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This paper explores the evolution of land use and natural resource management strategies over the past twenty to fifty years in a remote Sahelian region. The empirical example is Karagou village in SE Niger. Building on an in-depth survey from 1992 and a targeted, follow-up analysis of contemporary land use strategies in 2011, the change process is scrutinized.The analysis uses the conceptual lenses of land systems science, human–environmental timelines, and the notion of multiple exposures. Enabling and constraining conditions for local livelihoods in terms of the resource base (landscape, water, and population) are described. Results characterize how land use strategies have developed and how local people opportunistically use different landscape elements such as dune landscapes, valley bottoms (bas-fonds) and oases (cuvettes). Major concerns are rainfall variability, saturation of cropland, and perceived dwindling groundwater resources. It is concluded that the land use and livelihood strategies have remained remarkably stable in the face of the changing socio-ecological fringe conditions, but that this situation may hamper a sustainable transformation. 相似文献
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Oyster reef ecosystems used to form significant components of many temperate and subtropical inshore coastal systems but have suffered declines globally, with a concurrent loss of services. The early timing of many of these changes makes it difficult to determine restoration targets which consider interdecadal timeframes, community values and shifted baselines. On the Australian continent, however, the transition from Indigenous (Aboriginal) to Westernized resource use and management occurred relatively recently, allowing us to map social-ecological changes in detail. In this study, we reconstruct the transformations in the Sydney rock oyster (Saccostrea glomerata) wild commercial industry of central and southeast Queensland, and by extension its reef ecosystems, as well as the changing societal and cultural values related to the presence and use of the rock oyster through time. By integrating data from the archaeological, anthropological and fisheries literature, government and media accounts, we explore these transformations over the last two centuries. Before the 1870s, there was a relative equilibrium. Aboriginal peoples featured as sole traders to Europeans, supplying oysters and becoming a substantial component of the industry's labour pool. Effectively, Australia's commercial oyster industry arose from Aboriginal-European trade. During this initial phase, there was still a relative abundance of wild oyster, with subtidal oyster reef structures present in regions where oysters are today absent or scarce. By contrast, these reefs declined by the late 19th century, despite production of oysters increasing due to continued large-scale oyster recruitment and the expansion of oyster cultivation in intertidal areas. Production peaked in 1891, with successive peaks observed in regions further north. During the 1890s, flood events coupled with land-use changes introduced large quantities of silt into the system, which likely facilitated an increase in oyster pests and diseases, ultimately decreasing the carrying capacity of the system. Today oyster production in this region is less than one-tenth of historical peak production. Many cultural heritage components have also been lost. Indigenous management is now very minor due to the massive decimation of Aboriginal populations and their respective practices. Yet, we found strong cultural attachment to midden remains and oyster production continues within Indigenous communities, with considerable broader community support. This study highlights the value of conducting thorough analysis of early media accounts as a means for reconstructing historical resource decline and management. It further demonstrates the application of historical information and context for contemporary management, protection and restoration of much-altered coastal social-ecological systems. 相似文献
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Yu. S. Osipov 《Celestial Mechanics and Dynamical Astronomy》1977,16(2):191-208
The main result of this paper is a theorem on the trajectory equivalence of phase flows on isoenergetic surfaces with a positive energy level in the Kepler problem and perturbed kepler problem. The following two facts are crucial for proving it: firstly, an isomorphism of the phase flow on an isoenergetic surface in the Kepler problem and the geodesic flow in a constant curvature space. The isomorphism is studied in detail. In particular, all the integrals of the Kepler problem are obtained proceeding from the group-theory considerations. The second fact is a generalization of the theorem on structural stability of Anosov flows onto non-compact manifolds. 相似文献
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Recent climate change has brought changes to the water regime that has affected the traditional agro-pastoral production systems
and livelihoods in the Upper Kaligandaki Basin of the Nepal Himalayas. Based on fieldwork and available meteorological and
hydrological data, this paper examines the changing water regime and various adaptation strategies that local farmers have adopted
in this cold arid region. Increasing temperature and decreasing rainfall and snowfall have resulted in a negative water balance.
In this scenario, farmers have implemented six major adaptive strategies in the trans-Himalayan Upper Mustang Valley. 相似文献
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