Health condition and features of growth of age-old oak forests of natural origin

Досліджено продуктивність штучних дубових насаджень свіжих грабових дібров залежно від методу їхнього створення. За даними пробних площ у віці 10–68 років визначено основні лісівничо-таксаційні показники культур дуба звичайного (Quercus robur L.). Виявлено їхню залежність від методу створення і відмінність у продуктивності культур, які створені садінням сіянців і висівом жолудів на свіжих зрубах. Встановлено, що, починаючи з 10-річного віку, середні висоти культур дуба істотно залежать від методу створення культур. Висоти культур дуба, створеного висівом жолудів, у віці молодняка на 6–9 % більші, ніж за умови створення культур садінням сіянців. З часом ця різниця за висотами збільшується і в VІІ класі становить 11–19 %. Оцінено вплив методу створення на середні діаметри дерев дуба. Доведено, що до 40 років середній діаметр дерев дуба більший за умови створення насадження садінням, але з часом діаметри вирівнюються. Виявлено певну послідовність у збереженні чисельності дуба. За умови висівання кількість збережених дерев на 1 га в 10-річному віці на 37,5 % більша, але з часом різниця зменшується і в 68 років становить 17,3 %. Встановлено вплив методу створення на запас дерев дуба. За умови створення культур висівом, залежно від віку насадження, запас дерев дуба на 1 га збільшується в середньому до 40 %. Встановлено вплив методу створення культур на загальну продуктивність змішаних дубових деревостанів. З'ясовано, що за умови створення культур методом висіву жолудів, запаси насаджень на 1 га більші в середньому на 17 %. Культури дуба, створені висівом, мають краще очищення стовбурів від гілля і сучків, а стовбури є більш повнодеревними.

Deadwood is an important component of forest ecosystems, and difference in the deadwood carbon stock depends on many variables including forest management. The aim of our study was to determine the patterns of formation of deadwood stocks in oak (Quercus robur L.) forests in the Left Bank Forest-steppe of Ukraine. As an outcome of the research, the data on deadwood parameters were obtained. The growth characteristics and coarse woody debris (CWD) characteristics were measured on intensive monitoring and inventory plots. Assessment of morphometric parameters of the CWD in oak stands was carried out by measuring diameters at top and bottom cut and length; to determine the carbon content, deadwood density was used. The distribution of deadwood by tree species, sizes and stages of decomposition was defined. The stock of dead trees (snags) in oak forest is 15.2 m3/ha and that of logs is 21.5 m3/ha. The carbon accumulation in oak forest stands in the Left Bank Forest-steppe of Ukraine was 3.4 and 4.5 t C/ha in dead trees and logs, respectively. The dynamics of deadwood stocks according to the results of repeated observations was given.

Rational use and prevention of deflationary desertification of the sandy lands of the arid zone is impossible without their provision with protective forest plantations. On the pastures of the region, the stands of oak have a high protective effect and durability. The purpose of the study is to study the peculiarities of oak growth and water supply on different geomorphological types of sands, to improve their afforestation regimes and methods of growing oak forests in the region. The objects of the study were 68-85-year-old plantations on the Tersk and Bazhigansky sand massifs, growing at a precipitation rate of about 320 mm/year, with an evaporation rate of 800-1000 mm/year. The condition and growth of stands were studied in temporary test areas using generally accepted methods followed by mathematical processing of the data obtained. It has been established that the influence of atmospheric precipitation on the water supply of oak forests has a relatively low and extremely unstable effect. Only in 6-9% of the years it is provided by their number. In other years, the growth and viability of stands is determined by the availability of groundwater, which is replenished by the influx from neighboring non-forested areas. The best conditions for oak growth are formed on sandy loam soil of depressions with the occurrence of fresh or slightly mineralized groundwater at a depth of 2-4 m. On re-sown multi-layered sands, forest conditions worsen as the thickness of the soil layer previously moistened by precipitation decreases and with groundwater mineralization exceeding 8-9 g/l, as well as everywhere with the age of plantings, due to the depletion of the initial reserve of soil and soil moisture. Pasture digression of the herbage in adjacent pastures slows down this process and helps to increase the longevity of the stands. On all types of sands, fine-contoured plantings, their alternation with open areas of functioning pastures, moisture-accumulating tillage, the creation of clean crops, timely agrotechnical care and thinning of the stand are relevant.

Stream nitrate (NO3−) concentrations were 2.6–7.0 times lower in watersheds in which red oak (Quercus rubra) stands were present than in other forested watersheds in northwestern Pennsylvania. Also, seasonal variations in NO3− concentrations were smaller in watersheds with oak stands than in watersheds without oak stands. Stream water concentrations of calcium, magnesium, potassium, sodium, chloride, and sulfate did not differ significantly between the two groups of watersheds. The variability in NO3− concentrations among streams did not appear to be due to differences in atmospheric nitrogen deposition among watersheds. Low stream NO3− concentrations occurred even if only 10–20% of a watershed was covered by oak stands. We suggest that oaks, rather than directly controlling NO3− losses, instead merely occur on soils which have low NO3− losses.

Forest insects are among the most important factors of disturbance in European forests. The increase in and duration of drought stress events due to climate change not only increase the vulnerability of rural and urban forests but also predispose weakened stands to insect pest calamities. In this context, many German and European forest research institutes and environmental institutions report an increase in the densities and calamity developments of the oak processionary moth (Thaumetopoea processionea L.) not only in oak and mixed-oak forests but also in smaller areas where oak trees regularly occur, e.g., parklands, urban areas, copses, avenues, recreational forests, etc. It is expected that the oak processionary moth (OPM) will benefit from the overall weakened vitality of both individual oaks and oak stands in the future and that mass outbreaks will occur at an increased frequency. This paper reports on the effects that the OPM can have on tree performance for rural forest and urban oak trees by applying the chlorophyll fluorescence non-destructive diagnostic method for the identification and quantification of damage to oak leaves. The aim of the study was to investigate the effects of OPM frass activity on tree leaf health using chlorophyll fluorescence measurements, comparing infested host oaks with non-infested oaks in urban and forest environs. The study assessed: 1. the quantum efficiency of photosystem II (PS II), which counts as an indicator for leaf conditions, 2. the performance index, which indicates the efficiency of the photosynthetic light reaction, 3. the energy loss of the photosynthetic reaction, which is an indicator for cell damage, and 4. the degree of open reaction centers in PS II, which indicates how well light energy can be absorbed for photosynthesis. Infested urban and rural oaks showed a significantly reduced quantum yield of PS II by up to 10% compared to non-infested oak leaves. The leaf performance was significantly reduced by up to 35% for infested urban oaks and by up to 60% for infested forest oaks, respectively. The energy losses were two times higher for infested urban and forest oaks. However, OPM infestation led to a higher reduction in the photosynthetic performance in the leaves of forest oaks compared to that of urban oaks. In order to avoid permanent damage, suitable countermeasures must be taken quickly, as, immediately after pest infestation, the performance decreases significantly. A lower performance means a significant loss in biomass production as well as in tree vitality.

Integrative management to sustain biodiversity and ecological continuity in Central European temperate oak (Quercus robur, Q. petraea) forests: An overview

Herb layer vegetation of south Swedish beech and oak forests—effects of management and soil acidity during one decade

There are many data values describing deadwood in primary forests, however, there is much less information concerning managed forests, particularly in the Mediterranean area. Whole non-living woody biomass (deadwood) is the main component of forest types that plays a vital role in improving and maintaining biodiversity. The dynamics of deadwood and CO2 sequestration by deadwood were examined in three Mediterranean lowland forests: pine forest Pinus pinea L.), evergreen oak forest (Quercus ilex and Quercus suber L.), and deciduous oak forest (Quercus cerris L.). The aim of this study was to carry out a quantitative and qualitative evaluation of the deadwood to gather useful information for the Mediterranean forest management, and to provide some useful data that can be integrated into the methods of estimation for carbon stored in dead components of Mediterranean forest types. The investigations focused on the characterization of the deadwood, to determine which traits are dominant and their potentially functionality within the forest type. Results indicated the deciduous oak type had the highest amount of stand volume (379 m3/ha), deadwood volume (161.8 m3/ha), and C storage (31.43 t/ha). The major component of dead wood was the standing dead trees or snags. There was a higher volume of deadwood in the deciduous oak forest than in the pine and evergreen oak forests. In addition, the deciduous oak forest had a higher snag creation index, a higher fallen log creation index, and a higher past management index compared to pine and evergreen oak forest types. Deadwood volume increased as the decay class in the deciduous oak forest increased, while this trend decreased in the evergreen oak and pine forests. The amount of deadwood was affected by the forest type and forest management regime. Dynamic and past management of deadwood indices indicated that their structure was still in the initial phase of creation and decay in the pine and evergreen oak forests. A comparison with other studies on similar forest types brought out that the variation range of the main parameters for the management of deadwood fell within the variation of the parameters studied. However, the values of these parameters cover a broad range. The population of each forest type is extremely sensitive to the different evolutionary periods of the forest dynamics.

Oak stands are declining in many regions of southern Europe. The goal of this paper is to assess this process and develop an effective monitoring tool for research and management. Long-term trends of the Normalized Difference Vegetation Index (NDVI) were derived and mapped at 30-m spatial resolution for all areas with a stable land cover of cork oak (Quercus suber L.) and holm oak (Quercus ilex L.) forests and agroforestry systems in mainland Portugal. NDVI, a good proxy for forest health and productivity monitoring, was obtained for the 1984–2017 period using Landsat-5 TM and Landsat-7 ETM+ imagery. TM values were adjusted to those of ETM+, after a comparison of site-specific and literature linear equations. The spatiotemporal trend analysis was performed using only July and August NDVI values, in order to minimize the spectral contribution of understory vegetation and its phenological variability, and thus, focus on the tree layer. Signs and significance of trends were obtained for six representative oak stands and the whole country with the Mann Kendall and Contextual Mann-Kendall test, respectively, and their slope was assessed with the Theil-Sen estimator. Long-term forest inventories of six study sites and NDVI time series derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) allowed validating the methodology and results with independent data. NDVI has a good relationship with cork production at the forest stand level. Pettitt tests reveal significant change-points within the trends in the period 1996–2005, when changes in drought patterns occurred. Twelve percent of the area of oak stands in Portugal presents significant decreasing trends, most of them located in mountainous regions with shallow soils. Cork oak agroforestry is the most declining oak forest type, compared to cork oak and holm oak forests. The Google Earth Engine platform proved to be a powerful tool to deal with long-term time series and for the monitoring of forests health and productivity.

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.

After the investigation and long-lenn research, the structure, succession, energy flow, nutrient and water cycles, productivity, etc. of Mongolian oak (Quercus mongolica) forest ecosystems are synthetically summarized. The oak, with a simple stand composition, naturally distributes at hilltops, where the soil is and and infertile and lots of tree species can not grow, and stabilizes for a long period for its high adaptive capacity and long longevity, but it will grow better in good sites. Compared with other forest ecosystems in temperate zone, the oak forest has not only more intensive biological cycles of nutrients but higher productivity as well. Among the nine elements determined, the concentrations of Ca and Zn are the highest and lowest, amounting to 41.99% and 0.0015%, respectively. In the vegetation, the largest nutrient pool is root system, making up 47.75%; and the trunk steps the following, 25.13%. Among the main secondary forest types in Maoershan region, the oak stands have not only highest biomass but best biomass structure for in which the biomass of tree stratum reaches 95.6% of the total of the stands and that of trunk does 68.9% of the total of the tree. The oak stands have high stemflow, which amounts to 15.6% of the precipitation and carries a lot of nutrients, and high evapotranspiration, which is as high as 504.1 mm and for which 77.45% of the total radiation (123.3 KJ. cm-2) is consumed as latent heat transfer in the growing reason. The clearculting of the oak stands will result in not only increasing the surface runoff and interflow percentage but also intensifying the loses of N, Ca. Mg and Fe. Finally, it is proposed to pay a great attention to cultivating, rejuvenating and even planting the oak as high yield timber and water conservation forests.

In Ukraine, carbon stocks in forests are assessed by the gain-loss method since the national forest inventory is under development now. For the evaluation of main pools of oak and pine forest stands, typical for the Forest-steppe of Ukraine, the stock-difference method was used for the data of repeated observations on 18 intensive forest monitoring plots. The average carbon stock in the phytomass was 94.1 ± 19.8 tC·ha−1 and 93.4 ± 12.8 tC·ha−1, while in the deadwood, it was 8.8 ± 7.3 tC·ha−1 and 5.3 ± 4.3 tC·ha−1 for oak and pine forest stands, respectively. In terms of age classes, pine stands, due to their higher productivity, in general, had a higher carbon (C) stock in phytomass compared to oak. C stock changes in trees phytomass were the highest in younger stands, and they decreased with age, while in deadwood, they increased. At age 81–100 years, oak forest stands had higher carbon storage capacity than pine (total stock in main pools (phytomass, mortmass, and soils (30-cm layer)) was 191.7 tC·ha−1 for oak and 175.4 tC·ha−1 for pine stands). Trees phytomass carbon prevailed among other pools (50.3% in oak forests and 57.6% in pine).

The article shows the problems of researching the state of natural oak forests of the branch "Zhmerynske LH", which is in the functional structure of the regional forestry and hunting economy department of Vinnytsia region. In the research material of the article, an analytical review of the specialized enterprise's forest management database is carried out. The result of the analysis of forest management data and visual inspection within the forest areas of the Zhmerynske Forestry Branch is the determination of the taxonomic indicators of oak forest plantations of seed and vegetative origin. The preserved natural oak stands within the forest areas of the branch "Zhmerynske Forestry" grow in optimal forest and vegetation conditions. The vast majority of natural oak stands grow in fresh hornbeam forests and less in wet hornbeam forests. It has been established that natural oak forests within the forest fund of a forestry enterprise are represented by vegetative and seed plantations by origin. Analytical data show that there is a tendency to reduce the share of natural oak forests within the enterprise. It has been determined that the enterprise is dominated by oak forests of natural origin with a share of 9-10 units of oak, mostly 110 years old. The area of these plantations is the maximum and amounts to 159.3 hectares. It was found that the oak stands are characterized mainly by the 2nd class of bonita. The average stock ranges from 310-342 m3/ha. The result of the research is the establishment that in natural oak forests there is almost no sustainable natural regeneration of the main forest-forming species. Also, based on visual inspections, it was found that in the conditions of fresh pile, natural regeneration of oak is not found in the existing forest types.

During the period of the oak forests’ mass desiccation, Armillaria root rot became widespread, exacerbating the state of depression. The infection of stands by white sapwood rot caused by fungi of the genus Armillaria was more often detected in Bug-Polesia and Berezina-Pre-Polesia forest growth areas. The incidence of the disease in the oak forests of Belarus increases with the raising of the stands age and the decrease in their density. More often, the affliction with Armillaria root rot occurs in floodplain oak forests, as well as in the dry lands forest types with the most fertile soils. The oak’s proportion in the stand’s composition does not significantly affect the occurrence of the infection. Under the conditions of massive weakening of the Belarussian oak forests, facultative parasites from the Armillaria genus can occur as dangerous secondary pathogens that accelerate the death of weakened oak trees. Their pathogenicity persists in the north of the republic, where the negative role of other pathological factors in oak forests decreases. After the end of the depression period, the transition of Armillaria from a parasitic to a predominantly saprotrophic strategy was recorded. The affliction of oak forests by Armillaria root rot can act as one of the oak formation’s condition indicators, marking the depression phase in oak stands. Therefore, the spread of foci of Armillaria root rot should be monitored while conducting forest pathology surveys and monitoring the condition of oak forests.

Подано результати досліджень щодо характеристики дубових насаджень на притоках Ворскли у межах Сумської області. Визначено, що серед загальної площі вкритих лісовою рослинністю лісових ділянок на водозборі Ворскли (40464 га), найпоширенішими є дубові насадження, частка площі яких становить 64,4 % (26052 га). Проаналізовано розподіл площі цих насаджень на 10 притоках річки Ворскли за типами лісорослинних умов, походженням, класами віку та категоріями лісів. Наведено результати досліджень природного поновлення дуба й інших порід під наметом дубових насаджень і на зрубах. Підтверджено необхідність сприяння природному відновленню й ефективного його використання для відтворення дубових лісів на водозборах річок. Розподіл дубових насаджень за типами лісорослинних умов свідчить про сприятливі умови для їх росту, оскільки 90,7 % площі становлять свіжі груди. Вікова структура досліджуваних дубняків є розбалансованою. Переважають насадження IX–XII (52,4 %) та V–VIII (35,5 %) класів віку. Природні дубові ліси займають 58,3 % (15185 га) від загальної площі, а штучні (лісові культури) – 41,7 % (10867 га). Розподіл дубових насаджень за функціональним призначенням свідчить про переважання експлуатаційних лісів, частка яких становить 53,7 % (14001 га) від загальної площі. Частка захисних лісів становить 36,1 % (9387 га), лісів природоохоронного, наукового, історико-культурного призначення – 7,1 % (1856 га) та рекреаційно-оздоровчих лісів – 3,1 % (808 га). Ці ліси, окрім задоволення потреб суспільства в цінній дубовій деревині, виконують також надзвичайно важливі та різноманітні еколого-захисні функції. Закономірності поширення дубових насаджень на притоках Ворскли доцільно враховувати під час ведення лісового господарства з метою збереження їхнього різноманіття та посилення виконання ними важливих екологічних, захисних, рекреаційних і інших функцій. Окрім цього, особливості їхньої лісівничо-таксаційної й типологічної структури можуть бути враховані для удосконалення відповідних положень водозбірно-ландшафтного районування України.