土地资源结构与农林牧合理用地布局的探讨——以甘肃省河西走廊为例

本文以土地资源结构理论为依据,论述了甘肃省河西走廊地区的农业分区,土地资源质量数量结构、农林牧合理用地构成及区域开发的整体布局。     

Some determinants of the spatio-temporal fire cycle in a mediterranean landscape (Corsica,France)

Based on recent needs to accurately understand fire regimes and post-fire vegetation resilience at a supra-level for carbon cycle studies, this article focusses on the coupled history of fire and vegetation pattern for 40 years on a fire-prone area in central Corsica (France). This area has been submitted since the beginning of the 20^th century to land abandonment and the remaining land management has been largely controlled by frequent fires. Our objectives were to rebuild vegetation and fire maps in order to determine the factors which have driven the spatial and temporal distribution of fires on the area, what were the feed backs on the vegetation dynamics, and the long-term consequences of this inter-relationship. The results show a stable but high frequency of small fires, coupled with forest expansion over the study period. The results particularly illustrate the spatial distribution of fires according to topography and vegetation, leading to a strong contrast between areas never burnt and areas which have been burnt up to 7 times. Fires, when occuring, affect on average 9 to 12% of the S, SE and SW facing slopes (compared to only 2 to 5% for the N facing slopes), spread recurrently over ridge tops, affect all the vegetation types but reburn preferentially shrublands and grasslands. As these fire-proning parameters have also been shown to decrease the regeneration capacity of forests, this study highlights the needs in spatial studies (both in terms of fire spread and vegetation dynamic) to accurately apprehend vegetation dynamic and functionning in fire-prone areas.This revised version was published online in May 2005 with corrections to the Cover Date.     

Effects of land ownership and landscape-level factors on rare-species richness in natural areas of southern Ontario,Canada

Surprisingly few studies have considered the extent to which the nature of the ownership of land is associated with differences in biodiversity. We analysed ownership and other landscape-level effects on rare-species richness for both globally- and regionally-rare biota (including birds, herpetofauna, butterflies, mammals, and plants) in 289 designated natural areas (NAs) in southern Ontario, Canada. Information about each NA −including area, number of plant communities, ownership status and details of species diversity were collected from published sources. Length of perimeter of NA, relative isolation, and an estimate of fragmentation were measured using image analysis and GIS techniques. NAs were in general relatively small, with mean area of 158 ha (median 85 ha, range from 0.9 to 1278 ha) for private NAs; public NAs had mean area of 132 ha (median 16 ha, range from 0.1 to 1481 ha). Mean number of plant communities was 4.6 (median 4, range 1- 13) at private NAs and 3.8 (median 3, range 1-16) at public NAs. Our results show that, of several landscape-level factors, area had the greatest effects on rare-species richness and other biotic indices. Effects of area were followed by effects of plant community diversity, however this was itself significantly affected by area and the extent of perimeter of the NA. Both these factors were followed by effects of ownership of the NA and by effects of isolation of the NA (represented by minimum distance to nearest NA and by number of NAs in 10 km radius). Other landscape- level factors did not appear to have overall significant effects. Variation in area accounted for 0.1% to 29% of variation in number of rare species, with lower values for globally-rare, than for regionally-rare taxa. For all biotic groups, public ownership of NAs was associated with significantly greater rare-species richness compared to private ownership, even after other factors such as area were controlled. For all globally-rare biota except butterflies, area of NA had greater effects on rare-species richness than did ownership. Richness of regionally- rare birds was more affected by plant community diversity than by area of NA. Number of recorded plant communities accounted from 2.1% of variation in number of globally-rare plant species to as high as 31% of variation in regionally-rare butterflies. The diversity of plant communities was itself influenced by total site area (accounting for 45% of variation), extent of elongation of the NA, and both external- and interior- edge perimeters. Public NAs had greatest numbers of rare biota and so should be a significant focus for conservation programs. Smaller, privately-owned patches of natural area dominate (by number and area) in this densely populated region and their significance should not be overlooked. This revised version was published online in July 2006 with corrections to the Cover Date.     

The value of vegetation cover for ecosystem services in the suburban context

Latin-American cities can be characterized by dynamic processes of urbanization that encroach upon the natural and semi-natural surrounding landscapes. Our study presents the effects of landscape development, transformed from semi-natural conditions into a mostly disperse suburban settlement. We explore the impact that this transformation has had on this context by three ecosystem services that regulate rainwater runoff, enhance microclimate conditions and help to improve air quality by monitoring vegetation cover. We have designed a spatio-temporal hierarchical analysis which employs remote sensing techniques to capture the structural changes of this landscape over long, medium and short term scales on two spatial levels. This methodological approach was tested in the Metropolitan Area of Santiago (MAS) as case study area. Despite of the increase in impervious surfaces due to urban processes, there has also been an increase in vegetation cover, which has led to an improvement in the provision of the above-mentioned ecosystem services. Hence, if diverse urbanization processes continue and they are coupled with an increase in vegetation cover, the provision of ecosystem services could also expand. This phenomenon can be observed in some areas, where public and private green spaces are created and maintained. Our data analyses give evidence that certain types of suburban areas which increase the share of vegetation cover can provide daily ecological benefits for urban neighborhoods, and beyond, for adjacent areas. Moreover, suburban development can successfully provide ecological benefits to citizens. Such processes can only be ecologically sustainable if the composition of vegetation is well-adapted to the regional climatic conditions.     

土地开发整理前期地形图测绘调研分析

通过对重庆市彭水县高谷镇共和村土地开发整理测绘项目的实地调研分析,对该项目进行了归纳总结,介绍项目的测绘技术和流程,旨在为今后推进农村土地开发整理测绘提供实践依据。     

浅谈地票交易二级市场构建问题

明确了构建地票交易二级市场的思路,设定了构建地票交易二级市场应首先明确市场主体、客体、交易场所、交易方式、交易流程及规则等市场要素,并在此基础上分析了地票交易二级市场的开放步骤,最后对市场的监管机制进行了设计,以确保地票交易二级市场的平稳、健康运行。     

农村土地价值的影响因素分析

分析了农村土地价值的影响因素,并从提高土地收入保障角度寻求提高土地价值的途径和方法。结果表明：农村土地的价值不仅体现在土地产生的直接收益,还表现在土地为农民带来的间接收益,包括土地的交换价值和潜在的发展价值。通过产权制度改革、土地经营形式多元化、种植结构调整、农民组织的重构来改变土地利用方式可以增加土地价值,使土地从生存保障发展为投资保障,从而提高农村土地的价值。     

昌吉市土地利用对生态环境的影响分析

在分析昌吉市土地利用现状特点和动态变化的基础上,讨论土地利用对生态环境的影响,指出昌吉市相对脆弱的生态环境和突出的人地矛盾,并提出改善其对环境影响的对策建议。     

Shifts in microbial diversity through land use intensity as drivers of carbon mineralization in soil

Land use practices alter the biomass and structure of soil microbial communities. However, the impact of land management intensity on soil microbial diversity (i.e. richness and evenness) and consequences for functioning is still poorly understood. Here, we addressed this question by coupling molecular characterization of microbial diversity with measurements of carbon (C) mineralization in soils obtained from three locations across Europe, each representing a gradient of land management intensity under different soil and environmental conditions. Bacterial and fungal diversity were characterized by high throughput sequencing of ribosomal genes. Carbon cycling activities (i.e., mineralization of autochthonous soil organic matter, mineralization of allochthonous plant residues) were measured by quantifying ¹²C- and ¹³C-CO₂ release after soils had been amended, or not, with ¹³C-labelled wheat residues. Variation partitioning analysis was used to rank biological and physicochemical soil parameters according to their relative contribution to these activities. Across all three locations, microbial diversity was greatest at intermediate levels of land use intensity, indicating that optimal management of soil microbial diversity might not be achieved under the least intensive agriculture. Microbial richness was the best predictor of the C-cycling activities, with bacterial and fungal richness explaining 32.2 and 17% of the intensity of autochthonous soil organic matter mineralization; and fungal richness explaining 77% of the intensity of wheat residues mineralization. Altogether, our results provide evidence that there is scope for improvement in soil management to enhance microbial biodiversity and optimize C transformations mediated by microbial communities in soil.     

安徽省农民“退宅进城入镇”的实践与成效——以天长市铜城镇为例

天长市铜城镇根据当地工业基础较好、农村"空巢户"较多、农民进城入镇的愿望较强烈的现状,通过调查研究,在集中民意的基础上规范操作,开展试点,循序渐进,创造条件,引导农民"退宅进城入镇",并积极引导农村土地流转,解除"退宅进城入镇"农民的后顾之忧。通过开展"退宅进城入镇"工作,为开发土地资源,增加经济效益,促进农地规范流转及农业现代化发展,助推城镇化进程,提高居民的生活质量探索了新道路。