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1.
Wetlands have been determined as one of the most valuable ecosystems on Earth and are currently being lost at alarming rates. Large-scale monitoring of wetlands is of high importance, but also challenging. The Sentinel-1 and -2 satellite missions for the first time provide radar and optical data at high spatial and temporal detail, and with this a unique opportunity for more accurate wetland mapping from space arises. Recent studies already used Sentinel-1 and -2 data to map specific wetland types or characteristics, but for comprehensive wetland characterisations the potential of the data has not been researched yet. The aim of our research was to study the use of the high-resolution and temporally dense Sentinel-1 and -2 data for wetland mapping in multiple levels of characterisation. The use of the data was assessed by applying Random Forests for multiple classification levels including general wetland delineation, wetland vegetation types and surface water dynamics. The results for the St. Lucia wetlands in South Africa showed that combining Sentinel-1 and -2 led to significantly higher classification accuracies than for using the systems separately. Accuracies were relatively poor for classifications in high-vegetated wetlands, as subcanopy flooding could not be detected with Sentinel-1’s C-band sensors operating in VV/VH mode. When excluding high-vegetated areas, overall accuracies were reached of 88.5% for general wetland delineation, 90.7% for mapping wetland vegetation types and 87.1% for mapping surface water dynamics. Sentinel-2 was particularly of value for general wetland delineation, while Sentinel-1 showed more value for mapping wetland vegetation types. Overlaid maps of all classification levels obtained overall accuracies of 69.1% and 76.4% for classifying ten and seven wetland classes respectively.  相似文献   
2.
Object-based class modelling allows for mapping complex, hierarchical habitat systems. The riparian zone, including forests, represents such a complex ecosystem. Forests within riparian zones are biologically high productive and characterized by a rich biodiversity; thus considered of high community interest with an imperative to be protected and regularly monitored. Satellite earth observation (EO) provides tools for capturing the current state of forest habitats such as forest composition including intermixture of non-native tree species. Here we present a semi-automated object based image analysis (OBIA) approach for the mapping of riparian forests by applying class modelling of habitats based on the European Nature Information System (EUNIS) habitat classifications and the European Habitats Directive (HabDir) Annex 1. A very high resolution (VHR) WorldView-2 satellite image provided the required spatial and spectral details for a multi-scale image segmentation and rule-base composition to generate a six-level hierarchical representation of riparian forest habitats. Thereby habitats were hierarchically represented within an image object hierarchy as forest stands, stands of homogenous tree species and single trees represented by sunlit tree crowns. 522 EUNIS level 3 (EUNIS-3) habitat patches with a mean patch size (MPS) of 12,349.64 m2 were modelled from 938 forest stand patches (MPS = 6868.20 m2) and 43,742 tree stand patches (MPS = 140.79 m2). The delineation quality of the modelled EUNIS-3 habitats (focal level) was quantitatively assessed to an expert-based visual interpretation showing a mean deviation of 11.71%.  相似文献   
3.
本文以“社交媒体多层次信息流”为概念框架,分析了四川九寨沟7.0级地震发生后,个人、当地的组织、宏观层面的主流媒体使用社交媒体所发挥的作用。通过对微博的数据进行挖掘分析,总结出地震灾害发生后社交媒体所具有的5项功能:人际之间的交流,地方政府、本土组织以及当地媒体的传播渠道,大众传媒信息发布的渠道,信息的收集和分享,微观、中观以及宏观各主体间沟通的渠道。在强震发生后社交媒体有巨大的传播潜力,本文的研究成果对未来大震发生后如何利用社交媒体来应对灾害有一定的借鉴意义。  相似文献   
4.
Understanding the relationship between multi-level institutional linkages and conditions influencing the likelihood of successful collective action has practical and theoretical relevance to sustainable local resource governance. This paper studies the relationship between multi-level linkages and local autonomy, a facilitating condition found to increase the likelihood of local successful collective action. A technique known as fuzzy-set qualitative comparative analysis (fsQCA) was applied to a longitudinal comparative data set. In the context of the decentralization of a protected area system in Costa Rica (1986–2006), it traced the emergence and endurance of autonomy among local institutions for biodiversity conservation. The technique illustrates which set of multi-level linkages combined in different ways, and at different points in time, to reach the same outcome (local autonomy). The findings show that a unique set of combinations of multi-level linkages led to the emergence of local autonomy among institutions for biodiversity conservation governance. In contrast, a more diverse set was associated with the endurance of local autonomy over time, suggesting that institutional diversity may play a more prominent role in the maintenance of institutional robustness than in processes of institutional emergence.  相似文献   
5.
An innovative methodology for dual-polarized Synthetic Aperture Radar (SAR) data segmentation is proposed. The methodology is based on the thresholding of the 1D-histograms of the two images produced by the dual polarimetric bands. Thresholding of the histograms is performed using a nonparametric algorithm. Histograms after thresholding are combined together in a two dimensional histogram-based space in order to define sub-spaces, which are used for image segmentation. Sub-spaces are further divided based on two criteria which lead to a multi-level segmentation approach. Dual-polarized TerraSAR-X data, both HH and VV, are used in a study area located in the southwestern United Kingdom.  相似文献   
6.
7.
In this research, we match web-based activity diary data with daily mobility information recorded by GPS trackers for a sample of 709 residents in a 7-day survey in Beijing in 2012 to investigate activity satisfaction. Given the complications arising from the irregular time intervals of GPS-integrated diary data and the associated complex dependency structure, a direct application of standard (spatial) panel data econometric approaches is inappropriate. This study develops a multi-level temporal autoregressive modelling approach to analyse such data, which conceptualises time as continuous and examines sequential correlations via a time or space-time weights matrix. Moreover, we manage to simultaneously model individual heterogeneity through the inclusion of individual random effects, which can be treated flexibly either as independent or dependent. Bayesian Markov chain Monte Carlo (MCMC) algorithms are developed for model implementation. Positive sequential correlations and individual heterogeneity effects are both found to be statistically significant. Geographical contextual characteristics of sites where activities take place are significantly associated with daily activity satisfaction, controlling for a range of situational characteristics and individual socio-demographic attributes. Apart from the conceivable urban planning and development implications of our study, we demonstrate a novel statistical methodology for analysing semantic GPS trajectory data in general.  相似文献   
8.
Many difficulties have arisen from top-down approaches to the design and implementation of global environmental initiatives. The concept of translation and other analytical features of Actor-Network Theory (ANT) can offer a way of conceptualising these difficulties and their practical effects. By translation, we refer to what happens in-between the formulation of international goals and the results of implementation, and more specifically, relations and negotiations within this broader process. We examine several aspects of translation in the case of Reducing Emissions from Deforestation and Forest Degradation (REDD+), a prominent global environmental initiative. Using an ethnographic approach, we explore local responses in Central Kalimantan province, Indonesia, to REDD+ ideas and goals that originate at international and national levels. Following selection in 2010 as the official REDD+ pilot province, Central Kalimantan became a site for the convergence of actors and projects with varied sources of funding. The study identifies a central tension that emerged between an initial vision of Central Kalimantan as a pioneer, and local concerns about being used as an experimental subject or ‘guinea pig’ for the testing of externally designed schemes. Results show that greater flexibility in the design of programs and initiatives is needed, to provide space for local inputs. Implementation should pay attention to how local actors are included in planning processes that inform decision-making at higher jurisdictional levels. To bring about intended changes in land use, programs like REDD+ need to extend beyond a focus on short-term projects and targets, to instead emphasise long-term investments and forms of collective action that support learning.  相似文献   
9.
Land-use change is intertwined with tourism because land is used as a resource for human activities.Land-use change also provides an opportunity to evaluate the status of the ecoenvironment.Understanding the relationship between tourism and land use change would help to predict the effect of tourism on land use and encourage sustainable tourism development.Using the Li River Basin as a case study,a hybrid approach using multilevel modeling and logistic regressions was employed to analyze the distribution of land-usechange between 1989 and 2010 to examine potential driving factors.Results reveal that rapid tourism development and construction expansion expose this area to risk of deforestation and forest degradation.Construction increased by 141% between 1989 and 2000 and by 195% between 2000 and 2010.The primary driving force for construction expansion shifted from population growth between 1989 and 2000 to investment growth after 2000.New construction primarily occurred on crop and woodlands areas,with shares of 81.25% and 6.38%,respectively,between 1989 and 2000,and with shares of 57.79% and 15.29%,respectively,between 2000 and 2010.Moreover,these drastic increases in construction also led to frequent transitions between croplands,woodlands,and grasslands.Traits including distances to urban areas and roads and scenic locations exerted significant effects on land-use change.Woodland regrowth in the areas thatsurround scenic locations consisted of fluctuating woodlands,whereas stable woodland regrowth was often absent in these areas.Likewise,permanent woodland clearing tended to be closed to near scenic locations.That is,construction at scenic locations negatively affected forest conservation in the Li River Basin.  相似文献   
10.
Adaptation to climate change is widely recognized as a multi-level governance challenge because expected impacts and respective measures cut across governmental levels, sectors and societal domains. The present paper analyses the role of regional adaptation partnerships in Canada and England in the multi-level governance of climate change adaptation. We describe and compare three partnerships per country with regard to their evolution, membership and governing structures, coordination across levels and societal domains, and their adaptation activities and outputs. Although both partnership schemes represent new collaborative approaches, their genesis and governance differ. While the Canadian collaboratives are a government-centred approach that originated and partly operated top-down through a national programme for the period 2009–2012, the English partnerships follow a more pluralistic stakeholder-centred approach that evolved bottom-up already in the early 2000s. Both schemes have in common that they mediate between governmental levels, foster networking between public and private actors, and eventually build adaptive capacities and inform adaptation policies. We conclude that regional adaptation partnerships represent a new governance approach that facilitates climate change adaptation, albeit with limits. Since state actors play(ed) key roles in both partnership schemes, they do not represent a new sphere of authority outside the state. Instead of blurring or destabilizing governmental levels they complement (and perhaps even stabilise) them with multi-level interactions.  相似文献   
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