Influence of moss and lichen spatial mosaics on radial growth of Gmelin larch (Central Evenkia)

The results of research studies on the influence of high moss-and-lichen mosaicity typical for the northern taiga in Central Evenkia on the dynamics of radial growth of Gmelin larch trees (Larix gmelinii (Rupr.) Rupr.) are reported. Three sample plots were laid out in the larch ledum–cowberry–green moss forest on the northwest facing slope (8°–10°) in close proximity to each other; they differed in the proportions of area occupied by the principal components of a moss–lichen cover (Aulacomnium turgidum, Pleurozium schreberi, Cladonia rangiferina, and Hylocomium splendens), spatial distribution, and thermal properties of seasonally thawed soil layers. The worst thermal soil properties under the current climatic conditions have determined the comparatively low radial growth of trees in the sampling area, reduced response to air-temperature variations in the period of preseason cambium activity and at the beginning of the radial growth period, and heightened the response to this factor at the end of a season.     

A microbiological characterization of the permafrost soil of Tit-Ary Island (Yakutia)

The microbiological composition of the soil of the unique Tit-Ary Island in the lower reaches of the Lena River has been studied in detail for the first time. The specific features of the microbial population of the cryosolic soil have been revealed, including a high number of individuals of all microbial groups (10⁴–10⁸ CFU/g), comparable to the density of microorganisms in the steppe soil of Transbaikalia, and the specific pattern of their distribution in the soil profile without a decrease in their count with depth. Oligonitrophilic bacteria were prevalent in the humic gley soil of polygonal ridged tundra; their number varied from 70 × 10³ to 330 × 10⁶ CFU/g soil.     

Tree-ring growth of Gmelin larch under contrasting local conditions in the north of Central Siberia

While the forest-tundra zone in Siberia, Russia has been dendroclimatologically well-studied in recent decades, much less emphasis has been given to a wide belt of northern taiga larch forests located to the south. In this study, climate and local site conditions are explored to trace their influence on radial growth of Gmelin larch (Larix gmelinii (Rupr.) Rupr.) trees developed on permafrost soils in the northern taiga. Three dendrochronological sites characterized by great differences in thermo-hydrological regime of soils were established along a short (ca. 100 m long) transect: on a river bank (RB), at riparian zone of a stream (RZ) and on a terrace (TER). Comparative analysis of the rate and year-to-year dynamics of tree radial growth among sites revealed considerable difference in both raw and standardized tree-ring width (TRW) chronologies obtained for the RZ site, characterized by shallow soil active layer depth and saturated soils. Results of dendroclimatic analysis indicated that tree-ring growth at all the sites is mostly defined by climatic conditions of a previous year and precipitation has stronger effect on TRW chronologies in comparison to the air temperatures. Remarkably, a great difference in the climatic response of TRW chronologies has been obtained for trees growing within a very short distance from each other. The positive relation of tree-ring growth with precipitation, and negative to temperature was observed in the dry site RB. In contrary, precipitation negatively and temperature positively influenced tree radial growth of larch at the water saturated RZ. Thus, a complicate response of northern Siberian larch forest productivity to the possible climate changes is expected due to great mosaic of site conditions and variability of environmental factors controlling tree-ring growth at different sites. Our study demonstrates the new possibilities for the future dendroclimatic research in the region, as various climatic parameters can be reconstructed from tree-ring chronologies obtained for different sites.     

林龄对红松和落叶松人工林土壤温室气体通量的影响

探讨人工林发育过程中土壤温室气体排放及其机制,可为森林温室气体通量估算提供理论依据.采用室内培养方法研究了黑龙江省帽儿山地区不同林龄(15、30和50年生)红松(Pinus koraiensis)和落叶松(Larix gmelinii)人工林土壤温室气体排放/吸收速率及其调控因素.结果 表明:30年生红松和落叶松人工林...     

Seasonal and spatial variability of elemental concentrations in boreal forest larch foliage of Central Siberia on continuous permafrost

We measured the seasonal dynamics of major and trace elements concentrations in foliage of larch, main conifer species of Siberia, and we analyzed cryogenic soils collected in typical permafrost-dominated habitats in the Central Siberia. This region offers a unique opportunity to study element fractionation between the soil and the plant because of (i) the homogeneous geological substratum, (ii) the monospecific stands (Larix gmelinii) and (iii) the contrasted habitats (North-facing slope, South-facing slope, and Sphagnum peatbog) in terms of soil temperature, moisture, thickness of the active layer, tree biomass and rooting depth. The variation of these parameters from one habitat to the other allowed us to test the effects of these parameters on the element concentration in larch foliage considered with high seasonal resolution. Statistical treatment of data on larch needles collected 4 times in 3 locations during entire growing season (June–September) demonstrated that : (1) there is a high similarity of foliar chemical composition of larch trees in various habitats suggesting intrinsically similar requirements of larch tree growth for nutrients, (2) the variation of elemental concentrations in larch needles is controlled by the period (within the growing season) and not by the geographical location (South-facing slope, North-facing slope or bog zone) and (3) there are three groups of elements according to their patterns of elements concentration in needles over the growing season from June to September can be identified: (1): nutrient elements [P, Cu, Rb, K, B, Na, Zn, Ni and Cd] showing a decrease of concentration from June to September similar to the behaviour of major nutrients such as N, P and K; (2): accumulating elements [Ca, Mg, Mo, Co, Sr, Mn, Pb and Cr] showing an increase of concentration from June–July to September; (3): indifferent elements [Al, Zr, Fe, Ba, Ti, REEs (Pr, Nd, Ce, La, Gd, Er, Dy, Tb, Lu, Yb, Tm, Sm, Ho, Eu), Y, Th and U] showing a decrease of concentration from June to July and then an increase of concentration to September. A number of micronutrients (e.g., Cu, Zn) demonstrate significant resorption at the end of growing season suggesting possible limitation by these elements. Although the intrinsic requirement seems to be similar among habitats, the total amount of element stored within the different habitats is drastically different due to the differences in standing tree biomass. The partitioning coefficients between soil and larch appear to be among the lowest compared to other environments with variable plants, soils and climates. Applying the “space for time” substitution scenario, it follows that under ongoing climate warming there will be an increase of the element stock following enhanced above-ground biomass accumulation, even considering zero modification of element ratios and their relative mobility. In this sense, the habitats like south-facing slopes can serve as resultant of climate warming effect on element cycling in larch ecosystems for the larger territory of Central Siberia.     

Influence of Gmelin larch trees on postfire restoration of forest communities in the permafrost zone of Central Siberia

This article shows the phytocoenotic role of individual postfire trees of the Gmelin larch under conditions of the permafrost zone of Central Siberia. On the basis of the vital state of the trees, the limits of their influence on the recovery of the species of the lower layers of phytocenosis are defined and the formation of the new stand generation is shown.     

Carbon and nitrogen status of litterfall, litter decomposition and soil in even-aged larch, red pine and rigitaeda pine plantations

The carbon (C) and nitrogen (N) status in forest ecosystems can change upon establishment of plantations because different tree species have different nutrient cycling mechanisms. This study was carried out to evaluate C and N status of litterfall, litter decomposition and soil in three adjacent plantations consisting of one deciduous (larch: Larix leptolepis) and two evergreen (red pine: Pinus densiflora; rigitaeda pine: P. rigida × P. taeda) species planted in the same year (1963). Both the pine plantations showed comparatively higher C input from needle litter but significantly lower N concentration and input than the larch plantation (P < 0.05). During the decomposition process, the deciduous larch needle litter showed low C concentration and C remaining in soil, but high N concentration and N remaining in soil compared to the two evergreen pine needle litters. However, the soil C and N concentration and their content at a soil depth of 0–10 cm were not affected significantly (P > 0.05) by the plantation type. These results demonstrate the existence of considerable variation in C and N status resulting from needle litter input and litter decomposition in these three plantations grown at sites with similar environmental conditions.     

Water balance and adaptation strategy in insects of Central Yakutia to extreme climatic conditions

Original experimental data describing the strategy for cold adaptation of the winter form of blackveined white Aporia crataegi L. living in Central Yakutia, a region with a harsh continental climate and long and very cold winters, are presented in comparison with other insects of Yakutia. Open wintering insects were shown to develop an efficient water-saving mechanism in a frozen state. This can be significant for their survival in post-diapause. Certain relationships between water balance, wintering mode, and strategy for cold adaptation have been revealed by the example of several insect species of this region in comparison with insects living in less severe climatic conditions.     

Post-fire restoration of organic substance in the ground cover of the larch forests in permafrost zone of Central Evenkia

The role of ground fires in transformation of organic substance in the ground cover of larch stands in the permafrost zone of Central Siberia was studied as well as the post-fire restoration dynamics of organic substance. Ground fires lead to is a considerable decrease in concentrations and resources of organic carbon and its individual fractions in the ground cover and their restoration takes many decades.     

Effect of soil strength on root growth under different water conditions

The objective of this study was to determine the effects of soil water and soil strength on root growth in situations where the individual effects of both of these factors were important. Three grain legumes were grown from pre-germinated seeds for five days on 50-mm compacted columns of two major soils of Sri Lanka. Four or five levels of bulk density (1.1 to 1.8 Mg.m^–3) and five or six levels of matric potential (–0.02 to–2.0 MPa) were used.Soil strength and matric potential effects on root growth were independently significant for most crop and soil combinations. Under high (wet) matric potential (>–0.77 MPa) soil conditions, the effect of soil water on root growth was evident only in its effect on soil strength. Bulk density had a significant effect on root growth independent of soil strength and matric potential in three cases.For all crops and soils, root penetration was 80% of the maximum or greater when the average soil strength (soil water not limiting) was 0.75 MPa or less, and when the average matric potential (soil strength not limiting) was –0.77 MPa or greater (wetter). Root penetration was 20% of the maximum or less when the soil strength was greater than 3.30 MPa (soil water not limiting), and when matric potential (soil strength not limiting) was less than –3.57 MPa. The use of pre-germinated seeds, which contained imbibed water, combined with a lack of water loss from the closed chambers containing the plants is the probable cause for the very low (–3.57 MPa) matric potential that allowed root growth at 20% of the maximum.     

Cold adaptation in insects of Central Yakutia

The mode of cold hardening was for the first time assessed for 20 insect species living in the extremely cold climate of Yakutia. All insects tested were found to adapt through freeze tolerance, producing ice-nucleating agents that cause the hemolymph to freeze at high subzero temperatures. For the first time ice-nucleating agents were demonstrated in Lepidoptera. Pieris rapae exemplified the possibility of switchover in the survival strategy depending on the climatic conditions.     

Succession-driven transformation of plant and soil cover on solifluction sites in the permafrost zone of Central Evenkia

The impact of solifluction (soil-sliding) on soil and vegetation cover as well as their restoration during the period after the disturbance was analyzed in the continuous permafrost region of Central Siberia (Central Evenkia). The role of vegetation invading after a disturbance is demonstrated for accumulation of biogenic elements and soil development.     

Effect of organic mulches on the hydrothermal regime of soil and growth of potato crop in Northern India

Plant and Soil - Possibilities of manipulating hydrothermal regime of soil with different organic mulches and their effect on the growth of potato crop was studied. Mulches like mat (Typha sp....     

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.     

Dwarf pine invasion in an alpine tundra of discontinuous permafrost area: effects on fine root and soil carbon dynamics

Key message

Recent invasion of Pinus pumila , a highly productive shrub-like tree species, into alpine tundra does not significantly modify the dynamics of fine root and soil carbon in the tundra.

Abstract

Climate warming may directly and indirectly affect the large carbon stock in discontinuous permafrost soil at high latitudes. In recent decades, Siberian dwarf pine [Pinus pumila (Pall.) Regel] has been invading dry heath alpine tundra in the northern Amur region of Far East Russia. Siberian dwarf pine is known to have high aboveground productivity, comparable to that of tall coniferous trees. We hypothesised that the invasion of Siberian dwarf pine into alpine tundra could increase soil carbon stocks via an increase in fine roots. Contrary to our expectations, the invasion of dwarf pine did not significantly increase the fine root biomass and productivity of the tundra, probably due to the belowground competitive exclusion between the dwarf pine and alpine tundra plants. Furthermore, the invasion of the dwarf pine did not affect soil carbon in the alpine tundra ecosystem. These results show that the recent invasion of Siberian dwarf pine into tundra did not influence the fine root dynamics or the soil carbon stock in the study site. Together, these results implied that (1) it takes a long time for pine invasion to change the belowground ecosystem properties of tundra vegetation to that of pine thickets and therefore (2) the lack of an increase in soil carbon from recent tree invasion should be taken into account when modelling future carbon dynamics in alpine tundra.

     

Osmotic effects on radial growth rate and specific growth rate of three soil fungi

The radial growth rate on osmotically adjusted agar medium and the relative specific growth rate in osmotically adjusted liquid medium were determined for Rhizoctonia solani, Pythium ultimum, and Verticillium dahliae. On basal medium, an isolate of P. ultimum and R. solani had similar radial growth rates of 0.52 and 0.47 mm/h, respectively, whereas V. dahliae grew at a rate of 0.08 mm/h. Radial growth rate was reduced 50% at osmotic potentials of -16, -27, and -32 bars for P. ultimum, R. solani, and V. dahliae, respectively. No growth occurred at -32 bars for P. ultimum, -56.2 bars for R. solani, and -100 bars for V. dahlia. Specific growth rates in liquid culture were 0.011 h-1 for P. ultimum, 0.008 h-1 for V. dahliae, and 0.026 h-1 for R. solani. Ratios of radial growth rate (Kr) to specific growth rate (alphas) were computed for each fungus growing at different osmotic potentials. There was not a constant relationship between Kr on agar and alphas in liquid medium, e.g., Kr/alphas ratios varied from 8-41% from a mean ratio for a particular species. The results indicated that radial growth rate on osmotic agar was not useful as a measure of relative specific growth rate of a fungus in osmotically adjusted liquid medium.     

Effect of antitranspirant treatment on the water balance of pine seedlings,under different climatic and soil moisture conditions

Summary Antitranspirant treatment with Tag — a polyethylene based emulsion-reduced transpiration and increased height of potted pine seedlings under simulated hot and dry conditions when soil was moist. Under cool, humid conditions reduction of transpiration was very much less and growth was slightly reduced. Application of antitranspirants to pine seedling transplants, under hot dry field conditions, failed to improve, their water balance or to reduce mortality. Physiological tests made during the field trial and experiments with potted seedlings showed that when the soil is dry xeromorphic plants efficiently reduce their water loss and under such conditions anti-transpirants are of no benefit. It is calculated that antitranspirants would only be advantageous under moist soil and high evaporative demand conditions.