Transformation of soil organic matter in microarthropod community from the northern taiga of west Siberia

Recolonization of defaunated soil by springtails as well as by gamasid and oribatid mites and the changes in organic matter content of soil were studied in the northern taiga. After a one-year exposure in gauze bags (1.7 mm mesh), the abundance of microarthropods was higher but the number of species was lower compared to the surrounding soil. Large surface and litter forms did not colonize the samples, while the number of small and/or soil forms was higher. Soil samples inaccessible for microarthropods (0.15 mm mesh) were depleted of organic carbon compared to both surrounding soil and recolonized samples. The content of humic and fulvic acids was higher in the samples inaccessible to microarthropods. Humification processes prevailed in soils in the absence of microarthropods.     

Soil functioning in foci of Siberian moth population outbreaks in the southern taiga subzone of Central Siberia

The results of experimental studies on the contribution of zoogenic debris to transformation of soil properties in the southern taiga subzone of Central Siberia are analyzed. They show that water-soluble carbon outflow from the forest litter increases by 21–26% upon a Siberian moth invasion, with this value decreasing to 14% one year later. The burning of forest in an area completely defoliated by the pest leads to changes in the stock, fractional composition, actual acidity, and ash element contents of the litter. The litter-dwelling invertebrate assemblage is almost completely destroyed by fire and begins to recover only after two years.     

The structure of the micromycete complexes of oligotrophic peat deposits in the southern taiga subzone of West Siberia

The analysis of the micromycete complexes of oligotrophic peat deposits in the Vasyugan Marsh by direct count and culture methods showed that the micromycete carbon comprises no more than 3% of the total peat carbon and that the microscopic fungal biomass varies from 2 to 13 tons/hectare, depending on the season and the peat deposit thickness. Fungal spores were found in all layers of the peat deposits, whereas the mycelium was found only in the active peat layer. The high abundance of eukaryotic cells in the peats was due to the presence of yeastlike cells rather than fungal spores. Analyses by culture methods showed that micromycetes were present in all peat layers and that their abundance tended to decrease with depth, except for yeasts, which were uniformly distributed in a vertical direction. The micromycete complexes of the peat deposits were similar in the diversity and abundance of dominant species but differed in the composition of minor species. Peat yeasts were dominated by ascomycetes.     

The carbon balance in natural and disturbed forests of the southern taiga in central Siberia

Abstract. We evaluated the balance of production and decomposition in natural ecosystems of Pinus sylvestris, Larix sibirica and Betula pendula in the southern boreal forests of central Siberia, using the Yenisei transect. We also investigated whether anthropogenic disturbances (logging, fire and recreation pressure) influence the carbon budget. Pinus and Larix stands up to age class VI act as a net sink for atmospheric carbon. Mineralization rates in young Betula forests exceed rates of uptake via photosynthesis assimilation. Old‐growth stands of all three forest types are CO₂ sources to the atmosphere. The prevalence of old‐growth Larix in the southern taiga suggests that Larix stands are a net source of CO₂. The CO₂ flux to the atmosphere exceeds the uptake of atmospheric carbon via photosynthesis by 0.23 t C.ha^‐1.yr^‐1 (47%). Betula and Pinus forests are net sinks, as photosynthesis exceeds respiration by 13% and 16% respectively. The total carbon flux from Pinus, Larix and Betula ecosystems to the atmosphere is 10 387 thousand tons C.yr^‐1. Net Primary Production (0.935 t‐C.ha^‐1) exceeds carbon release from decomposition of labile and mobile soil organic matter (Rh) by 767 thousand tons C (0.064 t‐C.ha^‐1), so that these forests are net C‐sinks. The emissions due to decomposition of slash (101 thousand tons C; 1.0%) and from fires (0.21%) are very small. The carbon balance of human‐disturbed forests is significantly different. A sharp decrease in biomass stored in Pinus and Betula ecosystems leads to decreased production. As a result, the labile organic matter pool decreased by 6–8 times; course plant residues with a low decomposition rate thus dominate this pool. Annual carbon emissions to the atmosphere from these ecosystems are determined primarily by decomposing fresh litterfall. This source comprises 40–79% of the emissions from disturbed forests compared to only 13–28% in undisturbed forests. The ratio of emissions to production (NPP) is 20–30% in disturbed and 52–76% in undisturbed forests.     

Effects of fires in ribbon-like pine forests of southern Siberia

For the Tsasuchei, Balgazyn, Minusinsk, and Shushensk ribbon-like pine forests of southern Siberia, conditions of ignition and development of fires are analyzed and the flammability is evaluated. Fire effects on vegetation, including forest stand condition and reforestation, are evaluated. It is shown that a reduction in the area of ribbon-like pine forests of southern Siberia caused by crown fires leads to steppification of these areas.     

The soils of West Siberia middle taiga oil deposits and a predictive estimate of contamination hazard with organic pollutants

Regularities of distribution of the background soils of oil deposits in the middle taiga of West Siberia have been studied and the features of their morphogenetic and physicochemical properties have been revealed. It has been experimentally substantiated that soil contamination hazard with oil components depends on the position of soil in the elementary landscape-geochemical systems (ELGS), on the granulometric composition, and buffer capacity. The results may be used to perform soil ecological monitoring and soil revegetation.     

中亚热带不同类型米槠林凋落枝溶解性有机质动态及光谱学特性

以中亚热带不同类型米槠林为对象,研究了米槠天然林、次生林和人工林凋落枝在生产量持续增加阶段、高峰阶段、持续减少3种生产阶段溶解性有机质的动态及光谱学特性。结果表明:凋落枝生产阶段和森林类型显著影响米槠凋落枝溶解性有机质含量及光谱学特征。米槠天然林在凋落枝生产量持续减少阶段溶解性有机碳(DOC)含量较高,溶解性有机质在254、260和280 nm处的特征紫外吸光值(SUVA₂₅₄、SUVA₂₆₀、SUVA₂₈₀)较低,表明该阶段天然林凋落枝质量较高,具有较高的以溶解性有机质为载体的物质循环效率。米槠人工林在凋落枝生产量高峰阶段具有较高的总氮(TN)、总磷(TP)、溶解性总氮(TDN)和溶解性总磷(TDP)含量以及较低的DOC∶TDP和TDN∶TDP值,但次生林凋落枝溶解性有机质含量及其光谱学特征在各阶段无显著差异。米槠天然林和次生林凋落枝DOC、TDN和TDP与气温和降水量呈负相关,人工林凋落枝TDN、TDP与气温和降水量呈正相关。人工林凋落枝生产量在高峰阶段具有较高的养分含量,可能具有相对快速的物质循环效率,天然林在凋落枝生产量下降阶段以凋落枝溶解性有机质为载体的物质循环效率相对较高。     

Reserves of carbon in the organic matter of postfire pine forests in the southwest of the Baikal region

A change in the mass and composition of organic matter in the phytomass and soil of pine forests affected by mid-intensity and high-intensity fires is considered. It is shown that a mid-intensity fire did not catastrophically affect the pool of carbon in the middle-aged pine forests of the subtaiga forest-steppe and the taiga higher belt areas in the southwest of the Baikal region. Five years after a high-intensity fire, the carbon reserves in a mature taiga pine forest remain 20% lower than in an unaffected pine forest. Compared with the reference figures, the mass of C and soil cover in the stand phytomass decreased by 18 and 63%, respectively. In the easily mineralizable fraction of organic matter, the reserves of carbon decreased by half owing to burnout of waste wood (by 64%) and root detritus (by 50% compared with the reference tree stand figures).     

Removal of carbon and mineral nutrients upon clear felling of spruce forests in the middle taiga

We obtain an estimate of the influence of localized clear felling in a middle taiga spruce forest on the dynamics of organic mass and its content of carbon and elements of mineral nutrition. In an old-age myrtillus bilberry moist spruce stand, in which the reserve of organic mass is 180 t ha^?1, there are concentrated 86 t of carbon, 508 kg of nitrogen, and 904 kg of ash elements. On the logging area of this spruce forest in the undercut (incomplete felling), roots, and logging slash, there are 112 t ha^?1 of phytomass, where 53 t C ha^?1, 308 kg of nitrogen, and 723 kg of ash elements are concentrated. Upon the localized clear felling with removal of tree-length logs, the loss of carbon is 44%, nitrogen 28.3%, and ash elements 22.3% of their overall reserve in the myrtillus moist spruce stand. In the spruce-sphagnum forest, the phytomass of the stand is 194 t ha^?1 and contains 92 t ha^?1 of carbon, 580 kg of nitrogen, and 974 kg of ash elements. Upon cutting of the stand in this spruce forest, 77 t ha^?1 of organic mass were taken away, including 37 t of carbon, 140 kg of nitrogen, and 215 kg of ash elements, which are 39.5, 24.2, and 22% of their overall mass in woody plants of the cenosis, respectively.     

Structure and function of shisham forests in central Himalaya,India: dry matter dynamics

The biomass and net primary productivity (NPP) of 5- to 15-year-old Shisham (Dalbergia sissoo Roxb.) forests growing in central Himalaya were estimated. Allometric equations were developed for all above- and below-ground components of trees and shrubs for each stand. Understorey forest floor biomass and litter fall were also estimated in forest stands. The biomass (dry matter), forest floor biomass (standing crop litter), tree litter fall and NPP of trees and shrubs increased with increasing age of the forest stand, whereas the dry matter and herb NPP decreased significantly (P < 0.001) with increasing age of the forest. Total forest biomass and NPP ranged from 58.7 (5-year-old stand) to 136.1 t ha(-1) (15-year-old stand) and 12.6 (5-year-old stand) to 20.3 t ha(-1) year(-1) (15-year-old stand), respectively. Of these values, tree biomass accounted for 85.7 (5-year-old stand) to 90.1% (15-year-old) of total forest biomass, and tree NPP for 72.2 (5-year-old) to 82.3% (15-year-old) of total forest NPP. The biomass accumulation ratio (BAR) of the bole component (bole wood + bole bark) increased with increasing age of the forest stand. The bole BAR was 5.8 (5-year-old stand) to 7.9 (15-year-old stand). However, total BAR of the forest stand ranged from 5.5 (5-year-old) to 7.5 (15-year-old).     

The effect of various disturbing factors on the radial increment in pine forests of Central Siberia

The results of study of regeneration periods in pine forests after natural and anthropogenic disturbanses have been presented. It has been found that the rate of recovery depends on the type of disturbing factor. The differentiated effect of climatic factors (air temperature, amount of precipitation) on the growth rate of forests with different types of disturbances has been investigated.     

Modeling organic matter dynamics in conifer-broadleaf forests in different site types upon fires: A computational experiment

The effect of forest fires differing in intensity on organic matter dynamics in forest soils has been assessed in different types of forest sites using the EFIMOD system of models. Differences between the patterns of organic matter dynamics according to scenarios of forest ecosystem development under normal conditions and upon forest fires have been analyzed. Recovery rates of soil organic matter pools after fires depend on their intensity and frequency. The most profound changes take place upon high-intensity crown fires, which may even result in ecosystem destruction.     

Comparison of soil organic matter dynamics at five temperate deciduous forests with physical fractionation and radiocarbon measurements

Forest soils represent a significant pool for carbon sequestration and storage, but the factors controlling soil carbon cycling are not well constrained. We compared soil carbon dynamics at five broadleaf forests in the Eastern US that vary in climate, soil type, and soil ecology: two sites at the University of Michigan Biological Station (MI-Coarse, sandy; MI-Fine, loamy); Bartlett Experimental Forest (NH-BF); Harvard Forest (MA-HF); and Baskett Wildlife Recreation and Education Area (MO-OZ). We quantified soil carbon stocks and measured bulk soil radiocarbon to at least 60 cm depth. We determined surface (0–15 cm) soil carbon distribution and turnover times in free light (unprotected), occluded light (intra-aggregate), and dense (mineral-associated) soil fractions. Total soil carbon stocks ranged from 55 ± 4 to 229 ± 42 Mg C ha^?1 and were lowest at MI-Coarse and MO-OZ and highest at MI-Fine and NH-BF. Differences in climate only partly explained differences in soil organic matter ¹⁴C and mean turnover times, which were 75–260 year for free-light fractions, 70–625 year for occluded-light fractions, and 90–480 year for dense fractions. Turnover times were shortest at the warmest site, but longest at the northeastern sites (NH-BF and MA-HF), rather than the coldest sites (MI-Coarse and MI-Fine). Soil texture, mineralogy, drainage, and macrofaunal activity may be at least as important as climate in determining soil carbon dynamics in temperate broadleaf forests.     

The fleas of small mammals in the northern taiga of western Siberia

Data on the species composition of fleas, their abundance and distribution on hosts and on territory are given. Changes in the species composition and abundance of fleas in the latitude and meridional directions are shown.     

Soil formation and grouping of soils of the taiga zone in central West Siberia

Natural environments of the taiga zone in central West Siberia have been analyzed, with emphasis placed on the geological and morphological structure of the territory and morphology of soils. The main factors of soil formation are recognized, the main processes of soil formation are revealed, and a systematic list of soil kinds is compiled.     

The role of the pyrogenic factor in the productivity and dynamics of the pine forests in Transbaikalia

Peculiarities of the dynamics and productivity of the pine forests growing under the conditions of the Transbaikalia arid climate are considered. Their high inflammability is noted. Fires sharpen the limiting role of moisture in tree growth. The post-fire annual ring fluctuations on longitudinal sections of young pines are illustrated. Outward diagnostic signs characterizing the xylogenesis state in trees damaged by fire have been analyzed: the char height on trunks, thermal damage to crowns, reduction and change in the tint of needle coloring. The process of digression dynamics of pyrogenic tree stands has been traced. Their reparation potential has been found to become weaker with ageing. As a result of the permanent effect of the pyrogenic factor, the productivity of pine forests in Transbaikalia is 1.5–2 times lower than of those in Priangarie.     

Soil-productivity relationships and organic matter turnover in dry tropical forests of the Florida Keys

Soils and aboveground production in five types of upland forest in the Florida Keys were examined. Throughout the habitat gradient represented by these forest types, the soils were predominantly shallow and organic, forming in place directly on the limestone bedrock. However, the well-drained soils in the most productive broadleaved forests were deep enough to qualify as Histosols (Folists). Soils decreased in electrical conductivity and increased in nutrient content with increasing aboveground production. At 3–12 Mg ha^–1 yr^–1, production was within the range reported for dry tropical forests. Measured rates of decomposition were moderate or fast, and estimates of the organic C turnover of several soils based on their bomb radiocarbon signature were 100 years or less. In the face of these rapid turnover rates, we attribute the development of organic soils to the absence of mineral residues from weathering of the underlying limestone bedrock. Fast turnover of organic matter, and rapid and efficient cycling of nutrients are necessary to sustain the high production rates obtained on these shallow organic soils.     

Preservation of the plant and animal gene pools in Siberia]

The results of the work on preservation of the gene pools performed at the two experimental bases of the Institute of Cytology and Genetics of the Siberian Division of Academy of Sciences of the USSR are summarized. The collections obtained are represented by a number of aboriginal animal breeds (cattle, sheep, foxes, etc.) and plant variables (300 specimens belong to 113 species of 25 families.