Sample Plots Research Articles

The species diversity and phylogenetic structure patterns of desert plant communities in the Turpan-Hami region, Xinjiang

Desert plant communities play a crucial role in enhancing desert ecosystem productivity and stability but are highly susceptible to environmental changes owing to their limited resilience and resistance to disturbances, making it essential to understand the factors influencing their diversity patterns and community structure, particularly under the threat of climate change and intensifying droughts. This study focused on the Turpan-Hami desert region, a typical desert ecosystem in which diversity patterns and community structures remain unclear. We established 101 sampling sites ranging from elevations of -134 to 2056m and recorded community information, including species composition, height, coverage, and density, using the sample plot method. The diversity patterns were analyzed using regression analysis, and the phylogenetic structure was assessed. Additionally, Canonical Correspondence Analysis, Mantel tests, and General Linear Models were used to identify the key factors affecting community structure. Our results demonstrated that the species richness and phylogenetic diversity of plant communities exhibited a monotonic increase with elevation, and the phylogenetic structure exhibited low clustering and high dispersion along the elevational gradient. The annual mean temperature emerged as the most significant factor influencing diversity patterns, with soil nutrients, such as total potassium and available phosphorus, also affecting the spatial distribution of diversity. Notably, no significant correlations were found between community phylogenetic structure and abiotic factors, highlighting the complex interactions that drive diversity in the Turpan-Hami region. This study offers valuable insights into the mechanisms shaping desert plant community diversity and is essential for biodiversity conservation efforts in fragile desert ecosystems amid climate change.

Mapping percent canopy cover using individual tree- and area-based procedures that are based on airborne LiDAR data: Case study from an oak-hickory-pine forest in the USA

Canopy cover (CC) is the proportion of a forest floor covered by the vertical projection of tree crowns. Recently, it has become common to utilize LiDAR (light detection and ranging) canopy metrics to estimate CC over large areas. However, these metrics are primarily related to canopy density rather than the specific definition of CC. Here, two processes that employed individual tree segmentation (ITS) and area-based procedures based on LiDAR data are presented to estimate CC across the Talladega Division of the Talladega National Forest (93,694 ha) at the plot, stand, and landscape levels. The two analytical procedures were assessed using the results of a plot/grid method as a reference dataset, which focused on CC estimates within 255 field measurement fixed-area sample plots. The accuracy of a third process, employing an imagery-based visual CC assessment, was also compared against the two procedures and the reference dataset. The LiDAR-based analytical procedures were able to provide estimates of CC with an RMSE of approximately 15 %, which is acceptable for landscape-level assessments. Based on the results of this study, we conclude that CC maps, when created using LiDAR data, may be suitable for various operational tasks such as assessing the impact of forest disturbances and helping to determine the habitat suitability for certain wildlife species.

Basal Area, Soil, and Elevation Factors Affecting The Essential Oils Yield, Geranyl Acetate, and D-Limonene of Zanthoxylum acanthopodium

Andaliman (Z. acanthopodium) is an aromatic Non-Timber Forest Product (NTFP) plant species that contains essential oils (EOs), which have various benefits for cuisine, medicine, and cosmetics. This study is essential because it is not yet known what biotic factors (basal area) and abiotic factors (soil and elevation) influence the EOs yield, geranyl acetate, and D-limonene as skin anti-aging. This study investigated whether the basal area, soil, and elevation factors influence the EOs yield, geranyl acetate, and D-limonene content of Andaliman fruit. The biotic and abiotic factors were measured from 9 sample plots representing the Andaliman habitats in North Sumatra, Indonesia. A vegetation analysis was conducted to derive the Andaliman basal area of each sample plot. Soil samples were taken randomly in each plot and analyzed for their physicochemical (pH, C, SOM, N, CNR, P, K, Ca, Mg, CEC, BS, SA, DU, CL, WC, and BD) contents. Elevation gradients were measured on each plot. The EOs of Andaliman fruit include yield, geranyl acetate, and D-limonene as skin anti-aging. The data were analyzed using Partial Least Square Regression for Generalized Linear Models (PlsRglm) to determine which biotic and abiotic factors influenced the EOs yield, geranyl acetate, and D-limonene. This study confirmed that clay soil texture was the main factor influencing EOs of Andaliman fruit yield, geranyl acetate, and D-limonene. Apart from soil factors, basal area, and elevation factors were also essential to consider when cultivating Andaliman fruit as a source of skin anti-aging substances. HIGHLIGHTS To the best of the authors’s knowledge, the first study in Indonesia 2024 that integrated biotic and abiotic factors affecting the essential oils (EOs) yield, geranyl acetate and D-limonene contents derived from of acanthopodium fruit as skin anti-aging substance. Using Partial Least Square Regression for Generalized Linear Models (PlsRglm) method for analyzing basal area, soil factors and elevation that influence the EOs of acanthopodium fruit. Of all the abiotic and biotic factors studied, Clay soil texture is the most critical factor that influences acanthopodium fruit EOs as skin anti-aging substances. Basal area and elevation are also essential factors in the cultivation of aromatic Andaliman plants. GRAPHICAL ABSTRACT

Coexistence of territorial competitor ants in fragmented boreal forest landscape

The distribution of species in a patchy habitat may be influenced by competitive interactions. The dominant and highly competitive boreal ant species belong to the Formica rufa group. A pair of species, Formica aquilonia and Formica polyctena, require extensive territories due to their multi-nest breeding habits. The coexistence and habitat patterns of these two wood ant species in the boreal forest landscape were investigated. Forest characteristics in the vicinity of nests in forest patches were similar for both species, but they did not coexist in the same sampling plots of 0.79 ha in forest patches, indicating competitive exclusion. The sampling plots in large forest patches were more occupied by F. aquilonia, while no such association was found for F. polyctena. At a larger spatial scale (78.5 ha), we found that F. polyctena was more tolerant of smaller forest patches than F. aquilonia suggesting that these two ant species can coexist in moderately fragmented forest landscapes. However, forest habitat loss, fragmentation and climate-induced changes in forest tree structure may shift the species balance in favour of F. polyctena over F. aquilonia in the future.

Spatial patterns and effects of invasive plants on soil microbial activity and diversity along river corridors

Abstract Background and aims Invasive species represent a threat to the conservation of biological systems. Riparian ecosystems are vulnerable to plant invasions, as waterflow facilitates the dispersal of plant propagules, while invasive species may subsequently impact soil, including soil microbial communities. Downstream connectivity among disparate riverine segments is expected to cause spatial continuity of abiotic and biotic components of riparian ecosystems. Methods We studied diversity of microbial communities in three headwater streams in Central Europe. Plant diversity, soil properties and soil microbiota were assessed on 20 sample plots per river. Soil microbial activity and community-level physiological profiling were used to study the soil microbial community. Results While the α-diversity of plants and soil microbiota was similar among rivers, plant communities were substantially more differentiated than microbial communities. Richness in alien and invasive plants significantly differed among rivers, which was reflected in different spatial patterns of microbial activity and diversity. A high level of spatial continuity was observed in the Kysuca river with straightened riverbed and artificial surfaces in the adjacent areas. The cover of invasive plants affects the composition of microbial functional groups of riverbed soils. Conclusion The expectation of spatial continuity of riverbed soil properties including those of soil microbiota caused by connectivity between different river segments was only partially fulfilled. Spatial continuity strongly depends on the environmental setting and stream characteristics of a particular river. The presence of invasive herbs affected the functional composition of soil microbiota but had no effect on microbial activity and diversity.

Плотность всходов сосны обыкновенной в сосновых лесах под влиянием выбросов Карабашского медеплавильного комбината и лесных пожаров

We assessed the features of natural pine regeneration in forests with different ages of ground fires in the Southern Urals depending on the level of heavy metal pollution. Using the materials obtained from 81 sample plots laid in maturing, mature and over-mature pine forests of natural origin in three types of forest growth conditions (TFGC 1 – TFGC 3), the relationship between the density of pine seedlings and the state of forest stands (crown density, stand age, vital status index), with the characteristics of vegetation condition (total number of species, total projective cover of herb-shrub layer, projective cover of bryophytes layer), with external influences (pollution level, distance from emission source, duration of fire disturbance), and with the methodological features of the study (accounting year) was analyzed. The high variability of estimates of the density of pine seedlings did not allow us to identify the relationship between the density of seedlings and the level of pollution and/or fire disturbances. The density of seedlings is nonlinearly related to the protective cover of the herb-shrub layer. With increasing coverage of the herb-shrub layer, the density of seedlings increased in areas with high levels of pollution and decreased in areas with background pollution.

A Novel Method for Extracting DBH and Crown Base Height in Forests Using Small Motion Clips

The diameter at breast height (DBH) and crown base height (CBH) are important indicators in forest surveys. To enhance the accuracy and convenience of DBH and CBH extraction for standing trees, a method based on understory small motion clips (a series of images captured with slight viewpoint changes) has been proposed. Histogram equalization and quadtree uniformization algorithms are employed to extract image features, improving the consistency of feature extraction. Additionally, the accuracy of depth map construction and point cloud reconstruction is improved by minimizing the variance cost function. Six 20 m × 20 m square sample plots were selected to verify the effectiveness of the method. Depth maps and point clouds of the sample plots were reconstructed from small motion clips, and the DBH and CBH of standing trees were extracted using a pinhole imaging model. The results indicated that the root mean square error (RMSE) for DBH extraction ranged from 0.60 cm to 1.18 cm, with relative errors ranging from 1.81% to 5.42%. Similarly, the RMSE for CBH extraction ranged from 0.08 m to 0.21 m, with relative errors ranging from 1.97% to 5.58%. These results meet the accuracy standards required for forest surveys. The proposed method enhances the efficiency of extracting tree structural parameters in close-range photogrammetry (CRP) for forestry. A rapid and accurate method for DBH and CBH extraction is provided by this method, laying the foundation for subsequent forest resource management and monitoring.

Spatial pattern of forest aboveground biomass and its environmental influencing factors in Qinling-Daba Mountains, central China

Accurate estimation of forest aboveground biomass (AGB) is crucial for understanding and managing forest ecosystems in the context of global environmental change, and also provides a scientific basis for national and regional ecological planning and carbon emission reduction policies. In order to investigate the regional pattern of forest AGB and its influencing factors in central China, a total of 469 sample plots were measured along four sample transects and on six mountains in field survey. The results showed that: 1) Two longitudinal distribution patterns of forest AGB were found, and one was that the AGB in the Qinling Mountains and the Daba Moutains gradually decreased from east to west, and the other was that the AGB in the areas between the two mountains gradually increased from east to west. The latitudinal distribution pattern of the forest AGB showed an "increasing–decreasing-increasing–decreasing" trend from south to north. The altitudinal distribution pattern showed a "first increasing-then decreasing" pattern with increasing altitude. 2) The influence of each factor on the spatial pattern of forest AGB was manifested as temperature > precipitation > HAI > topography, indicating that the spatial pattern of forest AGB in central China was the result of the interaction of climate, human activities and natural factors.

Modelling and Mapping of Aboveground Carbon of Oluwa Forest Reserve Using LandSat 8 TM and Forest Inventory Data

This research was carried out within the Oluwa Forest Reserve to evaluate and forecast its capacity for aboveground carbon sequestration using data from the Landsat Thematic Mapper. The Oluwa Forest Reserve, situated in Ondo State, Nigeria, is renowned for its abundant biodiversity and vast expanse. Assessing the forest's aboveground biomass and carbon traditionally involves intricate and expensive processes necessitating the expertise of diverse professionals and specialized equipment. Hence, this study investigated the utilization of Geographic Information System (GIS) and Remote Sensing (RS) technology, employing Landsat bands to calculate spectral indices and construct linear models for predicting the aboveground carbon sequestration potential of the tropical rainforest ecosystem within the Oluwa Forest Reserve. The measured aboveground carbon from sample plots, alongside the estimated spectral indices, was utilized to simulate the distribution of aboveground carbon across the Oluwa Forest Reserve. A positive linear correlation was identified between the observed data and the estimated spectral indices. Consequently, linear models were developed, and the most suitable model was determined through statistical analysis. The average aboveground carbon estimated from the sample plots was 150.70 tons per hectare (t/ha), closely aligning with the predicted value of 149.80 t/ha. Statistical analysis yielded a coefficient of determination of 94% and a Root Mean Square Error of 6.38E-16. These results indicate that the selected model accurately predicts the distribution of aboveground carbon within the Oluwa Forest Reserve. This study underscores the importance of spectral data, GIS, and RS in the efficient modelling and mapping of aboveground carbon in extensive forest ecosystems.

Restoration of stand on the site of burnt spruce forest in the Central Forest reserve

With the warming of the climate, the intensification of droughts and the drying up of coniferous forests, the number of forest fires is also increasing. Therefore, the study of the post-fire dynamics of stands and prospects for reforestation on burnt areas is especially relevant. The research was carried out in the Central Forest State Natural Biosphere Reserve (southern taiga) on the burnt area formed in 1999 as a result of a thunderstorm. The purpose of the work was: to describe the state of vegetation 22 years after burnout; to find out the characteristics of the stand formed on the burnt area and the possibility of their use for reconstructing the history of disturbancies in old spruce forests. The objectives of the study included: monitoring vegetation changes in the 1999 burnt area; studying the growth of spruce undergrowth in the burnt area; finding out the number and ratio of preliminary and subsequent renewal of tree species; analyzing the distribution and amount of coals in the sample plots (depending on the intensity of burnout and the state of the pre-fire stand). To study the state of vegetation after the burnout of the blueberry-wood sorrel and wood sorrel – nemoral-herb spruce (Picea abies (L.) H. Karst.) forests, 14 sample plots (100 m2 each) were laid in the northwestern part of the burnt area. The sample plots covered 1.5 hectares. 22 years after the fire, a mixed small-leaved forest with a predominance of birch and a significant participation of spruce has been forming on the site of burnt spruce forests. Spruce is represented mainly by post-fire renewal. In the undergrowth, the ratio of pre- and post-renewal spruce is about 1 : 3. In the ground cover, a small number of nemoral herb species is recorded, and in the stand and undergrowth – almost complete absence of broad-leaved species. A lot of coals were found in soil digs in 4 sample plots (30%); there were no coals in 3 (20%) sample plots, and small coals in small amount were found in 7 (50%) sample plots. Assessing the possibilities of identifying the first post-fire generation of spruce in old stands, it must be said that none of the characteristics of a post-fire spruce stand is universal for its recognition. Only a set of features allows to identify the history of the stand. Distinctive features of the first post-old generation: the presence of coals in 30% of samples or more; a large admixture of birch and aspen; a large diversity of the aspen part of the stand; if there are broad-leaved species, they will be much younger than the spruce; the presence of a sharp decline, and then a rise in growths in a significant part of the oldest spruce trees; the main generation of spruce has initial radial growths on an average of 2.1 mm/year, and the absence of synchronous sharp rises of the growths at the beginning of life. The age of aspen most accurately corresponds to the year of the fire.

Cluster-Based Wood–Leaf Separation Method for Forest Plots Using Terrestrial Laser Scanning Data

Successfully separating wood and leaves in forest plots is a prerequisite for measuring structural parameters and reconstructing 3D forest models. Terrestrial laser scanning (TLS) can distinguish between the leaves and wood of trees through precise and dense point clouds. However, most existing wood–leaf separation methods face significant accuracy issues, especially in dense forests, due to the complications introduced by canopy shading. In this study, we propose a method to separate the wood and leaves in forest plots using the clustering features of TLS data. The method first filters a point cloud to remove the ground points, and then clusters the point cloud using a region-growing algorithm. Next, the clusters are processed based on their sizes and numbers of points for preliminary separation. Chaos Distance is introduced to characterize the observation that wood points are more orderly while leaf points are more chaotic and disorganized. Lastly, the clusters’ Chaos Distance is used for the final separation. Three representative plots were used to validate this method, achieving an average accuracy of 0.938, a precision of 0.927, a recall of 0.892, and an F1 score of 0.907. The three sample plots were processed in 5.18, 3.75, and 14.52 min, demonstrating high efficiency. Comparing the results with the LeWoS and RF models showed that our method better addresses the accuracy issues of complex canopy structures.

Remote Prediction of Soybean Yield Using UAV-Based Hyperspectral Imaging and Machine Learning Models

Early soybean yield estimation has become a fundamental tool for market policy and food security. Considering a heterogeneous crop, this study investigates the spatial and spectral variability in soybean canopy reflectance to achieve grain yield estimation. Besides allowing crop mapping, remote sensing data also provide spectral evidence that can be used as a priori knowledge to guide sample collection for prediction models. In this context, this study proposes a sampling design method that distributes sample plots based on the spatial and spectral variability in vegetation spectral indices observed in the field. Random forest (RF) and multiple linear regression (MLR) approaches were applied to a set of spectral bands and six vegetation indices to assess their contributions to the soybean yield estimates. Experiments were conducted with a hyperspectral sensor of 25 contiguous spectral bands, ranging from 500 to 900 nm, carried by an unmanned aerial vehicle (UAV) to collect images during the R5 soybean growth stage. The tests showed that spectral indices specially designed from some bands could be adopted instead of using multiple bands with MLR. However, the best result was obtained with RF using spectral bands and the height attribute extracted from the photogrammetric height model. In this case, Pearson’s correlation coefficient was 0.91. The difference between the grain yield productivity estimated with the RF model and the weight collected at harvest was 1.5%, indicating high accuracy for yield prediction.

Assessing the potential of species loss caused by deforestation in a mature subtropical broadleaf forest in central China

Deforestation is a major type of land use change to accommodate growing population, especially in developing countries. The risk of diversity loss due to habitat loss can be estimated using the species-area relationship based on abundance of each species. However, deforestation often occurs before there is any understanding of the impact of deforestation on tree diversity. Here, we assessed the potential effect of forest habitat destruction on the loss of species richness in a mature subtropical broadleaf forest in central China. We surveyed and constructed the species-area relationship for 54 400 m2 plots, and simulated habitat loss scenarios by randomly and aggregately sampling plots. Rank-abundance of the 21 tree species was best fitted by the Zipf-Mandelbrot model, and our sample size was sufficient by the criterion of Hill numbers at orders q = 0, 1, and 2. We found that the number of species lost due to habitat loss was well predicted by the random placement species loss-area loss curve, and was lower than that due to aggregated habitat destruction by less than one species. The probability of losing one species reached 40% when losing 16 plots by aggregated sampling, 10 plots fewer than that by random sampling. Moreover, the probability of losing two species was 10–22 % higher by aggregately sampling than that by randomly sampling when losing 17 – 34 plots (0.68 – 1.36 ha). Considering that aggregated deforestation is common in reality, the results imply that the number of tree species lost due to deforestation could be higher than the theoretical estimation. Our study suggests the importance of assessing the impact of deforestation on tree diversity before selective logging in subtropical forests.

Climate Warming Has Contributed to the Rise of Timberlines on the Eastern Tibetan Plateau but Slowed in Recent Years

The alpine timberline is a component of terrestrial ecosystems and is highly susceptible to climate change. Since 2000, the Tibetan Plateau’s high-altitude zone has been experiencing a persistent warming, clarifying that the response of the alpine timberline to climate warming is important for mitigating the negative impacts of global warming. However, it is difficult for traditional field surveys to clarify changes in the alpine timberline over a wide range of historical periods. Therefore, alpine timberline sites were extracted from 2000–2021, based on remote sensing data sources (LANDSAT, MODIS), to quantify the timberline vegetation growth in the Gexigou National Nature Reserve and to explore the impacts of climate change on timberline vegetation growth. The results show that the mean temperature increased significantly from 2000 to 2021 (R2 = 0.35, p = 0.0036) at a rate of +0.03 °C/year. The alpine timberline continued to shift upwards, but at a slower rate, by +22.87 m, +23.23 m, and +2.73 m in 2000–2007, 2007–2014, and 2014–2021, respectively. The sample plots of the timberline showing an upward shift experienced a decreasing trend. The timberline NDVI increased significantly from 2000 to 2021 (R2 = 0.2678, p = 0.0136) with an improvement in its vegetation. The timberline NDVI is positively correlated with the annual mean temperature (p < 0.05), February mean temperature (p < 0.05), June minimum temperature (p < 0.05), February maximum temperature (p < 0.01), June maximum temperature (p < 0.01), and June mean temperature (p < 0.01). It was also found to be negatively correlated with annual precipitation (p < 0.01). The study showcases the practicality of using remote sensing techniques to investigate the alpine timberline shifts and timberline vegetation. The findings are valuable in developing approaches to the sustainable management of timberline ecosystems.

Long-term grazing changed the spatial distributions of dominant species in typical steppe of Inner Mongolia

Dominant species occupy a pivotal role in plant community, influencing the structure and function of the ecosystem. The spatial distributions of dominant species can react to the effect of different grazing intensities, thereby reflecting their tolerance and adaptive strategies toward grazing. In this study, geostatistical methods were mainly used to study the spatial distribution characteristics of Stipa krylovii Roshev. and Leymus chinensis (Trin.) Tzvel. species at two interval scales (quadrat size 5 m × 5 m, 10 m × 10 m) and two treatments (free grazing, FG, 1.66 sheep·ha− 1·a− 1; control, CK, 0 sheep·ha− 1·a− 1) in typical steppe of Inner Mongolia. A systematic sampling method was used in each 100 m × 100 m representative sample plots to obtain the height, coverage, and density of all species in the community. The results showed that grazing altered the concentrated distribution of S. krylovii and the spatial mosaic distribution pattern of S. krylovii and L. chinensis while having no effect on the spatial clumped distribution of L. chinensis. It also found that the spatial distributions of dominant species are primarily affected by structural factors, and random factors such as long-term grazing led to a transition of S. krylovii from a concentrated distribution to a small patchy random pattern should not be overlooked. Our findings suggest that long-term grazing alters the spatial distribution pattern of dominant species and that adaptive strategies may be the key for maintaining the dominant role of structural factors.

Effects of Environmental Factors on the Diversity of Grasshopper Communities along Altitude Gradients in Xizang, China.

To determine the grasshopper species composition, altitudinal distribution patterns, and their main drivers, we conducted a study in Xizang using 33 sample plots ranging from 600 to 4100 m. Grasshoppers were collected from August to October during 2020-2022 using sweep nets. A total of 1159 grasshoppers from six families, 28 genera, and 44 species were identified, with Omocestus cuonaensis and Aserratus eminifrontus as the dominant species, comprising 30.03% and 10.26% of total grasshoppers, respectively. The results showed that species richness and the Margalef richness index of grasshopper communities decreased significantly (p < 0.05) with increasing altitude, peaking at 1100-1600 m and lowest values at 2600-3100 m. Similarly, the Shannon-Wiener index and Simpson dominance index also decreased significantly (p < 0.05) with an increase in altitude, showing the highest and lowest values at 600-1100 m and 3100-3600 m, respectively. The Jaccard similarity coefficients among grasshopper communities varied from 0 to 0.40 across altitudinal gradients, indicating different degrees of dissimilarity. The results of Pearson correlation analyses showed that the Shannon-Wiener index, species richness, Margalef richness index, and Simpson dominance index of grasshopper communities were significantly negatively correlated with the temperature factors and soil pH, but they were significantly positively correlated with the moisture factors. Hierarchical partitioning identified annual mean temperature-daily difference, precipitation in the coldest season, and driest month precipitation as the primary factors explaining variance in grasshopper community diversity in Xizang. These findings provided greater insights into the mechanisms underlying insect community structure, distribution patterns, and diversity in Xizang ecosystems, including implications for the effects of global warming on insect communities.

Recreational Assessment of Green Belt Forests of the Ulaanbaatar City

The classification of forest vegetation of the Tuul river basin within the green belt of the Ulaanbaatar city. Two associations (Linnaeo borealis–Pinetum sibiricae and Vaccinio vitis-idaeae–Laricetum sibiricae) were classified Vaccinio–Piceetea. Diagnostic signs and characteristics of the ecological and geographical peculiarities of the units were presented, anthropogenic transformation was assessed. To determine the models of succession processes, the series of permanent sample plots were established in the communities of the Linnaeo borealis–Pinetum sibiricae association, located at different distances from the city, in taxation units with unequal intensity of recreational load. Recreational forest assessment was calculated according to the approach by V.S. Romanov and L.N. Rozhkov (1974). In the Linnaeo borealis–Pinetum sibiricae association, large areas were occupied by moderately transformed communities. The Vaccinio vitis-idaeae–Laricetum sibiricae association is characterized by being weakly transformed forests. Different stages of anthropogenic pressure were formed serial communities, unequal in structure and species diversity. Serial plant communities of allogeneic succession were developed according to 2 models of geitogenesis — tolerance (Linnaeo borealis–Pinetum sibiricae ↔ Rhytidium rugosum; Linnaeo borealis-Pinetum sibiricae ↔ Chamaenerion angustifolium) and inhibition (Linnaeo borealis–Pinetum sibiricae ↔ Betula rotundifolia). A comprehensive assessment of the recreational potential was based on three indicators: natural conditions, air hygiene and landscaping. All activities aimed at increasing the recreational potential should contribute to the improvement of these indicators. A prerequisite for increasing the recreational forest assessment should be functional zoning of the territory with the allocation of infrastructure, walking and sanitary protective zones. Forest management is of great importance in increasing the recreational potential of forests. The forest management project for the organization of recreational forests should be aimed at the formation of sustainable and aesthetically attractive forest plantations.

Resilience of uneven-aged mixedwood stands altered by diameter-limit cutting and opportunities for their rehabilitation

Repeated diameter-limit cutting in mixedwood forests often leads to altered stand composition, quality, and regeneration, hence decreasing productivity and value over time. We studied the evolution of stand characteristics after diameter-limit cutting on a 15-year period, beginning from 11 to 43 years after cutting. We used 415 sample plots (200 m2) and three criteria: (i) ≥9.0 m2/ha overstory (trees ≥9.1 cm dbh [diameter at breast height, 1.3 m above ground]) acceptable growing stock (AGS, i.e. basal area of vigorous trees with sawlog potential), (ii) ≥3.0 m2/ha pole timber AGS (9.1 cm-23.0 cm dbh) and (iii) ≥60% sapling (dbh 1.1-9.0 cm) stocking of desired species. Stand initial quality was determined in function of overstory AGS at the beginning of the monitoring period: good quality (AGS≥9.0 m2/ha), impoverished (7.0≤AGS&lt; 9.0 m2/ha), degraded (AGS &lt;7.0 m2/ha). After 15 years, 47% of stands satisfied at least two criteria, but most stands (65%) had insufficient sapling regeneration. Stands in good quality and impoverished categories had sufficient basal area and AGS to support a new partial cutting cycle, contrary to stands in the degraded category. A conceptual model based on these three criteria is presented to guide silvicultural rehabilitation of uneven-aged mixedwood stands altered by past cutting practices.

Investigating changes of forest aboveground biomass induced by Moso bamboo expansion with terrestrial laser scanner

As a typical clonal plant, Moso bamboo expands excessively worldwide, causing changes in various aspects of the native forest ecosystem. Among these aspects, aboveground biomass (AGB) is a key indicator characterizing forest productivity and carbon sequestration. However, it is difficult to track AGB changes of a fixed plot in a relatively short period. In this paper, we utilized terrestrial laser scanner (TLS) to investigate AGB changes resulting from the intrusion of Moso bamboo using the space-for-time substitution method. Three sample plots including a China fir stand, a mixed stand and a pure Moso bamboo stand were chosen at an ecotone to represent the different stages of bamboo expansion in Hutou Village, Chongqing, China. Their point clouds were first scanned using TLS, and then segmented into individual plants through refinedly processing the stem intersections. Subsequently, tree and bamboo classification was achieved via combining the structural features, stem texture features, and point distribution features of individual plants. Finally, the compatible biomass models were employed to estimate plant AGBs and analyze the changes. As a result, the overall classification accuracy of trees and bamboos was improved to 92.67 %. The AGB per unit area initially increased and subsequently decreased at three stages of Moso bamboo expansion (5.83 kg/m2, 6.04 kg/m2 and 5.36 kg/m2), and the AGB differences among individual plants showed the similar tendency. Notably, the average AGB of individual China firs in mixed stand (78.97 kg) was higher than that in the pure stand (70.41 kg), so did the average AGB of individual Moso bamboos (21.22 kg vs 18.70 kg). These results indicated that maintaining a certain degree of tree-bamboo mixture was beneficial for improving the gross forest AGB.

Provenance and tectonic setting of sandstones of the Lomas Coloradas Formation, Cabullona Group, Sonora, México: Constraints on petrography and geochemistry

The sedimentary rocks of the Cabullona Group are well exposed in the Cabullona Basin of northeastern Sonora, México, which represent syntectonic sedimentation associated with Laramide-style deformation during the Campanian−early Maastrichtian. The sandstones of the Lomas Coloradas Formation deposited at the upper part of the Cabullona Group. Petrography and geochemical (major, trace, and rare earth elements) studies were carried out on the sandstones to interpret the palaeoweathering, provenance, and tectonic setting of the Lomas Coloradas Formation sandstones. Most of the sandstone modal analysis data plotted in the QFL and QmFLt ternary diagrams fall into the fields of dissected arcs and recycled orogens, respectively. Geochemically the sandstones are classified as litharenites while few samples plot into the arkosic field. The chondrite-normalized REE diagrams for sandstones have LREE-enriched, relatively flat HREE patterns with negative Eu anomalies. CIA values and the A‒CN‒K diagram indicate a low intensity of chemical weathering in the source area. The tectonic setting diagram suggests both arc and rift settings for the studied sandstones. The bivariate and ternary diagrams and elemental ratios suggest a felsic source for the Lomas Coloradas Formation. The average REE patterns of the studied sandstones are comparable with REE patterns of the granite from the Caborca block, the rhyolite and granite of the Tarahumara Formation, and the Mesozoic felsic volcanic rocks. The modeled mixture of 40% Proterozoic granite, 30% Triassic arc, 10% Jurassic arc, and 20% Laramide arc represents the probable source rocks for the Lomas Coloradas Formation.