Silver Birch Stands Research Articles

Trends in genetic diversity of silver birch: Insights from varied planting scenarios

This study explores the impact of planting strategies on genetic diversity in silver birch (Betula pendula Roth) stands using simulation models. We examine the influence of different proportions of planted stands and the number of open-pollinated families on genetic diversity, focusing on the Shannon-Weiner Diversity Index and expected heterozygosity. Results indicate optimal genetic diversity increases with 50–55% planted stands. Additionally, using more families in planting enhances diversity, peaking when 30 families were used compared to five. Simulations suggest that combining natural regeneration with planting seed lots from at least 20 families enhances genetic diversity at the landscape level, supporting sustainable forest management. However, using only the top-performing five families does not harm genetic diversity if planted stands remain below 55%. Acknowledging the limitation, this study considers only a single generation, which may affect long-term applicability of the results over multiple generations. Keywords: expected heterozygosity; Shannon-Weiner Diversity Index

Effects of forest management intensity and climate change severity on volume growth, timber yield, carbon stocks, and the amount of deadwood in Scots pine, Norway spruce, and silver birch stands in boreal conditions

We studied how management intensity and climate severity affect volume growth, timber yield, carbon stocks, and the amount of deadwood in Scots pine ( Pinus sylvestris (L.)), Norway spruce ( Picea abies (L.) Karst.), and silver birch ( Betula pendula Roth.) dominated stands in the Republic of Karelia and Arkhangelsk region of northwest Russia. Using the forest ecosystem model (SIMA) under different climates (current and representative concentration pathway scenarios, RCP4.5 and RCP8.5), no-thinning, low, medium, and high intensity thinning rotational forestry regimes were simulated. Under RCPs, the volume growth and timber yield (5%–53%), carbon stocks (1%–22%), and deadwood amounts (11%–75%) increased for all Scots pine and silver birch stands. The use of low intensity management increased volume growth and carbon stocks (3%–16%) and deadwood amount (up to 60%) under RCPs, but not timber yield (±3%) in these stands. For Norway spruce stands, the volume growth (5%–26%), timber yield (23%–75%), and carbon stocks (5%–15%) decreased under RCP8.5, but deadwood amount increased (up to 142%). Intensive management increased volume growth (4%–19%), timber yield (4%–63%), carbon stocks (up to 14%), and deadwood amounts (up to 49%). Our results highlight that effects of climate severity and management intensity are site and species-specific for Eurasian’s boreal forests.

Harvesting efficiency and understory damage with different cutting methods on two storied stands of silver birch and Norway spruce

Uneven-aged forests set certain challenges for cut-to-length harvesting work. It is a challenge to cost-effectively remove larger trees while leaving a healthy understory for regrowth. The study’s aim was to evaluate productivity and costs of harvesting two-storied Silver birch (Betula pendula Roth) and Norway spruce (Picea abies (L.) H. Karst.) stands by creating time consumption models for cutting, and using existing models for forwarding. Damage to the remaining understory spruce was also examined. Four different harvesting methods were used: 1) all dominant birches were cut; 2) half of them thinned and understory was preserved; compared to 3) normal thinning of birch stand without understory; and 4) clear cutting of two-storied stand. Results showed the time needed for birch cutting was 26–30% lower when the understory was not preserved. Pulpwood harvesting of small sized spruces that prevent birch cutting was expensive, especially because of forwarding of small amounts with low timber density on the strip roads. Generally, when taking the cutting and forwarding into account, the unit cost at clear cuttings was lowest, due to lesser limitations on work. It was noted that with increasing removal from 100 to 300 m3 ha–1, the relative share of initial undamaged spruces after the harvest decreased from 65 to 50% when the aim was to preserve them. During summertime harvesting, the amount of stem damage was bigger than during winter. In conclusion, two-storied stands are possible to transit to spruce stands by accepting some losses in harvesting productivity and damages on remaining trees.

Relationships between soil properties, vegetation and soil biota in extremely sulfurized mine soils

The study aimed to assess the influence of high sulfur (S) contamination and the properties of the reclaimed (e.g. neutralization/liming of contamination) soil on the regeneration of soil vegetation and fauna in the example of the former sulfur mine. An attempt was also made to assess minimal conditions for the development of soil microorganisms and mesofauna depending on the type of cover (reforestation/herbaceous vegetation/bare soil). Thirty sample plots were situated on three mainland categories–– i) plant cover vegetated mainly Pinus sylvestris L. (Scots pine stand category), ii) Betula pendula Roth (silver birch stand category), and iii) degraded area with bare soil (Bare_Central – in the central place of the plot and Bare_Edge usually 5.5 m from Bare_Central, Veg – 1 m from Bare_Edge). Basic soil chemicals (as pH, electrical conductivity EC, total sulfur S, total nitrogen TN, total organic carbon TOC), biological parameters (e.g. fungal and bacterial phospholipid fatty acids PLFAs, GRAM+, GRAM−, actinobacteria, total microbial biomass TM), and mesofauna density were analyzed to assess the level of contamination and colonization of the area by plants and soil fauna. The PLFA and the presence of soil microorganisms, always increased from a central point (Bare_Central) to an outer one (Bare_Edge) that was very close (about 1 m) to the vegetation (Veg). However, the highest biological parameters was found in Veg near the bare soil than in the stands with Scots pine. It was found that the highest microbiological biomass was positively correlated with the occurrence of vegetation. Mesofauna was limited by a high content of sulfur in the soil and high EC. Silver birch stands, through the larger and more favorable properties of plant litter, create conditions in which the growth of microorganisms is much greater than under Scots pine stands. On the other hand grasses area with single Scots pine was characterized by higher biological parameters than with the silver birch. In the plots with tree stands it was quite the opposite. To properly restoration this type of place, it is necessary to ensure the accuracy of the technical measures performed. The best effects of activating soil microorganisms are the introduction of trees with appropriate density. The activity of soil microorganisms allows for the growth of herbaceous vegetation, which will be a start-up source of organic matter and nourishment for soil biota. Herbaceous vegetation will create a good mixture with hard decomposed pines litterfall.

Macro- and Micronutrient Contents in Soils of a Chronosequence of Naturally Regenerated Birch Stands on Abandoned Agricultural Lands in Central Poland

Abandoned agricultural lands in Central and Northern Europe undergo a quite rapid secondary succession of woody species, especially silver birch (Betula pendula Roth.) as a pioneer tree species. Such a process is desirable both from natural and economic point of views, as afforestation involves a change to the entire ecosystem and, in particular, the transformation of anthropogenic habitats typical for agriculture into habitats similar to a natural forest. In the present study, we report the chemical properties of soils under birch stands that naturally regenerated on abandoned agricultural lands and answer the question of whether silver birch modifies the chemical properties of soils over a (relatively short—17 years) time and with depth in the soil profile. The research investigated the natural secondary succession of silver birch on 28 study plots established as a chronosequence in seven locations in Central Poland. The age of the stands ranged from 2 to 17 years. We analysed the contents of selected micro- and macroelements and heavy metals at three depths in the soil profile. The chemical properties of former agricultural soils covered with newly established silver birch stands, taking into account the depth in the soil profile, demonstrated tendencies to change over the time. In the first age class of birch stands, the stock of investigated nutrients in the soil was higher compared to the following age classes. Statistically significant differences were noted in the case of Cu and Cr. Along with the age of birch stands (age class IV), there was a tendency for stock of the analysed nutrients to grow, which can be associated with an increase in aboveground biomass and root system development. The changes in the contents of the macro- and microelements, as well as heavy metals, were characterised by a gradual increase of the elements analysed in the upper layer of the soil that, in the years following the birch influence on the soil, starts having an effect on the deeper layers. In the case of Cu, Pb, Cd, Ni and Cr, there was a statistically significant change in the depth of the soil. Longer chronosequences should be observed to see a clear trajectory in soil chemistry changes with birch stand ages.

CHANGES IN THE CONTENT OF BIOAVAILABLE HEAVY METAL COMPOUNDS IN THE SOILS OF THE CRIMEAN MOUNTAIN PLATEAUS AFTER AFFORESTATION

About 3 thousand hectares of forest stands were created on the surface of the Crimean mountain plateaus in the middle of the 20th century as a result of afforestation. Studies on the influence of these stands on the properties of mountain meadow soils (Phaeozems) showed that under the forest vegetation, the consolidation of structural aggregates, a decrease in the humus content, and an increase in acidity compared to the soils under the meadow vegetation, which could also affect other soil properties, including the mobility of some metals, were observed. The work objective of this research is to conduct a comparative analysis of the content of Pb, Mn, Cu, and Zn compounds available for biota (1 M ammonium acetate) in the soil under mountain meadows, natural beech forest, and artificial forest stands. Following the obtained results, the available Pb, Mn, and Cu compounds accumulated in the afforested mountain meadow soils relative to the adjacent mountain meadows areas. Thus, the average Pb content in the soil layer of 0–10 cm under the mountain pine stands in comparison with the soil under meadow vegetation was 1.6 times higher, Mn – 1.2 times, Cu – 1.2 times. The Pb content was 2.5 times higher, Mn – 1.5 times higher, and Cu – 1.2 times higher under the silver birch stands. The Pb content was 2.2 times higher, Mn – 2.4 times higher, and Cu – 1.5 times higher under Siberian larch stands. The Pb content was 1.9 times higher, Mn – 1.1 times higher, Cu – 1.3 times higher under the sycamore maple stands, compared to the meadow. Differences between afforested and meadow soils in the content of these elements in most cases were significant, except for the Zn content, signs of accumulation of which under artificial stands were not revealed. The Pb, Mn, and Cu content in the brown forest lessive soil (Luvisols) under the oriental beech corresponded to their concentration under the larch, and the Zn content was significantly higher compared to the soil under all species. The main reason for the increase in the mobility of some elements under tree stands is their transition from immobile forms under the influence of increased acidity of afforested soils. Wood litter due to the low content of trace elements in its composition cannot be a source of their accumulation in the topsoil.

Short-term effect of thinning on the carbon budget of young and middle-aged silver birch (Betula pendula Roth) stands

Although thinning is a widely used silvicultural method, its effect on stand carbon (C) cycling is still poorly studied at the ecosystem level. The present case study estimated the two-year post-thinning effect on the C balance of a pole and a middle-aged silver birch stand. The results demonstrate the multifaceted impact of thinning on the different C fluxes of deciduous forest ecosystems.The effect of thinning on the C budget of the studied stands was modest: net ecosystem production (NEP) decreased by 1.2 and 1.6 t C ha−1 yr−1 in the pole and the middle- aged stand, respectively; still, both stands remained C sinks. Lower annual production in the thinned stands as a result of the decreased standing biomass of the trees was the main factor for reduced C sequestration capacity. Thinning increased the C accumulation of the herbaceous plants in both stands, however, it did not compensate for the lower C accumulation by the trees. In general, thinning did not affect significantly the soil respiration fluxes; the small post-thinning increase of the annual soil heterotrophic flux, 0.33–0.68 t C ha −1, was most probably related to elevated soil temperature during the active growing season. The annual aboveground litter flux, i.e. the labile C source of Rh, was not significantly changed by thinning. Fine root production and the belowground C input to the soil remained at the same level in the pole stand and decreased slightly in the middle-aged stand. We conclude that the high production ability and fast C accumulation recovery of silver birch stands growing on fertile soils leads to a balanced C budget already during the short post-thinning period.

Seemingly Unrelated Mixed-Effects Biomass Models for Young Silver Birch Stands on Post-Agricultural Lands

Secondary succession that occurs on abandoned farmlands is an important source of biomass carbon stocks. Both direct and indirect tree biomass estimation methods are applied on forest lands. Using empirical data from 148 uprooted trees, we developed a seemingly unrelated mixed-effects models system for the young silver birch that grows on post agricultural lands in central Poland. Tree height, biomass of stem, branches, foliage, and roots are used as dependent variables; the diameter at breast height is used as the independent variable. During model elaboration we used restricted cubic spline: 5 knots at the quantiles (0.05, 0.275, 0.5, 0.725, and 0.95) of diameter at breast height provided sufficiently flexible curves for all biomass components. In this study, we demonstrate the use of the model system through cross-model calibration of the biomass component model using tree height measured from 0, 2, 3, and 4 available extreme trees feature in the plot in question. A different number of extreme trees were measured for final model system and our results indicated that for all analyzed components, random-effect predictions are characterized by higher accuracy than fixed-effects predictions.

Сучасний стан дубових насаджень Східного Полісся

За матеріалами лісовпорядкування проаналізовано лісовий фонд Східного Полісся, зокрема розподіл площі дубових насаджень за походженням, групами віку, типами лісу та категоріями лісів. Досліджено лісівничо-таксаційні показники дубових лісів регіону в розрізі їхнього походження. Представлено результати досліджень особливостей розподілу площ і запасів дубових насаджень у різних категоріях лісів. Виявлено розбалансованість вікової структури дубових насаджень із суттєвим переважанням середньовікових насаджень незалежно від їхнього походження, а також пристиглих дубняків природного походження і молодняків насіннєвого штучного походження. Запропоновано проведення лісогосподарських заходів у дубових лісах Східного Полісся щодо оптимізації вікової структури насаджень і забезпечення їхнього відновлення природним насіннєвим шляхом.

90Sr Content in the Stemwood of Forests within Ukrainian Polissya

The consequences of the Chernobyl disaster continue to threaten humans and ecosystems across fallout gradient in Northern Ukraine and nearby. Forest ecosystems contain substantial stocks of long-lived radionuclide 90Sr which was leached from the fuel matrix during the disaster. Nowadays, there is a lack of information about current transfer factors (TF) of this radionuclide from soil to the stemwood of native tree species. We have estimated 90Sr content in the forest stemwood of three tree species utilizing models of their growth and yield and collected woody samplings. TFs provided here vary greatly across studied tree species (18.0 × 2.1±1, 8.7 × 2.8±1, and 10.4 × 6.0±1 n × 10−3 m2·kg−1 (geometrical mean (GM) ± geometrical standard deviation, GSD) for the above species, respectively) and together with indicators of soil contamination allow us to reliably assess local stocks in the stemwood. Silver birch stands are estimated to deposit the highest 90Sr stocks. Herewith, at 25 years old Black alder stands could accumulate higher stocks (up to 35 MBq·ha−1) under rich growth conditions. TFs obtained in this study substantially exceed values provided by the International Atomic Energy Agency for studied tree species and thus could entail respective restrictions on use of firewood across large areas in Ukrainian Polissya. Data provided here may be harnessed to support decisions of respective stakeholders to provide credibly safe management of the contaminated forest ecosystems.

Моделювання перебігу росту за середньою висотою модальних деревостанів твердолистяних деревних видів України

In Ukrainian Polissia, forestry practices often deviate from reforestation and afforestation projects due to the intensive distribution and rapid growth of some tree species. In addition, there is an intensive process of afforestation of former agricultural lands by stands of Scots pine (Pinus sylvestris L.), silver birch (Betula pendula L.), black alder (Alnus glutinosa L.), and common aspen (Populus tremula L.). Based on the analysis of the current regulatory-reference tools, the absence of growth tables of mixed modal birch stands was determined and the necessity of creating reference materials using a unified system for forest mensuration of softwood deciduous stands was determined. Statistically significant differences in the growth of monocultures and mixed stands, seed and vegetative origin birch stands by major biometric indicators were established. The difference in the growth of mixed birch and pine-birch stands was found. According to the results of mathema tic modelling stands biometrical parameters, tables of the course of growth of modal mixed birch stands of Ukrainian Polissia have been developed. Other representatives of such stands can be Black alder and Common aspen. Mathematic models were tested for compliance with the biological features of the growth of stands. Thus, a system of models of the growth of modal birch stands was developed, which reflects the dynamics of the main biometric indicators, including average height, average diameter, basal area, growing stock volume and total productivity. Compiled yield tables for modal birch stands, reflecting the specific features of the growth of the studied forests, can be the basic regulatory-reference tools for their inventory. In addition, tables of growth modal stands are the basis for the solution of many other organizational, technical, and planned forest management calculations.

Silver birch health condition in the parks of Kharkiv National Agrarian University named after V.V. Dokuchaev

Recently health condition of silver birch (Betula pendula Roth.) stands worsens in the forest and ornamental stands. It is important to know the probability of its improvement or deterioration in particular stands to take the necessary measures in time. 
 The aim of the research was to assess the trends in the health condition dynamics of silver birch stands depending on their age class and the initial health condition of the trees. The research was carried out in 2015-2019 in the Silver birch linear stands in two parks of Kharkiv National Agrarian University named after V.V. Dokuchaev (49º53' N, 36º27' E). Five sample plots of the 3th age class are located in Veterans Park and the other 4 sample plots of the 5rd age class – in Arboretum of this University.
 For each inspected tree diameter at breast height (DBH) was measured in 2015 and 2019. Crown defoliation and health condition class were visually assessed in July of each year. Health condition index (HCI) was calculated as mean weighted from trees number of each category of health condition, separately for all living and dead trees (HCI1–6) and for living trees only (HCI1–4). Tree mortality was expressed as a percentage of lost (dead) trees for research period out of the total trees in 2015.
 It was shown that the silver birch stands of the 3rd age class didn't change their health condition for 2015-2019 or improved it. The stands of the 5th age class worsened their health condition in three sample plots and improved it in one sample plot. Within each age class, the stands of lower diameter class had a worse health condition. Tree mortality was registered in two out of five sample plots in the stands of the 3rd age class and in three out of four sample plots in the stands of the 5th age class. In the stands of the 5th age class the trees from the stands of the smallest diameter class characterized by the highest mortality level (22.4%) and the worse health condition (HCI1-4 =2.8).
 In pooled sample of plots, the death probability for silver birch trees, which 4 years ago had the 1st class of health condition is 3.5%, those of the 2nd class have the death probability of 10.7%, the trees of the 3rd class – 36.9%, those of the 4th class – 84.6%. As for an initially weakened stand, its trees which 4 years ago had the 1st, the 2nd, the 3rd or the 4th health condition class, have the death probability of 5%, 18.5%, 33.3%, and 100% respectively.
 Thus, the weakened silver birch stand which contains trees of 1st - 3rd classes of health condition is able to restore condition to a healthy one, and the deterioration may be expected only for severely weakened trees (having 3rd class of health condition in 2015). The weakened silver birch stand which has the trees of 1st - 4th health condition classes is most likely to weaken even more severely over 4 years.

The effect of thinning on annual net nitrogen mineralization and nitrogen leaching fluxes in silver birch and Scots pine stands

ABSTRACTThinning changes the functioning of the whole forest ecosystem, including carbon and nitrogen (N) cycling. The input of organic matter and N into soil, as well as soil temperature and moisture regimes change, which may have an impact on the intensity of the net nitrogen mineralization (NNM) process. The main aims of this study were to estimate the effect of thinning on annual NNM as well as N leaching intensity in young silver birch and Scots pine stands. Thinning increased annual NNM flux in the silver birch stand, as well as annual net nitrification, while there was no change in the annual net ammonification flux. The effect of thinning on nitrification was more pronounced in the first post-thinning year. The 13-year dynamics of annual NNM in the birch stand revealed a significant decrease, which may be attributed to the effect of previous land use. The annual NNM flux in the Scots pine stand was practically equal in both plots; thinning did not affect N net mineralization intensity. The effect of thinning on the annual NNM flux was site and tree species specific. Thinning did not induce more intensive N leaching. Moreover, in the birch stand thinning even reduced N leaching.

Elevated atmospheric humidity shapes the carbon cycle of a silver birch forest ecosystem: A FAHM study

Processes determining the carbon (C) balance of a forest ecosystem are influenced by a number of climatic and environmental factors. In Northern Europe, a rise in atmospheric humidity and precipitation is predicted. The study aims to ascertain the effect of elevated atmospheric humidity on the components of the C budget and on the C-sequestration capacity of a young birch forest. Biomass production, soil respiration, and other C fluxes were measured in young silver birch (Betula pendula Roth) stands growing on the Free Air Humidity Manipulation (FAHM) experimental site, located in South-East Estonia. The C input fluxes: C sequestration in trees and understory, litter input into soil, and methane oxidation, as well as C output fluxes: soil heterotrophic respiration and C leaching were estimated.Humidified birch stands stored C from the atmosphere, but control stands can be considered as C neutral. Two years of elevated air humidity increased C sequestration in the understory but decreased it in trees. Humidification treatment increased remarkably the C input to the soil. The main reason for such an increase was the higher root litter input into the soil, brought about by the more than two-fold increase of belowground biomass production of the understory in the humidification treatment. Elevated atmospheric humidity increased C sequestration in young silver birch stands, mitigating increasing CO2 concentration in the atmosphere. However, the effect of elevated atmospheric humidity is expected to decrease over time, as plants and soil organisms acclimate, and new communities emerge.

Forest biodiversity and production potential of post-mining landscape: opting for afforestation or leaving it to spontaneous development?

Abstract Land reclamation of post-mining sites strongly influences not only diversity and biomass of frequently studied ground vegetation, but also diversity of forest ecosystem. In most cases, spoil heaps are afforested after coal mining, but some reclaimed sites are left to spontaneous development, such as our study locality – surroundings of the Sokolov town, Czech Republic. Structure, species diversity and production potential were studied on three heap sites, artificially afforested by pedunculate oak (Quercus robur L.), black alder (Alnus glutinosa [L.] Gaertn) and silver birch (Betula pendula Roth) stands, and compared with three permanent research plots (PRP) left to natural succession processes with prevailing European aspen (Populus tremula L.), goat willow (Salix caprea L.) and also with silver birch. The timber production increased from the willow stand (28 m3 ha−1) to birch ones (97 m3 ha−1, all 45 years old). The mean stand volumes were significantly higher on afforested PRPs (74 m3 ha−1) than on succession PRPs (51 m3 ha−1), just as tree diameters. However, in terms of production quality, occurrence of breaks was significantly higher on afforested PRPs (15%) compared to succession PRPs (7%), while the opposite situation was observed in the stem quality. Horizontal structure of trees was regular on afforested PRPs, while spatial pattern on succession PRPs was aggregated. The highest differences in favor of succession PRPs was found in species richness and total stand diversity. These results imply a need for combined approaches in post-mining landscape management to support economic benefit and especially ecological value.

Effects of CMIP5 Projections on Volume Growth, Carbon Stock and Timber Yield in Managed Scots Pine, Norway Spruce and Silver Birch Stands under Southern and Northern Boreal Conditions

We investigated how recent-generation (CMIP5) global climate model projections affect the volume growth, carbon stock, timber yield and its profitability in managed Scots pine, Norway spruce and Silver birch stands on medium fertile upland sites under southern and northern boreal conditions in Finland. Forest ecosystem model simulations were conducted for the current climate and changing climate, under two representative concentration pathways (RCP4.5 and RCP8.5), using 10 individual global climate model (GCM) projections. In addition to the baseline thinning, we maintained either 20% higher or lower stocking in thinning over a 90-year period. In the south, the severe climate projections, such as HadGEM2-ES RCP8.5 and GFDL-CM3 RCP8.5, as opposed to MPI-ESM-MR RCP4.5, considerably decreased the volume growth, carbon stock and timber yield, as well as its profitability, in Norway spruce stands, but also partially in Scots pine stands, compared to the current climate. Silver birch gained the most from the climate change in the south and Scots pine in the north. The impacts of the thinning regime varied, depending on tree species, site and climate applied. Depending on the severity of the climate change, even opposing adaptive management measures may be needed in different boreal regions.

Plant Uptake of Per- and Polyfluoroalkyl Substances at a Contaminated Fire Training Facility to Evaluate the Phytoremediation Potential of Various Plant Species.

Fire training facilities and other areas suffer from serious per- and polyfluoroalkyl substance (PFAS) contamination in soil, surface water, and groundwater due to regular practices with PFAS-containing aqueous firefighting foams (AFFFs). Therefore, the uptake of 26 PFASs in plants and the contamination of soil and groundwater has been investigated at a fire training site at Stockholm Arlanda airport, Stockholm (Sweden) in 2016. Elevated ∑26PFAS levels were detected in soil and groundwater ranging from 16 to 160 ng g-1 dry weight (dw) and 1200-34 000 ng L-1, respectively. Samples from different plant species and tissues (i.e., roots, trunk/cores, twigs, leaves/needles) of the local plant community were taken, namely silver birch (Betula pendula), Norway spruce (Picea abies), bird cherry (Prunus padus), mountain ash (Sorbus aucuparia), ground elder (Aegopodium podagraria), long beechfern (Phegopteris connectilis), and wild strawberry (Fragaria vesca). The plants showed a high variability of concentrations with highest ∑26PFAS concentrations in vegetative compartments with up to 97 ng g-1 wet weight (ww) and 94 ng g-1 ww in birch leaves and spruce needles, respectively. Annual ground cover plants such as long beechfern and ground elder, and bushes like bird cherry showed concentrations up to 6.9, 23, and 21 ng g-1 ww, respectively. The bioconcentration factors (BCFs; plant/soil ratios) were highest in foliage, while the total tree burden of ∑26PFASs per tree was up to 11 mg for birch and 1.8 mg for spruce. Considering a shelterwood system with mixed stands of silver birch and spruce in combination with regular harvest of leaves and birch sap and an understory of ground elder, it is potentially feasible to remove 1.4 g of ∑26PFASs per year and hectare from (heavily) contaminated sites. An alternative approach is the coppicing of birch trees in combination with an understory of ground elder, potentially removing 0.65 g yr-1 ha-1 of ∑26PFASs, while a simple meadow with ground elder can remove 0.55 g yr-1 ha-1 ∑26PFASs.

Прогноз строения защитных лесополос Средней Сибири с учетом агротехнических особенностей насаждений

The study of the structure was based on a series of distribution by the steps of the thickness. Measurements were carried out in forest shelter belts of the southern part of Central Siberia. Plots were laid on the territory of the Republic of Khakassia (Ust- Abakan, Bay, Shirinsky, Shushensky districts), Krasnoyarsk territory (Minusinsk district) and the Republic of Tuva (Kyzylskiy district). Approximation of distribution rows by diameter has been implemented by two functions: normal distribution and Weibull distribution. With respect to protective forest belts for most forest stands, structure by diameter is more adequately approximated by normal distribution, indicating the symmetry rows. But at this, function of Weibull is characterized by high correlation of its ratios with parameters of plantations, in particular with average diameter and normalized variability. Based on the study of the structure of the plantings in diameter, the optimal agro-technical indicators for the cultivation of plantations presented a variety of wood species, were revealed. It is recommended to divide rows into two groups, before forecasting the series. The first category reflects the influence of the internal (growth) processes: growth, mortality, movement of trees on the steps. These rows can be predicted taking into account the average diameter of tree stand and theoretical density (square of nutrition of individual tree). The second group of rows was formed under the influence of external factors (supplement, renewal, felling, and forest fires).These rows are forecasted using the average diameter and standard deviation of trees. For the prediction of the structure of the stands of Siberian larch, silver birch, Siberian elm and black poplar, model based on the Weibull function, were obtained.

Carbon budgets in fertile silver birch (Betula pendula Roth) chronosequence stands

Carbon (C) budgets were compiled for silver birch chronosequence stands by synthesizing the above- and belowground C pools and fluxes with the aim to assess the impact of age on stand C sequestration and cycling.The fine root (d<2mm) biomass, production, turnover rate and longevity of 13-, 32- and 45-year-old silver birch stands were determined by the ingrowth core method. Fine root production after the third year from the installation of cores was 0.89, 1.44 and 1.31tha−1year−1 in the pole, middle-aged and premature silver birch stands, respectively.Soil respiration (Rs) was measured during the two growing seasons of 2010 and 2011; the trenching method was used to estimate the contribution of heterotrophic respiration (Rh) to total soil respiration. Soil temperature was the driving environmental factor of the temporal variation of Rs and Rh. Stand age affected significantly respiration rates. Annual Rs was 6.2, 9.7 and 8.2tCha−1 and annual Rh was 2.97, 4.21 and 3.61tCha−1 in the pole, middle-aged and premature silver birch stands, respectively. The annual contribution of Rh to Rs was similar in each stand ranging from 0.43 to 0.48.Total annual net primary production (NPP) of the ecosystems of 7.4, 7.9 and 8.5tCha−1year−1 was estimated in the pole, middle-aged and premature stands. After balancing the C input and output fluxes in the silver birch stands of different development stages, it appeared that they all acted as effective C sinks. Net ecosystem production (NEP) was 4.4, 3.7 and 4.9tCha−1year−1 in the pole, middle-aged and premature stands, respectively. In the premature stand the second layer of the spruce contributed significantly to the increased C input. The annual organic C input into the soil through above- and belowground litter occurred to be of the same magnitude as C loss via annual heterotrophic respiration. Thus, annual increment of woody biomass in fertile silver birch stands reflects annual organic C sequestration in the ecosystem. Among the studied stands, estimated NEP values were the lowest in the middle-aged stand and the highest in the oldest stand, indicating non-linear relationship between stand NEP and stand age.

Increased air humidity and understory composition shape short root traits and the colonizing ectomycorrhizal fungal community in silver birch stands

Climate change is predicted to bring about a rise in precipitation and air humidity at northern latitudes, which could have considerable impact on forest management. This paper investigates the effect of increased air humidity and understory composition on short root morphology and on the relative abundance of colonizing ectomycorrhizal (EcM) fungal associates in silver birch (Betula pendula Roth.) stands.Short root morphological traits of silver birch were analyzed at increased humidity and ambient conditions for two different understories (early-successional grasses and diverse “forest” understory) in three consecutive years (2009–2011). The fungal community was determined in 2010 (after three seasons of misting) using molecular methods. The study was conducted on the Free Air Humidity Manipulation (FAHM) experimental facility established in Estonia.Silver birches responded to the rise in air humidity by forming longer and thinner short roots, which can be interpreted as a morphological adaptation leading to an increase in the absorptive area. The response was stronger when humidification concurred with the species-poor understory of pioneer grasses. The inter- and intra-treatment variation in short root morphological parameters decreased by the third year. Using molecular methods, overall 64 EcM taxonomic units were distinguished. Hydrophilic fungal morphotypes dominated significantly in humidified plots, hydrophobic morphotypes in control plots.Our results suggest that rising air humidity causes a morphological stress response in EcM short roots. Young trees show the ability to adapt to climate change with great plasticity by modifying short root length, diameter and specific root length (SRL). Humidification leads to a shift in the fungal colonizers towards the dominance of hydrophilic taxa, which may alter ecosystem functioning.