Comprehensive study on ecological restoration and land exploitation of mining subsidence in suburbs of Chinese mining cities

China has nearly a hundred mining cities derived from mining development.While mining development has brought about immense achievements in a city’s economic construction,it has also resulted in different levels of damage to the eco-environment of the mining city,leaving behind a lot of subsided wasteland and heavily confining the sustainable development and transformation there.How to restore and exploit the land and eco-environment disrupted by mining development in an effective way,therefore,has become a pressing challenge that Chinese mining cities are facing.In this paper,the planning and construction of Nanhu Eco-city in the suburb of Tangshan City is analyzed as an example.After characterizing the coal-mining subsided lands in Kailuan Tangshan Mine originated in different periods and under different geological mining conditions and evaluating their safety level,the authors try to demonstrate how eco-restoration and comprehensive land exploitation should be implemented by making the best use of available local resources to achieve "economy-society-environment" sustainability and coexistence in a mining city.

Problems and countermeasures for land exploitation and utilization in China's development areas

s: The planning area and developing area in China's l29 national and 584 provincial development areas cover 8000 km2 and l500 km2 respectively. By typical field investigations we found that China's development areas have the characteristics of abundant categories, excessive quantities, large scales and dense localities in coastlands, border areas and river banks. And their utilization have 4 features of mainly collecting and occupying agricultural lands, minor rebuilding of old city; mainly taking up cultivated lands, minor exploiting and utilizing barren mountains and bleak sloping lands; collecting and occupying lands at first, utilizing afterwards; using large quantities of lands but obtaining comparatively fewer benefits. According to the analyses, China's development areas can be concluded into one of the four categories: constructed from cultivated lands, reconstructed from old cities, constructed from coastlands and islands, and constructed from barren mountains and desolate sloping lands. Their corresponding problems of unsuitable planning and distribution leaving cultivated lands unused, low remission price and chaotic management measures are analyzed in detail and the countermeasures are put forward. These include planning and distribution the lands in an integrated way, managing all these lands in a unified system. improving the growth pattern of their economy, and advancing their utilization and output ratios.

An evaluation of underlying mechanisms for“fishing down marine food webs”

Since the concept of ＂fishing down marine food webs＂ was first proposed in 1998, mean trophic level of fisheries landings（MTL） has become one of the most widely used indicators to assess the impacts of fishing on the integrity of marine ecosystem and guide the policy development by many management agencies. Recent studies suggest that understanding underlying causes for changes in MTL is vital for an appropriate use of MTL as an indicator of fishery sustainability. Based on the landing data compiled by Food and Agriculture Organization（FAO） and trophic information of relevant species in Fishbase, we evaluated MTL trends in 14 FAO fishing areas and analyzed catches of upper and lower trophic level groups under different trends of MTL and found that both the cases of a recovered MTL trend and a generally increasing MTL trend could be accompanied by decreasing catches of lower trophic level species. Further, community structure and exploitation history should be considered in using MTL after excluding species with trophic levels lower than 3.25 to distinguish ＂fishingthrough＂ from ＂fishing-down＂. We conclude that MTL used as an indicator to measure fishery sustainability can benefit from a full consideration of both upper and lower trophic level species and masking effects of community structure and exploitation history.

An index-based spatial evaluation model of exploitative intensity: A case study of coastal zone in Vietnam

Coastal zones play a major role in the conservation of marine ecosystems and the sustainable use of resources not only because of their special geographical environment but also because of their high temporal and spatial variability. With the development of urbaniza- tion, the exploitation and utilization of coasts have become important issues in the debate. To evaluate variations in the intensity of the land resource exploitation of coastal zones, an in- dex-based model has been proposed in this paper, and coastal Vietnam has been established as the study area. The model is based on four normalized indexes to realize rapid evaluation of the spatial distribution of the exploitative intensity after zoning. The model was established to characterize the different exploitative intensities in different segments of the coast and to graphically present a sequence of decision choices for decision-makers. The results are as follows. （1） The simplicity and rapidity of the index operations can address the fast-changing characteristics of coastal exploitation and meet the desired precision. （2） The choices of the landward buffers fit well with the banded characteristics of the coastal zone. The buffers are horizontally divided into equidistant subregions, which can quantify the spatial differentiation of the exploitative intensity along the coast and perpendicular to the coast. （3） The average exploitative intensity is low, and the proportion of area that is to be exploited accounts for approximately 50%.Considering its spatial variation from north to south, the land exploitative intensity in the north is higher than that in the south. Compared to the intensity of land re- source exploitation in the 20 km and 10 km buffers, the land exploitative intensity in the 5 km buffer is higher. The state of the intensity of land resource exploitation and how it can be used by stakeholders to manage coastal resources are then discussed.