新疆玛纳斯流域非农业种植地盐碱性空间变异特征

土壤盐渍化是导致干旱区土地退化的主要原因之一,也是影响干旱区可持续发展和环境改善的基本问题。充分挖掘不同分类体系下盐渍土空间变异性可以为实施开垦或恢复生态措施提供科学依据。以干旱区开垦近50a的玛纳斯流域为研究区,在不同分类体系下,以土壤盐度,p H值,离子类型为指标,分析该区域非农业种植地(弃耕地,盐碱地,裸地,沙地)盐渍土类型的空间分布特征。结果表明:(1)研究区68%的样本属于非盐渍化,不同类型的盐渍土主要以链状分布于泉水溢出带-冲积平原-干三角洲地带,由南向北,区域整体盐分大致遵循先升高后降低再升高趋势,半方差函数分析土壤盐分呈现弱变异,说明这种分布情况是受随机(人为)因素的影响;而p H整体由南向北递增,传统统计学和地统计学的分析结果都表明土壤碱化呈现中等变异,受结构(自然)因素和随机(人为)因素的共同影响。表层土壤除在溢出带为氯化物型盐渍土外,其他地区自南向北由硫酸-氯化物型逐渐变为氯化-硫酸盐型和硫酸盐土、苏打盐土,离子的半方差函数拟合模型结果均是弱变异和中等变异,与美国盐度实验室分类体系的变异性结果相同,此类分布特征也是结构因素和随机因素共同作用的结果。(2)分析五种典型地貌的盐渍土分布,方差分析结果表明,5种地貌类型均呈现盐分表聚特征,碱化度则由南向北递增;其中盐碱特征最为显著的是泉水溢出带。泉水溢出带的盐土垂直方向的变化趋势为由表层至深层,盐土类型由硫酸-氯化物盐土变为氯化盐土;冲积平原和干三角洲样点处全剖面为氯化物-硫酸盐土,冲积洪积扇和沙漠地区则包含所有阴离子盐土类型。对玛纳斯流域盐渍土特性的空间异质性进行分析,可以为下一步有针对性地治理与改善土壤盐渍化提供科学依据。

Analysis of the spatial variational characteristics of saline-alkaline soil types in non-agriculture land in Manas River Basin, Xinjiang, China

Soil salinization is one of the main causes of land degradation, and it affects both sustainable and environmental improvements in arid areas. In this study, we analyzed and exploited the spatial variability of saline-alkaline soil types in the study area under different currently popular saline-alkaline soil classification standards to obtain important information for land reclamation or restoration according to local conditions.The Manas River Basin, which was reclaimed nearly 50 years ago, was selected as the study area because it is a typical mountain-basin structure in western China. Soil properties (pH, soil salinity, and ions) were used as indicators to analyze the spatial characteristics of the distribution of different land-use types of non-agricultural land (abandoned farmland, salt-affected land, bare soil, and desert) with both statistical and geo-statistical methods. There were two popular classification standards used in this paper:The United States Salinity Laboratory classification and Russia Anion classfication (1) With respect to surface soil (0-20 cm), 68% of the surface samples were non-saline soil, and different types of saline soils (slight, moderate, severe and extreme saline soils) classified by the first classification were distributed all over the overflow zone, alluvial plain, and dry delta areas.From south to north, soil salinity increased, decreased, and then increased. The variation in soil salinity was low and affected by random factors, while pH increased overall with moderate variations, affected by both random and structural factors. The types of(Cl/SO₄^2-)anion soil types were classified into four classes:the sulfate, chloride-sulfate, sulfate-chloride and chloride soils, while (CO₃^2-/SO₄^2-) anion soil types were classified into three classes:the sulfate-soda soil,soda soil and soda-sulfate soil. The surface anion soil of the overflow zone area was chloride soil; other anion soil types were from sulfate-chloride soil type to chloride-sulfate soil; sulfate soil,soda saline soil type, exhibited a normal distribution from south to north. The variation in anions was slight and moderate, which means that the influence of random and structural factors was the same as that described in The United States Salinity Laboratory classification. (2) One-way analysis of variance of the characteristics of the saline soil types was carried out for 0-100 cm soil layers in the five landscapes (alluvial fan, alluvial plain, overflow zone, dry delta, and desert) showed that the soil salt content accumulated over the surface, pH increased from south to north either, and the most significant landscape type was the overflow zone. The anion soil types in the vertical (from top to bottom) profile of the overflow zone landscape changed from sulfate-chloride type to chloride type, while the anion soil types of the alluvial plain and dry delta landscapes were chloride-sulfate type; other anion soil types were distributed over the alluvial fan and desert. This study of the spatial heterogeneity of saline-alkaline soil types will provide scientific guidance for government to manage soil resources.