Land use/cover, landforms and fragmentation patterns in a tropical dry forest in the southern Pacific region of Mexico   总被引：1，自引：0，他引：1  

Leopoldo Galicia  Alba Esmeralda Zarco-Arista  Karla Ivette Mendoza-Robles  José Luis Palacio-Prieto  Arturo García-Romero 《Singapore journal of tropical geography》2008,29(2):137-154

In spite of widely documented studies of deforestation rates and land use/cover changes in tropical dry forests in Mexico, relatively little is known about fragmentation patterns in such forests. This study defines the spatial distribution of landforms and land use/cover types the lower Papagayo River basin and examines their influence on fragmentation patterns and biological diversity in a tropical dry forest in that southern Pacific region. The land use/cover map was constructed from aerial photographs, Landsat TM imagery (2000) and fieldwork. Landform units were defined based on altitude, slope, lithology and morphology. Landscape fragmentation parameters were obtained using FRAGSTATS (version 3.3) considering the numbers of patches, mean, minimum and maximum patch size, edge density, total edge and connectivity. Results show tropical dry forest to be remnant vegetation (~11 per cent), characterized by isolation and low connectivity. Land use/cover types have different effects on fragmentation patterns. Agriculture and cattle raising produce similar numbers of patches, but with a different mean size; and human settlements have a scattered distribution pattern. The abandonment of rural agricultural livelihoods has favoured the expansion of secondary tropical dry forest characterized by continuity and high connectivity, which suggests a high regeneration potential from land abandonment. It can be concluded that tropical dry forest fragmentation and recovery at regional scales depend on such landscape attributes as lithology, slope, geomorphology and management.  相似文献   

黄海和东海沉积物有机质活性及营养盐再生潜力初探   总被引：9，自引：0，他引：9  

陈建芳  金海燕  刘小涯  李宏亮  林以安  潘建明 《地球化学》2005,34(4):83-90

2000年秋季和 2001年春季,对黄海和东海 6个站位的水柱和沉积物样品进行了营养盐、沉积有机碳、有机碳同位素和氨基酸分析.结果表明, 表层沉积物的有机碳含量和有机质活性存在较明显的季节性变化,这主要由春秋两季表层水体生物量的差异引起.在泥质堆积区 E2、 E4、 E5站,春季表层沉积物有机碳的含量与活性均较高,而同期底部沉积物向上的营养盐梯度也明显增大, 显示有机碳的含量及活性与营养盐再生有密切关系.  相似文献   

Study on the physical properties and chemical compositions of artificially synthesized coral hydroxyl apatite （CHA） bone     

Zhaolin Li  Wen Li  Zunzhao Bo  Qingshui Yin  Yu Zhang 《中国地球化学学报》2009,28(4):421-426

Abstract  

To develop synthesized coralline hydroxyl apatite (CHA) bone graft-substitute and measure its physical and chemical characteristics.  相似文献   

塔里木河下游人工胡杨林生态恢复过程的初步研究   总被引：8，自引：3，他引：5  

古丽努尔·沙布尔哈孜  尹林克  严成 《干旱区地理》2004,27(3):384-387

在以植物群落调查样地为基础,对塔里木河下游不同林龄人工胡杨林的物种丰富度、物种多样性指数、群落均匀度、生态优势度等进行了分析,同时对土壤理化性质在21a间的变化情况也作了详细分析。通过分析,表明人工胡杨群落随着发育年限的增加,群落物种丰富度,物种多样性指数和均匀度指数不断增长,而群落生态优势度逐渐降低,同时土壤理化性质不断改善。在此基础上,对塔里木河植被的演变趋势作一初步的探讨和估计,从而对塔里木河下游植被的生态恢复也具有重要意义。  相似文献   

南京大都市空间演化与地域结构发展策略   总被引：1，自引：0，他引：1  

姚士谋  顾朝林 《地理与地理信息科学》2001,17(3):7-11

随着全球经济一体化、信息化时代的到来 ,各国各地区的城市发展策略亦受到深刻的影响。南京位于亚太地区我国沿海中部 ,具有江海优势 ,国务院在 90年代中期批复的南京市总体规划正在实施 ,有力地促进了南京城市的空间扩展及其城市内部空间结构深刻的变化。该文就南京都市圈内部城市空间结构的特征扩展模式及其发展趋势、策略作一个多层面的论证 ,从城市设计与规划艺术手法的高度作综合评述 ,为南京大都市的空间合理发展提供科学依据。  相似文献   

沙坡头地区人工植被油蒿种群结构与更新的研究   总被引：7，自引：7，他引：7  

马凤云  李新荣  龙利群  张景光 《中国沙漠》2002,22(6):571-575

采用野外调查和比较分析的方法,对沙坡头地区人工植被油蒿种群的结构和更新进行了研究.通过对不同固沙起始年代油蒿种群大小结构的分析发现,幼树个体的数量较多,中等大小的成年个体数量少,老龄个体的数量极少.年限较短的人工植被区油蒿幼树个体的数量多于年限较长的人工植被区,而油蒿幼苗的数量则呈相反的趋势.油蒿幼苗在不同的地形中分布数量也不同,丘间地有较多的幼苗,背风坡幼苗特别少.油蒿成年个体在人工植被区中呈均匀分布,油蒿幼苗则呈聚集分布.  相似文献   

地下水人工补给水质的研究--以西安市回灌为例     

谢娟  姜凌  李泉 《地球科学与环境学报》2002,24(4):67-72

以西安市地下水人工补给研究为例,探讨了人工补给地下水的意义,结合西安地区水文地质特点,着重对回灌水质进行了分析研究,指出在水污染严重的今天,研究地下水人工补给的重要性、必要性,提出水质改善及保护措施,利用人工补给可以解决水的有关问题,通过实际分析验证地下水回灌对水质的改善。  相似文献   

Assessing the discourses and practices of urban regeneration in a growing region     

Mike Raco 《Geoforum》2003,34(1):37-55

Most research on the discourses and practices of urban regeneration in the UK has examined case studies located in areas of relative socio-economic distress. Less research has been undertaken on regeneration projects and agendas in areas characterised by strong economic growth. Yet, it is in such places that some of the best examples of the discourses, practices and impacts of contemporary urban regeneration can be found. In some areas of high demand regeneration projects have used inner urban brownfield sites as locations for new investment. With the New Labour government’s urban policy agendas targeting similar forms of regeneration, an examination of completed or on-going schemes is timely and relevant to debates over the direction that policy should take. This paper, drawing on a study of urban regeneration in one of England’s fastest growing towns, Reading in Berkshire, examines the discourses, practices and impacts of redevelopment schemes during the 1990s and 2000s. Reading’s experiences have received national attention and have been hailed as a model for other urban areas to follow. The research documents the discursive and concrete aspects of local regeneration and examines the ways in which specific priorities and defined problems have come to dominate agendas. Collectively, the study argues that market-driven objectives come to dominate regeneration agendas, even in areas of strong demand where development agencies wield a relatively high degree of influence. Such regeneration plays a symbolic and practical role in creating new forms of exclusion and interpretations of place.  相似文献   

Cultural policy and place promotion: Swansea and Dylan Thomas     

Helen Watkins  David Herbert 《Geoforum》2003,34(2):249-266

As former industrial cities have experienced radical changes to the bases of their economies, the imperatives of finding new roles and functions has often led to the adoption of cultural policies. These are diverse and partial but have become part of place promotion policies designed to attract visitors and investors. The connection with a literary figure offers one exploitable quality and this paper explores the adoption of Dylan Thomas, poet and writer, as an icon for Swansea. What emerges is the existence of a diversity of interested individuals and groups, who start from different positions but work towards a common goal. The tensions about the life and works of the poet, evident over the 50 years since his death are still there but the key players, including the City and County of Swansea, are finding ways of reconciling their differences in the ‘production’ of Dylan Thomas. This use of a writer and his local connections forms part of the more general process of making a cultural policy for the city.  相似文献   

新疆干旱区天然植被最低生态耗水量概念分析     

杨海梅  李明思  彭玉刚 《干旱区地理》2005,28(6):770-774

干旱区天然植被的最低生态耗水量问题关系到该地区生态建设的标准问题，也是评价水资源生态承载力所必须考虑的指标。同时，天然植被的最低生态耗水量是制定绿洲农业用水和节水规划的依据之一。据不同的生态目标分析并提出了天然植被不同的最低生态耗水量的概念，指出植物的最低生态耗水量是最低生态效应下的植物的耗水量，而且不同生态区要求的生态效应不同，因此，植物在不同生态目标下会表现出的最低生态耗水量不同。进行天然植被最低生态耗水量评价时，首先要明确生态目标。另外，通过试验发现，天然植被存在着生态耗水效率的概念，水分的生态效应存在最优值。  相似文献