Assessment of land degradation in Mediterranean forests and grazing lands using a landscape unit approach and the normalized difference vegetation index

Land managers need sound, evidence-based information about land degradation patterns and about the effectiveness of their management responses. Obtaining such information is particularly difficult in Mediterranean grazing lands and forests, where a long history of anthropogenic pressure, high topographical and climatic variability, and frequent disturbances combine to create a highly diverse and unstable environment.Our study aimed at designing a methodology to provide land managers in three data-scarce drylands in Spain, Greece, and Cyprus with spatially explicit, up-to-date information on the state of their land, the pressures driving land degradation, and the effectiveness of their management efforts using remotely sensed NDVI data. To translate NDVI values into a land degradation assessment, we analysed the variance of the annual average NDVI within different landscape units, which we identified based on land cover, aspect, and slope steepness parameters. After calibrating and validating the land degradation mapping methodology using field observations, we related the obtained land degradation patterns with spatial information about grazing and wildfire, as well as controlled grazing and afforestation practices.Our methodology proved useful to assess land degradation and management measures in dry, semi-natural ecosystems. It also provided insights into the role of landscape in modulating land degradation. Results indicate that grazing is a significant cause of land degradation even in partially abandoned areas; repeated fires have a negative impact; slope steepness increases the land's sensitivity to grazing; north- and east-facing slopes are less sensitive to fire in the long term than south- and west-facing slopes; and the effectiveness of responses to land degradation is substantially affected by land cover and topography.The methodology presented can be used to overcome the lack of spatially explicit information on the state of the land in drylands of the Mediterranean and beyond, or as a basis for more in-depth studies to plan restoration interventions.     

我国坡地资源利用生态环境效应的研究现状综述

坡地资源是重要的土地资源,开发利用坡地资源是人类极为重要的物资来源。坡地资源利用存在正负两方面的生态环境效应,合理利用有利于养分和水分的循环,不适宜的开发利用将导致养分和水分循环的失调,坡地资源退化。因此,开展坡地资源利用及其生态环境效应研究,探讨各地开发、利用坡地资源模式及坡地资源退化防治措施,对农业生产实践具有十分重要的理论指导意义。文中从3个方面介绍我国坡地资源利用生态环境效应的研究现状:一是坡地资源利用研究的理论方法,包括实地观测试验与防治措施研究;二是从不同尺度包括区域尺度、小流域尺度和坡面尺度研究坡地资源利用的生态环境问题;三是研究坡地资源利用的生态环境效应。最后,综合分析我国坡地资源利用生态环境效应研究存在的问题,指出今后展开深入研究的方向。     

河北省农用地利用集约度时空变异分析

我国人多地少, 农用地集约利用成为社会经济发展的客观要求。本文以河北省县( 市) 为 评价单元, 从投入强度、利用程度、利用效率和持续状况四个层面构建评价指标体系, 采用熵值法 确定指标权重, 综合指数法计算1985~2005 年河北省各县( 市) 的农用地集约度, 并进行农用地利 用集约度的时空变异分析, 以期为河北省农用地集约利用和持续发展提供政策依据。结果表明: 土地投入强度对农用地集约利用水平的影响较大, 各县( 市) 农用地集约利用水平表现出明显的 区域性差异, 农用地的投入强度和持续状况都表现出提高的趋势, 而农用地的利用程度和利用效 率则有所下降。     

干旱区可持续土地利用模式——以天山北坡为例

Sustainable land use patterns are ecological and economic prerequisites of regional sustainable development. This is especially true for arid lands, where the environment is wholly fragile thanks to extremely limited precipitation, and where human activities have greatly transformed natural desert system by clearing natural vegetation, expanding oases and even building dams on inland rivers. However, the current studies on land use patterns are still characterized by field investigations and case studies, with almost no solid scientific basis. This paper holds that land types and their combination patterns are the principal basis for designing sustainable land use patterns, and that GIS and RS-based large-scale land type mapping and the study of their spatial combination structures should be coordinated with the demand of social development. The existing environmental problems induced by irrational land use mostly result from their deviation from the natural properties of land types. Taking the northern slope of the Tianshan Mountains (NSTM) as an example and considering land type patterns as the basis of land use patterns, this paper improves the vertical oasis- and-mid-mountain two-belts development model and the sustainable mountain land use model for arid lands put forward in recent years; and in terms of oases patterns, it outlines oasis development models, including intensive land use pattern in alluvial-diluvial fans, moderate agricultural development pattern in alluvial plains, and ecological land use pattern in river-end oases.     

农业多功能性与都市区土地利用管理——框架和案例分析

采用理论和案例分析相结合的方法探讨了农业多功能性对都市区土地利用管理的意义和实现途径。论文从农业多功能性的多尺度嵌套层级结构出发,构建了基于农业多功能性评价的都市区土地利用管理框架,然后基于高清卫星遥感影像解译、文献资料整理等分析了北京市海淀区1968—2014年间土地利用、农业多功能性和土地利用管理措施的变化及相互作用。研究指出：都市区土地利用管理者应该在区域尺度和农户/农园尺度农业多功能性评价的基础上,围绕农户/农园与区域、国家等各级社会经济系统的相互作用,从改进土地用途管制分区和发展多功能农业两个方面进行区域的农业用地管理。最后,展望了未来的研究方向,希望优化都市区土地利用管理,推动都市型现代农业建设,并促进区域可持续发展。     

干旱地区径流农业系统和保水方法的试验研究——以宁夏盐池县为例

本文通过小流域径流农业系统的合理布局、最佳结构形式以及防洪、防淤的试验研究。根据坡地径流理论,建立坡地表面径流平衡方程,计算了坡面不同技术处理的多年平均流量。降雨集存系统和保水技术对于改善干旱地区生态环境,加速某些地区的沙漠化综合治理,对封闭农业环境进行人工调控,为干旱地区创造成本低、质量高的新水源等提供科学依据。     

Sustainable land-use patterns for arid lands:A case study in the northern slope areas of the Tianshan Mountains

Sustainable land use patterns are ecological and economic prerequisites of regional sustainable development. This is especially true for arid lands, where the environment is wholly fragile thanks to extremely limited precipitation, and where human activities have greatly transformed natural desert system by clearing natural vegetation, expanding oases and even building dams on inland rivers. However, the current studies on land use patterns are still characterized by field investigations and case studies, with almost no solid scientific basis. This paper holds that land types and their combination patterns are the principal basis for designing sustainable land use patterns, and that GIS and RS-based large-scale land type mapping and the study of their spatial combination structures should be coordinated with the demand of social development. The existing environmental problems induced by irrational land use mostly result from their deviation from the natural properties of land types. Taking the northern slope of the Tianshan Mountains (NSTM) as an example and considering land type patterns as the basis of land use patterns, this paper improves the vertical oasis- and-mid-mountain two-belts development model and the sustainable mountain land use model for arid lands put forward in recent years; and in terms of oases patterns, it outlines oasis development models, including intensive land use pattern in alluvial-diluvial fans, moderate agricultural development pattern in alluvial plains, and ecological land use pattern in river-end oases.     

土地征收中生态补偿缺失对农民权利的影响

文章采用资料分析,理论分析的方法,归纳总结了国内外土地征收补偿中都存在着生态补偿缺失的问题, 尤其是中国的征收补偿制度存在明显缺陷,如补偿理论支持不足、补偿范围小、补偿额度低、补偿不到位等。这种制 度缺陷不仅造成了大量的耕地流失,同时也造成了农业生态环境的破坏,直接影响了土地使用权人———农民的相 关利益,如土地被征收导致土地分割,形成不经济的土地规模,造成土地利用效率的损失,降低了相邻土地的生产 力,影响了农民的相邻权;土地又是农民世代生存、繁衍、发展之所在,是农民的基本生活保障和基本生活来源,农 民失去土地就意味着失去了生存和发展的基础,影响了生存权和发展权;土地的资源属性表明,土地征收必然涉及 到土地利用的变化和生态环境因素的改变,涉及到农民的环境权的保障。为此,必须完善土地征收制度,建立有效 的市场化运作手段,通过对农地生态价值的正确评估,公平、合理的补偿失地农民的损失,以实现社会公平、和谐。     

呼和浩特市居住用地地价分布的时空特征

分析城市内部基准地价的时空格局,有助于土地市场的宏观调控和土地资源的优化配置。本文以呼和浩特 市区为研究区,在城市居住用地土地价格调查和动态监测的基础上,对2001~2007 年居住用地分布的时空特征进 行分析。主要结论如下：城市主城区居住用地的级别和基准地价由内向外顺次降低,但级别边界受到城市道路的直 接影响;基准地价与级别之间存在着显著的负相关关系,随着城市的发展,高低级别间基准地价的差距进一步扩 大;研究期内,基准地价变化在时间上呈现出阶段性特征,在空间上城市中心区和城乡结合部基准地价增幅最快, 城市腹地稍慢,近郊区最慢。     

田间滴灌入渗与蒸发条件下土壤水盐分布特征

2006年在新疆阿克苏阿瓦提丰收灌区通过田间试验,研究了滴灌入渗和蒸发条件下土壤水盐分布规律。结果表明:滴头流量增加时水平方向含水量增加,纵向含水量减小;滴头下方土壤含盐量与滴头流量成负相关关系,随着滴头流量的增加,盐分累积的深度依次减小;土壤盐分的淋洗效率和压盐深度均与灌水历时成正比;覆膜不仅对表层土壤含水量减小具有显著抑制作用,而且对表层土壤盐分累积有较好的抑制作用,不覆膜处理在0～10 cm深度处土壤盐分增加值最大,覆膜处理盐分增加值的最大值出现在20～30 cm深度处。     

喀斯特山区石漠化成因的差异性定量研究——以贵州省盘县典型石漠化地区为例

珠东区的轻中度石漠化主要由人为因素引起,强度以上石漠化则由人为因素和恶劣的自然条件共同造成;保基区的轻中度石漠化主要是人为因素引起,强度以上石漠化则由自然因素造成;红果区的自然条件好于其它两个研究区,石漠化尤其是强度石漠化主要是土地利用强度大造成的,坡耕地发生中度甚至极强度石漠化。喀斯特石漠化土地的成因类型与恢复治理模式密切相关,在确定石漠化土地的治理恢复模式和治理重点时,有必要考虑石漠化土地的土地利用成因和成因的地域差异性。     

基于坡耕地与聚落空间耦合的三峡库区腹地奉节县人地关系研究

以三峡库区腹地奉节县的27个乡镇为例,应用网格分析技术,以1km×1km网格为单元,揭示了聚落与坡耕地资源之间的配置关系以及不同岩性区聚落-坡耕地耦合模式差异,并对研究区人地关系做了类型划分。结果表明：①奉节县27个乡镇聚落和坡耕地的空间分布表现出较强的空间趋同性,二者用地比、斑块等级大小高值都主要位于北部梅溪河河谷和中部长江河谷地区,低值主要分布于南部石灰岩地区;②坡耕地偏多型主要分布于砂岩区,坡耕地偏少型主要分布于石灰岩区,而坡耕地-聚落均衡型则表现出随机分布格局;③研究区坡耕地大量存在的原因主要归结于坡耕地基数大和坡耕地退耕难度大。受坡耕地分布的影响,坡耕地偏多型的土壤侵蚀较其他耦合类型严重;④27个乡镇人地关系划分为人地矛盾突出型、人地矛盾较突出型、人地矛盾较缓和型和人地矛盾缓和型四种类型,而人地矛盾较突出类型所占比重最大,面临着退耕压力和耕地压力突出的双重问题。     

甘肃省近30a来耕地空间动态变化与驱动力分析

通过采用主成分分析法与GM(1,1)模型,分析了近30 a来甘肃省耕地变化的总体趋势、空间差异、耕地复种指数的动态变化与耕地变化驱动力,并对未来耕地变化趋势进行了预测,结果表明:1978年以来,甘肃省耕地面积时增时减,总体呈递减趋势;各市(州)与全省耕地变化相比存在明显空间差异;耕地复种指数呈波动性上升,虽然总体水平在上升,但是耕地复种指数并不高,耕地利用程度有待提高;经济发展水平、人口因素、农业产业结构调整和农业现代化水平是耕地变化的主要驱动力;GM(1,1)预测分析表明在今后一段时间内,在影响因子不变的前提下,耕地面积将持续减少。     

首都圈防沙治沙典型区水土资源优化配置——以河北省怀来县为例

以怀来县为例 ,在分析该县水土资源及土地利用现状的基础上 ,发现水土资源利用存在的问题是 :水资源难以满足土地利用的需求 ,土地利用结构与布局不合理 ;利用灰色线性规划模型 ,进行水土资源的优化配置 ,得出了不同节水条件、不同生态经济目标下 ,9种典型的土地资源优化配置方案 ,为首都圈防沙治沙和水土资源的充分合理利用提供决策依据     

南水北调中线工程水源区农耕地分等定级研究

选取了坡度、土地利用类型、土壤类型、海拔高度、坡向等5个主导评价因子.采用等差指数多因子综合分析与最低限制性因子分析相结合的方法,利用ARCGIS 9.0软件提取相关信息,对南水北调中线工程水源区农耕地进行了分等定级.结果表明,最适宜和中度适宜的土地面积分别占3.4%和36.5%,以中低产田为主;临界适宜和不适宜的土地面积占16.8%和43.4%,具有潜在的宜林宜牧利用价值.研究结果对于水源区制定农业发展政策,科学合理、高效利用土地尤其是耕地资源,实现生态环境保护与经济的协调发展具有重要意义.     

基于转移矩阵的高度城市化区域土地利用演变信息挖掘——以江苏省苏州市为例

深入分析土地利用转移矩阵和地类转移概率矩阵,提出利用连续分时段土地利用转移矩阵求算总时段转移矩阵的方法,进而改进地类变化量和地类动态度计算模型,提出了地类转移无序度的概念、含义并构造计算模型。以苏州市为例进行实证分析,结果显示:1999-2008 年苏州市耕地的总变化量最大,其次是其它农用地和独立工矿用地;其中耕地和独立工矿用地的主导变化是净变化,而其它农用地以交换变化为主;10 年间位列各地类动态度前三位的依次为独立工矿用地、其它农用地和建制镇用地,综合动态度在2004 年和2002 年最大,1999-2001 年较低;地类转移无序度的前二位是其它农用地和交通运输用地,其它地类该值均不高,说明苏州市10 年间的土地利用演化较为有序。研究表明,基于转移矩阵的相关模型的改进和构造深入挖掘了土地利用演变信息,有利于对土地利用变化进行深入研究。     

陕北长城沿线地区1986-2000年沙漠化动态变化分析

 以毛乌素沙地的东南缘部分——陕北长城沿线地区为研究区,以1986—2000年沙漠化动态数据为依据,分析了陕北长城沿线20世纪80年代中期到2000年沙地变化情况。结果表明:该地区14 a来沙漠化土地减少735.1 km2,局部处于稳定的逆转过程,沙地逆转以半固定沙地和半流动沙地为主。但耕地、草地和林地沙漠化仍非常严重,而且新增沙漠化土地中极重度沙漠化土地所占比例较大。近14 a来,沙漠化逆转的原因主要是人类采取了一系列积极的治理沙地措施和国家政策导向。但是由于人口的增加,滥垦、滥牧和滥樵的继续存在,及大规模煤矿资源开发和治理保护的不相协调,致使土地仍在发生沙漠化。     

重庆市梁平县农用地节约集约利用分析与研究

以重庆市梁平县1999年到2005年土地利用状况为依据,结合梁平县的自然、社会、经济条件,建立农用地节约集约利用评价指标体系,采用“熵”值法确定各指标权重,利用指标权重法分别对梁平县近7年来农用地节约集约利用状况和2005年重庆市、重庆市三大经济区及其对应代表区县的农用地节约集约利用情况进行纵向及横向评价,得出梁平县农用地节约集约利用度总体呈现提高趋势但较最高水平仍有差距的结论,并针对评价结果提出相应的建议和措施。     

Assessing farmland dynamics and land degradation on Sahelian landscapes using remotely sensed and socioeconomic data

Through the integration of SPOT HRV, biophysical and socioeconomic information, the study identified population carrying capacities and their vulnerability to land degradation. Land use intensification on the landscapes was quantified into expansion, early and late phases based on the Ruthenberg index calculated using a biennial series of SPOT images for the period 1986-96. Subsequently, farmland dynamic on different landscapes was calculated while observed patterns were linked with agricultural intensification and population carrying capacity. Results show a pattern of agricultural land degradation due to increasing pressure of population and agricultural intensification within a system characterised by little or no use of inputs. Fifty-six percent of the study area supports a population density higher than the carrying capacity (≤ 15 pers/km^-2). Sixty-three percent of the study area is under early to late phases of agricultural intensification. Between 1986-96, cultivation declined 2-3% annually on landscapes with Low risk of degradation but increased by 1-2% on those with Average/Extreme risks. This emphasises the process of land abandonment as farmers move on to cultivating marginal lands despite above normal seasonal rainfalls observed during most of the period. By 1996, cultivation tended to include fields much farther away from the vicinity of villages, compared with 10 years earlier. Furthermore, by 1996, farmlands in the zones of late intensification declined from 12 to 4% and increased from 6 to 11% in the zone under the expansion phase. Indicating that by 1996 substantial amount of the land area required increasing lengths of fallowing. The spatial GIS modelling approach allowed not only identification of zones but synthesis of the observed pattern of landscape degradation. The paper highlights the need for combining remote sensing, biophysical and socio-economic data in environmental degradation studies in developing countries with their poor data availability. The role of developing countries scientists is stressed in taking the forefront to tackle environmental problems, which affect their region. The paper calls for increased co-operation between these scientists and regional and international data providers to overcome data availability problems and pave the way for better local and regional studies on environmental degradation.