河北坝上地区土地荒漠化现状及生物对策研究

近几年春季的沙尘暴天气引起了全国上下各界人士的高度关注，河北省坝上地区是悬在京津头顶的沙源地之一，坝上生态环境的优劣对京津乃至广大华北地区影响重大．通过实地考察，了解了坝上地区草场退化及沙化现状，并从生物防治的角度提出了相应的治理措施．

哈萨克斯坦的土地荒漠化问题

1994年6月17日,联合国在巴黎通过了《与荒漠化作斗争公约》,其目的是控制沙漠化进程、恢复利用荒漠化的土地、提高居民生活水平。哈萨克斯坦55%的国土被荒漠覆盖,所有的农业耕作地区经常遭受周期性的旱灾;由于人类活动的影响,共有66%的国土经常受到不同程度的荒漠化威胁。在农业地区,耕地丧失了30%的腐殖土;在工业地区。

沧州滨海二县二场盐荒土地资源及其利用

沧州滨海区域盐荒土地的发生、变化与地域性因素密切相关。所论范围现有盐荒土地１９６．２７２万亩．占其国土总面积的４６％。按照有关原则和指标．将其区分为４个一级类型（土地类）、１４个二级类型（土地型）和５０个三级类型（土地相）。应根据土地属性，因地制宜．采取综合措施利用丰富的盐荒土地资源。

农村土地丢荒问题与治理对策

随着社会经济的发展,城市化建设发展迅速,不少农民纷纷"洗脚上田",来到城市生活。大量良田闲置,耕地逐年荒废,农村土地丢荒现象比比皆是,已成为我国迈入农业现代化进程中一块不可忽视的绊脚石。基于此,本文主要分析土地丢荒的原因、后果,并提出治理对策。

土地规划管理与城乡规划实施的矛盾及建议

经济的发展,对于城乡发展而言,无疑是一次洗礼,城市出现了“土地荒”,这也是有目共睹的,因此城乡规划必须贯彻到底,在土地资源开发利用过程中,土地规划管理与城乡规划实施两者切实存在矛盾。本文重点从矛盾与建议两个方面进行分析阐述,仅供参考。

土地规划管理与城乡规划实施的矛盾及建议

随着社会经济的发展,我国的土地规划管理工作越来越受到重视。在土地资源开发利用过程中,土地规划管理与城乡规划实施两者切实存在矛盾。本文重点从矛盾与建议两个方面进行分析阐述,仅供参考。

农村税费改革中的八难

从目前农村税费改革试点的情况来看,农村税费改革主要有"八难".

战胜“黄风怪”的新武器

《西游记》中,孙悟空遇到黄风怪时,那怪有两大法宝——“干热风”和“黄沙”,十分厉害．后来孙悟空得到灵吉菩萨的“定风丹”和“飞龙宝杖”, 任由黄风怪吹风扬沙,在狂风中岿然不动,终于战胜了凶恶的黄风怪．这个“定风丹”、“飞龙宝杖”降伏风沙恶魔的故事,反映了古代人们的一个愿望:希望能有一种神奇的物质,一种方法,有效地避免由于狂风造成“沙漠化”的危害．

Sedimentation effects of the Dongting Lake Area

According to a long series of measured sediment data, the sedimentation effects of the Dongting Lake Area （DIP,） were studied in light of the relationship between sedimentation characteristics and resources and environment. The result shows that the long-term deposition and the impact of human activities have led to a cycle of the evolution of sedimentation pattern, resulting in sediment disaster effects and resources effects in the DLA. The main features are as follows： 1） The water beach, silt beach, lake marsh beach, reed beach and other types of beach shaped by sedimentation effects constitute the main body of the giant lake system. 2） The disaster chains are induced, i.e., sedimentation → marshland expansion and reclamation → flood function decline, fish resource depletion, biodiversity reduction dis- aster chain, sedimentation → marshland expansion → floods, water pollution disaster chain, sedimentation → marshland floating vegetation rising → schistosomiasis, rodents virulence disaster chain, sedimentation → flood embankment bursting → land desertification disaster chain. 3） Sedimentation has created about 98.13×10^4 hm^2 of land in the past 55 years. Rational development and utilization of marshland resources have produced tremendous economic benefits.

LAND RECLAMATION PROCESS IN NORTHEAST CHINA SINCE 1900

Northeast China is an important agricultural region in China. The NortheastPlain is the largest plain in the country and one of the three famous black soil zones in the world.Despite of fertility of the soil, however, large-scale agricultural development mainly took placesince 1900. The land exploitation and utilization has been fast and intensive in this region sincethen and change in the land-cover process has been remarkable. Both national and internationalresearchers on land use and land cover are paying more attention to these processes in this regionand their implication for local ecological environment. This article discusses the land reclamationprocesses and their main driving forces in Northeast China since 1900. According to the research,the 20th century was the most important period for land reclamation in Northeast China. In theseyears the rate, intensity and quantity of land reclamation have been staggering, and more than 100000km^2 of land was converted into farmland. This magnitude of land reclamation inland is unique inthe world. Research on the land reclamation of Northeast China can provide some data on the effectof human activity on environment. As in many other places in the world, the primary driving force ofreclamation in Northeast China was the increasing pressure of population. In the 20th century thepopulation increased from 10 x 10~6 to 110 x 10~6 in Northeast China and from 400 x 10~6 to 1. 3 x10^9 in China. Population pressure is thus the most important driving force for land reclamation.

Modelling Regional Land Change Scenarios to Assess Land Abandonment and Reforestation Dynamics in the Pyrenees(France)

Over the last decades and centuries,European mountain landscapes have experienced substantial transformations.Natural and anthropogenic LULC changes(land use and land cover changes), especially agro-pastoral activities,have directly influenced the spatial organization and composition of European mountain landscapes.For the past sixty years, natural reforestation has been occurring due to a decline in both agricultural production activities and rural population.Stakeholders, to better anticipate future changes,need spatially and temporally explicit models to identify areas at risk of land change and possible abandonment.This paper presents an integrated approach combining forecasting scenarios and a LULC changes simulation model to assess where LULC changes may occur in the Pyrenees Mountains,based on historical LULC trends and a range of future socio-economic drivers.The proposed methodologyconsiders local specificities of the Pyrenean valleys,sub-regional climate and topographical properties,and regional economic policies.Results indicate that some regions are projected to face strong abandonment, regardless of the scenario conditions.Overall, high rates of change are associated with administrative regions where land productivity is highly dependent on socio-economic drivers and climatic and environmental conditions limit intensive(agricultural and/or pastoral) production and profitability.The combination of the results for the four scenarios allows assessments of where encroachment(e.g.colonization by shrublands) and reforestation are the most probable.This assessment intends to provide insight into the potential future development of the Pyrenees to help identify areas that are the most sensitive to change and to guide decision makers to help their management decisions.

Analyses of environmental impacts of underground coal mining in an arid region using remote sensing and GIS

The influences of coal mining in an arid environment on vegetation coverage, land-use change, desertification, soil and water loss were discussed. A series of available TM/ETM＋ images with no cloud cover from July/August in different years （1990, 1995, 2000 and 2005） were used to analyze the change in various land environmental factors over time. The results show that while mining activity initially had a marked adverse impact on the environment, mine rehabilitation measures have also subsequently played a great role in improving vegetation cover and controlling land desertification and loss of water and soil. The effect of coal mining on vegetation cover is dependent upon the soil type and natural indigenous flora. Results of this investigation imply that mining activity has a greater effect on the vegetation of loess areas than at sandy sites. Although local vegetation coverage was improved by planting in the mining area, the total area of land affected by desertification still in- creased from 26.81% in 1990 when large-scale mine construction was introduced, to 46.79% in 1995. With continuous efforts at rehabilitation, the vegetation cover in the Shendong coal mining area was increasing, and loss of water and soil were effec- tively controlled since 1995. Subsequently, the total area of extreme desertification decreased to 23.24% in 2000 and further to 18.68% in 2005. The total area affected by severe loss of water and soil also decreased since the early 1990＇s （70.61% in 1990, 71.43% in 1995）, to 43.64% in 2000 and 34.93% in 2005, respectively.

Evaluating the Spatial Uncertainty of Future Land Abandonment in a Mountain Valley(Vicdessos, Pyrenees-France): Insights from Model Parameterization and Experiments

European mountains are particularly sensitive to climatic disruptions and land use changes.The latter leads to high rates of natural reforestation over the last 50 years. Faced with the challenge of predicting possible impacts on ecosystem services,LUCC models offer new opportunities for land managers to adapt or mitigate their strategies.Assessing the spatial uncertainty of future LUCC is crucial for the definition of sustainable land use strategies. However, the sources of uncertainty may differ, including the input parameters, the model itself, and the wide range of possible futures. The aim of this paper is to propose a method to assess the probability of occurrence of future LUCC that combines the inherent uncertainty of model parameterization and the ensemble uncertainty of the future based scenarios. For this purpose, we used the Land Change Modeler tool to simulate future LUCC on a study site located in the Pyrenees Mountains(France) and two scenarios illustrating two land use strategies. The model was parameterized with the same driving factors used for its calibration. The definition of ‘static vs. dynamic' and ‘quantitative vs.qualitative(discretized)' driving factors, and their combination resulted in four parameterizations. The combination of model outcomes produced maps of the spatial uncertainty of future LUCC. This work involves adapting the definition of spatial uncertainty in the literature to future-based LUCC studies. It goes beyond the uncertainty of simulation models by integrating the uncertainty of the future to provide maps to help decision makers and land managers.

STATUS, CAUSES AND COMBATING SUGGESTIONS OF SANDY DESERTIFICATION IN QINGHAI-TIBET PLATEAU

The Qinghai-Tibet Plateau is one of the major sandy desertification regions of China. Based on the recent investigation on sandy desertification, this paper analyses the status such as the type, area, distribution and damage of sandy land desertification in the plateau. Through the analysis on the factors affecting sandy desertification in the region’s natural and socio-economic systems as well as the processes and their interrelations, it can be concluded that sandy desertification in the Qinghai-Tibet Plateau resulted from the combined actions of normal natural sand drift processes, natural sandy desertification processes caused by climatic changes and man-made sandy desertification caused by improper human activities. In addition, it also predicts the possible developmental trend including the increase in desertification area and the enhancement in desertification developmental degree with the exacerbation of the complex processes, and finally puts forward some strategic suggestions to combat sandy desertification in the coming years.

Land Deterioration of a Semi-desert Grazing Area in the North-Eastern Zone of Libya （Cyrenaica）

The study focused on one of the important contemporary environmental problems, land deterioration, carried out on a semi-desert rangeland constrained by aridity, in an area stretching between two small cities （Solouk and A1-Abyar） south of the city of Benghazi in north eastern Libya. The vegetation analysis revealed that the plant life is mainly confined to wadis （valleys）. Average vegetation cover was ranging between 39.53% and 69.20%. Biomass was ranging between 28.33 gm/m2 and 129.42 gm/m2, （average soil depth was between 30 cm and 50 cm）, meanwhile 25% of the area is covered by hummocks. The total number of sampled soil seed bank was 25,870 seed/m2, in which the important forage family Fabaceae constituted 450 seed/m2. Life forms spectrum was： 55.2% Therophytes, 26.3% Chamaeopytes, 11.4% Cryptophytes and 7.1% Phanerophytes. Alpha diversity 1.3%-3.4%, and Beta diversity 11.9%-77.6%. The soil showed low organic matter content an lean to alkalinity. The study showed that the area is characterized by harsh climate elements which led to land degradation in the form of low productivity, retrogressive succession, soil erosion, and sandy encroachment from the south desert area. In the last decades the land degradation was accelerated by the accumulative anthropogenic.

Description of desertification evolution in Fuxin district of Liaoning province based on fractal theory

Desertification is the most serious environmental problem in the world today. Fractal feature of granularity composition was studied by using the fractal theory in view of desertification soil in Fuxin district, thereby evolution patterns of desertification was promulgated. The result shows that the self-formation degree of the developing desertification areas is higher than the relatively steady desertification areas. Evolution of desertification is beginning of forming sandy soil of framework composition, and then the sandy soil be came complex by the effect of environment, climate and anthropo-activity.

Determination of the Status of Desertification in the Capital of Mauritania and Development of A Strategy for Combating It

Mauritania, located in the Western Sahara, is one of the least developed countries in the Sahara Desert. Its capital, Nouakchott, which is home to 23% of its population, suffers from soil erosion from the Sahara and saltwater intrusion from the Atlantic Ocean. The local environment is under pressure from the combined effects of climate and socio-economic factors, with desertification being recognized as the greatest threat to life. In this context, high-resolution remote sensing images of Nouakchott obtained during the winters of 1985, 1988, 2000, 2006, and 2010 are selected for interpretation and classification. Analysis of the types of desertification and land use reveals the temporal and spatial characteristics of five distinct time periods from 1985 to 2010. This study analyzes the current status of desertification in Nouakchott and suggests five preventive measures.

Soil Macrofaunal Communities are Heterogeneous in Heathlands with Different Grazing Intensity

Moderate grazing by cattle increases the heterogeneity of soil and vegetation. This has been suggested as an ecologically sustainable mean of managing natural environments endangered by tree encroachment, such as heathlands. Our study was performed to test the impact of grazing intensity on soil macroinvertebrate communities in heterogeneous landscapes in a private property eligible to the Natura 2000 European Network of Special Protection Areas within the Brenne Natural Regional Park （Indre, ~rance）. We sampled macroinvertebrates along a broken line crossing 5 different land-use types, from pasture to pine forest, passing through a besom heath （Erica scoparia） heathland at 3 levels of cattle pressure. We hypothesized that： i） litter-dwelling （mostly arthropods and mollusks） and soil-dwelling macroinvertebrates （mostly earthworms） would respond in an opposite manner to various grazing intensities, and ii） intermediate cattle pressure （pastured heath） would increase soil and community heterogeneity. The results supported the first hypothesis, which was explained by land-use impacts mediated by soil properties. However, our results supported only partly the second hypothesis since maximum dissimilarity （whether in the composition of soil macroinvertebrate communities or in soil features） was observed in only one out of the two pastured heaths where cattle pressure was intermediate.