An integrated methodology for assessing soil salinization, a pre-condition for land desertification

Soil salinization is mainly an arid-zone problem leading to land desertification. It reduces soil quality and limits the growing of crops. The control of this problem involves inventorying, mapping, and monitoring soil salinity, which requires cost-effective, rapid, and reliable methods for determining soil salinity in the field, and rapid, specific data-processing methods. This paper shows the usefulness of an integrated methodology involving a hand-held electromagnetic sensor (Geonics-EM38) and the ESAP (Electrical conductivity or salinity, Sampling, Assessment and Prediction) software for assessing, predicting, and mapping soil salinity. The salinity of a 0.45-ha surface-irrigated plot was analysed by reading the EM38 at 161 locations, and by employing the ESAP software for calibrating the sensor, and predicting and mapping soil salinity at multiple depths. To calibrate the EM38 sensor, the electrical conductivity of the saturation extract (ECe) of 57 soil samples taken at 19 points was measured. The multiple linear regression (MLR) calibration model predicted ECe from EM38 readings with R² ranging from 0.71 to 0.95 for the multiple-depth profile. Furthermore, the MLR calibration model provided field range average estimates of soil salinity. Fifty-seven percent of the field had ECe values above 4 dS m⁻¹. The salinity levels and distribution in the root zone identified areas with inverted profiles, which revealed drainage problems. The integrated method presented is a breakthrough in the ability to accurately and rapidly assess soil salinity in agricultural lands.     

聊城市沙化现状及防治对策的研究与探讨

沙漠和沙漠化是当今重要的环境和发展问题.本文结合聊城市的沙化现状,详细介绍了该市土地沙漠化治理的路线及主要治理模式,并对研究开发的经验与存在的问题进行了分析.     

西藏贡嘎机场周边风沙灾害成因分析研究

西藏贡嘎机场周边因沙源丰富，造成每年的1-5月扬沙满天，严重影响了飞机正常的起降和周边居民的生产、生活乃至生存。经实地调查和气象、水文资料的收集，以及对沙漠化影响因子相关性分析，提出机场周边地区土地沙化和风沙灾害的成因是自然因素和人为因素综合作用的结果，人为因素中的耕地面积、土地垦殖率因子和自然因素中的大风日数因子是风沙灾害形成的主导因子。     

晋西北地区土地沙漠化与农业可持续发展研究

根据野外调查和测年资料,认为晋西北地区土地沙漠化问题,至少在有史记载以前的晚更新世末期（即２７０００￣１００００ａＢＰ）就已继续存在。现代土地沙漠过程是自然环境特别是干旱多风的气候因素起控制作用,而人类不合理的经济活动对沙漠化的发生与发展也起着重要的作用。并讨论了区域沙漠化对农业可持续发展的危害和土地沙漠化防治对策。     

Division of desertification climate types and determination of potential range of desertification in China

ＤｉｖｉｓｉｏｎｏｆｄｅｓｅｒｔｉｆｉｃａｔｉｏｎｃｌｉｍａｔｅｔｙｐｅｓａｎｄｄｅｔｅｒｍｉｎａｔｉｏｎｏｆｐｏｔｅｎｔｉａｌｒａｎｇｅｏｆｄｅｓｅｒｔｉｆｉｃａｔｉｏｎｉｎＣｈｉｎａＣＩＬｏｎｇｊｕｎＷＵＢｏＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＦｏｒ...     

Epibionts, their hard-rock substrates, and phosphogenesis during the Cenomanian–Turonian boundary interval (Bohemian Cretaceous Basin, Czech Republic)

Hard inorganic substrates (rock clasts and rocky bottom) belonging to the Ka k Member of the Korycany Formation (upper Cenomanian–?lower Turonian) and to the Bílá Hora Formation (lower Turonian) have offered a good opportunity for the study of encrusting faunas of the Cenomanian–Turonian boundary interval. Distributional features of cemented epibionts and the recorded period of phosphogenesis enabled the differentiation of two-phases in the Ka k Member conglomerate formation. During the first phase, the rock substrates were occupied by a so-called A-association of encrusters (29 species, with dominance of oysters and bryozoans). This fauna partly changed during the subsequent phosphogenic period and not only survived the following period of reworking and the second phase of conglomerate formation, but also persisted until the onset of calmer sedimentation in the early Turonian. This changed community is named theAtreta-Bdelloidinacommunity (23 species). The opportunistic agglutinated foraminifersBdelloidina cribrosaand/orAcruliammina longalocally dominated the respective communities during several physico-chemically stressed episodes. On sloping substrates, the bivalvesAtretaandSpondylusattached themselves in a preferred orientation (so-called slope orientation). This feature indicates the original position in which some mobile substrates were colonized. Other questions, such as the taphonomy of encrusters and the character of their substrates are also briefly discussed.     

论气候在西非萨赫勒地带荒漠化中的作用：兼谈近期人类活动的影响

西非萨赫勒地带是世界上最严重的荒漠化地区。本文论述了气候在其荒漠化中的作用这一理论问题。文中提出，不能简单化和绝对化对看待这个问题。气候在该地带荒漠化中的作用具有复杂性，既有直接作用，又有间接作用；既能单独起作用，又能与人类过度经济活动因素结合在一起发挥巨大的作用。     

SPATIAL CORRELATION ANALYSIS BETWEEN KARST ROCKY DESERTIFICATION AND LITHOLOGY IN DU''AN YAO AUTONOMOUS COUNTY IN GUANGXI

Du'an Yao Autonomous County is a typical area for the distribution of karst rocky desertification in Guangxi.The indices for the grades of rocky desertification are selected according to the scientific meaning of karst rocky desertification and after the interpretative symbol system of rocky desertification. RS images are established by the landscape characteristics of Du'an karst and its TM image. Relying on RS & GIS means and taking land use map as base map, this paper conducts synthetic analysis on the 1999a TM image (126-043) and the correlation data involving landform, soil, geological map and GPS-database and photo on the spot, and brings forth a map showing the Du'an rocky desertification grades and a digital lithology map. As can be viewed from spatial correlation, the inherent connection is also illuminated between the various levels of rocky desertification and the carbonate lithology.     

吉林省通榆县土地沙化现状分析与综合治理

通榆县是吉林省土地沙化最严重的典型县之一 ,沙化土地面积为 19 75 5× 10 4 hm2 ,占吉林省土地总面积的 2 3 0 %。日趋严重的土地沙化 ,己成为这一地区农业和经济可持续发展最为主要的障碍性因子。通榆县近几十年来的土地沙化 ,主要是在自然背景下 ,人为的影响因素强烈干扰所致 ;过度的人为经济活动对资源的破坏是造成本区土地沙化迅速发展的最主要原因。因此 ,必须坚持人与自然和谐共存的原则 ,并辅之以限制人为过度经济活动的配套措施 ,才能有效地防治土地沙化     

论岩溶石漠化地质背景及其研究意义

石漠化的形成和发展，是脆弱的生态环境地质条件和不合理的人为工程活动共同作用的结果。该文以贵州省岩溶石山地区为例，根据石漠化的分布规律，分析了石漠化的地质成因、区域地质背景以及地质背景研究在石漠化防治中的意义。