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Copyright of Avances is the property of Instituto de Informacion Cientifica y Tecnologica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

At the time of European settlement, an extensive graminoid wetland existed at the confluence of the East and West Holland Rivers at the southern end of Lake Simcoe, Ontario. However, by 1925, clearing and draining of the marsh for specialty agriculture (i.e., market gardens) had begun and, by the 1940s, ~46% of the wetland had been cleared and another 13% was lost before 2016. Concurrent with marsh conversion has been an increase in Narrow-leaved Cattail (Typha angustifolia) in the remnant wetland. This study documents the change in the Holland Marsh wetland by delineating boundaries between marsh, fen, and shrub communities on aerial photographs taken at ~10-year intervals between 1946 and 2015 and documenting vegetation change along transects running perpendicular to tributaries bisecting the wetland. The extent of fen habitat within the Holland Marsh has been decreasing since 1946 at an average rate of 0.24 ha/year because of increases in both shrub and marsh (i.e., T. angustifolia) communities. Typha angustifolia expansion has been predominantly from along the margins of the Holland River where soil phosphorus concentration is significantly higher than in the core of the fen. Beyond 30 m from the river, vegetation dominance shifts from T. angustifolia to sedges (Cyperaceae). Managing phosphorus loading from upstream land uses will be of critical importance in protecting this habitat, which is rare in southern Ontario. [ABSTRACT FROM AUTHOR]

In the framework of a landslide inventory map of the Sierra Costa Region, we identified and classified landslides on the basis of extensive field-verified aerial photo interpretation. Geological and geomorphological data were gathered to assess the spatial distribution of the landslides, occurrence characteristics and possible associated risk. Of the 1262 landslides analysed and classified, the main geomorphological units for landslide occurrence were fluvial valleys located in the mountains (1007 landslides) and in the rolling hills (260 landslides). Debris flows were mostly controlled by lithological contacts (478 landslides) and slope gradient (367 landslides); debris slides were mainly influenced by lithological features, more specifically sedimentary rocks (208 landslides). Another significant factor was fault systems associated with fluvial valleys (92 landslides). The identification, location and classification of major mass movement types, in combination with the assessment of controlling factors, allow us to understand the nature of slope instability in the region and contribute to land planning efforts. [ABSTRACT FROM AUTHOR]

Copyright of VertigO is the property of La Revue Electronique en Sciences de l'Environnement VertigO and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Regulation of Lake Ontario water levels since the St. Lawrence Seaway began operation in the early 1960s reduced the range of lake-level fluctuations and resulted in alteration of wetland plant communities, especially invasion of sedge/grass meadow marsh by cattails. A new regulation plan was implemented in January 2017 that seeks to restore some of the natural range in lake levels to benefit the environment. An adaptive management process accompanied the new Plan 2014, requiring before-after data for evaluation. Aerial photographs from 2014/2015 were obtained from existing sources for 16 wetlands previously assessed from 2001 photographs, and photointerpretation was used to re-map the vegetation types from the earlier study. The updated data set provides further information on wetland response to lake-level regulation. Overall, area of Meadow Marsh decreased from 2001 to 2014/2015 in most wetlands. In some cases, losses were due to increased Cattail abundance and in others to Mixed Emergent abundance. Although area of Cattail did increase at half the sites, expansion landward into Meadow Marsh was likely limited to an upper elevation with drier soils that had not been flooded for at least 15 years. Waterward expansion of Cattail was slow because it occurs by formation of vegetatively-expanding floating mats. The updated data set can now serve as a baseline for future adaptive management evaluations, including response to extreme high lake levels in 2017 and future low lake levels that Plan 2014 should allow during periods of low water supply. [ABSTRACT FROM AUTHOR]

Highlights • Experts largely disagree on visually interpreted shadows. • A risk-based shadow detection method is presented. • Difference in shadow detected automatically and by the experts is within expectations. Abstract Land cover identification and area quantification are key aspects in determining support payments to farmers under the European Common Agricultural Policy. Agricultural land is monitored using the Land Parcel Identification System and visual image interpretation. However, shadows covering reference parcel boundaries can hinder effective delineation. Visual interpretation of shadows is labor intensive and subjective, while automated methods give reproducible results. In this paper we compare shadow detection on satellite imagery obtained by expert photointerpretation to a proposed automated, data-driven method. The latter automated method is a thresholding approach employing both panchromatic and multispectral imagery, where the former has a finer spatial resolution than the latter. Thresholds are determined from automatically generated training data using a risk-based approach. Comparison of the total shadow area per scene showed that more pixels were labelled as shadow by the automatic procedure than by visual interpretation. However, the union of shadow area independently identified by twelve experts on a subscene was larger than the automatically determined shadow area. The limited intersection of the shadow areas identified by the experts demonstrated that experts strongly disagreed in their interpretations. The shadow area labelled by the automated method was in between the intersection and the union of the areas interpreted by experts. Furthermore, the automated shadow detection method is reproducible and reduces the interpretation effort and skill required. [ABSTRACT FROM AUTHOR]

Urban agriculture (UA) has been acknowledged for several positive effects such as access to fresh food, human activities moderation, agro-biodiversity and social and cultural relationships. In the city of Rome due to social and economic trends this kind of activity is spreading, but so far very few attempts have been addressed to inventorying the UA areas (e.g., community gardens, residential gardens, school gardens, illegal vegetable gardens, urban farms, etc.). Some mapping experiences have been carried out but all lack of a well-established methodology to be applied for a complete inventory. In this paper we propose a conceptual framework and methodology for mapping the UA in Rome through Earth Observation techniques by using the concepts of photointerpretation and the features of the most used web-mapping services. Google Earth has been used as a basic tool for visual interpretation and polygon digitalization, while other services have been used for the availability of additional features (e.g., the oblique view of Microsoft Bing Maps). The integration of the web-mapping services combined with ancillary data improved the UA site detection, allowing to define both the land use and the UA typologies. We argue that the integration of the web-mapping services for building urban agricultural land use datasets is cost-effective compared to processing commercial remote sensing images. The inventory can enable administrators to perform analysis about the interactions between agricultural activities and the urban environment, and to enact informed policies for green and vacant urban spaces management. [ABSTRACT FROM AUTHOR]

Abstract: Although always a part of city life, urban agriculture has recently attracted increased attention from diverse groups in the United States, which promote it as a strategy for stimulating economic development, increasing food security and access, and combatting obesity and diabetes, among other goals. Developing effective policies and programs at the city or neighborhood level demands as a first step the accurate mapping of existing urban agriculture sites. Mapping efforts in major U.S. cities have been limited in their focus and methodology. Focusing on public sites of food production, such as community gardens, they have overlooked the actual and potential contribution of private spaces, including home food gardens, to local food systems. This paper describes a case study of urban agriculture in Chicago which used the manual analysis of high-resolution aerial images in Google Earth in conjunction with ArcGIS to identify and map public and private spaces of food production. The resulting spatial dataset demonstrates that urban agriculture is an extensive land use type with wide variations in the distribution of sites across the city. Only 13% of sites reported to be community gardening projects by nongovernment organizations and government agencies were determined, through image analysis, to be sites of food production. The production area of home gardens identified by the study is almost threefold that of community gardens. Study results suggest opportunities may exist for scaling up existing production networks—including home food gardens—and enhancing community food sovereignty by leveraging local knowledges of urban agriculture. [Copyright &y& Elsevier]

Photointerpretation studies were conducted to evaluate vegetation changes in wetlands of Lake Ontario and the upper St. Lawrence River associated with regulation of water levels since about 1960. The studies used photographs from 16 sites (four each from drowned river mouth, barrier beach, open embayment, and protected embayment wetlands) and spanned a period from the 1950s to 2001 at roughly decadal intervals. Meadow marsh was the most prominent vegetation type in most wetlands in the late 1950s when water levels had declined following high lake levels in the early 1950s. Meadow marsh increased at some sites in the mid-1960s in response to low lake levels and decreased at all sites in the late 1970s following a period of high lake levels. Typha increased at nearly all sites, except wave-exposed open embayments, in the 1970s. Meadow marsh continued to decrease and Typha to increase at most sites during sustained higher lake levels through the 1980s, 1990s, and into 2001. Most vegetation changes could be correlated with lake-level changes and with life-history strategies and physiological tolerances to water depth of prominent taxa. Analyses of GIS coverages demonstrated that much of the Typha invasion was landward into meadow marsh, largely by Typha x glauca. Lesser expansion toward open water included both T. x glauca and T. angustifolia. Although many models focus on the seed bank as a key component of vegetative change in wetlands, our results suggest that canopy-dominating, moisture-requiring Typha was able to invade meadow marsh at higher elevations because sustained higher lake levels allowed it to survive and overtake sedges and grasses that can tolerate periods of drier soil conditions. [ABSTRACT FROM AUTHOR]

In the creation of forest type maps, photointerpreters first identify features that are the most certain, and subsequently identify features that are less certain in order to complete the map. In the present study, a method of photointerpretation is proposed in which only those features that an interpreter believes to be -100 percent certain#are identified. This results in interpretations that are not polygonal and that do not cover an entire photograph but that are instead treated using spatial interpolation to produce surfaces containing fuzzy membership values (FMVs) for all map classes at all locations in the area under study. These FMV surfaces can then be manipulated to produce thematic maps in which areas have a known certainty. The method is demonstrated using a synthetic image. It is concluded that maps resulting from this alternative method of photointerpretation are no more or less accurate than those produced from conventional polygon-based photointerpretation procedures. However, the alternative method provides considerable time savings and also provides an estimate of thecertainty of each area on the final thematic map -- something that the conventional photointerpretation method does not produce. [ABSTRACT FROM AUTHOR]