Abstract

Soil and geobotanical studies were carried out in a landscape district within the Northern Sarpa lowland of the Caspian Depression in a zone of light-chestnut soil. The collected data made it possible to assess the variation of soil-salinity values typical for dry-steppe plant species and communities in the Republic of Kalmykia and to produce digital models for a geobotanical indication of soil salinity. Geobotanical plots, soil test pits, and boreholes up to 2 m deep were established along a 64-m transect at 1 m intervals. The pNa salinity index was measured in aqueous suspensions of soil samples (1 : 5). As a result, it became possible to determine the salinity at depths of 0–30, 0–50, and 0–100 cm for 12 plant species and 7 plant communities registered on the transect and to distinguish three plant groups based on their tolerance to soil salinity. The first group includes species confined to nonsaline soils (salt concentrations vary within a narrow range). Plants belonging to the second group tolerate a broad range of salinity values and prefer nonsaline soils. The third group consists of salt loving species (halophytes) confined to saline and highly saline soils. Of the seven plant communities registered on the transect, two occur on nonsaline (down to a depth of 2 m) soils (Stipa lessingiana + Festuca valesiaca + Artemisia lerchiana and Stipa lessingiana + Festuca valesiaca + Tanacetum achilleifolium); two others tend to occur in soils that are not saline to a depth of 50 cm (Festuca valesiaca + Artemisia lerchiana + Tanacetum achilleifolium and Artemisia lerchiana + Tanacetum achilleifolium + Artemisia pauciflora); and three communities occur only on soils that are saline from a depth of 25–50 cm (Kochia prostrata + Artemisia pauciflora, Artemisia pauciflora, and Poa bulbosa + Anabasis aphylla). The Classification and Regression Tree (CART) method makes it possible to predict the soil salinity based on the occurrence of plant species identified as predictors. The prediction accuracy is 80% for the 0- to 30-cm layer, 81% for the 0- to 50-cm layer, and 64% for the 0- to 100-cm layer. The following plants have been identified as important (rank > 60) predictors: Kochia prostrata, Tanacetum achilleifolium, Artemisia austriaca, and Festuca valesiaca. Other species feature low prediction importance (validity) values and therefore cannot be used as predictors.

中文翻译：

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干草原土壤盐分的数字植物指示（卡尔梅克共和国）

摘要

土壤和地质植物学研究在里海-陷北部萨尔帕低地的一个风景区进行，该区位于浅栗树土壤中。收集到的数据使得有可能评估卡尔梅克共和国的典型干草原植物物种和群落的土壤盐度值的变化，并产生用于土壤盐度地球化学指示的数字模型。沿着64 m的样条线以1 m的间隔建立了高达2 m的地质植物学图，土壤测试坑和钻孔。在土壤样品的水悬浮液中（1：5）测量了pNa盐度指数。结果，可以确定0–30、0–50，在样带上注册的12种植物和7个植物群落的0-100 cm区域，并根据其对土壤盐分的耐受性来区分三个植物群。第一组包括仅限于非盐渍土壤的物种（盐浓度在狭窄范围内变化）。属于第二类的植物可以忍受各种盐度值，并且喜欢非盐渍土。第三类由仅限盐和高盐土壤的嗜盐物种（盐生植物）组成。在样带上注册的七个植物群落中，有两个发生在非盐碱土（最深2 m）土壤上（第三类由仅限盐和高盐分土壤的嗜盐物种（盐生植物）组成。在样带上注册的七个植物群落中，有两个发生在非盐碱土（最深2 m）土壤上（第三类由仅限盐和高盐分土壤的嗜盐物种（盐生植物）组成。在样带上注册的七个植物群落中，有两个发生在非盐碱土（最深2 m）土壤上（针茅lessingiana +沟羊茅+蒿lerchiana和针茅lessingiana +沟羊茅+菊蒿属achilleifolium）; 两个人趋向（在不是盐水至50厘米的深度的土壤发生高羊 valesiaca +蒿lerchiana +菊蒿属achilleifolium和蒿lerchiana +菊蒿属 achilleifolium +蒿少花）; 并且三个群落仅出现在含盐的25–50 cm深度的土壤中（地肤+蒿），青蒿和波阿婆+ Anaphylis aphylla）。分类回归树（CART）方法可以根据识别为预测因子的植物物种的出现情况来预测土壤盐分。对于0到30厘米的层，预测精度为80％，对于0到50厘米的层为81％，对于0到100厘米的层为64％。下面的植物已被确定为重要（等级> 60）预测：木地肤，菊蒿achilleifolium，蒿austriaca和沟羊茅。其他物种的预测重要性（有效性）值较低，因此不能用作预测变量。