak River, 1:25000-scaled topographic maps from 1957, panchromatic aerial photographs from 1962, a KH-9 Hexagon satellite image from 1980, an Ikonos satellite image from 2002, and a WorldView-2 satellite image from 2017 were used. The west and east sides of the river mouth were divided into six main groups and assessed. Each group included a time series for the shorelines. The groupings were based on the time series. For each group, the net shoreline change (m) was calculated using the net shoreline movement (NSM), and erosion rate (m/year) was calculated using the linear regression rate (LRR). According to NSM computations, net shoreline change varied from - 235.04 to 379.18m. The greatest evolutions in net shoreline change were observed for group I, with a minimum of - 1101.11m. According to LRR analysis, the calculated erosion rate varied from - 6.83 to 19.06m/year. The greatest changes in erosion rate were observed for group II, with a minimum of - 30.63m/year. There is a close relationship between the construction dates of the dams in the Yeşilırmak Basin and the shoreline changes in the Delta.

Land use and forest cover dynamics in the North-eastern Addis Ababa, central highlands of Ethiopia

BackgroundThe Ethiopian highlands have experienced intense levels of land use dynamics and forest cover transformations over the past few decades. Multiple socio-economic, demographic and bio-physical factors have driven such transformations. Nevertheless, recent expansion of urban settlements and infrastructural development could have accelerated the rate at which land cover transformations preceded but little is known about their impacts on land cover transformations in the vicinity of Addis Ababa, Ethiopia. This study, therefore, focuses on detecting long term dynamics of land use/land cover (LULC) change since the 1950s and current state of forest susceptibility to degradation in North-eastern Addis Ababa, Ethiopia. In this study Panchromatic Aerial photographs (1957), MSS (1975), TM (1995) and Sentinel-2 (2017) images were used to generate LULC types. We employed object-based classification techniques to generate LULC types for 1957 aerial photographs and maximum likelihood algorithm for images of 1975, 1995 and 2017. We also generated forest degradation susceptibility map for the study area by employing a multi-criteria approach on the ArcGIS analysis platform.ResultsOver the course of 60 years (1957–2017) the extent and direction of LULC have become more dynamic. Agricultural land and forest land showed a comparably equal extent of net change (+ 36.7% and − 37.8%, respectively) but to opposite directions. Forest lost 25.1% and 18.7% of its cover to barren land and agricultural land, respectively. The net change for forest was negative except for the period 1975–1995, with varying rates of deforestation during the four distinct study periods. However, a heightened level of deforestation occurred after the mid-1990s due to rapid urban growth and a change in government economic policy. A 6.2% net change of urban/settlement served as a catalyst for LULC transformations in the last two decades. Our findings also revealed that 97.2% of forests were located at a radius of 1 km distance from urban centers and settlements whereas 92% of them were accessible by road networks of a km radius. Similarly, 71% of forests suffer from edge effects while biophysical factors such as streams as vectors of disturbance and slopes expose about 35% of forests to degradation.ConclusionOver the last six decades the study area has shown an unprecedented level of LULC change. The main drivers of change were the combination of bio-physical processes especially drought cycles, demographic dynamics (population growth, density and internal migration), urbanization and successive government development policies. The massive conversion of forests to agricultural land and barren land in the study area will have far reaching impact on biodiversity and ecosystem services, land degradation and a change in local hydrological regime.

Enhancement of spectral quality of archival aerial photographs using satellite imagery for detection of land cover

Archival aerial photographs are often the only reliable source of information about the area. However, these data are single-band data that do not allow unambiguous detection of particular forms of land cover. Thus, the authors of this article seek to develop a method of coloring panchromatic aerial photographs, which enable increasing the spectral information of such images. The study used data integration algorithms based on pansharpening, implemented in commonly used remote sensing programs: ERDAS, ENVI, and PCI. Aerial photos and Landsat multispectral data recorded in 1987 and 2016 were chosen. This study proposes the use of modified intensity-hue-saturation and Brovey methods. The use of these methods enabled the addition of red-green-blue (RGB) components to monochrome images, thus enhancing their interpretability and spectral quality. The limitations of the proposed method relate to the availability of RGB satellite imagery, the accuracy of mutual orientation of the aerial and the satellite data, and the imperfection of archival aerial photographs. Therefore, it should be expected that the results of coloring will not be perfect compared to the results of the fusion of recent data with a similar ground sampling resolution, but still, they will allow a more accurate and efficient classification of land cover registered on archival aerial photographs.

Karst Morphology of Karangbolong Area, Java-Indonesia

The Karangbolong karst is situated in the southern zone of Java where Miocene limestone has been uplifted and has experienced karstification since the late Pliocene. The research documented here aims at exploring morphological characteristic of the area. Special interest is attributed to differentiation of valley or depression morphology, conical karst morphology, and the roles of jointing system and uplift history in their development. The morphology investigation was mostly undertaken using aerial photograph visual interpretation of panchromatic aerial photograph and analytically shaded DEM, as well as field observations. The results show that the general morphological features of Karangbolong karst are characterized by aligned valleys and aligned enclosed depression with three different patterns. The orientation of the valleys and enclosed depressions coincide with the structural pattern of the area, indicating that the formation of aligned valleys and aligned enclosed depressions is preferential dissolution through jointing. The residual hills are typified by conical karst morphology with sharp peaks. It is found that tight joint spacing appears to be the main reason for the sharp peak of the conical hills. Asides from jointing system, morphology of the area is likely governed also by topographical position and gravity sliding of the limestone bed during the uplift. Uplift history has important control on the differentiation of morphology between plateau part and sloping part. Limitation of this research is that the aerial photograph was not rectified well, because the analyses in this research were more on pattern identification. More accurate rectification is needed for better morphometric analyses. Key words: Southern Java, Karangbolong karst, polygonal karst, tropical geomorphology.

A comparison of lineament and fracture trace extraction from LANDSAT ETM+ panchromatic band and panchromatic aerial photograph in Gunungsewu karst area, Java-Indonesia

This paper aims at exploring interpretability of the panchromatic band of Landsat Enhanced Thematic Mapper Plus (ETM+) compared to the panchromatic aerial photograph in lineament and fracture trace extraction. Special interest is addressed to karst terrain where lineaments and fracture traces are expressed by aligned valleys and closed depressions. The study area is an single aerial photographic coverage in the Gunungsewu Karst, Java-Indonesia which is characterized by a lineament-controlled cone karst and labyrinth-cone karst. The result shows that the recording time of the Landsat ETM+ with respect to the shadow resulting from the sun illumination angle is the key factor in the performance of lineament and fracture traces extraction. Directional filtering and slicing techniques significantly enhance the lineament interpretability of the panchromatic band of Landsat ETM+. The two methods result in more lineaments and fracture traces which T-test affirm in 0.001 and 0.004 significant levels. Length based lineament analysis attains a better result compared to frequency based analysis.

Change in woody cover at representative sites in the Kruger National Park, South Africa, based on historical imagery.

BackgroundThe coexistence of woody vegetation and grass is a key characteristic of savanna ecological balance. Gains in woody vegetation at the expense of grass can lead to changes in grazer and browser carrying capacities on the savannas. This study examined long-term change in woody cover at four study sites representative of the geology and rainfall in the Kruger National Park, South Africa. Scanned 1940/1942, 1968, and 1977 high spatial resolution (0.44–1.35 m) panchromatic aerial photographs were used, supplemented by 5 and 10 m resolution 1998 and 2012 panchromatic and red band grey scale digital SPOT images. The imagery datasets of the respective study sites were georeferenced to the UTM projection. Woody cover on the imagery was enhanced using texture analysis, and mapped by unsupervised classification of the texture images using the K-means clustering algorithm. Change in woody cover was mapped using Boolean addition Geographic Information System overlay analysis.ResultsThe results indicated 29 and 40 % reductions in woody cover for the southern granites and southern basalts sites, respectively. The northern granites and northern basalts sites, on the other hand, had gains in woody cover over the analysis period. The location context-specific factors of fire frequency and elephant density, and not rainfall fluctuations, explained most of the change in woody cover.ConclusionsThe results point to the need for location context-specific management of fire and elephant concentrations. The changes in woody cover are likely to have effects on the grazer and browser carrying capacities of the savannas in the Kruger National Park.

Quantification of Deltaic Coastal Zone Change Based on Multi-Temporal High Resolution Earth Observation Techniques

A series of methodologies are described in this paper aiming to quantify the natural hazard due to the coastal changes at a deltaic fan. The coastline of Istiaia (North Evia, Greece) has been chosen for this study as several areas of accretion and erosion have been identified during the past few decades. We combined different types of datasets, extracted from high resolution panchromatic aerial photographs and traced the contemporary shoreline by high accuracy surveying with Real Time Kinematics (RTK) GPS equipment. The interpretation of all shorelines required geo-statistical analysis in a Geographical Information System. A large number of high resolution morphological sections were constructed normally to the coast, revealing erosional and depositional parts of the beach. Retreating and extension rates were calculated for each section reaching the values of 0.98 m/yr and 1.36 m/yr, respectively. The results proved to be very accurate, allowing us to expand the developed methodology by using more complete time-series of remote sensing datasets along with more frequent RTK-GPS surveying.

Estimating stand attributes of boreal forests using digital aerial photography and a shadow fraction method

The aim of this study was to develop an imputing method to map forest stand attributes (height and volume) using panchromatic aerial photographs with a spatial resolution of 30 cm and Landsat images. The method was tested on several sites in Québec, Canada, that are dominated by black spruce. The method involved four sets of procedures: (i) measuring the shadow fraction from panchromatic aerial photographs, (ii) generating regression models between the shadow fraction and forest attributes, (iii) locally mapping the forest attributes as a grid layer (30 m × 30 m), and (iv) expanding the forest attributes from the local maps to a large study area using an imputing approach. Regression models between the shadow fraction and stand attributes were calibrated with ground sample plots and a series of 73 aerial photographs. General results from linear relationships between the shadow fraction and two stand attributes showed linear shapes but had low values for the goodness of fit ( of 0.24 for height and 0.31 for volume). However, the results improved significantly ( of 0.40 for height and 0.59 for volume) when the portion of the aerial photograph used was restricted to its centre (between 6.2° and 11.3°). This restricted area of the aerial photographs produced small local maps of stand attributes from the shadow fraction. These local maps were used as the training dataset for an imputing approach, a k nearest neighbours algorithm, with the aim of mapping forest attributes over a large area.

Urban drainage control applying rational method and geographic information technologies

Abstract The objective of this study is to develop a method of controlling urban drainages in the town of Ingeniero White motivated by the problems arising as a result of floods, water logging and the combination of southeasterly and high tides. A Rational Method was applied to control urban watersheds and used tools of Geographic Information Technology (GIT). A Geographic Information System was developed on the basis of 28 panchromatic aerial photographs of 2005. They were georeferenced with control points measured with Global Positioning Systems (basin: 6 km2). Flow rates of basins and sub-basins were calculated and it was verified that the existing open channels have a low slope with the presence of permanent water and generate stagnation of water favored by the presence of trash. It is proposed for the output of storm drains, the use of an existing channel to evacuate the flow. The solution proposed in this work is complemented by the placement of three pumping stations: one on a channel to drain rain water which will allow the drain of the excess water from the lower area where is located the Ingeniero White city and the two others that will drain the excess liquid from the port area.

Land-use and land-cover change and its environmental implications in a tropical highland watershed, Ethiopia

This study analysed long-term land-use and land-cover change (LUCC) in a highland watershed covering an area of about 154 km2 in the Blue Nile basin of Ethiopia. Two sets of panchromatic aerial photographs (1957 and 1982) and a Landsat TM image (2001) were the main input data from which three land-use and land-cover maps were produced by employing geographical information systems/remote sensing techniques. These data were complemented by some socio-economic data that were generated by using household survey, key-informant interview and group discussion methods. The results show that in regard to land-use and land-cover, the major change has been the reduction of areas under natural vegetation cover and expansion of open grassland, cultivated areas and settlements. Over the four and a half decades considered, areas of forest and dense tree cover and shrub grassland decreased by 64 and 6%, respectively. Forest and dense tree cover experienced the greatest change; from accounting for ∼9% of the total area of the watershed in 1957 to only ∼3% in 2001. In general, much of the de-vegetation occurred between 1982 and 2001. Cropland and rural settlement showed a small but consistent increase between 1957 and 2001. Riparian vegetation decreased during the first period, but increased almost to the same level during the second period by gaining land from the other land-use and land-cover types. The observed LUCCs were driven by a combination of proximate and underlying causes. These include increasing demographic pressure and associated demands on environmental resources, widespread rural poverty and inadequate management of common property resources owing to poorly defined ownership arrangements. There is a need for short-term and long-term strategies to ensure sustainable land management and agricultural development in the watershed.

Penafsiran Volume Pohon Pinus merkusii melalui Foto Udara (Studi Kasus BKPH Majenang, KPH Banyumas Barat)

Interpretation of Stock Volume of Pinus merkusii using Aerial Photographs (Case Study in BKPH Majenang, West Banyumas FMUThe study aims to compile and analyse the growing stock volume of Pinus merkusii by using stand parameter measured through aerial photographs. The study was conducted by using black-white panchromatic aerial photographs produced in 2005 and the scale was 1 : 20,000. The study was conducted in Pinus merkusii taping plots in the Majenang BKPH, under the forest districts of west Banyumas, Perum Perhutani using tree height, crown diameter and number of trees per hectare as parameters. Data analysis was done to define the relationship among these parameters in regression equation. The steps of the study were defining measurement plots in aerial photographs, measurement of stand parameters in the aerial photographs and field observation. Data analysis was performed using micro computer. As a result, the regression equation for each location as follows: V = 72,415 – 0,231 N + 35,242 H – 24,454D – 0,923 (N x D), with the determination coefficient was 0,789 and the significance of 95%. Where: V = growing stock volume (m3), N = the number of trees per hectare, H = tree height (m) and D = crown diameter (m). It was concluded that number of tree per hectare, tree height and crown diameter were good predictors for standing stock volume of Pinus merkusii.

Use of non-orbital images on the planimetric assessment of large farms

The use of vertical aerial photographs, which are among the products of Remote Sensing, became frequent in surveying, planning and soil exploration projects, mainly for assisting other cartographic databases. In this study, panchromatic aerial photographs in nominal scale 1:25000 (in 1962) and colored aerial photographs in nominal scale 1:30000 (2010) were used, aiming at showing the possibility of performing a more complete and reliable analyses of area values in Botucatu-SP through the Geographic Information System (GIS). The values were obtained directly from the photograph without corrections scale, using as reference maps from the Sao Paulo State Cartographic and Geographic Institute, resulting in an error coefficient that shows the differences of the areas through the two study methods proposed. Regarding the aerial photographs in 1962 and 2010, it can be stated that the images from 2010 showed less difference in area (43.48 ha) in relation to the area values determined in reference map, once the colorful images facilitated the interpretation of the landscape, making the border lines more accurate, and thus offering greater precision in their definitions.

Interplay between mass movement and fluvial network organization: An example from southern Apennines, Italy

Relationships between landslides and drainage network arrangement have been investigated by classical and quantitative geomorphological analysis in an intermountain valley (i.e. the upper valley of the Sinni River) of the southern Italian Apennines. The 120km2-wide test-area is characterized by very low grade metamorphic rocks (mainly shale) and associated crystalline-metamorphic rocks which underwent high exhumation and uplift rates during Quaternary times. We recognized and mapped 534 landslides through the stereoscopic interpretation of one set of 20 panchromatic aerial photographs 1:33,000 scale. Landslides were classified according to both type of movement and relative age. We detected and mapped 35 new landslides after a long rainfall period during the winter 2008–2009. The percentage of area affected by landslides (DL) of the area has a high value (about 37%). Analysis of distribution of landslides areas within different age classes suggests that recent/present-day landslide distribution is strongly influenced by the legacy of widespread large and ancient landslides, probably generated within a different morpho-climatic setting. A quantitative geomorphological analysis of the drainage network has been performed to evaluate the influence of landslide processes on morphometric properties of the drainage network. In particular, the degree of hierarchical organization of the drainage network is assessed through the hierarchical anomaly density, a measure of the number of anomalous confluences (i.e. channels of u order not flowing in channels of order u+1) in drainage basins. On the basis of statistical relationships between morphometric indices of the drainage network and DL, we argue that the activity of more recent mass movements rather than very old landslides can act as a disturbing element within the development of the drainage network, generating anomalous confluences of the 1st order. Empirical relationships between suspended sediment yield and some geomorphic parameters of the drainage network allowed the estimation of short-term denudation rates in the study area. The comparison between uplift and denudation rates suggests that the landscape system has not reached a steady state between uplift and erosion, in which tectonic uplift can represent a disturbing element within the recent morphogenesis. On the basis of the data presented, (large) mass movements in the study area are mainly linked to the relief growth promoted by Quaternary tectonics, whereas litho-structural and morpho-climatic factors assume a minor role.

Morphostructure Control Towards the Development of Mahawu Volcanic Complex, North Sulawesi

DOI: 10.17014/ijog.v7i1.134The studied area, situated in northeastern part of North Sulawesi Arm, is dominantly occupied by the Mahawu, Linau, Tompusu, and Kasurutan volcanic rocks. Using remote sensing data, such as landsat image, black and white panchromatic aerial photograph, and IFSAR image, morphology-origin unit and morphology lineament can be interpreted. Four morphology-origin units, those are Mahawu Volcano Complex, Intra-montane Plain structure, Linau Volcano Complex, and Lacustrine Plain are recognized. Furthermore, morphological lineament pattern was statistically processed to find out the general stress direction in the area to determine the probability of the structural morphology occurrence in the Mahawu Volcano Complex. The result shows that generally the development pattern of volcanic cones are irregular, except the Mahawu Volcano Complex showing a linear pattern. This lineament pattern is interpreted as a NW - SE fault pattern controlling the rise of magma. At least, two tectonic and two eruption periods occurred regularly at different time from the Quaternary age till the present.

Surficial materials mapping in Nunavut, Canada with multibeam RADARSAT-2 dual-polarization C-HH and C-HV, LANDSAT-7 ETM+, and DEM data

Our study assesses the use of multibeam RADARSAT-2 dual-polarization C-HH and C-HV, LANDSAT-7 ETM+, and Digital Elevation Model (DEM) data for mapping surficial materials in Nunavut, Canada. The RADARSAT-2 images were acquired using standard beam 1 and 7 modes in both ascending and descending orbits. RADARSAT-2 images were filtered to reduce speckle and then orthorectified. Representative training areas of distinct surficial deposits (bedrock, boulders, organic deposits, sand and gravel, thick till with dense vegetation, thick till with sparse vegetation, and thin till) were identified from field information and by interpreting panchromatic aerial photographs and LANDSAT-7 ETM+ images. Maximum likelihood supervised classifications were conducted on the RADARSAT-2 C-HH and C-HV images, individually and combined with LANDSAT-7 ETM+ and (or) DEM data. The best overall classification accuracy was obtained by combining RADARSAT-2 C-HH and C-HV images with LANDSAT-7 ETM+ and DEM data. Confusion between several surface materials was reduced, but confusion between “bedrock” and “boulders” and between “sand and gravel” and “organic deposits” or “thin till” class still remains. Another limitation of the study includes the lack of a field survey to validate training areas for three of the four detailed analysis areas. Nonetheless, this study produced surficial materials maps covering eight 1:250000 scale National Topographic System of Canada sheets that provide important geological information about this remote area.

The Importance of Temporal and Spatial Vegetation Structure Information in Biotope Mapping Schemes: A Case Study in Helsingborg, Sweden

Temporal and spatial vegetation structure has impact on biodiversity qualities. Yet, current schemes of biotope mapping do only to a limited extend incorporate these factors in the mapping. The purpose of this study is to evaluate the application of a modified biotope mapping scheme that includes temporal and spatial vegetation structure. A refined scheme was developed based on a biotope classification, and applied to a green structure system in Helsingborg city in southern Sweden. It includes four parameters of vegetation structure: continuity of forest cover, age of dominant trees, horizontal structure, and vertical structure. The major green structure sites were determined by interpretation of panchromatic aerial photographs assisted with a field survey. A set of biotope maps was constructed on the basis of each level of modified classification. An evaluation of the scheme included two aspects in particular: comparison of species richness between long-continuity and short-continuity forests based on identification of woodland continuity using ancient woodland indicators (AWI) species and related historical documents, and spatial distribution of animals in the green space in relation to vegetation structure. The results indicate that (1) the relationship between forest continuity: according to verification of historical documents, the richness of AWI species was higher in long-continuity forests; Simpson's diversity was significantly different between long- and short-continuity forests; the total species richness and Shannon's diversity were much higher in long-continuity forests shown a very significant difference. (2) The spatial vegetation structure and age of stands influence the richness and abundance of the avian fauna and rabbits, and distance to the nearest tree and shrub was a strong determinant of presence for these animal groups. It is concluded that continuity of forest cover, age of dominant trees, horizontal and vertical structures of vegetation should now be included in urban biotope classifications.

Mapping and interpreting historical land cover/land use changes in a Natura 2000 site using earth observational data: The case of Nestos delta, Greece

Land cover/land use (LCLU) transitions and landscape changes were mapped and interpreted in a deltaic Natura 2000 habitat site in northern Greece. Multi-temporal maps created over a period of about 65 years and based on panchromatic aerial photographs and high spatial resolution satellite data, helped to assess LCLU transformations. These changes were associated with human interference and major socio-economic processes occurring in the area during the study period. In 1945, forests and wetlands dominated the delta area, occupying 63% of the total land cover. Subsequently, these land cover types severely reduced in coverage, and agricultural areas dominated the landscape as a result of policies introduced to accommodate the settlement of refugees from Asia Minor. This transition increased landscape fragmentation in 1960. Due to relative increase of swap changes, the landscape became less heterogeneous in 1992. Finally, in 2002, agricultural areas exhibit a small decrease in coverage having converted back to natural areas following the introduction of EU Common Agricultural Policy. About 77% of the deltaic ecosystem experienced LCLU changes during the first period of the analysis (1945–1960). Almost two thirds of this change is attributed to intercategorical transitions, while the rest is related to swap changes. During the second period of the analysis (1960–1992), half the study area was transformed due to net and swap changes. Finally, in the third, most recent time period (1992–2002), 85% of the landscape showed persistence while net changes were twice as frequent as swap changes. Human interference was the key factor beyond the landscape transformations and intercategorical transitions observed in the delta. During the previous century natural habitats were pressured by major socio-economic processes that transformed their composition and structure. Assessing these changes is critical to develop area-specific policies that minimize negative influences and provide a framework for restoring habitats to their natural conditions.