Quantitative Mapping and Assessment of Environmentally Sensitive Areas to Desertification in Central Iran

Desertification is one of the main environmental and also social and economic problems facing Iran. Seventeen out of 31 Iranian provinces, which are home to approximately 70% of the total population, are affected by desertification. This study aimed to use geographic information system (GIS) and fuzzy logic for mapping environmentally sensitive areas to desertification based on Mediterranean Desertification and Land Use approach in Isfahan province, central Iran. Six desertification indicators including climate, soil, vegetation, soil erosion, groundwater, and management and policy quality were used to determine various types of environmentally sensitive areas to desertification. Seventeen desertification indices affecting the quality of each indicator were spatially mapped and assigned a value between 0 and 1 using a fuzzy logic option of ArcSDM3 software in GIS environment. Results showed that a 21·7% of the study area was classified as critical, 70% as fragile and 5·5% as potential, and 2·9% of the area was not affected by desertification. In the town of Borkhar, 64·2% of the area was classified as critical, followed by the towns of Isfahan and Nayin with 40·2% and 31·8%, respectively. Results at provincial scale indicated that the climate indicator and humidity index with a weighting mean of 0·71 and 0·77 were the most affective factors in the desertification of the study area. The developed model in this study can be used for mapping desertification status in other 16 provinces that contain desert areas. These assessments provide a GIS‐based desertification database that Iran as a member of the United Nation Convention to Combat Desertification can use to report the condition of desertification at national scale. Copyright © 2013 John Wiley & Sons, Ltd.     

贵州省柚木适生区域研究

采用设置样地的方法对贵州省引种的柚木进行生长情况的调查分析.结果表明,贵州省引种柚木的适生区域是南部的南、北盘江低热河谷地区,红水河、南盘江岸边海拔700 m以下以及北盘江两岸海拔550 m以下地区.在适生区域发展柚木采用四旁植树的方法效果最佳,坡地造林宜选择土层厚度80 cm以上的地域,采取反斜坡带状整地效果较好.     

粤北石漠化地区土壤侵蚀的137Cs法研究

据2005年10月的野外调查及对TM卫星影像解译分析结果,研究了粤北不同程度的石漠化地区、不同利用类型土地的¹³⁷Cs区域分布以及土壤侵蚀速率特征。结果表明:粤北石漠化地区土壤¹³⁷Cs活度的平均值为(6.54±0.57) Bq·kg^-1,土壤中¹³⁷Cs水平随石漠化程度增加有先降低然后升高的趋势,表明在重度石漠化阶段,过高的基岩裸露率导致其周围土壤对¹³⁷Cs的集中吸附,¹³⁷Cs在某些沉积小环境内逐渐富集。研究区¹³⁷Cs背景值为(1 433.60±131.40) Bq·m^-2,低于北半球的平均值,¹³⁷Cs剖面分布基本符合指数分布,最高值出现在2~4 cm深度范围内。在轻度、中度石漠化地区,非耕作土壤侵蚀速率的平均值分别为1 369.0、1 833.5 t·km^-2·a^-1;耕作土壤侵蚀速率远高于非耕作土壤,坡度对土壤侵蚀影响非常明显。     

沙漠化草地的恢复与重建途径

在分析国内外草地沙漠化治理现状的基础上,研究1985-1998年沙化草地的自然恢复与人工恢复,结果表明:自然恢复属于进展演替类型,经历"沙生、一年生植物群落"、"根茎禾草杂类草群落"和"丛生禾草群落"三个演替阶段,最终向地带性植被类型发展;其植被物种组成,覆盖度、产草量均呈增加趋势,土壤有机质增加,表土结构变好;人工恢复的效果显著,播种抗旱、抗风沙型植物,可以快速建成植被覆盖地面,同时生产大量优质牧草,是我国沙化草原恢复重建的一条重要途径.     

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。     

1QY—0.9型悬挂式灌渠清淤机的研制

为实现有护坡林木沟渠的机械化清淤，研制出了1QY—0.9型悬挂式灌渠清淤机。该机通过起土铲将淤土铲起，沿轴向喂入到抛土部件中，由抛土部件中的抛土叶轮沿径向抛向沟渠坡顶。试验结果表明：该机平均清淤深度的变异系数为12.20%～13.80%；抛土距离的变异系数为21.50%～32.70%；生产率在抛土距离为11.75～4.90 m时为123.75～210.88 m³·h^-1。该机各项技术指标达到设计要求，并且较为稳定，工作可靠性较好。与传统清淤机械相比，具有可进沟作业，不受沟渠护坡林木的影响，机动性好的优点，作业质量完全满足黄灌区排灌渠道清淤作业的质量要求。     

青海省共和县土地沙化与土地覆盖变化遥感监测研究

以Landsat-TM、ETM＋遥感数据为信息源，对青海省共和县1987年至2002年的土地沙化和土地覆盖变化进行了监测．研究结果表明．应用TM、ETM＋等中分辨率遥感影像，对以县为单位的区域性土地沙化和土地覆盖变化进行监测是适宜的．监测精度可达90％以上；监测期内．研究区的沙化土地面积不断增加，沙化程度也迅速加深，说明沙化土地治理的效果不明显；由于草地围封面积的扩大，一、二类草地的面积显著增加，草场质量显著改善，但由于未封育草地的过牧仍很普遍，三类草地沙化仍很严重；国营农场的撤离和国家退耕还草工程的实施是农田和居民地面积减少的主要原因。     

Prioritisation of conservation areas in the Western Ghats, India

Areas of high conservation value were identified in the Western Ghats using a systematic conservation planning approach. Surrogates were chosen and assessed for effectiveness on the basis of spatial congruence using Pearson’s correlations and Mantel’s tests. The surrogates were, threatened and endemic plant and vertebrate species, unfragmented forest areas, dry forests, sub-regionally rare vegetation types, and a remotely sensed surrogate for unique evergreen ecosystems. At the scale of this analysis, amphibian richness was most highly correlated with overall threatened and endemic species richness, whereas mammals, especially wide-ranging species, were better at capturing overall animal and habitat diversity. There was a significant relationship between a remote sensing based habitat surrogate and endemic tree diversity and composition. None of the taxa or habitats served as a complete surrogate for the others. Sites were prioritised on the basis of their irreplaceability value using all five surrogates. Two alternative reserve networks are presented, one with minimal representation of surrogates, and the second with 3 occurrences of each species and 25% of each habitat type. These networks cover 8% and 29% of the region respectively. Seventy percent of the completely irreplaceable sites are outside the current protected area network. While the existing protected area network meets the minimal representation target for 88% of the species chosen in this study and all of the habitat surrogates, it is not representative with regard to amphibians, endemic tree species and small mammals. Much of the prioritised unprotected area is under reserve forests and can thus be incorporated into a wider network of conservation areas.     

Conservation of Northern European plant diversity: the correspondence with soil pH

Effective biodiversity conservation requires an analysis of the existing reserve system. In temperate and boreal regions, plant diversity has a strong positive association with soil pH. Consequently, in order to protect plant diversity effectively, a relatively large proportion of protected areas should be on high pH soils. Since biodiversity data are never complete for all taxa, biodiversity indicators, e.g., threatened species, should be used. We studied soil pH distributions in protected areas in Northern Europe and tested whether soil pH requirement differs between threatened and non-threatened bryophyte and vascular plant species. As result, the proportion of high pH soils in protected areas was significantly greater than the proportion of these soils in general. This ensures that a large regional pool of plant species preferring high pH soils is relatively well protected. Threatened and non-threatened species in Northern Europe did not differ in their soil pH requirements, but threatened species required a narrower soil pH range than non-threatened species. Consequently, threatened species diversity can be used for indicating overall plant diversity.     

花椒林在喀斯特石漠化治理中的碳汇效益

[目的]评价石漠化地区花椒林的碳汇功能,为石漠化治理工程的碳汇效益提供技术示范与参考。[方法]以贵州省花江喀斯特石漠化治理示范区生态环境综合治理模式下顶坛花椒(Zanthoxylum planispinum)为研究对象,依据当地的石漠化现状,通过测定强度、中度和轻度石漠化和不同龄级的花椒林生物量、土壤深度和持土量,对花椒林碳汇量进行估算。[结果]石漠化程度越高,花椒林碳汇量越低,反之,石漠化程度越低,花椒林碳汇量越大,其中轻度石漠化花椒林碳密度为3.24t/hm2,中度石漠化为3.12t/hm~2,强度石漠化为2.81t/hm~2,轻度中度强度;随着土壤深度和持土量的增加,花椒林碳汇量也呈现增加的趋势。[结论]花椒林的平均碳密度为3.06t/hm~2,花椒林的综合最优碳汇经济效益为1.92×10~4~2.56×10~4元/hm~2。