Development of Diameter Growth Models by Thinning Intensity of Planted Quercus glauca Thunb. Stands

Background and objective: This study was conducted to develop diameter growth models for thinned Quercus glauca Thunb. (QGT) stands to inform production goals for treatment and provide the information necessary for the systematic management of this stands.Methods: This study was conducted on QGT stands, of which initial thinning was completed in 2013 to develop a treatment system. To analyze the tree growth and trait response for each thinning treatment, forestry surveys were conducted in 2014 and 2021, and a one-way analysis of variance (ANOVA) was executed. In addition, non-linear least squares regression of the PROC NLIN procedure was used to develop an optimal diameter growth model.Results: Based on growth and trait analyses, the height and height-to-diameter (H/D) ratio were not different according to treatment plot (p > .05). For the diameter of basal height (DBH), the heavy thinning (HT) treatment plot was significantly larger than the control plot (p < .05). As a result of the development of diameter growth models by treatment plot, the mean squared error (MSE) of the Gompertz polymorphic equation (control: 2.2381, light thinning: 0.8478, and heavy thinning: 0.8679) was the lowest in all treatment plots, and the Shapiro-Wilk statistic was found to follow a normal distribution (p > .95), so it was selected as an equation fit for the diameter growth model.Conclusion: The findings of this study provide basic data for the systematic management of Quercus glauca Thunb. stands. It is necessary to construct permanent sample plots (PSP) that consider stand status, location conditions, and climatic environments.

Model of mixed effects of height dependence on tree diameters in pine stands

Основными исходными данными для определения запаса служат результаты обмеров диаметров и высот деревьев. Но обмеры диаметров деревьев на высоте груди выполнить намного проще, чем обмеры высот, поэтому ограничиваются замерами высот 15–25 деревьев. Цель исследования – по материалам измерения модельных деревьев в сосновых древостоях выбрать наиболее адекватную простую модель, которая передает зависимость между высотой деревьев и диаметром на высоте груди. Объектом исследования послужили сосновые древостои искусственного происхождения на постоянных пробных площадях в Лесной опытной даче Российского государственного агарного университета – МСХА имени К.А. Тимирязева. В работе используются данные обмеров деревьев на 17 постоянных пробных площадях с 1934 по 2005 гг. Возраст древостоев на момент проведения измерений от 50 до 125 лет. По итогам проведения 77 перечетов массив данных составил 1157 наблюдений. И модель фиксированных эффектов, и модель смешанных эффектов адекватно описали зависимость между высотами и диаметрами деревьев в культурах сосны. Но, как и ожидалось, первая модель имеет худшие значения метрик качества по сравнению со второй. Модель со смешанными эффектами более точно предсказывает значения высот по сравнению с моделью фиксированных эффектов. Недостающие значения высот большого количества деревьев на участке можно вычислить более точно с помощью модели смешанных эффектов, а не применения модели фиксированных эффектов или использования только фиксированной части (средний отклик) модели смешанных эффектов. Применение разработанной модели должно ограничиваться только в тех условиях, к которым относятся экспериментальные материалы The main data for the stock of research results is the diameter of measurements and heights of trees. But measurements of the diameter at breast height are much easier to perform than measurements of heights, therefore, they are limited to measuring the heights of 15–25 trees. The aim of the study is to select the most adequate simple model based on the measurements of model trees in pine antiquities, which conveys the relationship between the height of trees and the diameter at breast height. The object of the study was pine stands of artificial origin on permanent test plots in the Forest Experimental Station Russian State Agararian University – Moscow Timiriazev Agricultural Academy. The work uses data from tree measurements on 17 permanent sample plots from 1934 to 2005. The age of the stands at the time of measurements was from 50 to 125 years. As a result of 77 enumerations, the data array amounted to 1157 observations. Both the fixed effects model and the mixed effects model adequately describe the relationship between heights and diameters of trees in pine stumps. But, as expected, the first model has worse quality metrics than the second. The mixed effects model more accurately predicts heights from the fixed effects model. The missing heights of a large number of trees on a site can be calculated accurately using mixed effects models, rather than using fixed effects models or using only a fixed portion (mean response) of the mixed effects model. The application of the developed model should be limited only in those conditions to which the experimental materials are applied.

Large, near-term increases in climate-induced tree growth may help offset impacts of increasing disturbance across Canadian boreal forest

Large projected increases in forest disturbance pose a major threat to future wood fibre supply and carbon sequestration in the cold-limited, Canadian boreal forest ecosystem 1–4. Given the large sensitivity of tree growth to temperature, warming-induced increases in forest productivity have the potential to reduce these threats, but research efforts to date have yielded contradictory results attributed to limited data availability, methodological biases, and regional variability in forest dynamics 5–8. Here we apply a novel machine-learning algorithm to an unprecedented network of over 1 million tree growth records from 18,715 permanent sample plots distributed across both Canada and the US, spanning a 16.5°C climatic gradient, and project the near-term (2050s time period) growth of the six most abundant tree species in the Canadian boreal forest. Our results reveal a large, positive effect of increasing thermal energy on tree growth for most of the target species, leading to 40-52% projected gains in growth with climate change under RCP 4.5 and 8.5. The magnitude of these gains, which peak in the colder and wetter regions of the boreal forest, suggests warming-induced growth increases should no longer be considered marginal, but may in fact significantly offset some of the negative impacts of projected increases in drought and wildfire on wood supply and carbon sequestration and have major implications on ecological forecasts and the global economy.

Application of allometric systems for compatible area-based LiDAR-assisted estimation in the Province of Nova Scotia

Light detection and ranging (LiDAR) is used to estimate tree, stand, and forest characteristics across large geographic areas. In the province of Nova Scotia, an enhanced forest inventory (EFI) was developed to provide high-resolution spatial forest inventory estimates across the landscape. For various forest attributes, independent LiDAR-based relationships were built leading to mathematical and biological inconsistency among forest attribute estimates. A systems approach, composed of allometric equations describing the relationships between volume per unit area, Lorey’s average height, basal area, quadratic mean diameter, and density, is developed to address these inconsistencies. Previous results showed that applying the systems approach provided reasonable and compatible estimates and eliminated inconsistency issues among forest attributes. This study evaluates application of the systems approach applied to eastern Nova Scotia using field data from a network of permanent sample plots and recent LiDAR acquisitions. The independent EFI estimates had inconsistencies of greater than 100% for basal area and implied stand-level form factor. These inconsistencies were eliminated using the systems approach. Results show that the systems approach can be scaled to larger landscape areas and that long-term field data can be leveraged to fit the allometric systems producing mathematically and biologically consistent estimates.

TYPES PRODUCTIVITY IN CONDITION OF THE SOUTH URAL TAIGA SUBZONE

По данным материалов 10 постоянных пробных площадей (ППП) рассмотрены лесоводственно- таксационные показатели древостоев сосняков ягодникового типа леса, пройденных выборочными руб- ками (первый приём равномерно-постепенной рубки). Все ППП были заложены на территории Ураль- ского учебно-опытного лесхоза. Изучаемые древостои характеризуются высокой относительной пол- нотой до рубки (0,76–1,0), I–III классами бонитета в возрасте 110–130 лет и высокой густотой. Запас стволовой древесины варьируется до рубки от 323,0 до 619,0 м3/га, что указывает на высокую эксплуа- тационную ценность сосновых насаждений ягодникового типа леса. Преобладающей породой в составе всех пробных площадей является сосна. Встречаются и другие хвойные породы – ель, пихта и листвен- ница. Доля участия в составе последних сильно варьирует. Из лиственных пород доминирует береза. Также в состав лиственных пород входят липа и осина, на их долю приходится не более одной единицы состава. Формула состава древостоя существенно не изменилась через 4 года после рубки, сосна оста- лась преобладающей породой. Средний показатель диаметра увеличился на 2,3 см, высоты – на 1,3 м. Густота в среднем сократилась на 193 дерева/га. Запас деревьев сосны снизился на 148 м3/га, запас сухо- стойных деревьев – на 2 м3/га. Проведенные исследования доказывают, что при вырубке в первый прием равномерно-постепенной рубки в условиях сосняка ягодникового удаляются сухостойные, отставшие в росте, фаутные деревья и деревья 4 и 5 класса роста по Крафту. Отмечается положительное изменение лесоводственно-таксационных показателей насаждений. В частности, улучшаются их эстетические ха- рактеристики и антропогенная привлекательность, а также рубки способствуют повышению продуктив- ности и производительности насаждений. According to the materials of 10 permanent sample plots (PPP), silvicultural and taxation indicators of forest stands of berry-type pine forests passed by selective felling were considered (the fi rst method of uniformly gradual felling). All permanent test plots were laid on the territory of the Ural training and experimental forestry enterprise. The studied stands are characterized by a high relative density before felling (0,76–1,0), I–III quality classes at the age of 110–130 years and high density. The stock of stem wood varies before felling from 323,0 to 619,0 m3/ha, which indicates a high operational value of pine plantations of berry forest type. Pine is the predominant species in all sample plots. There are also other conifers – spruce, fi r and larch. The share of participation in the composition of the latter varies greatly. The dominant deciduous species is birch. Also, the composition of deciduous species includes linden and aspen, they account for no more than one unit of composition. The formula of the stand composition did not change signifi cantly 4 years after logging, pine remained the predominant species. The average diameter increased by 2,3 cm, height by 1,3 m. The average density decreased by 193 trees/ha. The stock of pine trees decreased by 148 m3/ha, the stock of dry trees by 2 m3/ha. The conducted studies prove that when cutting down in the fi rst step of evenly-gradual felling in the conditions of a berry-type pine forest, the queue of dry, stunted, faut trees and trees of the 4th and 5th growth class according to Craft contributes to a positive change in the forestry and taxation indicators of plantings, this improves their aesthetic and anthropogenic attractiveness, and also contributes to increasing the productivity and productivity of such plantings.

Modeling tolerant hardwood sapling density and occurrence probability in the Acadian forests of New Brunswick, Canada: Results 14 years after harvesting

Natural forest regeneration after natural or anthropogenic disturbance is difficult to predict given its high variability. The process is poorly documented for commercial northern hardwood species in the Acadian forest of eastern Canada. Our objective was to identify the silvicultural, environmental, and ecological factors that best explain the variability in sapling density and occurrence of two commercial tolerant hardwood species in New Brunswick: American beech (Fagus grandifolia Ehrh.) and sugar maple (Acer saccharum Marsh.). Forty-three permanent sample plots were established in 2002 and measured before harvesting in 2004. Sapling density and occurrence were measured 14 years after harvesting. The results showed that the interactions between the species and the residual merchantable basal area and between the species and the percent of hardwoods in the original stand best explained the sapling density and occurrence variation of tolerant hardwoods. The sapling density of sugar maple increased with increasing merchantable residual basal area. However, the effect of this variable was not significant for the density of American beech saplings. The density and occurrence of tolerant hardwood saplings both increased along with the percent of hardwoods in the original stand. These results provide an improved understanding about tolerant hardwood regeneration dynamics in New Brunswick forests.

Quantitative and qualitative attributes of dead wood in dominated by Carpinus betulus L. forests in Kaniv Nature Reserve

The article presents the quantitative and qualitative attributes of dead wood in forests dominated by Carpinus betulus L. in Kaniv Nature Reserve. The study was conducted in 130–140-year natural common hornbeam forests on two permanent sample plots of 0.24 ha each by identifying and measuring all components of standing and lying (fallen) dead wood. It was found that wood detritus has an average volume of 39.8 m3/ha consists of standing dead trees (23.1%) and fallen dead wood (76.9%). The species composition is dominated by common hornbeam (96.5%), and the share of Norway maple (Acer platanoides L.) is low (3.5%). Wood of II (13.2 m3/ha, 33.1%) and III (12.2 m3/ha, 30.7%) classes of destruction predominates. Standing dead wood is formed by only one tree species — common hornbeam and has an average volume of 9.2 m3/ha. It is represented mainly by standing broken trees. The volume of standing dead wood is dominated by wood detritus of the II stage of decomposition (95.7%). Fallen dead wood is formed by two tree species — common hornbeam (95.4%) and Norway maple (4.6%), has an average volume of 30.6 m3/ha. It is represented by whole uprooted and broken fallen trees (trunks), fragments of fallen trees (trunks) and rough branches. Lying dead wood is represented by detritus of all five classes of decomposition, but wood of III (12.2 m3/ha, 39.9%) and IV (9.6 m3/ha, 31.4%) classes predominates. The volume of fallen dead wood is mainly formed by components with an average diameter of 10.1–30.0 cm (75.7%). The diversity of fractions and components, structural features, sizes and stages of decomposition of dead wood can be important in the formation of potential habitats and substrates for a number of species of living organisms.

Spatial and compositional structure of European oak urban forests in Kyiv city, Ukraine

Forest dimensional structure and tree species composition strictly define ecosystem resilience, success of its functioning and development. Spatial structure of forest compartments provides an additional information on the forest stand heterogeneity. The aim of this study is to examine structural patterns (both spatial and nonspatial ones) in European oak (Quercus robur L.) urban forests located in Kyiv city, Ukraine. We compared two middle-aged (~ 80 years) and two mature (~ 180 years) oak stands in terms of structural metrics collecting a data from geo-referenced trees on the established permanent sample plots. Younger stands reached similar tree diameter diversity (9.07 and 10.45 vs. 11.42 and 14.05 of Shannon indices), while the compositional diversity was driven by the dominance of either oak or European hornbeam (Carpinus betulus L.). We have not found any differences in the species mingling and deadwood distribution indices except a clear occurrence pattern for the stand located near roads. Herewith, the largest distance between the plot and park pathways was an indicator of changed spatial variation and tree dimensional differentiation within one middle-aged stand. We hypothesize that human impacts can alter structural development in urban deciduous forests providing both positive (gap formation, deadwood occurrence and ecosystem complexity) and negative (shifts in compositional and successional trajectories) effects on such forest stands.

Growth and structure of pre-mature mixed stands of Scots pine created by direct seeding in the boreal zone

The purpose of the research is to analyse the successful creation of an artificial pine forest by seeding and develop recommendations for the guaranteed reproduction of pine stands in Northern European Russia. In recent decades, there has been a steady decline in the share of pine stands and their replacement with low-value and low-yielding tree species. We surveyed 12 permanent sample plots that were laid out in various variants of forest crops. The taxation parameters were obtained by a standard analysis of the experimental data. The evaluation parameters of the stands vary within the following limits: the average diameter of the pine trees varied from 21.9 to 30.9 cm; the total basal area of the pine varied from 19.1 to 38.8 m2∙ha–1; the average height of the pine varied from 20.1 to 26.8 m; the number of growing trees varied from 754 to 1 952 ha–1; the pines varied from 382 to 762 ha–1; the growing stocks of stands varied from 416 to 608 m3∙ha–1. The distribution of pine trees by thickness steps showed that all the studied samples were close to the normal distribution curve. The results of the correlation and multidimensional analyses showed that the creation method of the forest crops had a significant impact on the value of the taxation parameters. It was found that the best options for growing pure pine stands that can be recommended for practical production are plots with a large share of soil cultivation and the size of the seedbed.

Growth and yield of lodgepole pine stands disturbed by mountain pine beetle in the Lower Foothills of Alberta

Changes in the structure and dynamics of lodgepole pine stands following the 2006 outbreak of mountain pine beetle in western Alberta were investigated by monitoring attacked permanent sample plots over the following decade and projecting future stand development with locally validated growth models. Results suggest that a wide range in growth and yield of attacked stands is likely, with projected impacts varying from minor and inconsequential modifications to full stand replacement. Severely disturbed stands are unlikely to naturally regenerate to pine. The degree to which timber production is naturally restored in such stands will depend to a large extent on the amount and composition of non-pine advance growth and regeneration. Variation in attack severity and tree species composition will, in the absence of clearcutting following disturbance, result in increased diversity in stand and forest structure. Recommendations are made for scheduling salvage and restoration operations to ameliorate losses in timber supply.