Detection of Vegetation Encroachment in Power Transmission Line Corridor from Satellite Imagery Using Support Vector Machine: A Features Analysis Approach

Vegetation encroachment along electric power transmission lines is one of the major environmental challenges that can cause power interruption. Many technologies have been used to detect vegetation encroachment, such as light detection and ranging (LiDAR), synthetic aperture radar (SAR), and airborne photogrammetry. These methods are very effective in detecting vegetation encroachment. However, they are expensive with regard to the coverage area. Alternatively, satellite imagery can cover a wide area at a relatively lower cost. In this paper, we describe the statistical moments of the color spaces and the textural features of the satellite imagery to identify the most effective features that can increase the vegetation density classification accuracy of the support vector machine (SVM) algorithm. This method aims to distinguish between high- and low-density vegetation regions along the power line corridor right-of-way (ROW). The results of the study showed that the statistical moments of the color spaces contribute positively to the classification accuracy while some of the gray level co-occurrence matrix (GLCM) features contribute negatively to the classification accuracy. Therefore, a combination of the most effective features was used to achieve a recall accuracy of 98.272%.

Applications of a hydro-geomorphic (dis)connectivity framework to study vegetation transitions in semiarid ecosystems.

<p>Changes in hydro-geomorphic connectivity have been previously linked to catastrophic shifts in landscape structures and function leading to irreversible degradation. Here we present evidence and new observations to better understand the link between connectivity of water and sediments and possible phase transitions for the case of semiarid ecosystems at the catchment and hillslope scales.  We first focus on rangelands, where coevolving vegetation and landform structures lead to a distinct connectivity pattern responsible for the healthy functioning of the system. Positive feedbacks, triggered by disturbances in vegetation, water or sediment structures can alter the hydro-geomorphic connectivity leading to degradation. Our results for rangelands in Australia, from both simulations and observations, suggest that an increase in connectivity beyond a threshold may lead to irreversible degradation, meaning that the system return to a functional state is unlikely without extensive management interventions. We also analyse the case of semi-arid floodplain wetlands of the Murray-Darling Basin, where we observe that dis-connectivity during droughts promote terrestrial vegetation encroachment and degradation. Simulations and observations also indicate the presence of thresholds beyond which the recovery of the system is unlikely without interventions.</p>

Conservation Strategies for Protecting Tiger Beetles and Their Habitats in the United States: Studies With Listed Species (Coleoptera: Carabidae: Cicindelidae)

Tiger beetles are a popular, widely studied group of charismatic insects that are a flagship taxon for insect conservation. Five species are currently listed in the United States as Federally Endangered or Threatened, two others have recently been delisted, and many more are listed by individual states. To date, the status of some of these species has been improved or their decline slowed by various conservation strategies. In this article, we review the background and the recent conservation activities for all federally listed tiger beetle species. These species have lost much of their historic habitat and remain at risk because of continuing impacts from vegetation encroachment of native or invasive plants, water-level changes, and other human-related activities. Conservation efforts are limited because for most species there is little or no potential habitat remaining, even following restoration activities. Effective strategies have included long-term monitoring of population size and research activities, acquisition and protection of occupied sites, methods for controlling vegetation encroachment to improve habitat quality, and recent efforts with translocations using beetles from existing populations or from captive rearing. Because tiger beetle life histories are similar, successful management and research methods for any one species can be applicable to others. This presents an opportunity to coordinate taxon-level conservation for all U.S. species through cataloged information and conservation leadership

DEEP LEARNING MONITORING OF WOODY VEGETATION DENSITY IN A SOUTH AFRICAN SAVANNAH REGION

Bush encroachment in African savannahs has been identified as a land degradation process, mainly due to the detrimental effect it has on small pastoralist communities. Mapping and monitoring the extent covered by the woody component in savannahs has therefore become the focus of recent remote sensing-based studies. This is mainly due to the large spatial scale that the process of woody vegetation encroachment is related with and the fact that appropriate remote sensing data are now available free of charge. However, due to the nature of savannahs and the mixture of land cover types that commonly make up the signal of a single pixel, simply mapping the presence/absence of woody vegetation is somewhat limiting: it is more important to know whether an area is undergoing an increase in woody cover, ever if it is not the dominant cover type. More recent efforts have, therefore, focused in mapping the fraction of woody vegetation, which, clearly, is much more challenging. This paper proposes a methodological framework for mapping savannah woody vegetation and monitoring its evolution though time, based on very high-resolution data and multi-temporal medium-scale satellite imagery. We tested our approach in a South African savannah region, the Northwest Province (> 104,000 km2), 0.5m-pixel aerial photographs for sampling and validation and Landsat data.