Pine Sites Research Articles

Calibration and Validation of the Cosmic Ray Neutron Rover for Soil Water Mapping within Two South African Land Classes

Knowledge of soil water at a range of spatial scales would further our understanding of the dynamic variable and its influence on numerous hydrological applications. Cosmic ray neutron technology currently consists of the Cosmic Ray Neutron Sensor (CRNS) and the Cosmic Ray Neutron Rover (CRNR). The CRNR is an innovative tool to map surface soil water across the land surface. This research assessed the calibration and validation of the CRNR at two survey sites (hygrophilous grassland and pine forest) within the Vasi area with an area of 72 and 56 ha, respectively. The assessment of the calibrations showed that consistent calibration values (N0) were obtained for both survey sites. The hygrophilous grassland site had an average N0 value of 133.441 counts per minute (cpm) and an average error of 2.034 cpm. The pine site had an average N0 value of 132.668 cpm and an average error of 0.375 cpm between surveys. The validation of CRNR soil water estimates with interpolated hydro-sense soil water estimates showed that the CRNR can provide spatial estimates of soil water across the landscape. The hydro-sense and CRNR soil water estimates had a R2 of 0.439 at the hygrophilous grassland site and 0.793 at the pine site.

Nutrient and carbon cycling along nitrogen deposition gradients in broadleaf and conifer forest stands in the east of England

Forest fragmentation dominates the landscape in England and there is a concern about the associated forest edge effect especially in areas with high N inputs. This study quantifies this effect and the impact of high N deposition on forest and soil biogeochemical processes under 26 year old Corsican pine and 72 year old beech forest stands at Thetford forest, the lowest rainfall area of East Anglia, UK. Nutrient and C cycling were studied along 200 m N deposition gradients away from intensive pig and chicken rearing units, over five years. The site is underlain by argillic brown sand over chalk. Total N deposition at the Corsican pine was 46 kg N ha−1 at the edge reducing to 22 kg N ha−1 in the inner forest, composed of 70% dry deposition, with 50% NH4-N. Under the beech total N deposition was 36 kg N ha−1 at the edge, reducing to 22 kg N ha−1 at 200 m, of which 63% was dry N deposition at the edge, composed of one third NH4-N.The results indicate a strong edge effect with an N deposition gradient along which soil acidity and soil available N (as NO3-N and NH4-N) significantly increased under both pine and beech. Tree N uptake also increased with increasing N deposition, which reduced the uptake of P and K. Uptake of Ca and Mg was not affected. Nitrogen deposition stimulated the growth of both species and enhanced litter and fine root decomposition at the beech but inhibited decomposition at the pine site. This had a positive effect on soil C storage under pine, which was negative under beech. Tree physiological responses to N deposition included an increase of beech flowering and Corsican pine coning, but reduced beech seeding.The edge effect was detectable across 200 m in these stands. Coniferous and broadleaved species in this study responded differently to N addition, due to different N cycling processes both above and belowground. Coniferous systems are more prone to N saturation than broadleaved through scavenging by forest canopy and soils, but they could be the more effective tree type/species choice in N abatement natural strategies. Local effects of N deposition should be accounted for in forest design plans in order to minimise edge effect impacts on the forest environment.

Spatial variation of pine tree-ring growth in the Solovetsky Islands

The paper presents the results of an analysis of the spatial variability of pine tree-ring growth in the Solovetsky Islands. As a result of the field work, tree-ring network containing 14 dendrochronological pine sites in various habitats were developed. For each site, a local tree-ring width pine chronology (from 472 to 271 years) is obtained, representing pine growth features in different habitat conditions. A comparison between chronologies revealed synchronious growth of pine in various habitats in the late 17th, in the first half of the 18th and the beginning of the 19th centuries. The use of cluster analysis allowed to identify several groups of chronologies with similar characteristics. So, trees growing on swamps, on a sandy substrate and in a green-moss pine forest or in a mixed forest are allocated in separate clusters. This clustering is also confirmed by the results of a dendroclimatic analysis of local chronologies. It turned out that the increase in the pine’s growth in the mixed forest and in the green-moss pine forest depends on the July air temperature variation. Inside this group, samples from pine forests have a common feature – a positive relationship of growth with the precipitation of September. The only site located on the sands showed a different climatic signal than the other chronologies, namely, the dependence on the temperature of August.

Лісовісовідновні процеси в деревостанах за участю модрини європейської в умовах Кременецького горбогір'я

Досліджено лісовідновні процеси в модринових деревостанах віком від 25 до 109 років, які ростуть в умовах від бідних суборів до свіжих і вологих грудів Кременецького горбогір'я. Частка модрини у складі цих деревостанів становить 1-10 одиниць. Встановлено, що в модринових деревостанах різного віку виявлено від 2,31 до 27,89 тис. екз./га підросту деревних видів. У його складі в різних деревостанах трапляється від одного до шести деревних порід – сосни звичайної, дуба звичайного і червоного, модрини європейської, кленів гостролистого і явора, в'яза голого, бука лісового, граба звичайного, ялини європейської, а їхня кількість залежить від типу лісорослинних умов. Трапляння підросту коливається в межах 45-100 %. Вікова структура підросту є різною і залежить від видового складу і його властивостей до виживання за недостатньої освітленості під наметом деревостанів. Однорічки трапляються на всіх дослідних ділянках у кількості 2,0-51,7 %, 2-3-річки становлять 3,9-45,3 %, 4-8-річки – 18,2-62,9 % і 9-15-річки – в межах 7,2-45,8 %. Одно- і 2-3-річний підріст сформувався переважно сосною, модриною, дубом звичайним і червоним. Кількість здорових рослин підросту в деревостанах становить від 18,8 до 47,1 %, середньоослаблених – 30,8-55,3 % і дуже ослаблених – 10,0-28,0 %. У деревостанах переважає дрібний (21,9-100,0 %) і середній (0,0-77,2 %) за висотою підріст. Великий підріст трапляється на окремих ділянках із часткою 0,2-7,1 %. До дрібного підросту належить все потомство сосни, модрини, дуба звичайного і червоного та ясена. Групу середнього і великого за висотою підросту формує молоде покоління ялини, клена гостролистого і явора, в'яза голого та граба.

Long-term succession of closed boreal forests at their range limit in eastern North America shows resilience to fire and climate disturbances

The distribution of vegetation zones in northeastern North America forms a gradual transition from closed to open forests, and to tundra. Closed forests near the open forest/tundra boundary generally correspond to residual patches of a once larger forest community. Whether these forest patches have survived as untouched, fire-free communities or as resilient communities during the Holocene remains unknown. To answer to this question, we reconstructed the successional history of two black spruce closed-crown forests and one jack pine forest near the northern limit of closed forest ecosystems. Stand-scale postfire succession was analysed based on charcoal macrofossils. Extensive 14C dating and botanical identification of charcoal fragments located at the organic soil surface and buried in the mineral podzolic solum were used to reconstruct the successional pathways of the sites. The forest sites developed in a context of continuous fire disturbance, except for a short interval of several centuries. The fire history of the three sites is similar with a fire frequency of 34–37 fires over the last 5000–5800 years, which corresponds to a mean fire interval of 150–180 years. Based on parametric and non-parametric estimators, the regional fire regime of the Laforge area (combined fire data of two sites located about 7 km from each other) was most likely characterized by 38 fires over the last 5000–5800 years, i.e., at an interval of about 150–160 years. Birch (Betula papyrifera) was present in the spruce sites between 5800 and 3000 cal. years BP. Jack pine arrived at the pine site about 3000 cal. years BP, at the time when birch was extirpated from the spruce forests. The closed-crown forests near the open forest/tundra boundary are resilient postfire ecosystems which regenerated successfully since mid-Holocene. Compositional change of these forests, which led to the decline of birch but maintained the dominance of conifers, appears related to cooler and wetter conditions of late Holocene. Climatic conditions also slowed the eastward migration of jack pine, which explains the late arrival of this species at its northeastern range. Our data suggest that fire disturbance in these sites of the boreal biome has been a continuous and positive regenerative process since mid-Holocene despite the influence of climatic change on the tree flora.

Формування лісової підстилки в деревостанах за участю модрини європейської в умовах Кременецького горбогір'я

Досліджено формування лісової підстилки в 14–109-річних деревостанах за участю модрини європейської. У складі деревостанів частка модрини змінюється в межах 1–10 одиниць. Встановлено, що під наметом деревостанів за участю модрини європейської запас лісової підстилки в абсолютно сухому стані становить 0,30–1,96 кг/м². У її складі маса листя і хвої змінюється в межах 0,22–1,18 кг/м², або 9,4–84,9 %, а пагонів, шишок, кори тощо – від 0,08 до 1,55 кг/м², або 15,1–90,6 % від загальної її маси. У модрини у віці молодняків розпочинається і продовжується в середньовікових деревостанів до 50–60 років інтенсивне відмирання пагонів та очищення стовбурів дерев від сучків. Воно призвело до збільшення у складі лісової підстилки маси пагонів і кори до 50–90 %. У чистих модринових деревостанах нагромаджується більший запас лісової підстилки, ніж у мішаних. У молодняків запас лісової підстилки в чистому модриновому деревостані перевищує мішані на 2,1–88,6 %. У середньовікових, стиглих і перестиглих деревостанів такі відмінності становлять 4,7–75,4 %. Показано, що лісостани характеризуються різним варіюванням маси лісової підстилки загалом чи її фракцій у межах деревостану. Коефіцієнт варіації маси лісової в деревостанах виявився в основному середнім і рідше слабким (V = 6,1–20,5 %). Поряд з цим значно зростає варіювання фракцій лісової підстилки. Так, варіювання маси хвої і листя змінюється в межах 6,8–33,1 %, а фракції пагонів, шишок, кори тощо – 6,1–42,9 %.

Біоелектричні потенціали модрини європейської в деревостанах Кременецького горбогір'я

Досліджено біоелектричні потенціали модрини європейської, дуба звичайного, ялини європейської і сосни звичайної, які формують деревостани в різних типах лісорослинних умов Кременецького горбогір'я. Вік деревостанів становить 12–109 років. Частка модрини в їх складі змінюється в межах 1–10 одиниць. Модрина європейська в умовах суборів і сугрудів характеризується нижчими абсолютними показниками БЕП кореневої шийки, порівняно з сосною звичайною, а в умовах грудів – вищими, порівняно з дубом звичайним і ялиною європейською. Встановлені відмінності між деревними видами зберігаються упродовж дня. Відмінності між модриною і дубом за абсолютними показниками біопотенціалів посилюються у другій половині дня. У модрини в мішаних молодняках і середньовікових деревостанах абсолютні значення БЕП виявились вищими, ніж у чистих деревостанах. Встановлено три типи денних біопотенціалограм, які характеризують динаміку проходження метаболічних процесів у деревних видів у деревостанах різних лісорослинних умов та видового складу. Між біометричними показниками модельних дерев різних деревних видів і середньоденними показниками біопотенціалів переважно спостережено помірний і значний прямий кореляційний зв'язок. Більш тісною залежність денної зміни біопотенціалів виявлено від денної динаміки температури і вологості повітря, аніж від інтенсивності світла. Між вологістю повітря і біоелектричними потенціалами існує зворотний кореляційний зв'язок.

Санітарний стан соснових насаджень на рекультивованих землях

Проаналізовано санітарний стан соснових насаджень, створених на рекультивованих землях Юрківського буровугільного кар'єру. Насадження ростуть у складних умовах на переміщених, малопотужних ґрунтах із вуглистими пісками. За даними 61 кругової пробної площі, які охоплюють типові умови зростання соснових культур на площі 141,1 га, обчислено показники санітарного стану насаджень. Аналіз показника санітарного стану показав, що соснові насадження належать до сильно ослаблених. Ослаблені дерева сосни становлять 44,7 %, а показник санітарного стану змінюється у межах 3,01–3,41. Стан соснових насаджень V класу віку наближається до категорії насаджень, що всихають з найвищою величиною показника стану 3,41. Встановлено, що найвпливовішими чинниками істотного погіршення санітарного стану соснових культур на рекультивованих землях Юрківського буровугільного басейну є ураження кореневою губкою і всихання дерев унаслідок зменшення живлення рослин, які досягли порушеного материнського горизонту на глибині понад 40–50 см. Для запобігання розвитку кореневої губки необхідно створювати мішані культури сосни звичайної з введенням до 50 % листяних порід, які водночас будуть протипожежним бар'єром поширення низових пожеж. Для оздоровлення соснових насаджень, підвищення меліоративної ефективності та ліквідації осередків кореневої губки доцільно проводити суцільні санітарні рубки з подальшим висаджуванням листяних порід.

Natural regeneration after gap cutting in Scots pine stands in northern Finland

ABSTRACTThe objective of the study was to examine the success of regeneration in gaps of variable size in pine-dominated stands in terms of seedling density. It was based on an experiment in central Lapland containing circular clear-cut gaps of 20, 40 and 80 m in diameter on typical sub-xeric and xeric pine sites with site preparation (patch scarification). The observation period covered the first five years after cutting. The average number of seedlings that had emerged after gap cutting was about 22 000 ha−1 for pine and 7 000 ha−1 for birch. The proportion of regeneration sample plots without any pine seedlings was less than 10%. The seedling density diminished constantly with greater distance from the edge stand but indicating sufficient density up to the largest gap size in the study (diameter 80 m, area ca. 0.5 ha). Site preparation promoted regeneration remarkably, and we conclude that successful regeneration would be achieved in most cases with soil scarification exposing just 10–20% of the soil surface.

Do stand structure and admixture of tree species affect Scots pine aboveground biomass production and stability on its natural site?

The paper analyses stand structure and production on two experimental forest stand series of mature pure and mixed Scots pine stands, growing on natural Scots pine sites in the Czech Republic. Sessile oak was the main admixed species. In mixed stands, Scots pine constituted the dominant level of the stand, admixed species grew mostly as subdominants. Admixture increased stand densities and aboveground biomass production compared to pure stands. Sessile oak with the 20–30% number share within the Scots pine stand led to an increase of the Scots pine tree dimensions and mean stem merchantable wood (DBH ≥ 7 cm) volume compared to the pure Scots pine stand of similar density. The Scots pine and sessile oak slenderness ratios increased in mixed stands compared to monocultures, however, the stand mechanical stability was not threatened.

Carbon and Oxygen Isotope Composition in Soil Carbon Dioxide and Free Oxygen within Deep Ultisols at the Calhoun CZO, South Carolina, USA

ABSTRACTIn order to evaluate effects of three land uses on isotopic compositions of CO2 and O2 of soil air to 5 m soil depth, a field study was conducted in the Calhoun Critical Zone Observatory, located in the subtropical climate of the Southern Piedmont of South Carolina, USA. Soil gas reservoirs were installed in ecosystems with three different land uses, each replicated three times: (i) reference hardwood stands that were never cultivated; (ii) currently cultivated plots; (iii) pine stands, which had been used for growing cotton in 19th century but were abandoned in about the 1930s and 1940s when they were regenerated with pines that are today 70–80 yr old. In addition to soil CO2 and O2 concentration measurements, soil gas samples were analyzed for Δ14C, δ13C, and δ18O. Stable carbon isotopic composition becomes lighter with the depth in soils of all three land uses: in the cultivated site δ13C decreases from –18‰ at 0.5 m to –21‰ at 5 m, in pine site from –22 to –25‰, and in hardwood from –21.5 to –24.5‰, respectively. Δ14C increased with depth from 40 to 60‰ in the top 0.5 m to about 80–140‰ at 5 m depending on land use. While surficial soils had relatively similar Δ14C in CO2, between 40 to 60‰ at 0.5 m, at 3 and 5 m, cultivated soils had the highest Δ14C, hardwood the lowest, and pine in between, a pattern that emphasizes the importance of contemporary respired CO2 in hardwood stands. Oxygen isotopic composition of CO2 did not change with depth, whereas free O2 was greatly enriched in lower horizons of forest soils, which we attribute to strong fractionation by respiration.

A comprehensive analysis of interseasonal and interannual energy and water balance dynamics in semiarid shrubland and forest ecosystems

Accurate estimation of ecosystem-scale land surface energy and water balance has great importance in weather and climate studies. This paper summarizes seasonal and interannual fluctuations of energy and water balance components in two distinctive semiarid ecosystems, sagebrush (SB) and lodgepole pine (LP) in the Snake River basin of Idaho. This study includes 6 years (2011–2016) of eddy covariance (EC) along with modeled estimates. An analysis of the energy balance indicated a higher energy balance ratio (0.88) for SB than for LP (0.86). The inclusion of canopy storage (CS) increased the association between turbulent fluxes and available energy in LP. Green vegetation fraction (GVF) significantly controlled evapotranspiration (ET) and surface energy partitioning when available energy and soil moisture were not limited. Seasonal water balance in the Budyko framework showed severe water-limited conditions in SB (6–9 months) compared to LP (6–7 months). Based on the validated Noah land surface model estimates, direct soil evaporation (ESoil) is the main component of ET (62 to 79%) in SB due to a large proportion of bare soil (60%), whereas at the lodgepole pine site, it was transpiration (ETran, 42–52%). A complementary ratio (CR) analysis on ET and potential ET (PET) showed a strong asymmetric CR in SB, indicating significant advection. Both SG and LP showed strong coupling between soil moisture (SM) and air temperature (Ta). However, a weak coupling was observed in SB when the soil was dry and Ta was high. This weak coupling was due to the presence of net advection. The results presented here have a wider application: to help us understand and predict the survival, productivity, and hydroclimatology of water-limited ecosystems.

Abiotic factors modulate post-drought growth resilience of Scots pine plantations and rear-edge Scots pine and oak forests

The proportion of planted forests in the Mediterranean Basin is one of the largest in the world. These plantations are dominated by pine species and present a series of characteristics such as low elevation, high competition or small tree size that make them more vulnerable to droughts. However, quantitative assessments of their post-drought growth resilience in accordance with species, site factors and tree characteristics are lacking. In this study we sampled 164 trees at four forest sites located in the drought-prone Sierra Nevada, southeastern Spain. We compared growth responsiveness to drought in rear-edge planted vs. relic natural Scots pine (Pinus sylvestris) and coexisting Pyrenean oak (Quercus pyrenaica) stands. Our objective was to characterize and compare the different growth responses to drought between species and sites and the effect of the main physiographic factors (altitude, aspect, and slope) on these responses since the influence of these factors on post-drought resistance and resilience has received little attention to date. Our results reveal that the planted pine sites with the lowest mean growth rates displayed greater resistance during drought, and that higher altitude was associated with improved resistance and/or resilience for all species and sites. Natural pine and Pyrenean oak stands were better adapted to the dry climatic conditions of the Mediterranean region where the study was undertaken, displaying greater resistance and/or resilience and lower influence of drought on growth in comparison to stands of planted pines. These results suggest that promoting the conservation of high-elevation pine plantations and enhancing the regeneration of natural pine and oak may improve the resistance and resilience of these drought-prone forest ecosystems.

IMPACT OF ORGANIC FERTILIZER "DOSTATOK" ON THE SURVIVAL AND GROWTH OF PINE PLANTATIONS

The survival and growth of pine plantations, created at the clear cuttings, with the use of organic fertilizer "Dostatok" are analyzed. The research was conducted in 11 forest units of the State Enterprise "Vyshche-Dubechna Forestry" in the fresh poor and rich forest sites. The plantations were created according to the following schemes: 4 rows of Scotch pine and 1 row of red oak with placement of seedlings 1.5×0.5 m and 1.5×1.0 m by planting them in a furrow formed by a plow PKL-70. The total forest pine plantations with application of fertilizer amounted to 22.2 hectares. The agrochemical analysis revealed that 40.6 % of organic matter was concentrated in the fertilizer, whereas in the organic layer of fresh poor and rich pine sites, the content of humus was 22.2 % and 30.7 % respectively. At the same time, fertilizer is characterized by a neutral environment, while the organic soil of fresh poor and rich pine sites has a very high acidity of the pH of the salt extract, which fluctuates within 3.5–3.6. The double predominance of the organic matter content in the fertilizer promotes the survival and growth of pine plantations. It was established that the introduction of fertilizer "Dostavok" in the form of tablets on the root system of pine seedlings increases the survival of forest plantations, which on sandy and sandy loam soils, respectively, reaches 90 and 95 %. Values of pH salt extraction indicate that the soils are very acid (3.5 and 3.1), with an average level of humus (2.4 and 7.4 %), low levels of ammonia and nitrate nitrogen and mobile phosphorus. Soil of fresh poor pine site has an elevated level of mobile potassium (139.87 mg·kg-1), while the fresh rich pine site is characterized by a low level of potassium, which is 46.39 mg·kg-1. Granulometric analysis of the soil showed that the poor sites are represented by sandy soils and rich sites – rough-dust sandy loam soils. Almost double the predominance of the organic matter content in the fertilizer "Dostatok" contributes to the survival and growth of pine plantations. The annual increment of pine seedlings on 4–7 cm was more than at the control. The use of bio-fertilizer also reduces the number of manual care and accelerates the closure in the rows, which in turn allows the transfer of forest crops to covered forest area a year earlier.

Delineating limits: Confronting predicted climatic suitability to field performance in mistletoe populations

Abstract Biotic stressors such as hemiparasites have a profound impact on forest functioning. However, predicting the future incidence of these stressors on forests remains challenging because climate‐based distribution does not consider tree–hemiparasite interactions or the impacts of extreme climate events on stressors’ performance. We use species distribution models (SDMs) and ecophysiological and demographic field data to assess whether climatic suitability is a proxy for the performance of the hemiparasite mistletoe (Viscum album) in two forests with contrasting climatic conditions. Two host tree species representing wet‐cold (Scots pine) and dry‐warm (Aleppo pine) conditions were selected. We fitted SDMs based on climate variables, and measured different ecophysiological variables capturing cold‐ (photoinhibition) and drought tolerance (intrinsic water‐use efficiency, iWUE). We also assessed demographic variables related to seed germination and establishment rates of mistletoe through a translocation experiment. Species distribution models showed a high climatic suitability of mistletoe in both forests. Mistletoes living in the Scots pines site presented a higher cold tolerance, while those inhabiting the Aleppo pine site showed a higher iWUE. Seedlings coming from local seeds showed a lower mortality than seedlings coming from translocated seeds. Germination and seedling establishment showed temporal mismatches when comparing local and translocated seeds. Synthesis. Habitat suitability predicted by SDMs based on climate data and field performance were related in this mistletoe species. However, ecophysiological and demographic variables indicated a lower fitness of mistletoe in the dry‐warm site associated with drought stress. In conclusion, predicted climate suitability based on SDMs forecasts should be refined using field data on actual performance and considering plant‐to‐plant interactions and extreme climate events.

THE DYNAMICS OF MENSURATIONAL INDICES AND THEIR SHORT-TERM PREDICTION IN BIRCH-PINE STANDS UNDER A2 TYPE CONDITIONS (FRESH INFERTILE PINE SITE TYPE)

Здійснено моделювання основних лісівничо-таксаційних показників для березово-соснових деревостанів в умовах свіжого соснового бору. Використання деревом площі живлення у повному обсязі є верхнім обмеженням росту у фіксований момент часу. Досягнення максимальних біометричних показників дає змогу дереву найкраще використовувати потенційну родючість ґрунту. З погляду теорії систем, деревостан, що досягає стану динамічної рівноваги, називають оптимальним, який характеризується найвищою продуктивністю. Вплив природних чинників на формування деревостанів зумовлює природний, без антропогенного втручання, розвиток лісостанів, за якого ріст і розвиток дерев забезпечується саморегуляцією. Внаслідок цього формуються динамічно врівноважені,максимально продуктивні біологічні системи. Докладний аналіз процесів росту і розвитку деревостанів у конкретних умовах дає змогу визначати моделі короткотермінового прогнозу окремих показників деревостану для розрахунку інтенсивності та повторюваності доглядових рубань. Встановлено, що збільшення обсягу вирубуваноїдеревини сосни веде до зменшення запасу та істотного збільшення середнього діаметра кращих дерев. Результати прогнозу отримано для інтенсивності доглядових рубань в межах 16–30 % від запасу деревостану на контрольній пробній площі. Отримані динамічні ряди основних таксаційних показників соснових деревостанів у свіжому сосновому борі запропоновано використати як теоретичну основу для подальшого проектування доглядових рубань та формування березово-соснових насаджень із поліпшеною товарною структурою.

THE STOCKS OF SURFACE FOREST FUELS IN THE FORESTS OF KYIV POLISSYA ZONE, UKRAINE

Large forest fires cause the most devastating consequences. Global climate change, excessive man-made pressures are accompanied by frequent forest fires, especially in pine plantations, which are the most hazardous. The article reports the changes in the stocks of forest fuels in the pine plantations of the Boyarka Forestry Research Station in the Kiev Polissya zone. The stocks of fraction composition for 1st and 2nd groups of forest fuels were analysed by age. Separately, the stock of forest fuels of the 1st group was evaluated as a part of the total stock of forest fuels of 1st and 2nd groups. It was established that the stocks of the forest fuels of 1st group exceeded the 2nd group stocks at a young age, in particular at the age of 15 in a fresh fairly fertile sites and at the age of 23 in fresh fairly infertile pine site type. Features of forest fuel stocks in pure pine plantations were analyzed depending on the type of forest site conditions and the age of pine plantations. The accumulation trend of forest fuels was revealed depending on the age of the plantation. The most fire-dangerous plantations of Scots pine were determined, taking into account their age and the stock of surface forest fuels. This will allow predicting the occurrence of fires in the pine forests of the Boyarka Forestry Research Station, to create an information database on the stocks of forest fuels, and to reveal patterns of their accumulation with age in different types of forest sites.

Modifications of 2:1 Clay Minerals in a Kaolinite-Dominated Ultisol under Changing Land-Use Regimes

AbstractChemical denudation and chemical weathering rates vary under climatic, bedrock, biotic, and topographic conditions. Constraints for landscape evolution models must consider changes in these factors on human and geologic time scales. Changes in nutrient dynamics, related to the storage and exchange of K+ in clay minerals as a response to land use change, can affect the rates of chemical weathering and denudation. Incorporation of these changes in landscape evolution models can add insight into how land use changes affect soil thickness and erodibility. In order to assess changes in soil clay mineralogy that result from land-use differences, the present study contrasts the clay mineral assemblages in three proximal sites that were managed differently over nearly the past two centuries where contemporary vegetation was dominated by old hardwood forest, old-field pine, and cultivated biomes. X-ray diffraction (XRD) of the oriented clay fraction using K-, Mg-, and Na-saturation treatments for the air-dried, ethylene glycol (Mg-EG and K-EG) solvated, and heated (100, 350, and 550°C) states were used to characterize the clay mineral assemblages. XRD patterns of degraded biotite (oxidized Fe and expelled charge-compensating interlayer K) exhibited coherent scattering characteristics similar to illite. XRD patterns of the Mg-EG samples were, therefore, accurately modeled using NEWMOD2® software by the use of mineral structure files for discrete illite, vermiculite, kaolinite, mixed-layer kaolinite-smectite, illite-vermiculite, kaolinite-illite, and hydroxy-interlayered vermiculite. The soil and upper saprolite profiles that formed on a Neoproterozoic gneiss in the Calhoun Experimental Forest in South Carolina, USA, revealed a depth-dependence for the deeply weathered kaolinitic to the shallowly weathered illitic/vermiculitic mineral assemblages that varied in the cultivated, pine, and hardwood sites, respectively. An analysis of archived samples that were collected over a five-decade growth period from the pine site suggests that the content of illite-like layers increased at the surface within 8 y. Historical management of the sites has resulted in different states of dynamic equilibrium, whereby deep rooting at the hardwood and pine sites promotes nutrient uplift of K from the weathering of orthoclase and micas. Differences in the denudation rates at the cultivated, pine, and hardwood sites through time were reflected by changes in the soil clay mineralogy. Specifically, an increased abundance of illite-like layers in the surface soils can serve as a reservoir of K+.

Пространственное варьирование температуры корнеобитаемого слоя почв северной тайги Западной Сибири

Studies of soil heat regime are commonly confined to one vertical soil profile. Some studies on the basis of short-term temperature data series reported significant horizontal variation of topsoil horizons due to spatial variation in tree stand densities, plant cover and soil cover heterogeneity. Introduction of programmed automated temperature data loggers facilitated studies of horizontal heterogeneity in soil temperature, i.e. so called temperature fields with long temporal data series. However horizontal variation of soil temperature has not practically been studied in most Russian ecosystems, including those in the West Siberian northern taiga zone. The study of soil temperature regime was carried out in the environs of Noyabrsk (Yamalo-Nenetsky Autonomous Region, Russia) in the four key study sites: climax larch (Larix sibirica Ledeb.) and Scots pine (Pinus sylvestris L.) forests, and flat palsa mire (separately palsa and adjacent hollow). On each study site automated temperature data loggers were used in 5 replicated subsites to measure soil temperature with 0.5°С and record it every 4 hours, i.e. at 1, 5, 9, 13, 17 and 21 o’clock, daily. The loggers were placed at 10 cm soil depth in the root zone. The data from the meteorological station in Noyabrsk were also used in the study. The standard deviation of temperature values, recorded in a study site at one time point, was used as a measure of temperature variation. In all study sites the maximal temperature variation was observed at the beginning of the warm season. In both forest sites soil temperature began varying already after snow thawed, which was most likely due to the heterogeneity of vegetation cover and forest litter; in the pine site soil the heterogeneity of direct solar radiation as a result of the crown shadowing also contributed to temperature variation. The biggest soil temperature variation during this period was observed at the pine forest site, with difference between simultaneous replicated measurements reaching at certain time points as much as 9.6oС. In the larch study site the corresponding difference in June did not exceed 7-8oС. The minimal spatial variation of soil temperature in the root zone was observed in hollows of the flat palsa mire site, most likely due to the absence of the microrelief influence and high water saturation. The highest standard deviation values were observed during snow thawing at the beginning of May, when temperature difference between replicated measurements could be as high as 9.5oС. In June soil temperature variation decreased, staying low during the rest of the year. The palsa soil temperature at the flat palsa mire site and its variation in winter time showed strong response to changing air temperature. This winter variability was most likely due to unevenness of the snow cover thickness, resulting from the pronounced surface microrelief. During show thawing period the root zone temperature varied less, apparently because of even penetration and distribution of snowmelt water throughout the studied soil layer. Rapid soil warming resulted in increased temperature variability, which remained high during entire summer and the beginning of autumn, with differences between replicates being as high as 10.1oС. Summer variability of soil temperature at this site could be attributed to the permafrost layer, which in different microrelief positions is located at different depth as related to the root zone, thus exerting different influence on the temperature of the soil layers above. The most pronounced effect of diurnal fluctuations of root-zone temperature on its spatial variability was observed in pine forest during entire summer period, whereas on the palsa mire ecosystem it was observed at the beginning of summer during intensive thawing of the seasonally frozen layer.

Micronutrient concentrations vary between peat–mineral mix and substrates in revegetated sites in the Alberta oil sands

Adequate supply of micronutrients is essential for plant growth in reclaimed sites in the Athabasca oil sands region. The objectives of this study were to determine boron, iron, manganese, copper, and zinc concentrations in peat–mineral mix (PMM), tailings sand (TS), and overburden (OB) materials and to assess whether lodgepole pine (Pinus contorta) planted on PMM over TS and white spruce (Picea glauca) planted on PMM over OB had low foliar micronutrient concentrations. Micronutrient concentrations determined using LiNO3 and Mehlich-3 extractions were different between PMM and TS in the pine sites while only LiNO3 extractable boron was different between PMM and OB in the spruce sites (p iron > manganese > zinc > copper in all soil layers with concentrations ranging from 0.04 to 39.56 μg g−1. The low foliar concentration of copper in pine and spruce was consistent with low LiNO3 extractable copper in the soil in both the pine and spruce s...