Policies related to combating desertification in the United States of America

Desertification in the United States of America is very complex and difficult to combat on a continuing basis and on a large scale. It can be due to improper agricultural practices, livestock grazing, mining, fire management, recreation practices, deforestation, urbanization, and introduction of exotic species. Thus, national, state, and local policies must deal with a wide range of circumstances and land uses, and they must be comprehensive and dynamic, providing flexibility as issues, knowledge, and needs change. The United States can demonstrate many causations, but also successes, in combating desertification. However, much more work is needed to assure sustainable use of millions of hectares, particularly in the drylands of the western United States. A vigilance on policies and their implementation is required to assure that efforts to combat desertification are effective. Over time, some policies outlive their purpose and require change, but that is not always easy to achieve, and many times it takes a concentrated effort over several years or more to bring about, especially if that policy has its basis in law. Although this process sometimes seems slow, new laws continue to be enacted and policies are adopted that address land uses and the difficult task of combating desertification. Several examples are offered to show the variety of actions taken and processes used in the United States. © 1998 John Wiley & Sons, Ltd.     

库布齐沙漠东缘防沙治沙生态效益评价

[目的]研究库布齐沙漠东缘防沙治沙生态效益,为沙漠化治理效益评价提供科学参考。[方法]通过建立了库布齐沙漠东缘防沙治沙生态效益评价指标体系,采取层次分析法和模糊综合评价法进行生态效益评价。[结果]在生态效益评价指标的权重中,排在前3位的分别是植被盖度、地上生物量、草层高度评价指标,植被因子在沙漠化治理中较其他因子更为重要,植被恢复状况对库布齐沙漠化治理的影响显著;基于模糊综合评价结果可知,研究区防沙治沙生态效益值为53,属于一般状况。当地农户普遍认为防沙治沙明显改善了当地生态环境,大多数农户对沙漠化治理工作认同度较高。[结论]随着生态政策和治理措施的推进,治理效益将呈现良好态势;农户生态环保意识较差,还需加强农户生态环保意识,并提高农民文化水平。     

我国农牧交错区土地退化研究——以宁夏盐池县为例

 从荒漠化发展历史角度出发,通过收集历史资料和固定样地观测,采用数学分析方法,利用马尔可夫链(Markov)模型和模糊模式识别方法对盐池荒漠化现状、动态变化以及荒漠化治理措施效益进行分析。结果表明:1)盐池县近半个世纪以来土地荒漠化呈急剧扩大趋势,荒漠化土地面积平均年增长率4.03％。2)盐池县荒漠化主要原因是在脆弱生态环境基础上,人为不合理经济活动所致。3)如果能做到严格执法,全面落实禁牧政策并加强防沙治沙工程管理,盐池县荒漠化土地将得到全面治理,否则盐池县荒漠化形势将继续恶化。认为能否全面落实禁牧和退耕还林政策,将直接影响盐池县荒漠化防治。     

Soil degradation in environmentally sensitive areas driven by urbanization: an example from Southeast Europe

Rapid urbanization together with policy ineffectiveness in controlling urban growth is often associated to soil and land degradation in both the developing and developed world. The present study analyses the relationship between urban expansion and soil degradation in an arid Mediterranean region (Attica, Greece) where the compact settlement pattern has been replaced by low‐density urban development. The study area is one of the most densely populated areas in the Mediterranean basin that has experienced an impressive growth in population during the last 60 yr. Low‐density, dispersed urban settlements developed during the last decade (2000–2010) occupy primarily land at medium‐low soil quality. However, the overall quality conditions of vegetation, climate and soil assessed by our study shows that urban expansion consumed high‐quality land previously classified as non‐vulnerable to desertification. By contrast, compact urban settlements have consumed land of intermediate or even high soil quality, but experience poor climatic and vegetation conditions that are classified as highly vulnerable to desertification. Regional planning should incorporate multi‐dimensional indicators of soil, climate and vegetation quality to evaluate the environmental impact of urban expansion.     

中国防沙治沙60年

根据60年来我国防沙治沙的发展实际,将我国的防沙治沙分为新中国成立初至70年代中期、70年代中期至90年代末期和新世纪3个阶段,分别对不同阶段的有关防沙治沙的环境背景、防沙治沙的开展情况、防沙治沙的成就进行简要的分析和总结,并从历史和现实的角度分别对某些社会关注或有争议的问题客观地表述了作者的看法。     

Combating Aeolian Desertification in Northern China

Progress in combating aeolian desertification (land degradation resulting from wind erosion) has been achieved in an agro‐pastoral ecotone of northern China since the mid‐1980s. This paper reviews three common measures used to combat and control aeolian desertification in such regions. In addition, it introduces a case study on the recovery of a degraded semi‐arid ecosystem to provide regional lessons and support theoretical and practical approaches to desertification prevention and reversal on a global scale. On the basis of the analysis and evaluation of three kinds of typical measures and one regional scale case, this study shows that human‐caused aeolian desertified land can be rehabilitated. Although the technologies and management of combating aeolian desertification in an agro‐pastoral ecotone of northern China still need further improvement through more experimentation and practical application in the future, the experience gained to date contains important lessons for the recovery of degraded land on a global scale. Copyright © 2013 John Wiley & Sons, Ltd.     

Desertification in north China: background,anthropogenic impacts and failures in combating it

Desertification in north China is ongoing despite the endeavours to mitigate it over the past 50 years. Overall examination of the context of desertification and defects of desertification‐combating programmes is a prerequisite for desertification control, which is now attracting general concern in China. The physiographic circumstances of north China, including the dry, continental, mid‐latitude climate, easily erodible soil surface and water shortage, provide the background to desertification. Climatic aridity and the evolution of land use and land management in recent decades have produced great stress on the land. The ineffectiveness of anti‐desertification measures ascribed to inadequate scientific involvement in decision‐making, neglect of the human dimension and the lack of a well‐organized desertification monitoring system are discussed in this paper. Copyright © 2005 John Wiley & Sons, Ltd.     

黔中白云岩石漠区小流域土地利用变化及生态效益

为明析灰质白云岩石漠区和砾质白云岩石漠区综合治理工程中植被恢复模式的治理效果,采用科研示范和工程治理相融合、遥感影像和实地调查相结合的方法,在黔中不同白云岩组石漠化小流域分析了相应研究区及不同林草恢复模式的生态效益变化。结果表明:(1)普定研究区属灰质白云岩石漠区,凯里研究区属砾质白云岩石漠区,2016年2个研究区农林地景观基质相似度较高,普定研究区石漠化趋势性较强。(2)2016—2020年,普定研究区和凯里研究区林地面积转入量>转出量、耕地面积转入量<转出量。植被覆盖率增加、土壤侵蚀模数降低和石漠化等级面积率降低,普定研究区综合治理生态效益显著。(3)普定研究区和凯里研究区植被覆盖率增加量、土壤侵蚀模数降低率和石漠化等级面积降低率呈生态修复模式>封山育林模式>草地畜牧业模式的变化趋势,生态修复模式和封山育林模式的生态效益呈普定研究区>凯里研究区的变化趋势。综上,具有相似景观背景的石漠化小流域经综合治理后,呈植被覆盖率增加、土壤侵蚀模数降低和石漠化等级面积率降低的趋势,石漠化治理效果呈生态修复模式>封山育林模式>草地畜牧业模式的变化趋势,灰质白云岩石漠区治理效果比砾质白云岩石漠区显著。     

西部沙漠化防治技术与模式

总结了我国西部地区沙漠化防治的5大系列，14项适用技术，指出技术推广应解决的问题，并阐述了西部不同气候区沙漠化防治成功模式及其生态、经济效益，介绍了国外利用龟裂地集水、太阳能脱盐建立性畜饮水点工程典型技术模式。     

我国石漠化现状及其防治综述

 从概念、分布范围、成因、研究现状、防治技术和措施等方面对我国石漠化进行分析,提出了石漠化的研究思路、防治技术和措施。     

关岭自治县花江石漠化的成因及防治措施

 花江石漠化综合防治工程自1991—2003年治理石漠化面积47.63 km2,其中,轻度以上石漠化面积30.88 km2,占总面积的65%。通过山坡下部坡改梯,种植花椒和砂仁等经果林,配套小型水利水保工程,以及山坡上部加强植被管护,发挥生态自我修复能力等措施,石漠化的发展得到有效遏制。项目区贫困人口由1997年的3072人减少到2003年的764人,年人均纯收入由120元增加到1800元,林灌草覆盖率由14.16%增加到21.29%。该项目为今后大规模治理石漠化积累了经验。     

中国沙漠化研究

中国沙漠化研究伴随着北方干旱和半干旱区自然资源的开发利用，经历了近50年的艰苦探索历程，为国民经济建设和我国沙漠科学体系的建立与发展都做出了重要贡献。重点阐述了中国沙漠化研究领域在有关沙漠化的环境背景研究、沙漠化的物理学和生物学过程研究、沙漠化监测与评价、沙漠化景观生态学研究、沙漠化的植物逆境生理学研究、沙漠化地区水土资源的高效利用与可持续发展、沙漠化整治模式和技术体系研究等方面的主要进展及成就。并进一步明确了开展中国北方沙漠化过程及其防治研究的主要科学问题、研究内容和目标。     

The nature,causes and consequences of desertification in the drylands of Africa

The dryland environment of Africa poses formidable problems for sustainable development. Among these are unpredictable and severe drought, desiccation or aridification due to persistent drought and dryland degradation or desertification. Because these problems overlap in their effects on the ground, often those who seek sustainable development for these drylands tend to view the problems as one and the same. Yet to facilitate the development of appropriate and effective mitigating measures it is important that the differences and interrelationships be clearly understood. This article starts by outlining the differences and interlinkages between desertification, drought, desiccation and climate change and their causal factors. The central theme is the human causes and consequences of desertification in the drylands of Africa. An attempt has been made to unravel the changing views on the human causes, this is followed by a brief outline of the intervening plans and actions to stem the problem. A significant drawback in combating desertification and drought is the failure of African governments to devolve power to the people who are affected, and to link environmental degradation to economic policy. Consequently, many programmes lack local support or are undermined by conflicting trade and agricultural policies pursued by governments. It is contended that, for sustainable development strategies to work, policies should put the welfare of the people in these drylands at the centre of the development agenda and give them the rights and the power to determine their future. They should empower the people to sustain adaptive strategies towards sustainable livelihoods. Also the threats posed to environment and sustainable development by protectionism and overconsumption in the north and structural adjustment programmes (SAPs), call for the removal of distortions created by the import barriers of developed country, the curbing of overconsumption and a fundamental revision in the structure of SAPs to help alleviate poverty and protect the environment in these African countries. It is in the interest of the global community that the environment in Africa is protected. © 1998 John Wiley & Sons, Ltd.     

Effects of land use and landscape on spatial distribution and morphological features of gullies in an agropastoral area in Sardinia (Italy)

According to the United Nations Convention to Combat Desertification (UNCCD), soil erosion is one of the main causes of desertification in the Northern Mediterranean. Recently, the role of channelled erosion in sediment delivery has been underlined by several studies. The aim of this paper is to describe a simplified experimental methodology settled up for studying the relationships between gully erosion and land use.The experimental site, which is wide about 720 ha, is located in a hilly area threatened by desertification in Central Eastern Sardinia (Italy). This area is characterised by irregular morphology with steep slopes, where agropastoral activities, particularly tillage with heavy machinery and overgrazing, are causing severe soil erosion and compromising agricultural productivity. Previous studies carried out in the same area highlighted the need to quantify and monitor soil erosion in order to outline management guidelines for farmers. In this study, an integrated methodology that uses aerial photographs and field surveys was applied to inventory the gullies of the area. The degree of activity and morphological characteristics of gullies were assessed in the field by measuring the position and shape of gully heads, and their width and depth. Total gully volume was also estimated. Relationships among distribution, density and morphological characteristics of gullies, and geomorphological features, land use and land use historical dynamics of the area have been studied. The results show the very significant impact of agricultural activities on gully activity and density.     

我国荒漠化地区土地退化的防治措施

该探讨了荒漠化的定义及我国荒漠化危害，从荒漠化过程监测、生物措施稳定性、荒漠化治理综合效益、荒漠化土地造林技术和荒漠化的防治途径方面进行了研究和探讨，并对今后我国荒漠化防治工作提出了几点建议。     

Fifty Years on: Long‐term Patterns of Land Sensitivity to Desertification in Italy

The Mediterranean region has been regarded as a critical hotspot for desertification due to the impact of soil degradation, the land‐use changes and the climate variations. Few large‐scale studies have been devoted to analyse trends in land sensitivity to desertification in the northern Mediterranean basin. The present paper contributes to this deserving issue by quantifying the level of land sensitivity to desertification in Italy at seven points between 1960 and 2010 at a fine spatial scale. The approach used followed the Environmentally Sensitive Area scheme that assesses changes in four key themes (climate, soil, vegetation and land management) related to land degradation processes. Italian land was classified into four levels of sensitivity to desertification (non‐affected, potentially affected, fragile and critical) according to the Environmentally Sensitive Area framework. Interestingly, although land surface area classified as ‘fragile’ and ‘critical’ grew homogeneously in Italy between 1960 and 1990, the increase observed in the most recent time period was spatially clustered and contributed to reverse the polarisation in ‘structurally vulnerable’ and ‘non‐affected’ regions observed in Italy. The paper discussed these trends in the light of socioeconomic changes that occurred in Italy after World War II. Copyright © 2013 John Wiley & Sons, Ltd.     

浑善达克沙地荒漠化灾害预警指标体系的研究

以防为主的荒漠化防治策略是荒漠化危害预警的基本出发点,因此对于荒漠化预警的研究尤显重要,但是长期以来人们一直没有形成一个统一的荒漠化预警指标体系,使预警工作难以进行.以地表稳定性为依据,结合当地植被盖度,通过对实地调查数据进行分析,初步提出浑善达克沙地荒漠化灾害预警指标体系.但是由于研究问题本身的复杂性以及工作范围的局限,建立普遍适用的荒漠化预警体系和模型还有待于进一步的深入.     

我国荒漠化评价研究综述

 中国是世界上受荒漠化危害最为严重的国家之一,准确、全面、及时的荒漠化评价有助于人类制订有效的治理措施。从指标体系、评价方法和基准3方面评述了我国近30a来荒漠化评价的研究成果,指出以景观生态学原理和遥感技术为基础的评价指标体系已成为近年来的研究热点,但目前仍存在指标选择标准不明确,分级阈值确定存在主观性和评价结果缺乏可信度等问题。评述了欧氏距离法、沙漠化程度指数等评价模型的优点和不足,指出近年来荒漠化评价方法研究与景观生态学和3S技术结合,逐步向多尺度、定量化和简便快捷发展,但仍需对方法的可靠性进行验证。介绍了荒漠化基准研究中的主要观点,并提出可以将荒漠化治理的目标作为基准。     

中国荒漠化的形成原因和分布特征

 世界上的沙漠主要分布在副热带,唯独我国的沙漠分布在温带。根据有关文献和1994年我国沙漠化普查资料,介绍国内外现代干旱和沙漠化现状,分析青藏高原隆升、末次大冰期、水土资源分布、气候变化、社会经济干旱和人类不合理经济活动对我国北方沙漠化形成和分布的影响,以及未来发展趋势。建议要尽快实施跨流域调水、节水林牧业和依法治沙,彻底改变“三北”地区的干旱荒漠面貌。     

喀斯特石漠化生态治理技术集成及其多尺度综合配置

[目的] 构建石漠化治理技术库体系及其综合配置方法,旨在为今后石漠化治理提供参考依据。[方法] 通过查阅大量文献资料,以水土保持综合治理为导向,对现有石漠化治理技术和模式进行系统总结。[结果] 构建了一个能满足不同石漠化土地类型和不同尺度石漠化治理需要的石漠化治理技术库体系。并提出了一套可在不同治理背景下快速筛选和多尺度优化配置石漠化治理技术的方法。此外,还对一些石漠化治理相关的重要概念进行了厘清和界定。[结论] 新时代的石漠化治理是一条将石漠化治理融入地区绿色高质量发展,以高质量生态建设保障高质量发展的道路。因此,石漠化治理没有万能公式,任何方案均需结合治理区的立地条件和区域社会经济条件来确定和细化。