Forests

The Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) is extensively utilized in various fields, such as forestry, oceanography, geology, and hydrology. However, due to limitations in radar side-view imaging, the SRTM DEM still contains gaps and anomalies, particularly in areas with an intricate topography, like forests. To enhance the accuracy of the SRTM DEM in forested regions, commonly employed approaches include regression analysis and artificial neural networks (ANN). Nevertheless, existing regression methods struggle to accurately capture the intricate nonlinear relationship between the error and influencing factors. Additionally, traditional ANN models are susceptible to overfitting, resulting in subpar accuracy. Deep Belief Network (DBN) is a highly precise algorithm in deep learning. However, the intricate combination of hyperparameters often leads to limited generalization ability and model robustness when correcting DEM. The present study proposes an error prediction model based on the DBN optimized by Particle Swarm Optimization (PSO) for SRTM DEM correction. By utilizing the PSO algorithm, we aim to identify the optimal combination of hyperparameters of DBN, including the number of neurons in the hidden layer and the learning rates. The experiment focuses on two regions in Hunan Province, China, characterized by abundant vegetation cover. The reference data utilized for comparison is ICESat/GLAS data. The experimental results demonstrate that the mean error (ME) and root mean square error (RMSE) of the SRTM DEM corrected by the proposed algorithm in these two regions are significantly reduced by 93.5%–96.0% and 21.5%–23.5%, respectively. Moreover, there is an improvement of over 26.1% in accuracy within complex terrain areas. Specifically, in broadleaf forest, the PSO-DBN method exhibits a remarkable accuracy improvement of 26.2%, while the DBN-corrected SRTM DEM shows an improvement of 15.3%. In coniferous forest, the PSO-DBN method achieves an accuracy improvement of 14.8%, whereas the DBN-corrected SRTM DEM demonstrates a gain of 5.8%. The approach provides a more effective and robust tool for correcting SRTM DEM or other similar DEMs over vegetated mountain areas. Full article

Climatic warming advances the start of the growing season (SOS) and sequentially enhances the vegetation productivity of temperate forests by extending the carbon uptake period and/or increasing the growth rate. Recent research indicates that the vegetation growth rate is a main driver for the interannual changes in vegetation carbon uptake; however, the specific effects of an earlier SOS on vegetation growth rate and the underlying mechanisms are still unclear. Using 268 year-site PhenoCam observations in temperate forests, we found that an earlier SOS reduced the vegetation growth rate and mean air temperature during the green-up period (i.e., from the SOS to the peak of the growing period), but increased the accumulation of shortwave radiation during the green-up period. Interestingly, an earlier-SOS-induced reduction in the growth rate was weakened in the highly humid areas (aridity index ≥ 1) when compared with that in the humid areas (aridity index < 1), suggesting that an earlier-SOS-induced reduction in the growth rate in temperate forests may intensify with the ongoing global warming and aridity in the future. The structural equation model analyses indicated that an earlier-SOS-induced decrease in the temperature and increase in shortwave radiation drove a low vegetation growth rate. Our findings highlight that the productivity of temperate forests may be overestimated if the negative effect of an earlier SOS on the vegetation growth rate is ignored. Full article

The increasing density of cities poses a huge threat to public health, so pocket parks with high accessibility and flexibility have become potential resources to promote public health. In this context, the ways in which pocket parks can improve public health have become the focus and challenge of current research. This study selected 10 different types of pocket parks in Fuzhou, China, as the research subjects and collected real-time psychological and physiological data of participants by watching videos of the sample plots. The aim was to explore the impact of the environmental characteristics of pocket parks on the psychological and physiological responses of recreational users. The results of the study showed that: (1) the environmental characteristics of pocket parks significantly affect the psychological and physiological responses of recreationists. Different environmental characteristics can affect recreationists’ emotional state, attention recovery, environmental preferences, and the indicators of IBI, HR, SDNN, RMSSD, pNN50, SCL, and EMG to varying degrees. (2) The environment of pocket parks may encourage recreationists to generate positive psychological benefits when the site is larger and has a higher degree of scenic beauty, and when the space is not effectively confined. A pocket park environment with a low paving ratio, open view, cultural elements, topographic changes, special vegetation and distributing space can also have a positive effect on the psychological benefits of recreationists to a certain extent. Low canopy density and high green visibility can also play a role in suppressing negative emotions. (3) Pocket parks with high levels of depression and off-site disturbance are not conducive to positive physiological responses from recreationists, while pocket parks with high levels of green visibility and beauty and specialized vegetation are more likely to provide health benefits to them. Full article

Trees in forests can obstruct falling rocks and serve as a natural barrier to reduce the velocity of falling rocks. Recently, there has been growing interest in utilizing forests to safeguard against potential rockfall. Nevertheless, there is a dearth of research regarding the impact of rock size and forest structure on forest preservation against rockfall. This study takes the Jiweishan rock avalanche that occurred in China in June 2009 as an example to discuss the protection mechanism of forests against rockfall in rock avalanche disasters. Three sizes of rockfalls from the Jiweishan rock avalanche were simulated and analyzed with and without forests using Rockyfor3D software. The findings indicate that forests can mitigate the energy impact of falling rocks. Especially in the debris flow area of rock avalanches, the protective effect of trees on small-sized falling rocks is most obvious, reducing the runout distance and damage range of the debris flow. Moreover, the protective effect of forest structures on rockfall risk was explored. It was found that broad-leaved forests had the best protection against falling rocks, followed by coniferous broad-leaved mixed forests, and coniferous forests had the worst protective effect. Furthermore, increasing forest planting density and tree diameter at breast height (DBH) can result in better protection against rockfall. Thus, rational planning of forest species and planting density in areas of rockfall can effectively reduce the threat of rockfall risk. The research ideas in this study can provide a basis for evaluating the mitigation of rockfall hazards by forests and provide a reference for constructing and planning protective forests in rockfall and rock avalanche hazard areas. Full article

Vertical vegetation differentiation is the most important form of spatial pattern in mountainous areas. It is of great significance to accurately divide vegetation into vertical zones for the study of mountain ecosystems and ecological protection. In order to accurately divide the vertical zone of mountain vegetation and determine the spatial distribution of mountain vegetation, the relationship between the vegetation index of various vegetation types and altitude was examined using remote sensing and geographic information technology. Taking Taibai Mountain, the main peak of the Qinling Mountains in China, as the study area, based on the difference in NDVI between summer and autumn (DNSA), this work constructed a DEM-NDVI scatter plot and quantified the boundary of the vertical zone by the half-peak width calculation method. The findings showed that: (1) the vertical distribution pattern of mountain vegetation may very well be reflected in the scatterplot that NDSA and DEM created; (2) Six vertical belts could be accurately identified to the meter level on Taibai Mountain’s south slope. Up to the altitude, the oak forest zone from the bottom of the mountain to the elevation of 1919 m, the pine-oak mixed forest zone is distributed in 1919–2331 m, the birch forest is distributed in 2115–2585 m, the fir forest is distributed in 2516–3150 m, the redwood forest is distributed in 3109–3551 m, and the alpine scrub meadow is distributed in 3551 m to the peak. On the north slope, 1053–2087 m above sea level is oak forest, 2087–2693 is birch forest, 2562–3006 is fir forest, 2987–3513 m is redwood forest, and 3513 to the top of the mountain is alpine scrub meadow; and (3) the distribution pattern of the vegetation vertical belt on the DEM-NDVI scatter plot was essentially compatible with the vegetation classification results derived from remote sensing images. The DEM-NDVI scatter plot can reflect the average distribution of vegetation population and can more accurately express the characteristics of vegetation vertical zone changes with altitude. Full article

Managed and natural vegetation restorations are two vital measures of land restoration; however, their effects on soil microbial communities at a large scale are not clearly understood. Hence, changes in the microbial community composition after 15 years of vegetation restoration along a climatic gradient in the subtropical karst region of Southwest China were assessed based on phospholipid fatty acids (PLFAs) profiles. Managed (plantation forest) and natural (naturally recovered to shrubbery) vegetation restoration types were compared, with cropland and mature forest serving as controls. Soil microbial community abundance was significantly higher under the two vegetation restoration types than in the cropland; however, it was lower than in the mature forest. The abundance, composition, and structure of soil microbial communities did not differ significantly between plantation forest and shrubbery. Soil organic carbon or total nitrogen was the primary factor positively affecting soil microbial abundance, whereas the mean annual temperature (MAT) was recognized as the primary factor contributing to the variation in the soil microbial community structure. Moreover, temperature had opposite effects on different indicators of microbial community structure. That is, it positively and negatively affected the ratios of gram-positive to gram-negative bacterial PLFAs (GP:GN) and fungal to bacterial PLFAs (F:B), respectively. Our results show that both vegetation restoration types have the ability to improve soil productivity in karst areas. Furthermore, shifts in soil microbial community structure (GP:GN and F:B ratios) induced by warming are likely to lead to a higher proportion of labile carbon, which is sensitive to soil tillage. Hence, more attention should be paid to ecological restoration in warmer karst areas to alleviate the severe loss of soil carbon in croplands. Full article

Seismic lines are the dominant anthropogenic disturbance in the boreal forest of the Canadian province of Alberta, fragmenting over 1900 km² of peatland areas and accounting for more than 80% of all anthropogenic disturbance in this region. The goal of this study is to determine whether the wildland fires that burn across seismic lines in peatlands result in the regeneration of woody vegetation within the ecotonal areas adjacent to seismic lines. We use a combination of seismic line and vegetation structural characteristics derived from multi-spectral airborne lidar across a post-fire peatland chronosequence. We found an increasing encroachment of shrubs and trees into seismic lines after many years since a fire, especially in fens, relative to unburned peatlands. Fens typically had shorter woody vegetation regeneration (average = 3.3 m ± 0.9 m, standard deviation) adjacent to seismic lines compared to bogs (average = 3.8 m ± 1.0 m, standard deviation), despite enhanced shrubification closer to seismic lines. The incoming solar radiation and seismic line age since the establishment of seismic line(s) were the factors most strongly correlated with enhanced shrubification, suggesting that the increased light and time since a disturbance are driving these vegetation changes. Shrub encroachment closer to seismic lines tends to occur within fens, indicating that these may be more sensitive to drying conditions and vegetation regeneration after several years post-fire/post-seismic line disturbance. Full article

Urban development and its climatic consequences have caused urban decision-makers to establish strategies to mitigate climate change. The implementation of different green spaces is one of the main strategies to reduce the environmental and climatic consequences of urbanization. Therefore, the main objective of this research is to reveal the effect of different green space scenarios on micro-bioclimatic conditions of a hospital located in Gorgan city, Golestan province. Therefore, in order to determine the position of the hospital building relative to Gorgan’s urban heat island (UHI), the location and changes in UHI intensity of Gorgan were determined as evidence of urban expansion. Since 27 July was determined as the hottest day in Gorgan city based on historical data analysis, the climatic conditions during 27 July 2021 were measured using an AR847 data logger installed in the hospital environment. Additionally, four different conditions, including actual environmental conditions of the hospital (actual conditions), along with the application of cypress trees (scenario A), plane trees (scenario B), and Buxus shrubs (scenario C), have been used to analyze the impact of different vegetation species on the bioclimatic conditions of 5 Azar Hospital during two time intervals, including observational periods (1970–2020) and the decade of the 2040s. Finally, spatiotemporal patterns of the predicted mean vote (PMV) thermal index were calculated for the observational period and during the 2040s using the ENVI-met micro-scale model. Results showed that the study site is in the UHI, which can affect the micro-bioclimatic conditions and the patient’s thermal perception. For all designed scenarios, results indicate that the average PMV index will increase by the 2040s. However, implementing different green space scenarios showed that the minimum and maximum values of PMV were found in scenario B, of 2.7. The actual PMV conditions of the studied site increased by 3.5. The scenario introduction of green spaces during the 2040s indicates that the average PMV at the hospital site will be decreased by 0.9 compared to the actual conditions. The study proves that appropriate green space strategies can reduce thermal loads occurring due to global climate change and improve the thermal conditions in the study area. Full article

Cunninghamia lanceolata is an important species in plantations and is widely planted in sub-tropical regions of China because of its fast-growing and productive characteristics. However, the monoculture planting is carried out in the pursuit of economic value. This planting mode has led to problems such as the exhaustion of soil fertility, decrease in vegetation diversity, and decrease in woodland productivity. In order to restore soil fertility and increase timber production, the introduction of broad-leaved tree species to plantations is an effective transformation model. Understanding how forest age changes and stand structure differences drive the composition and diversity of soil microbial communities is helpful in understanding the trend of soil–microbial changes in plantations and evaluating the effects of the introduction of broad-leaved tree species in soil–plant–microbial ecosystems in plantations. Therefore, the purpose of our study is to investigate the effects of forest age and pure forest conversion on C. lanceolata–P. bournei-mixed forest soil microbial community structure and diversity by detecting soil nutrients, enzyme activities, and soil microbial 16S and ITS rRNA gene sequencing. According to the findings, the diversity and abundance of bacterial communities in C. lanceolata plantations of different ages increased first and then decreased with the increase in forest age, and the max value was in the near-mature forest stage. The fungal abundance decreased gradually with stand age, with the lowest fungal diversity at the near-mature stand stage. During the whole growth process, the bacterial community was more limited by soil pH, nitrogen, and phosphorus. After introducing P. bournei into a Chinese fir plantation, the abundance and diversity of the bacterial community did not improve, and the abundance of the fungal community did not increase. However, soil nutrients, pH, and fungal community diversity were significantly improved. The results of these studies indicate that the introduction of broad-leaved tree species not only increased soil nutrient content, but also had a significant effect on the increase in the diversity of soil fungal communities, making the microbial communities of mixed forests more diverse. Full article

The modification of Scots pine sapwood (Pinus sylvestris L.) with the heterocyclic compounds imidazole and succinimide was investigated. Pressure-impregnation with aqueous solutions containing imidazole, imidazole + citric acid, succinimide, succinimide + citric acid, and citric acid + sorbitol (CIOL^®) with solid contents of 5%, 10%, and 15% was followed by oven-curing at 220 °C for 1 h. During the treatment steps, the changes in mass, bending properties, and anti-swelling efficiency (ASE) were examined. The results indicate that solid concentrations within the range of 5% to 10% were optimal. The results seem to show that there are two differing mechanisms in the modification of imidazole and succinimide, respectively. Mass loss due to heat treatment was highest in the imidazole-treated specimens, whereas it remained low and concentration-independent in the succinimide-treated specimens. After three cycles, the ASE reached 31% for the imidazole-treated specimens and improved to 38% with the addition of citric acid. For succinimide, the ASE increased from 17% to 41%. The bending properties generally showed improvement, except for succinimide + citric acid and CIOL^®, which displayed a reduced modulus of rupture. Chemical analyses are warranted to fully understand the reaction mechanisms of these treatments. The positive effects of imidazole treatment are suggested to stem from a thermal reaction between the chemical and the wood, indicated by substantial mass loss during leaching and specimen darkening. Succinimide and citric acid might exhibit polymerization with each other and with wood components, which is akin to the CIOL^® process. Further research should delve into the reaction mechanisms and the impact of imidazole and succinimide on biological durability. Full article

Hopea chinensis (Merr.) Hand.-Mazz. is a Class II national key protected plant and Plant Species with Extremely Small Populations in China. In order to further analyze why H. chinensis is endangered and optimize conservation techniques, we carried out a study on the effects of seed biological characteristics and environmental factors on the seed germination and seedling growth of H. chinensis. The results show that there were no significant differences in seed morphology between four populations in southern China, but there were significant differences in calyx lobe morphology and seed germination. The removal or retention of the calyx lobes or the seed coat had no significant effect on seed germination. The weight of individual H. chinensis seeds was mainly >1.0 g, with small seeds (<0.5 g) not germinating, whereas seeds >2.0 g had the highest germination rate and fastest seedling growth. H. chinensis produces typical recalcitrant seeds, being sensitive to natural dehydration, with dehydration for 8 d reducing seed viability by 50%, whereas dehydration for 16 d resulted in seeds with zero viability. H. chinensis seeds are light-neutral and capable of germination at a temperature of 30 °C and on a substrate with good water retention and aeration. The seeds are not tolerant of drought, salinity, or flooding. In conclusion, the unique biological characteristics of H. chinensis seeds and the specific habitat which they inhabit contribute to a significant loss of viable seeds, which negatively affects the population’s ability to regenerate and achieve maintenance. Full article

Landslides cause significant disturbances to mountainous ecosystems and human activities. Due to climate change, the frequency of landslides as secondary disasters has notably increased compared to the past. Further exploration is needed to understand the effects of different restoration methods on post-landslide plant communities and soil properties over different periods of time. In this regard, we selected Lantian County in the northern foothills of the Qinling Mountains as our study area. We conducted surveys on artificially restored and naturally recovered plots at 1, 6, and 11 years after landslide events. Undamaged areas were chosen nearby as control plots. We identified vegetation types and species diversity after artificial and natural recovery and further analyzed the impact of different restoration strategies on vegetation patterns and soil properties. The research results indicate that, compared with natural recovery, artificial restoration can more quickly improve vegetation and soil. With the increasing time gradient, the average ground cover of the herbaceous layer in natural recovery decreased gradually from 47% at year one to 34% at year eleven. In contrast, in artificial restoration, the average ground cover of the herbaceous layer increased from 27% at year one to 44% at year eleven. For the shrub layer, in natural recovery, the average ground cover gradually increased to 39% over eleven years. While in artificial restoration, the average ground cover for the shrub layer gradually increased to 46% over the same period. In the artificial restoration plots, soil pH gradually increased (from 6.2 to 8.2), while TN content gradually decreased (from 1.7 g/kg to 0.9 g/kg). Similarly, TK content decreased (from 22.4 g/kg to 14.5 g/kg), and AP content showed a decreasing trend (from 20.7 mg/kg to 11.4 mg/kg). In the natural recovery plots, DNA content gradually increased (from 3.2 μg/g/d to 142.6 μg/g/d), and SC content gradually increased as well (from 2.4 mg/d/g to 23.1 mg/d/g). In contrast, on sites undergoing natural recovery, the short-term restoration rates of vegetation and soil are lower, but they show greater stability over a longer time. This study provides a new perspective on vegetation restoration strategies and is expected to offer insights for the optimization of post-landslide recovery in the future. Full article

Scent is the key character of the horticultural ornamental plant rose, and benzenoid–phenylpropanoid compounds are the main source of scent. However, the underlying biosynthesis mechanism of these benzenoid–phenylpropanoid scent metabolites during Rosa flowering is poorly understood. In this study, the volatile metabolome and transcriptome conjoint analysis was conducted on the six stages petals of the variety ‘Lanxing’ to investigate the synthesis of benzenoid–phenylpropanoid metabolites. A total of 25 benzenoid–phenylpropanoid volatile compounds were identified, of which eugenol possessed the highest content. Meanwhile, transcriptome analysis produced 87.9 million clean reads and 22,004 differentially expressed genes (DEGs). Group pairwise comparison of gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis found DEGs were enriched into phenylpropanoid compound synthesis related pathway. Weighted gene co-expression network analysis (WGCNA) found a MEgreenyellow gene module (650 DEGs) correlated with phenylpropanoid compounds. Based on the eugenol content variation and gene spatio-temporal expression, a key candidate gene RcEGS32 related to the synthesis of eugenol was identified. Co-expression network analysis found that five transcription factors, RcMYB1, RcBES1, RcERF2, RcbHLH1, and RcTUB, may act as regulators in the eugenol synthesis process by directly binding to RcEGS32 or forming a complex unit. This study provided key insights into the formation of the scent substance eugenol during flowering, offering a valuable volatile metabolome and transcriptome resource for the future target trait-related gene discovery of roses. Full article

The timber degradation and overexploitation of Tilia amurensis necessitate strategic genetic resource management. This study presents a comprehensive approach to plus-tree selection, focusing on growth evaluation. Drawing from the procedures developed for evergreen oak, it encompasses base population selection, criteria establishment, forest stand investigation, standardized measurements, and tree selection. This study advances the baseline selection methods by emphasizing growth differentiation through age and environmental adjustments. A total of 62 superior individuals were selected from 176 candidates across 20 populations, effectively expanding the geographical boundaries. This growth-centric improved approach offers practical insights for selective breeding and genetic conservation, and addresses the ecological characteristics of the species. This study underscores the need for further exploration of genetic differentiation and biological traits to provide a foundation for refining T. amurensis tree improvement programs. In a broader context, these findings contribute to the understanding and sustainable management of diverse broadleaf forests. Full article

Creep performance is a crucial factor that must be considered in structural design. This paper aims to investigate the creep failure mode, creep strain, creep compliance, and other creep properties of bamboo scrimber under long-term tension in parallel-to-grain. To establish a general creep life prediction method for the full stress level of the bamboo scrimber, a multi-branch Kelvin–Voigt model, a generalized Maxwell model, and a creep finite element simulation were employed. The results showed that the creep strain curve of bamboo scrimber included the unsteady creep stage and the stable creep stage, but not the accelerated creep stage. When the stress ratio was less than 0.3, the residual strength decreased gradually. Below 70% of the ultimate load capacity, the creep characteristics of the bamboo scrimber were linear viscoelastic, and the creep compliance was generally independent of the load level. The creep finite element model of bamboo scrimber could accurately calculate the creep deformation of specimens. Based on this creep finite element model and creep failure rules, a life prediction model for the full stress level of bamboo scrimber was established, which could accurately predict the creep life. This paper provides theoretical guidance for the creep design of bamboo scrimber in engineering structures. Full article

In recent years, accurate estimation and spatial mapping of above-ground carbon (AGC) storage in forests have been crucial for formulating carbon trading policies and promoting sustainable development strategies. Forest structure complexities mean that during their growth, trees may be affected by the surrounding environment, giving rise to spatial autocorrelation and heterogeneity in nearby forest segments. When estimating forest AGC through remote sensing, data saturation can arise in dense forest stands, adding to the uncertainties in AGC estimation. Our study used field-measured stand factors data from 138 forest fire risk plots located in Fenglin County in the Northeastern region, set within a series of temperate forest environments in 2021 and Sentinel-2 remote sensing image data with a spatial resolution of 10 m. Using ordinary least squares (OLS) as a baseline, we constructed and compared it against four spatial regression models, spatial lag model (SLM), spatial error model (SEM), spatial Durbin model (SDM), and geographically weighted regression (GWR), to better understand forest AGC spatial distribution. The results of local spatial analysis reveal significant spatial effects among plot data. The GWR model outperformed others with an R² value of 0.695 and the lowest rRMSE at 0.273, considering spatial heterogeneity and extending the threshold range for AGC estimation. To address the challenge of light saturation during AGC estimation, we deployed traditional linear functions, the generalized additive model (GAM), and the quantile generalized additive model (QGAM). AGC light saturation values derived from QGAM most accurately reflect the actual conditions, with the forests in Fenglin County exhibiting a light saturation range of 108.832 to 129.894 Mg/ha. The GWR effectively alleviated the impact of data saturation, thereby reducing the uncertainty of AGC spatial distribution in Fenglin County. Overall, accurate predictions of large-scale forest carbon storage provide valuable guidance for forest management, forest conservation, and the promotion of sustainable development strategies. Full article

In the context of a changing environment, understanding the interaction between vegetation and climate is crucial for assessing, predicting, and adapting to future changes in different vegetation types. Vegetation exhibits high sensitivity to external environmental factors, making this understanding particularly significant. This study utilizes geospatial analysis techniques, such as geographic information systems, to investigate vegetation dynamics based on remote sensing data and climatic variables, including annual air temperature, annual precipitation, and annual solar radiation. The research methodology encompasses data collection, processing, and analysis, incorporating multispectral imagery and multilayered maps of various parameters. The calculation of the normalized difference vegetation index serves to evaluate changes in vegetation cover, identify areas experiencing variations in green biomass, and establish strategies for the future development of different vegetation types. During the period from 2001 to 2022, the average normalized difference vegetation index value in the Southeastern Crimea region amounted to 0.443. The highest average values were recorded in the year 2006, reaching a magnitude of 0.469. Conversely, the lowest values were observed in the years 2001–2002, constituting 0.397. It has been ascertained that an overarching positive trend in the evolution of NDVI values from 2001 to 2022 is apparent, thus implying a notable augmentation in vegetative biomass. However, adversarial trends manifest in discrete locales adjacent to the cities of Sudak and Feodosia, along with the coastal stretches of the Black Sea. Correlation analysis is employed to establish relationships between vegetation changes and climatic indicators. The findings contribute to our understanding of the vulnerability of various vegetation types and ecosystems in the Southeastern Crimea region. The obtained data provide valuable insights for the development of sustainable vegetation resource management strategies and climate change adaptation in the region. Full article

This paper reports on the location of sources contributing to a point flux measurement in the southern taiga, Russia. The measurement tower is surrounded by a coniferous forest with a mean aerodynamically active height of 27 m (h). Aerodynamical parameters of the forest, such as displacement height d and aerodynamic roughness $z_0$, derived from wind speed profile measurements for 2017–2019, were used to estimate the seasonal and daily behavior of the flux footprint. Two analytical footprint models by Schuepp et al. and by Kormann and Meixner driven by d and z₀ were used to estimate the footprint for canopy sources. The Lagrangian simulation (LS) approach driven by flow statistics from measurements and modeling was used to estimate the footprint for ground-located sources. The Flux Footprint Prediction (FFP) tool for assessing canopy flux footprint (Kljun et al.) applied as the option in the EddyPro v.7 software was inspected against analytical and LS methods. For model comparisons, two parameters from estimated footprint functions were used: the upwind distance (fetch) of the peak contribution in the measured flux (X_max) and the fetch that contributed to 80% of the total flux (CF₈₀). The study shows that X_max varies slightly with season but relies on wind direction and time of day. All methods yield different X_max values but fall in the same range (60–130 m, around 2–5 h); thus, they can estimate the maximum influence distance with similar confidence. The CF₈₀ values provided by the FFP tool are significantly lower than the CF₈₀ values from other methods. For instance, the FFP tool estimates a CF₈₀ of about 200 m (7 h), whereas other methods estimate a range of 600–1100 m (25–40 h). The study emphasizes that estimating the ground source footprint requires either the LS method or more complex approaches based on Computational Fluid Dynamics (CFD) techniques. These findings have essential implications in interpreting eddy-flux measurements over the quasi-homogeneous forest. Full article

This study investigates the prospects for preserving the main Pinus sylvestris L. (Scots pine) ecotypes in Poland, considering the habitat conditions of their occurrence. Scots pine is known for its wide distribution and natural adaptability to various habitats. However, there is an increasing vulnerability of pine forests to damage from biotic factors and a decrease in natural regeneration, particularly in areas under legal protection. Additionally, projected climate change has raised concerns about the future of Pinus sylvestris, placing it in the “losing” group of tree species. The aim of the study was to analyze the habitat conditions of the seven main selected Pinus sylvestris L. ecotypes to assess the sustainability of pine stands in their natural habitat conditions. Out of the seven populations of studied pine ecotypes, only one grows under conditions representing a typical form of pine forest (Leucobryo–Pinetum plant association). Two populations grow under conditions corresponding to potential deciduous forests (Galio sylvatici–Carpinetum and Calamagrostio arundinaceae–Quercetum petraeae). The remaining populations represent potentially mixed oak–pine forests. Such a distribution of plant communities, except for Leucobryo–Pinetum, does not guarantee the continuity of the studied pine stands as a result of their natural regeneration. Therefore, it is necessary to preserve the offspring of the studied populations outside their occurrence sites, but the studied pine stands should be preserved until their natural death in their natural habitats. In the conducted research, the NDVI turned out to be very useful, showing a high correlation with the trophicity of habitat expressed in the diversity of plant communities, as well as with the height and diameter of the studied stands. Full article