Forest Stands Research Articles

Microclimate of Pedunculate Oak (Quercus robur L.) Sustainable Managed Forest Stands—A Study of Air and Soil Temperatures in Shelterwood Cutting

Forest management and tree felling in the stand change the structural characteristics, which causes changes in the microclimate conditions. The microclimate is a key in sustainable forest management because soil temperature and moisture regimes regulate nutrient cycling in forest ecosystems. The aim of this research was to determine the changes in air and soil temperatures in pedunculate oak forest stands in different stages of shelterwood that stimulate natural regeneration. The research was conducted in pedunculated oak forests in Spačva area. The microclimatic parameters were measured in a mature old forest stand without shelterwood cutting and in stands with preparatory cut, seed cut, and final cut. The intensity of shelterwood had an impact on the amplitudes and values of air and soil temperatures. The highest average air temperature was in the stand with a preparatory cut. Extreme values of air and soil temperatures were measured in the stands with a final cut. The highest air and soil temperature amplitudes were in the stand with a final cut, with the exception of most of the winter, when the highest soil temperature amplitude was in the stand with a seed cut. The highest number of icy, cold, and hot days was in the stand with a final cut. SARIMA models establish that the difference between microclimatic parameters is not accidental.

Oak decline: pest outbreak threat or opportunity for saproxylic beetles? A case study from the Czech Republic

Commercially managed forests are often poor in terms of biodiversity. Saproxylic beetle species could be a useful bioindicating group for the conservation of forest stands. In recent decades, oak stands have been affected by a wide range of factors that have intensified stand decline. Saproxylic beetle richness was investigated in declining oak stands that have been consequently targeted for clearcutting due to concerns about insect pest outbreaks. The research was conducted at six managed oak forests, where we compared beetle occurrences in declining stands and in healthy stands that did not show any symptoms of decline. Beetles were collected using window traps placed on the basal and mid-trunk sections of trees. A total of 2925 adults belonging to 239 saproxylic beetle species were captured, of which 56 species are on the IUCN Red List. The results show that declining stands were richer in saproxylic species, and that the diversity of beetle species was greater in these stands. Approximately 1.4 times more species were caught within declining stands than in healthy ones (1.6 times for Red List species). Declining stands hosted more pest species (e.g., cambiophagous and xylophagous species). However, only low numbers of these species were recorded in these stands. In summary, results of this study suggest that decline of managed oak stands is creating a wide spectrum of habitats for many saproxylic species. Thus, salvage logging of declining oak trees can represent a natural trap and reduce local beetle biodiversity, mainly for saproxylic, endangered or low-mobility species that would be attracted by new suitable habitats.

Динамическая модель роста и производительности сосновых древостоев (Pinus sylvestris L.) Унженской низменности

Scots pine is one of the main forest-forming species in the Kostroma region, therefore it is necessary to have tools that allow one to make informed decisions on managing the forest growing process, planning forest management, designing forest management activities and increasing the efficiency of forest stands performing environmental functions. The purpose of the study is to develop a dynamic model of growth and yield of pine stands in the Unzhensky Lowland (Kostroma region) based on repeated observations on permanent trial plots. The data for modeling the growth and yield of pine stands were materials from repeated censuses on 21 permanent trial plots of the Chernolukhovsky experimental forestry enterprise and 3 permanent trial plots of the Manturovo section of the Kologrivsky Forest Nature Reserve. To model growth by average height and average diameter, 15 dynamic equations based on 9 basic functions were analyzed, and to model thinning of forest stands, 14 dynamic equations were analyzed. The resulting regression equations for predicting the dynamics of average heights and diameters, thinning together form a model of growth and yield of pine forest stands, which belongs to the category of empirical models for predicting stand characteristics at the level of an individual forest stand, and its advantages are the invariance of the relative base age and the ability to give forecasts over a wide range of initial parameter values. The developed model can serve as an alternative to traditional tables of course of growth when designing and justifying forestry activities, when forests inventory using the updating method, as well as for making management decisions when managing pine forests. In combination with additional equations, it can be part of more complex models that allow predicting the structure of forest stands, commercial and carbon sequestration potential, and the impact of forestry activities.

Effects of different urban vegetation cover and green space types on soil greenhouse gas emissions and carbon sequestration

The development of urbanization has led to the creation of various types of green spaces, which have a direct influence on vegetation types and soil management, This, in turn, results in differences in soil carbon sequestration capacities. However, the factors affecting soil carbon sequestration in different vegetation types within urban green spaces remain largely unexplored. To address this gap, the study focused on the soil of urban green space. A one-year field observation was conducted, utilizing local management archives and historical data, to evaluate variations in soil greenhouse gas (GHG) emission and soil organic carbon sequestration across grassland (GL), shrubs (SH), and forests stands (FS) within three types of green spaces: park green space (P), residential green space (Ra), and street green space (s). The results indicated that: (1) In comparison to grassland (GL), the CO2 flux of shrubs (SH) and forests stands (FS) declined by 10.73% and 14.46%, respectively, while the N2O and CH4 fluxes remained insignificant. Additionally, the annual increase in soil organic carbon was lower by 8.92% and 10.80% in shrub and forests stand, respectively; (2) Variations in greenhouse gas fluxes were also observed among the three types of green spaces. In comparison to park green spaces, the CO2 flux of residential and street soils decreased by 2.11% and 3.25%, respectively, while the N2O flux dropped by 16.61% and 22.41%, respectively. The CH4 flux remained insignificant. The annual increase of SOC in residential and streets was notably lower than that in parks green spaces, by 9.59% and 15.20%, respectively, indicating significant differences. This suggests that soil carbon sequestration capacity is highly responsive to changes in vegetation coverage and green space types, with WSOC, NH4+-N, and pH identified as the primary factors influencing the greenhouse gas flux in the three soils. This study provides data and a theoretical basis for the strategic selection of urban soil management measures, particularly in the context of achieving carbon neutrality goals.

Recultivation Strategies for Peat Extraction Fields: a Case Study in Latvia

Peat bogs are serving as habitats for diverse species and essential components of the natural environment. Currently, peat extraction is actively carried out in various regions to meet the demands of industries such as horticulture and in some cases even energy production. To mitigate land degradation caused by peat mining, the European Commission, through the Nature Restoration Law (Regulation (EU) 2024/1991), has established a goal to restore habitats. This includes repurposing peat mining fields into areas designated for various restoration measures. When defining a repurposing strategy for a specific peat extraction field, an important aspect is to assess the environmental impact of the different scenarios. This study is made in cooperation with the Latvian peat extraction company with the goal of achieving climate neutrality by the year 2050. The company is a significant producer of peat substrate with a capacity of 115 thousand tonnes per year. Ten recultivation scenarios were identified for the company’s peat extraction field: afforestation, blueberry cultivation, cranberry cultivation, paludiculture, waterbodies, croplands, grasslands, renaturalisation, solar parks and wind parks. These scenarios were compared with the baseline scenario, i.e. the situation if peat extraction were to continue in this field. The required data for the recultivation scenarios were collected and normalized to the functional unit of 1 ha. The obtained life cycle assessment results for each recultivation scenario were assigned to the respective planned area for each scenario foreseen by the company’s climate neutrality plan. All scenario emissions have been attributed to 50 years of land use, starting from implementation of the scenarios in 2025. Three main emission reference points were identified for the 50-year greenhouse gas emissions assessment: short-term 2030 (when peat extraction for energy in Latvia must cease), medium-term 2050 when climate neutrality must be achieved and long-term - emissions after 50 years (2075), when the vegetative life of berry plants has reached its end and when forest stands have reached the optimum age for tree harvesting. The results show that the highest emissions per 1 ha over 50year period are from the installation and reconstruction of solar panels. For each scenario, the emissions per respective planned area were calculated. It was determined that each scenario individually results in lower emissions compared to the baseline. However, when the emissions from all scenarios are added together, the sum is greater than the baseline. Therefore, it is necessary to investigate the recultivation scenarios further and optimise the land areas to optimise the recultivation scenario area and impact from them.

Влияние усыхания на изреживание еловых древостоев и на изменение породного состава лесных насаждений Пермского края

The phenomenon of a massive drying out of spruce stands, which has been taking place in recent decades in our country and in other countries of the world, has many negative consequences: reduction of the area of forests acting as a carbon sink, inability of forests to perform their protective, environment-forming, water-protecting functions, and loss of habitat. A massive drying out of spruce stands can lead to changes in forest composition, significant thinning of spruce stands, and the change of the species. The focus of our research was on spruce forests in the southern part of the Perm Krai, specifically within the Oktyabrsky and Tchaikovsky forestries. 52 forest stands had been examined within our study area, primarily focusing on spruce forests of the wood sorrel and linden forest types, in the summer periods of 2017-2024. As a result of the study in the above years, it was found that in terms of sanitary condition, the predominant species of spruce stands are spruce stands that are dying out, their share exceeding 50 %. Additionally, around 17.3% of the surveyed stands were found dead. The calculated coefficient of variation indicates that the variability of the average weighted scores of the sanitary condition increases with the age of spruce stands in plantations of both studied forest types. The dependence of variability of weighted average sanitary condition scores on the age of the stands is described by a polynomial function. On average, 30.7 to 47.3% of spruce trees survive after drying out in plantations of both types of forest. The species composition of plantations changed in 75% of cases as a result of drying out. The predominant stands are those where the share of spruce in the composition of stands has decreased by 10 %. In a number of cases there is a change from native spruce stands to soft stands. At the same time, the share of stands in which the drying out process led to the complete death of spruce trees is 5.8%. As a result of the density study, it has established that the drying out of some spruce trees led to the formation of spruce stands of low density and sparse forests.

Запасы углерода в фитомассе и биологическая продуктивность спелых и перестойных древостоев Пригородного лесничества Воронежской области

Forest-steppe ecosystems, representing an ecotone between forests and steppes, are particularly vulnerable to climate change. The observed trends of temperature increase and precipitation decrease in the southern European part of Russia affect the productivity of natural ecosystems, transforming their carbon balance. This may have implications for the sustainable functioning of forest-steppe ecosystems and biodiversity conservation. Assessment of carbon stocks and fluxes in forest ecosystems is crucial for understanding their role in climate change mitigation. A comprehensive study of carbon stocks and biological productivity of mature and over-mature forest stands in the Suburban Forestry of the Voronezh region has been conducted. It was found that the maximum carbon stocks in phytomass are characteristic of both coniferous stands (up to 133 tC/ha) in pine forest landscapes and mixed deciduous stands in upland oak forests (up to 141 tC/ha). Patterns of carbon distribution across phytomass components in tree stands of various species composition have been identified. The biological productivity of the studied tree stands was found to vary depending on forest growing conditions and species composition. The highest values of annual carbon increment in phytomass were observed in mixed stands dominated by Quercus robur L. (up to 2.60 tC/ha per year). The obtained results can serve as a scientific basis for developing regional programs to optimize the carbon balance of forest ecosystems and improve methods for assessing their ecological functions.

Tracking the Recovery of Forest Moth Community Composition (Lepidoptera) Following Small-Scale Logging in Oak Hardwood Forest Stands

Tracking the Recovery of Forest Moth Community Composition (Lepidoptera) Following Small-Scale Logging in Oak Hardwood Forest Stands

Composition, structure and regeneration strategy of Campnosperma panamense (Anacardiaceae) swamp forests in Darien, Panama

Introduction: Orey swamp forests (Campnosperma panamense) are found on the Caribbean coast of Central America, from Nicaragua to Panama, and in the Pacific of Colombia to Northern Ecuador. In Panama, orey grows in monospecific stands or is the dominant species in inundated mixed forests, mainly along the coasts of Bocas del Toro province and Comarca Ngäbe-Buglé. The species was known to occur in Darien province, in the Pacific, although almost no information on its distribution and forest extension in the region existed. Objective: To describe the structure and floristics of orey forests in Darien, map their extension, and propose a model for their regeneration strategy. Methods: This work is part of a vegetation mapping project of the Matusagaratí complex of wetlands. It includes the use of drones, ground truthing, vegetation sampling through temporary plots, and general plant collecting. A supervised classification of a Landsat satellite image was performed to delimit the orey forest extension. To study the orey forest regeneration strategy, a digitalization of forest gaps in high resolution WorldView-2 and Planet Scope images over years was performed. Gap frequency and turnover time for forest stands were calculated. Results: Several monospecific orey mature forest patches were found in remote areas of the Matusagaratí complex of wetlands, for a total of 1 267 hectares. A description of the floristics and structure of orey forests in Darien is presented. A conceptual model of orey mature forest development and gap regeneration is proposed. Conclusions: Our knowledge of the floristic composition, structure and distribution of orey forests in the Republic of Panama has increased. For the first time, a model about their regeneration strategy is proposed. These forests seem to be evolving to different formations. Finally, some hypotheses are proposed about how they might respond to changing environmental conditions.

Comparative Analysis of Novel View Synthesis and Photogrammetry for 3D Forest Stand Reconstruction and Extraction of Individual Tree Parameters

Comparative Analysis of Novel View Synthesis and Photogrammetry for 3D Forest Stand Reconstruction and Extraction of Individual Tree Parameters

Application of Unmanned Aerial Vehicle and Airborne Light Detection and Ranging Technologies to Identifying Terrain Obstacles and Designing Access Solutions for the Interior Parts of Forest Stands

Application of Unmanned Aerial Vehicle and Airborne Light Detection and Ranging Technologies to Identifying Terrain Obstacles and Designing Access Solutions for the Interior Parts of Forest Stands

The diversity of radial variations of wood properties in European beech (Fagus sylvatica L.) reveals the plastic nature of juvenile wood

Key messageRadial variations in wood quality result from the changes in wood properties with tree age. Here, we show that, at least in beech (Fagus sylvatica L.), these patterns of variations are diverse, and reflect a plastic adaptation to changes in the mechanical needs of the trees during their life.ContextThe radial variation of wood properties in the young age of the tree can be interpreted as the result of either cambium ageing (ontogenetic juvenility) or adaptation to the changing mechanical constraints during growth (adaptive juvenility).AimsRing width, specific gravity and specific modulus are important parameters for the mechanical stability of a standing tree. We aim at assessing whether their variations correspond to ontogenetic or adaptive juvenility.MethodsThese parameters were measured at several positions across diametrical boards from 86 beech trees from 9 high forest stands. Their variance and correlations were analysed globally, between plots and between trees, and variations from pith to bark quantified according to the slope and curvature of radial profiles.ResultsFor the three parameters, the plot and tree effects were very significant, but within-tree variations were dominating, representing at least 50% of the total variance. These variations occurred both in the radial and the circumferential direction, as revealed by the frequency of non-symmetric diametral profiles. The patterns of radial variations were very diverse both between plots and within plots, being either increasing, decreasing or non-monotonous.ConclusionEven if there is some ontogenetic influence in the measured juvenile patterns, their large variability suggests that adaptive juvenility dominates largely.

When can we detect lianas from space? Toward a mechanistic understanding of liana-infested forest optics.

Lianas, woody vines acting as structural parasites of trees, have profound effects on the composition and structure of tropical forests, impacting tree growth, mortality, and forest succession. Remote sensing could offer a powerful tool for quantifying the scale of liana infestation, provided the availability of robust detection methods. We analyze the consistency and global geographic specificity of spectral signals-reflectance across wavelengths-from liana-infested tree crowns and forest stands, examining the underlying mechanisms of these signals. We compiled a uniquely comprehensive database, including leaf reflectance spectra from 5424 leaves, fine-scale airborne reflectance data from 999 liana-infested canopies, and coarse-scale satellite reflectance data covering 775 ha of liana-infested forest stands. To unravel the mechanisms of the liana spectral signal, we applied mechanistic radiative transfer models across scales, establishing a synthesis of the relative importance of different mechanisms, which we corroborate with field data on liana leaf chemistry and canopy structure. We find a consistent liana spectral signal at canopy and stand scales across globally distributed sites. This signature mainly arises at the canopy level due to direct effects of more horizontal leaf angles, resulting in a larger projected leaf area, and indirect effects from increased light scattering in the near and short-wave infrared regions, linked to lianas' less costly leaf construction compared with trees on average. The existence of a consistent global spectral signal for lianas suggests that large-scale quantification of liana infestation is feasible. However, because the traits responsible for the liana canopy-reflectance signal are not exclusive to lianas, accurate large-scale detection requires rigorously validated remote sensing methods. Our models highlight challenges in automated detection, such as potential misidentification due to leaf phenology, tree life history, topography, and climate, especially where the scale of liana infestation is less than a single remote sensing pixel. The observed cross-site patterns also prompt ecological questions about lianas' adaptive similarities in optical traits across environments, indicating possible convergent evolution due to shared constraints on leaf biochemical and structural traits.

Forest Stand Identification in the Geumpang Protected Forest Area, Pidie Regency, Aceh

Forest Stand Identification in the Geumpang Protected Forest Area, Pidie Regency, Aceh

Determination of Mixed Forest Stand Density Using Spectral Indices in the Atrush Area, Northern Iraq

Abstract Evaluating mixed and pure forests is important to determine the various products and services they provide. Therefore, remote sensing and geographic information systems (GIS) techniques were used based on the Sentinel-2 satellite, the digital terrain model (DEM), and the ArcGIS10.8 program to draw maps of elevations above sea level, facades, and slopes for the study area. We conducted the classification process of the satellite image for the growing season, from which (6) categories of land uses were distinguished, which are (forests, soil, water, roads, agricultural lands, and vegetation cover). To determine the percentage of each layer, the total area and rate of each type in the site were calculated. It was found that the largest area among the types was for soil (404.02) km2, followed by forests with an area of (63.96) km2, while the water type had the lowest percentage among the types with an area of (0.18) km2. To calculate the classification accuracy, the Confusion Matrix was adopted, and through it, we obtained an overall classification accuracy of (98%), as well as the Kappa coefficient, which gave a value of (0.946). To determine the density of the vegetation cover, spectral indicators (NDVI and SAVI) were used using Sentinel-2 satellite data for the seasons (August 4, 2021) and (January 21, 2023) to distinguish deciduous from needle-bearing. It was noted through the analysis of the space data using the NDVI index for the growing season for August that high-density forests were concentrated in the highlands and their foothills, while medium-density and low-density forests were present in most of the study area, except for the southern regions and part of the central region.

Vegetation and carbon storage in mature natural forest stand areas (case study at one of the industrial forest plantation companies in Bener Meriah District, Aceh Province)

Abstract Forests as carbon sinks are important for maintaining the intensity of carbon in the environment. There are two approaches to mitigate atmospheric carbon dioxide: emission reduction and emission sequestration. The stands in the forest provide a place for carbon storage or deposition (carbon sink). One of the forests that can be used as a carbon sink area is Natural Forest. Research on natural forests in Bener Meriah Regency has never been conducted. In fact, carbon storage information can be used in order to provide one indicator to assess forest quality. The carbon stock referred to in this study consists of stands (seedlings, saplings, poles, and trees). The purpose of this study was to determine the amount of carbon stocks and carbon dioxide absorption in Natural Forest Stands in Bener Meriah Regency. The research was conducted in one of the Natural Forest blocks in an industrial plantation forest company in Bener Meriah Regency with an area of 1,029.4 ha. The sampling intensity used was 1.2% with 30 plots. The non destructive sampling method was used with carbon stock estimation using the allometric equation. Plot placement was determined using the systematic sampling with random start method and plot placement used uniform systematic sampling with distance between plots, the distance between plots is 100 m. The results of the study found 31 species, 19 families and 466 stands, the results of the analysis showed that the total carbon stock was 144.782,42 tC with an average of 129.56 tC/ha. The total carbon dioxide uptake in natural forest stands in Bener Meriah Regency was 109,702.91 tCO2 with an average of 475.49 tCO2/ha.

Assessing sampling efficiency and artificial neural networks for tree height prediction and site index classification in forest stands

Forest management relies on accurate growth and harvest stock estimations, typically obtained through forest inventories. This study evaluated sampling strategies for training Artificial Neural Networks (ANNs) to predict tree heights, aiming to minimize sampling effort and associated costs, and assessed the efficiency of using these predictions for site index classification. Data were collected from Pinus taeda L. spacing experiment in southern Brazil, encompassing measurements from 3 to 15 years of age. Four scenarios were evaluated: (a) adjusting height-diameter equations with varying sample sizes, (b) applying equations from one age to the next, (c) training ANNs with different sample sizes, and (d) using ANNs trained in one year for subsequent years. Results showed that ANNs, particularly with a sample of three trees per plot (Scenario c), provided superior height predictions compared to traditional height-diameter relationships, achieving higher correlation and lower error. While applying ANNs trained in one year to the next (Scenario d) showed reduced accuracy, Scenario (c) maintained high precision. The use of ANN-predicted heights for site index classification was also deemed viable. The study demonstrates that ANNs can significantly reduce the sampling effort required for forest inventories while maintaining accuracy in height estimation and site productivity assessment. The findings support the continued use of the established practice of measuring three trees per plot for ANN training, optimizing both cost and precision in forest inventory processes.

Interactions Between Migration, Forest Crime, and Land Use Change in Tekirdağ, Türkiye

Aim of study: This study aims to investigate the interactions between land use classes, population change, and forest crimes in the Tekirdağ Forest Planning Unit for the period 2007-2023. Area of study: Tekirdağ was chosen as the case study area because it is one of the provinces that receive the most immigration in Türkiye. Material and method: Stand maps, population information, and forest crime numbers were obtained for use in the study. Land use classes for 2008 and 2016 were created using stand maps. Additionally, forest crime numbers for the 2002-2023 period and population data for the 2007-2023 period were provided. Changes in land use classes, population, and forest crimes were examined according to the relevant years, and the relationships between them were investigated. The relationships between population and forest crimes were determined by Pearson's correlation coefficient. Main results: The most significant changes in land use classes were determined as an increase of 6138.8 ha in broadleaf forests and a decrease of 13673.0 ha in agricultural areas. During the 2007-2023 period, the population increased continuously at variable rates. The relationships between annual population and forest crimes were examined in the 2007-2023 period, and it was determined that the highest relationship was negative between population and grazing crime (r=-0.641). Research highlights: In-migration in the study area and the decrease in the rural population have been effective in forest crimes committed in the region. In-migration has led to a decrease in grazing crime and an increase in individual occupation crimes in rural areas.

The presence and distribution of nematode Litylenchus crenatae ssp. mccannii, the causative agent of beech leaf disease, in forest stands across Ohio.

Fagus grandifolia is an important forest tree species in North America that has been afflicted with beech leaf disease (BLD) since 2012. BLD can lead to substantial canopy thinning and eventual tree mortality. Current evidence suggest that Litylenchus crenatae ssp. mccannii (hereafter LCM) is the causative agent of BLD. However, the etiology of this disease is poorly understood. In this study, we conducted multi-year monitoring to examine the presence of LCM and BLD symptoms across Ohio, including both symptomatic and asymptomatic forest stands. We collected buds each spring before leaf-out and used molecular methods to detect the presence of LCM. Symptomatic sites had a high proportion of buds colonized by LCM across all sampling years. Detection of LCM DNA in asymptomatic forest stands was largely inconsistent across years; however, its presence overall was a significant predictor of BLD symptoms developing in the county surrounding our sampling site in the following years. LCM DNA was also detected on both Acer sp. and Quercus sp. buds, but detection frequency was low. We found significant correlations between the proportion of buds infested with LCM and the forest basal area consisting of F. grandifolia, suggesting it is the host for this nematode. Our results indicate that LCM is more widespread than BLD symptoms might suggest and can be present in forests containing a greater occurrence of F. grandifolia even when the trees are asymptomatic.

Remote Sensing of Forest Gap Dynamics in the Białowieża Forest: Comparison of Multitemporal Airborne Laser Scanning and High-Resolution Aerial Imagery Point Clouds

Remote sensing technologies like airborne laser scanning (ALS) and digital aerial photogrammetry (DAP) have emerged as efficient tools for detecting and analysing canopy gaps (CGs). Comparing these technologies is essential to determine their functionality and applicability in various environments. Thus, this study aimed to assess CG dynamics in the temperate European Białowieża Forest between 2015 and 2022 by comparing ALS data and image-derived point clouds (IPC) from DAP, to evaluate their respective capabilities in describing and analysing forest CG dynamics. Our results demonstrated that ALS-based point clouds provided more detailed and precise spatial information about both the vertical and horizontal structure of forest CGs compared to IPC. ALS detected 27,754 (54%) new CGs between 2015 and 2022, while IPC identified 23,502 (75%) new CGs. Both the average gap area and the total gap area significantly increased over time in both methods. ALS data not only identified a greater number of CGs, particularly smaller ones (below 500 m2), but also produced a more precise representation of CG shape and structure. In conclusion, precise, multi-temporal remote sensing data on the distribution and size of canopy gaps enable effective monitoring of structural changes and disturbances in forest stands, which in turn supports more efficient forest management, e.g., planning of forest regeneration.