Soils of Mountainous Forests and Their Transformation under the Impact of Fires in Baikal Region

Data on postpyrogenic dynamics of soils under mountainous taiga cedar (Pinus sibirica) and pine (Pinus sylvestris) forests and subtaiga–forest-steppe pine (Pinus sylvestris) forests in the Baikal region are analyzed. Ground litter–humus fires predominating in this region transform the upper diagnostic organic soil horizons and lead to the formation of new pyrogenic organic horizons (Opir). Adverse effects of ground fires on the stock, fractional composition, and water-physical properties of forest litters are shown. Some quantitative parameters of the liquid and solid surface runoff in burnt areas related to the slope gradient, fire intensity, and the time passed after the fire are presented. Pyrogenic destruction of forest ecosystems inevitably induces the degradation of mountainous soils, whose restoration after fires takes tens of years. The products of soil erosion from the burnt out areas complicate the current situation with the pollution of coastal waters of Lake Baikal.     

Algological and Mycological Characterization of Soils under Pine and Birch Forests in the Pasvik Reserve

The structure of algological and mycological complexes in Al–Fe-humus podzols (Albic Podzols) under pine and birch forests of the Pasvik Reserve is characterized. The number of micromycetes is higher in more acid soils of the pine forest, while the species diversity is greater under the birch forest. The genus Penicillium includes the largest number of species. The greatest abundance and occurrence frequency are typical for Penicillium spinulosum, P. glabrum, and Trichoderma viride in pine forest and for Umbelopsis isabellina, Mucor sp., Mortierella alpinа, P. glabrum, Aspergillus ustus, Trichoderma viride, and T. koningii in birch forest. Cyanobacteria–algal cenoses of the investigated soils are predominated by green algae. Soils under birch forest are distinguished by a greater diversity of algal groups due to the presence of diatoms and xanthophytes. Species of frequent occurrence are represented by Pseudococcomyxa simplex and Parietochloris alveolaris in soils of the pine forest and by Tetracystis cf. aplanospora, Halochlorella rubescens, Pseudococcomyxa simplex, Fottea stichococcoides, Klebsormidium flaccidum, Hantzschia amphioxys, Microcoleus vaginatus, and Aphanocapsa sp. in soils under birch forest     

Postpyrogenic Variability of Litter in Mountain Forests of Baikal Region

Eurasian Soil Science - The data of experimental studies on the postpyrogenic dynamics of the litter in mountain taiga cedar (Pinus sibirica), pine (Pinus sylvestris) and subtaiga forest-steppe...     

Atmospheric Nitrogen Deposition and the Properties of Soils in Forests of Vologda Region

Twenty plots (20 m² each) were selected in coniferous and mixed forests of the industrial Vologda district and the Vytegra district without developed industries in Vologda region. In March, snow cores corresponding to the snow cover depth were taken on these plots. In August, soil samples from the 0- to 20-cm layer of litter-free soddy-podzolic soil (Albic Retisol (Ochric)) were taken on the same plots in August. The content of mineral nitrogen (N_min), including its ammonium (NH⁺₄) and nitrate (NO^-₃) forms, was determined in the snow (meltwater) and soil. The contents of total organic carbon, total nitrogen, and elements (Al, Ca); pH; particle size distribution; and microbiological parameters―carbon of microbial biomass (C_mic) and microbial respiration (MR)―were determined in the soil. The ratio MR/C_mic = qCO₂ (specific respiration of microbial biomass, or soil microbial metabolic quotient) was calculated. The content of N_mic in meltwater of two districts was 1.7 mg/L on the average (1.5 and 0.3 mg/L for the NH⁺₄ and NO^–₃ forms, respectively). The annual atmospheric deposition was 0.6–8.9 kg N_min/ha, the value of which in the Vologda district was higher than in the Vytegra district by 40%. Reliable correlations were found between atmospheric NH⁺₄ depositions and C_mic (–0.45), between NH⁺₄ and qCO₂ (0.56), between atmospheric NO^-₃ depositions and the soil NO^-₃ (–0.45), and between NO^-₃ and qCO₂ (–0.58). The content of atmospheric N_min depositions correlated with the ratios C/N (–0.46) and Al/Ca (–0.52) in the soil. In forests with the high input of atmospheric nitrogen (>2.0 kg NH⁺₄/(ha yr) and >6.4 kg N_min/(ha yr)), a tendency of decreasing C_mic, C/N, and Al/Ca, as well as increasing qCO₂, was revealed, which could be indicative of deterioration in the functioning of microbial community and the chemical properties of the soil.     

Moisture Regime of Loamy Sandy Soils of Moscow Meshchera Region under the Impact of Different Surface Planning Operations

Regularities of the moisture regime of soddy-podzolic soils in Moscow Meshchera region under the impact of different surface planning operations were studied in the recreational zone. Soil moisture was determined in the samples taken with an auger. Data on the dynamics of soil moisture in 2014–2016 under different surface conditions—natural and artificial covers (backfill, mulching materials, and paving elements)— were obtained. A reliable (at the level of significance α = 0.05) increase in the soil water content in the 1-m-deep layer was observed on average for all years of research in three experimental variants: a “dry creek” cover with a possible additional inflow of water, mulching of a flat soil surface with shell rock, and mulching with pine needles. The increase in the soil water reserves on these plots reached 31.4, 22.5, and 19.4% in comparison with the control, where the average soil water reserves did not exceed 112 mm of the water layer and were close to the water content at 0.7 of the field water capacity (108 mm of the water layer). In comparison with the control, the unsealed areas of the soil within the rockery and within the paved surface were characterized by the decrease in the water storage by 4.0 and 11.2–30.7% during relatively wet and dry years, respectively. In wet years, this difference was statistically insignificant; in dry years, it was significant. The analysis of chronoisopleths of soil moisture attested to differentiation of the studied variants according to the degree of moistening of the soil profiles.     

Stable Carbon Isotopic Composition of Organic Matter of the Late Pleistocene and Holocene Soils of the Baikal Region

Eurasian Soil Science - The results of studying stable carbon isotopes of the organic matter of Late Pleistocene and Holocene soils of the Baikal region are presented. The δ13С values in...     

Soils of paleocryogenic hummocky-hollow landscapes in the southern Baikal region

The features of ancient periglacial phenomena are widespread in landscapes lying beyond the modern permafrost zone. The specificity of the paleogeographic conditions in the south of the Baikal region resulted in the formation of paleocryogenic landscapes with hummocky-hollow landforms. The paleocryogenic mounds (hummocks) are of rounded or elongated shape, their height is up to 2–3 m, and their width is up to 20–25 m. They are separated by microlows (hollows). This paleocryogenic microtopography favors the differentiation of the pedogenesis on the mounds and in the hollows, so the soil cover pattern becomes more complicated. It is composed of polychronous soils organized in complexes with cyclic patterns. Light gray and gray forest soils and leached and ordinary chernozems are developed on the mounds; gray and dark gray forest soils and chernozems with buried horizons are developed in the hollows. The soils of the paleocryogenic complexes differ from one another in their morphology, physical and chemical properties, elemental composition, and humus composition. For the first time, radiocarbon dates have been obtained for the surface and buried humus horizons in the hollows. The results prove the heterochronous nature of the soils of the paleocryogenic landscapes in the south of the Baikal region.     

Effects of Chinese Fir,Loblolly Pine and Deciduous Oak Forests on Nutrient Status of Soils in Northern Subtropics of China

This paper deals with a study on the effects of Chinese fir,lobolly pine and deciduous oak forests o the nutrient status of soils in northern subtropics of China,adopting the principle of forest ecology in the case of similar climate and soil type.The experimental area was situated in the Xiashu Experimental Centre of Forest,where the soil is yellow-brown soil derved from siliceous slope wash.Sample plots of these 3 stands were established to study the nutrient status in litter ,the amount of nutrient uptake by roots,the quantity of nutrient output by percolating water outside the deep layer of soil,and the seasonal dynamics of available nutrient in surface soil.It was whown that the intensity of nutrient cycling in soil under deciduous oak was the highest,and the effect of oak in improving soil fertility was the best.The result of improving soil fertility by Chinese fir was the most inferior,though the intensity of nutrient cycling under that stand was higher than that under loblolly pine stand.The influence of loblolly pine on the improvement of soil fertility was better than that of Chinese fir,in spite of its lowest intensity of nutrient cycling.     

Impact of Sewage Sludge Application on the Long-Term Nutrient Balance in Acid Soils of Scots Pine (Pinus Sylvestris,L.) Forests

The objective of the investigation was to determine the effectsof sewage sludge application on nutrient concentrations in soil and plant biomass fractions in Scots pine forests (Pinus sylvestris, L.), situated on sandy soils with low pH, in a south to north temperature gradient in Sweden. Twenty tons dw ha^-1 of sewage sludge was applied in 50 to 60 yr old pine forests at foursites from Brösarp in South Sweden to Jukkasjärvi in thenorthern parts of the country.Application of 20 ton dw ha^-1 of sewage sludge significantlyincreased the concentrations of extractable N, P, K, Ca, Mg and Na, in both the mor layer and in the upper 10 cm of the mineral soil. Three years after sludge application K concentrations were only significantly increased in the upper 10 cm of the mineral soil. After 11 yr the concentrations of P were still at the samelevel in the mor layer as after three years. The concentrations of Ca, Mg and Na had slightly decreased only in the mor layer. There was, in most cases, a statistically significant positive correlation between the amount of applied sludge and nutrientconcentrations in the soil, as well as in pine needles and in leaves of Vaccinium vitis-idaea.In all sites, Mg concentrations in the mor layer was positivelyand significantly correlated with Mg concentrations in current-year pine needles. Similarly, concentrations of Ca, Mg,and P in the mor layer were correlated with concentrations of these elements in current-year shorts of Vaccinium vitis-idaea.     

Soil Pollution in Urbanized Centers of Baikal Region

Eurasian Soil Science - A comparative assessment of soil pollution in urbanized centers of the Baikal region is given. It is based on statistical information, cartographic materials, and data of...     

黄土丘陵沟壑区典型林地土壤微生物、酶活性和养分特征

通过对陕西吴起县黄土沟壑区退耕还林地不同林分(沙棘、刺槐、油松、小叶杨)根际与非根际土壤养分、酶活性和微生物特征进行研究,比较4种典型林分及退耕草地“根际效应”及根际对养分的截留效应,评价根际效应对土壤特性产生不同改良效果,为黄土沟壑区退耕地人工林科学选择造林树种提供理论支持。研究表明:1根际与非根际土壤中有机质含量、有效磷含量、碱解氮含量和速效钾含量表现出显著差异,有机质、有效磷、速效钾含量均呈现明显的根际聚集现象。2根际土壤微生物数量和土壤酶活性总体高于非根际,仅油松样地中过氧化氢酶活性和小叶杨样地中脲酶活性根际低于非根际。3根际土壤中脲酶活性与细菌和真菌数量相关性达到显著水平,过氧化氢酶活性与真菌相关性达到显著水平;有机质含量与细菌、放线菌数量和脲酶活性相关性达到显著水平;碱解氮、有效磷含量均与细菌、真菌数量和脲酶活性相关性达到显著水平。在非根际土壤中,土壤养分含量与土壤微生物、土壤酶活性的相关性明显降低。4从土壤肥力综合水平看,根际土壤肥力水平综合得分总体上大于非根际土壤,其中根际土壤中沙棘小叶杨油松刺槐草地。沙棘能大幅度提高土壤肥力,具有较好的土壤改良效果。     

Influence of Zeolite Application on Nitrogen Efficiency and Loss in Canola Production under Sandy Soils Conditions

A field experiment was carried out in a semi-arid region of Iran during the 2006–2007 growing season to investigate canola seed yield as affected by nitrogen (N) and natural zeolite (Z) rates. This experiment studied N efficiency and N leaching loss in a sandy soil. Experimental treatments consisted of a factorial combination of three N levels (90, 180, and 270 kg N ha^?1) and four zeolite rates (0, 3, 6, and 9 t zeolite ha^?1). The result showed that the greatest seed yield (2452.3 kg ha^?1) was obtained from the N₂₇₀Z₉ treatment whereas the control treatment (N₀Z₀) produced the lowest seed yield (1038.3 kg ha^?1). Moreover, use of 270 kg N ha^?1 without zeolite (N₂₇₀Z₀) led to the greatest amount of N leaching loss (144.23 kg ha^?1). Zeolite application clearly reduced N leaching loss in all N rates. This justified low N-use efficiency in high N applications. More N uptake and more canola seed yield is attributed to zeolite application.     

Postpyrogenic Polycyclic Soils in the Forests of Yakutia and Transbaikal region

Periodical forest fires are typical natural events under the environmental and climatic conditions of central and southern Yakutia and Transbaikal region of Russia. Strong surface fires activate exogenous geomorphological processes. As a result, soils with polycyclic profiles are developed in the trans-accumulative landscape positions. These soils are specified by the presence of two–three buried humus horizons with abundant charcoal under the modern humus horizon. This indicates that these soils have been subjected to two–three cycles of zonal pedogenesis during their development. The buried pyrogenic humus horizons accumulate are enriched in humus; nitrogen; total and oxalate-extractable iron; exchangeable bases (Са⁺² and Mg⁺²); and the fractions of coarse silt, physical clay (<0.01 mm), and clay (<0.001 mm) particles in comparison with the neighboring mineral horizons of the soil profile. The humus of buried pyrogenic horizons is characterized by the increased content of humic acids, particularly, those bound with mobile sesquioxides (HA-1) and calcium (HA-2) and by certain changes in the type of humus.     

Degradation and Leaching of Simazine in Arctic Sandy Soils

Abstract

Degradation and leaching of ¹⁴C-labelled simazine in coarse sandy soils at 15 + 1°C were investigated using radiometric and mass-spectrometric methods. During 6 months incubation approx. 4–7% of the applied ¹⁴C-simazine was evolved as ¹⁴CO₂. 4–9% of the simazine still remained in the soil. Addition of hen manure or acidification by addition of peat did not clearly influence the rate of degradation of simazine, whereas mechanical treatment significantly increased its degradation. In a nitrogen atmosphere the rate of degradation of simazine was reduced.

9–15% of the simazine or its radioactive metabolites leached through a 33 cm sandy moraine soil column (diameter 6 cm) in ca. 1770 mm of precipitation over a 4 month period, and 2% was leached from a fine sand soil under the same conditions.     

砂质农业土壤养分积累和迁移特点的研究

研究表明，砂质土壤开垦农用后，土壤有机质和保肥性（CEC）明显下降。除大棚蔬菜地外，施用的氮和钾肥不易在土壤中积累，很容易在短时间内沿剖面迁移至地下水，或随地表径流迁移至周围水体。但磷可以活性较高的可提取态形式积累在砂质土壤剖面中，并可逐渐随水进入地下水或迁至地表水，对环境造成危害。长期施用化肥的砂质农地地下水中磷、氮浓度可达到较高的水平。田间观测和模拟淋洗试验表明，砂土中养分极易随水迁移，高浓度的养分流失常发生在施肥后的降雨过程中。因此在砂质土壤上应避免高量施肥，肥料宜少量多次施用，不宜在雨前施用肥料。     

毛乌素沙地巴图塔沙柳沙障对植被恢复作用的研究

以毛乌素沙地巴图塔沙柳基地为研究区域,采用野外调查和统计分析相结合的方法,对沙障设置前后的植被动态变化、物种多样性进行研究,进而分析沙柳沙障对植被恢复的影响。研究结果表明:随着沙障设置年限的增加,群落的物种数增加;群落类型由沙障设置前的沙米+沙竹群落发展成沙柳人工植被群落,在演替过程中无物种消失,物种多样性与沙障设置年限基本呈正相关关系。证明流动沙丘上植被恢复过程中沙柳沙障起着重要促进作用。     

不同林型红松林土壤真菌群落组成和多样性

采用基于ITS(Internal Transcribed Spacer)序列的Illumina MiSeq高通量测序技术,分析凉水国家级自然保护区的云冷杉红松林、椴树红松林、红松人工林和红松天然次生林四种林型的土壤真菌群落组成和多样性。共获得1 316个OTUs,四种林型的土壤含有大量未知真菌,在已知真菌类群中,子囊菌门(Ascomycota)和担子菌门(Basidiomycota)为优势菌门,其中后者在四种林型土壤中的分布差异显著(P0.05)。α多样性分析结果表明:原始红松林(云冷杉红松林和椴树红松林)真菌群落丰富度指数(Ace和Chao1指数)显著高于红松天然次生林(P0.05)。β多样性分析显示:四种林型土壤真菌群落组成差异显著(R=0.537,P=0.001),但两种原始红松林之间、人工林和天然次生林之间组成无显著差异。土壤全氮、总有机碳、pH、水分含量和总孔隙度是显著影响四种林型土壤真菌群落组成的环境因子(P0.05)。研究结果为原始红松林的保护、人工植被恢复和真菌资源的开发利用提供依据。     

砂质土壤磷素的组成特点与释放规律研究

砂质土壤磷素主要以可提取态形式积累,有很高的释放潜力。该类土壤磷素的释放受土壤pH、土水作用时间和土壤溶液化学组成等的影响。土壤酸化、土壤溶液中Na+浓度的提高及土壤与水的作用时间增加可促进土壤磷素的释放。用淋洗方法和平衡提取等2种方法对土壤磷素的释放评价表明,淋洗方法测得的P量较小,可代表土壤短期内P释放强度;而平衡提取法提取的P数量较大,可代表土壤P长期释放的容量。     

科尔沁沙地不同风沙土的风蚀特征

通过风洞实验，研究了科尔沁沙地两种典型风沙土的风蚀特征。流动沙丘土样和农田土样的风蚀率随风速的增加均呈幂函数关系增长。风干的农田土样在风速3．7m／s时开始出现风蚀现象，但流沙土样的临界起沙风速是4．3m／s。在低风速段．农田土样的风蚀率大于流沙土样，但当风速增加到大约5．7m／s以上时，流沙土样的风蚀率开始大于农田土样，并且差值随风速的增加而加大。两种土样的风蚀率随土样含水率的增加呈负幂函数关系迅速减小。但流沙土样风蚀率的减小要比农田土样更迅速。流沙土样的临界起沙风速随含水量的增加呈线性关系增长，而农田土样的临界起沙风速随含水量的增加呈二次幂函数关系增长。两种风沙土在风蚀特征方面的差异，主要是由质地不同引起的。增加土壤含水量，是本地区风季减小风蚀的有效方法。