Transformation of old-plowed gray forest soils under the influence of differently aged pine forests in the middle Angara River region

The long-term (55–85 years) influence of pine forests on old-plowed gray forest soils (in the middle Angara River basin) has been reflected in the character of the biological cycle and intensity of the biological processes. The population of actinomycetes decreased, and that of fungi increased, within the whole profiles of these soils. The soil profiles became more differentiated according to eluvial-illuvial types. The thickness of the humus (former plowed) horizons decreased. The thicker differently decomposed litter with the abundant fungal mycelium was formed. The most conservative were relic morphological characteristics: plow sole, humus tongues, and the illuvial-metamorphic horizon.     

The influence of pine forests of different ages on the biological activity of layland soils in the middle Angara River basin

The influence of pine forests of different ages (from 25 to 85 years) restoring on old plow land soils is reflected in the biological processes proceeding in them. The drastic decrease in the absolute and relative number of actinomycetes, along with an increase of the fungal population in the microbial complexes of the soils (within the whole profiles), indicates that the microbocenoses acquire “forest” properties. In the soils under the younger pine forests, the processes of microbiological mineralization and specific respiration activity are more active than in the soils under the older pine forests. With the age of the pine forests, the soil profiles become more differentiated according to the eluvial-illuvial type.     

Microbiological diagnostics of the status of pyrogenically changed pine forests in the Lower Angara River basin

The structure and functions of the microbial complexes in the soils after surface fires of different intensity were studied. The fires of high and medium intensity were found to lead to a significant decrease in the number and functional activity of microorganisms participating in the nitrogen-carbon cycle. The degree of changes in the postfire status of the soil microbocenoses was revealed to be related to the joint action of pyrogenesis and the hydrothermal conditions at the moment of the fire rather than to the fire intensity. The favorable combination of the elevated soil moisture and soil heating stimulates the microbiological processes of organic matter mineralization, thus, improving the forest-growing conditions for the pine forests. The microbial biomass, basal respiration, and the microbial metabolic coefficient are shown to adequately reflect the postfire status of the microbial complexes.     

Post-pyrogenic changes in the hydrothermal parameters of soils in middle-taiga pine forests

Results of long-term studies in middle-taiga pine forests on sandy podzols after controlled surface fires are presented. The changes in the soil hydrothermal conditions caused by the pyrogenic transformation of the soil and the pyrogenic and postpyrogenic changes in other components of the forest biogeocenoses were revealed. Along with the general character of the changes in the soils’ hydrothermal conditions, some differences in the degree of their manifestation between different regions due to the different fire intensities were revealed. It was concluded that the pyrogenic impact disturbed the existing material and energy exchange between the atmosphere and the soil, which is the main process of soil formation and development. Consequently, forest fires are a powerful and active factor of recent pedogenesis.     

Post-fire transformation of the microbial complexes in soils of larch forests in the lower Angara River region

The postfire transformation of the functional activity of the microbial cenoses and the main soil properties under mixed larch forests were studied in the lower reaches of the Angara River. It was shown that the intensity of the postfire changes in the population density, biomass, and activity of the microorganisms in the dark podzolized brown forest soil depended on the degree of burning of the ground cover and the surface litter during the fire. The maximum effects of the fire on the microbial cenoses were observed in the litter and the upper 5-cm-thick layer of the dark-humus horizon in the areas of intense burning. The postfire restoration of the structural-functional activity of the microbial cenoses was determined by the degree of transformation of soil properties and by the postpyrogenic succession in the ground cover. The microbial complexes of the dark podzolized brown forest soils under mixed larch forests in the studied region restored their functional activity after the fires of different intensities quicker than the microbial cenoses of the sandy podzols in the pyrogenic lichen-green-moss pine forests of the same zone.     

长江中游水稻土潜育作用的特点

The gleyization of representative paddy soils in the middle reaches of the Yangtze River was characterized, taking oxidation-reduction potential(Eh), the amount of active reducing substances and the forms of iron and manganese as the parameters. The Eh value was linearly related with the logarithm of the amount of active reducing substances, which was contributed by ferrous iron by 83% on an average. The degree of gleyization of different horizons was graded as ungleyed, slightly gleyed, mildly gleyed and gleyed. The Eh of the four grades was > 500, 300-500, 100-300 and < 100 mV, respectively, and the corresponding amount of active reducing substances was < 1, 1-7, 7-30 and > 30 mmol_c kg^-1, respectively. The amount of ferrous iron of the four grades was < 0.5, 0.5-5, 5-25 and > 25 mmol kg^-1, respectively. The extent of gleyization of a soil was classified as upper-gleyed, middle-gleyed and lower-gleyed, depending on whether the depth of the gley horizon was less than 30 cm, 30-60 cm or more than 60 cm.     

黑河中游绿洲麦田土壤水气热参数田间尺度空间分布特征

为了明确黑河中游绿洲麦田土壤水气热传输动力学特征的空间变异性,该文采用地理信息系统和地统计学相结合的方法,以黑河中游临泽县麦田的水气热参数的空间分布特征为基础进行相关研究。结果表明地统计学方法可以较好地模拟土壤水气热参数的空间结构和变异特征;水气热参数的拱高与基态值之比均高于75%,采样间隔距离设为10m可以达到较为理想的研究目标;Kringing插值研究结果表明,该区域土壤水气参数变化具有良好的一致性;总的来说,研究区域的土壤导热率具有中间高,南北两侧低的马鞍形变化趋势。该研究将为当地土壤水气热参数田间尺度空间变异研究提供一定的参考。     

Transformation of microbial cenoses in soils of light coniferous forests caused by cuttings and fires in the Lower Angara River basin

The influence of surface fires and cutting on the quantitative and functional parameters of microbial cenoses in the soils of light coniferous forests in the Lower Angara River basin was studied. In the litters of soddy-podzolic soils under pine forests, the microbial biomass was 4080–4700 μg C/g; the basal respiration was 17.00–20.32 μg C-CO₂/g/h; and the qCO₂, 4.17–4.33 μg C-CO₂/mg C_mic/h. In the humus-accumulative horizon, these values were 880–1160 μg C/g, 2.48–4.12 μg C-CO₂/g/h, and 2.83–3.55 C-CO₂/mg C_mic/h, respectively. In the litter of the one-year-old felled area, the content of microbial biomass carbon was by two times lower; in the litter of burned plots, it was by 60–70% lower than in the litter of the control area. The intensity of the microbial respiration did not change proportionally to the microbial biomass content, which resulted in an imbalance between the processes of the organic matter mineralization-immobilization towards a release of CO₂ as evidenced by the increase of the qCO₂ values by 2–4 times. In the five-year-old felled area, at the stage of restoring the herbaceous vegetation, a tendency towards the stabilization of the destructive microbiological processes was revealed. In the felled areas, the high number of heterotrophic microorganisms, the reduced oligotrophy of the soil organic horizons, and the more intense microbiological mineralization of the organic matter were observed. The surface fires in the felled areas and forests significantly affected the structure and the number of ecological-trophic groups of microorganisms in the litters, the humus-accumulative horizons, and in the upper mineral soil layers. The maximal structural and functional disturbance in the soil microbial complex was found in the logged areas affected by fires.     

渭河中上游聚落地理与水土保持

<正> 聚落地理是研究居民聚落的形成、演变和分布规律的学科。在黄土高原地区,人类活动对自然环境的影响极为深刻,甚至决定着黄土高原景观生态的演变。因此,研究黄土高原聚落地理,无疑对黄土高原的国土整治和水土保持事业有一定的参考价值。我们借助遥感图象及1/5万地形图,结合外业系统考察,对渭河中上游的聚落地理进行了初步分析,从聚落地理的角度探讨了各聚落地理区的水土保持工作。     

Dynamics of denitrification and ammonification activities in the abandoned and intensely cultivated gray forest soils (Tula oblast)

The results of experimental study of daily dynamics of denitrification activity and the activity and population density of ammonifiers in the abandoned (converted to long-term fallow) and intensely cultivated gray forest soils (Luvic Retic Greyzemic Phaeozems (Aric)) are discussed. The potential denitrification activity in the arable soil is higher than that in the fallow soil, whereas the actual denitrification activity in the arable soil is lower. Data on the dynamics of ammonification do not show reliable differences between the activities of ammonifiers in the arable and fallow soils, though the number of ammonifying bacteria is considerably higher in the arable soil. Differences in daily dynamics of the numbers of ammonifiers in the fallow and arable soils are shown.     

Transformation of forest litter properties under controlled burning of fir forests defoliated by Siberian moths in the Lower Angara River basin

The results of studying the dynamics of forest litter properties in the loci of a Siberian moth (Dendrolimus sibiricus) mass outbreak are considered. As a fir forest defoliated by this pest burns, the reserves and fractional composition of the forest litter, its actual acidity, and its chemical composition drastically change. Upon the burning out of such forests, the litter complex of invertebrates is fully destroyed and begins restoring only two years after the fire.     

黑河中游绿洲不同质地土壤水分的入渗与再分布

该文利用双环入渗仪,通过定水头法研究了黑河中游绿洲地区玉米地和防护林地土壤水分的入渗过程,并利用Hydrus-1D模型和Trime-IPH手持式TDR分别对土壤水分的入渗和再分布过程进行了动态模拟和测定。结果表明:不同质地土壤水分入渗和再分布差异明显。土壤下部粘土夹层不仅对水分入渗起到显著的阻碍作用,而且具有较强的持水保水能力。统计分析表明,试验期间模拟土壤含水量的均方根误差和相对误差分别在0.02cm3/cm3和0.68%以下,模拟剖面储水量的均方根误差和相对误差分别在0.908 cm和0.9%以下,因此Hydrus-1D模型对绿洲地区土壤水分在垂直方向的运移模拟具有较高的精确度,这为该区域水分管理和可持续发展提供理论依据。     

沱江流域中游土壤有机质的空间变异特点及其影响因素

土壤有机质(SOM)是陆地生态系统中碳循环的重要源与汇[1-3]。其不仅能提高土壤肥力和生产力,且其对碳的固定也是人类应对大气CO2浓度升高的重要途径[4-5]。在区域尺度上,土壤有机质主要受气候、土地利用方式、地理因素如海拔高度、坡度和质地等差异的影响[6-9]。且不同自然地理条件和社会经济发展水平的区域,其土壤有机质的主要影响因素及其影响程度也会有所差异[10-12]。     

阿什河上游小流域不同森林类型土壤水分时空分布

 在阿什河上游光明沟小流域内,选取樟子松、红松、兴安落叶松、水曲柳及杂木林5种森林类型,采用传统土壤水分研究方法,研究不同森林类型间土壤水分时空分布特征。结果表明:除水曲柳林外,其他4种森林类型土壤含水量随土层深度增加而降低,为降低型;兴安落叶松林0～40cm土层土壤含水量最大,为32.91%,其次为水曲柳林(28.79%)、杂木林(25.99%)、红松林(23.64%)和樟子松林(18.76%);各森林类型土壤含水量在生长季内大致上遵循高—低—高—低的规律,与降雨量间存在较一致的对应关系,森林对该小流域内土壤含水量起到了显著的调节作用。     

Changes in the properties of cultivated gray forest soils after their abandoning

Changes in the physical, physicochemical, and biological properties of cultivated gray forest soils after their abandoning and overgrowing with meadow and forest vegetation for 8–10 years are clearly seen in the upper part of the former plow layer. The organic matter content and the content of available forms of phosphorus and potassium increase; a significant increase in the root biomass and in the soil biological activity is observed. Changes in the physical properties—an increase in the degree of soil aggregation and a decrease in the bulk density values—are seen in the upper and middle parts of the former plow layer. The biological factor is the major factor of transformation of formerly cultivated gray forest soils upon their abandoning and overgrowing with meadow and forest vegetation. At the same time, a significant role in the improvement of the structural state of the soils belongs to the physical shrink-swell and freezing-thawing processes.     

福建闽江上游不同林地类型土壤水库“库容”的特性

 以裸露地为对照,研究木荷林地、杉木林地、封山育林地的土壤水库“库容”组成及其特性,以探讨森林土壤水库的蓄水调水机制。结果表明:木荷林地、杉木林地和封山育林地土壤水库总“库容”,分别为503.95、471.62和451.48mm,分别是裸露地的1.23、1.15、1.10倍;兴利库容分别为326.87、332.21和309.94mm,分别是裸露地的1.23、1.25、1.17倍;死库容分别为114.29、89.60和101.46mm,分别是裸露地的1.11、0.87、0.99倍;防洪库容分别为62.79、49.81和40.08mm,分别是裸露地的1.52、1.21、0.97倍。最大有效库容为389.66、382.02和350.02mm,分别是裸露地的1.27、1.25、1.14倍。不同林地类型土壤水库的“库容”组成,均表现为兴利库容>死库容>防洪库容。与裸露地相比,林地土壤水库“库容”的增加,与林木生长对林地土壤结构的改良作用和林地地表的良好覆盖有关。     

The role of soils in the regional carbon budget of pine forests in Karelia

The carbon pool and its fluxes were studied in Karelian pine forests of automorphic sites for the characterization of the regional carbon cycle. On the permanent sample plots arranged in pine stands (dominant forest types) of the middle and northern taiga, the structure and dynamics of the phytomass, as well as the composition of the soil organic matter, were investigated. The contribution of different components of the forest ecosystems to the regional carbon budget was studied. The carbon pools in the soils of the middle and northern taiga subzones were 330–440 × 10² and 440–550 × 10² kg/ha, respectively. The share of soil carbon in the total carbon pool of the forest biogeocenoses studied amounted to 46–35 and 33–24%, respectively. The period of considerable carbon fixation in the pine ecosystem (nearly 20 × 10² kg/ha/yr) turned out to be limited to the middle-aged stands. In the mature and overmature pine forests, only 4 × 10² kg of C/ha/yr were fixed. The main part of carbon in the soil (65–75%) was contained in the illuvial horizons, although its content there was less that 1% as compared to 30–50% in the forest litters. On industrial harvesting of wood, the main reserves of soil carbon are not spent; only the fund of mobile carbon in organic horizons of poor soils is exhausted or carbon accumulates intensely due to the development of continuous plant cover on fertile soils.     

Geobotanical indication of the trophic status and moistening of reclaimed oil-polluted oligotrophic peat soils in the middle reaches of the Ob River

Changes in the trophic status and moistening of oligotrophic peat soils subjected to oil pollution and subsequent reclamation in the middle reaches of the Ob River are discussed. The main plants-indicators are listed. Numerical estimates of the trophic level and the degree of moistening of natural and transformed soils of the widespread bog biogeocenoses—pine-dwarf-shrub-sphagnum, complex ridged-hollow, and cotton grass-sphagnum bogs—are suggested on the basis of the ecological scales developed by L.G. Ramenskii. These estimates have been grouped into several classes used to describe the ecological conditions in natural biogeocenoses of the middle taiga subzone. The main tendencies in the transformation of ecological conditions are revealed. Indicative characteristics of the anthropogenic salinization of peat soils are established.     

Microbial activity in the profiles of gray forest soil and chernozems

Soil samples were taken from the profiles of a gray forest soil (under a forest) and southern chernozems of different textures under meadow vegetation. The microbial biomass (MB) was determined by the method of substrate-induced respiration; the basal respiration (BR) and the population density of microorganisms on nutrient media of different composition were also determined in the samples. The microbial metabolic quotient (qCO₂ = BR/MB) and the portion of microbial carbon (C mic) in C org were calculated. The MB and BR values were shown to decrease down the soil profiles. About 57% of the total MB in the entire soil profile was concentrated in the layer of 0–24 cm of the gray forest soil. The MB in the C horizon of chernozems was approximately two times lower than the MB in the A horizon of these soils. The correlation was found between the MB and the C org (r = 0.99) and between the MB and the clay content (r = 0.89) in the profile of the gray forest soil. The C mic/C org ratio in the gray forest soil and in the chernozems comprised 2.3–6.6 and 1.2–9.6%, respectively. The qCO₂ value increased with the depth. The microbial community in the lower layers of the gray forest soil was dominated (88–96%) by oligotrophic microorganisms (grown on soil agar); in the upper 5 cm, these microorganisms comprised only 50% of the total amount of microorganisms grown on three media.