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Forests, Volume 15, Issue 7 (July 2024) – 194 articles

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21 pages, 3240 KiB  
Article
Predicting the Integrated Fire Resistance of Wildland–Urban Interface Plant Communities by Spatial Structure Analysis Learning for Shanghai, China
by Manqing Yao, Deshun Zhang, Ruilin Zhu, Zhen Zhang and Mohamed Elsadek
Forests 2024, 15(7), 1266; https://doi.org/10.3390/f15071266 (registering DOI) - 20 Jul 2024
Abstract
Abstract: Fire is a prevalent hazard that poses a significant risk to public safety and societal progress. The continuous expansion of densely populated urban areas, exacerbated by global warming and the increasing intensification of urban heat islands, has led to a notable increase [...] Read more.
Abstract: Fire is a prevalent hazard that poses a significant risk to public safety and societal progress. The continuous expansion of densely populated urban areas, exacerbated by global warming and the increasing intensification of urban heat islands, has led to a notable increase in the frequency and severity of fires worldwide. Incorporating measures to withstand different types of calamities has always been a crucial aspect of urban infrastructure. Well-designed plant communities play a pivotal role as a component of green space systems in addressing climate-related challenges, effectively mitigating the occurrence and spread of fires. This study conducted field research on 21 sites in the green belt around Shanghai, China, quantifying tree morphological indexes and coordinate positions. The spatial structure attributes of different plant communities were analyzed by principal component analysis, CRITIC weighting approach, and stepwise regression analysis to build a comprehensive fire resistance prediction model. Through this research, the relationship between community spatial structures and fire resistance was explored. A systematic construction of a prediction model based on community spatial structures for fire resistance was undertaken, and the fire resistance performance could be quickly judged by easily measured tree morphological indexes, providing valuable insights for the dynamic prediction of fire resistance. According to the evaluation and ranking conducted by the prediction model, the Celtis sinensis, Sapindus saponaria, Osmanthus fragrans, Koelreuteria paniculata, and Distylium racemosum + Populus euramericana ‘I-214’ communities exhibited a high level of fire resistance. On the other hand, the Koelreuteria bipinnata + Ligustrum lucidum, Ginkgo biloba + Camphora officinarum + Ligustrum lucidum, and Ligustrum lucidum + Sapindus saponaria communities obtained lower scores and were positioned lower in the ranking. It is emphasized that the integration of monitoring and regulation is essential to ensure the ecological integrity and well-being of green areas in the Wildland–Urban Interface. Full article
(This article belongs to the Section Urban Forestry)
16 pages, 5399 KiB  
Article
Altitudinal Difference of Growth–Climate Response Models in the Coniferous Forests of Southeastern Tibetan Plateau, China
by Shanshan Xu, Chaogang Zheng, Zhigang Zhang, Zhiyuan Shang, Xinggong Kong and Zhijun Zhao
Forests 2024, 15(7), 1265; https://doi.org/10.3390/f15071265 (registering DOI) - 20 Jul 2024
Abstract
Characterized as a climatologically sensitive region, the southeastern Tibetan Plateau (STP) is an ideal location for dendrochronological research. Here, five tree-ring width (TRW) chronologies were developed: three for Picea likiangensis along altitudinal gradients from 3600 to 4400 m a.s.l. and two for Sabina [...] Read more.
Characterized as a climatologically sensitive region, the southeastern Tibetan Plateau (STP) is an ideal location for dendrochronological research. Here, five tree-ring width (TRW) chronologies were developed: three for Picea likiangensis along altitudinal gradients from 3600 to 4400 m a.s.l. and two for Sabina saltuaria and Abies squamata from 4200 m a.s.l. Significant differences in the growth rates and age composition of Picea likiangensis were observed at various elevation gradients. The chronology statistics (mean sensitivity, etc.) fluctuated with the elevation gradient. Picea likiangensis showed distinct growth patterns in response to climatic variability along the altitude gradient: the minimum temperature influenced tree growth at lower and middle altitudes, while higher altitudes were affected by precipitation. The radial growth of different tree species growing in the same region is controlled by the same climatic factors. Sabina saltuaria and Abies squamata exhibited similar growth responses to Picea likiangensis. Stand conditions (wind speeds, slope, and elevation) and biotic factors (the depth of root, forest type, tree age, and sensitivity) can partially explain why the ring width–climate relationships change with altitude. Full article
(This article belongs to the Section Forest Meteorology and Climate Change)
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16 pages, 2871 KiB  
Article
Sensitivity of Fire Indicators on Forest Inventory Plots Is Affected by Fire Severity and Time since Burning
by James E. Smith and Coeli M. Hoover
Forests 2024, 15(7), 1264; https://doi.org/10.3390/f15071264 (registering DOI) - 20 Jul 2024
Abstract
Forest inventory data are useful for determining forest stand structure, growth, and change. Among the information collected on forest inventory plots by the USDA Forest Service Forest Inventory and Analysis Program, attributes characterizing various types of disturbance provide researchers a means of selecting [...] Read more.
Forest inventory data are useful for determining forest stand structure, growth, and change. Among the information collected on forest inventory plots by the USDA Forest Service Forest Inventory and Analysis Program, attributes characterizing various types of disturbance provide researchers a means of selecting plots specifically affected by disturbances, such as fire. We determine the performance of three of these attributes as indicators of recent fires on forest inventory plots of the United States by comparing them to independent records of wildland fire occurrence. The indicators are plot-level observations of fire effects on (1) general site appearance, (2) tree mortality, and (3) damage to live trees. Independent spatial layers of wildland fire perimeters provide an approach to test indicator performance and identify characteristics of fires that may affect detection. The sensitivities of indicators are generally higher in the West relative to the East. Detection rates exceed 90 percent for the Pacific Coast forests but seldom reach 80 percent in the East. Among the individual indicators, site appearance has higher identification rates than tree indicators for fires in the Pacific Coast, Great Plains, North, and South regions. Tree mortality is the most important single indicator for identifying Rocky Mountain fires. Tree damage is more important than tree mortality in the South; otherwise, the tree damage indicator is of relatively lower importance, particularly where high-severity fires are common, and tree survival is low. The rate of detection by the indicators is affected by the severity of the fire or the recency of the fire. The joint effect of severity and recency influence all three indicators for the Pacific Coast and Rocky Mountain fires, as well as the site appearance indicator in the South. Only a small proportion of fires are clearly missed by all three of the indicators. Full article
(This article belongs to the Section Natural Hazards and Risk Management)
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21 pages, 1158 KiB  
Article
Analysis of Driving Factors for Vegetation Ecological Quality Based on Bayesian Network
by Jin Cai, Xiaojian Wei, Fuqing Zhang and Yuanping Xia
Forests 2024, 15(7), 1263; https://doi.org/10.3390/f15071263 - 19 Jul 2024
Viewed by 100
Abstract
Vegetation is a crucial component of ecosystems, and understanding the drivers and spatial optimization patterns of its ecological quality is vital for environmental management in the middle reaches of the Yangtze River Urban Agglomeration. Traditional evaluations employing single indices may not fully capture [...] Read more.
Vegetation is a crucial component of ecosystems, and understanding the drivers and spatial optimization patterns of its ecological quality is vital for environmental management in the middle reaches of the Yangtze River Urban Agglomeration. Traditional evaluations employing single indices may not fully capture the complexity of vegetation elements and require evaluation through various indicators. Therefore, this study introduced the Multi Criteria Vegetation Ecological Quality Index (VEQI), coupled with vegetation cover and vegetation ecological function indicators, to explore the driving factors of vegetation quality in the middle reaches of the Yangtze River and identify key areas where vegetation quality declines or improves. By constructing a Bayesian network for VEQI, we identified the driving variables that influence the index. Additionally, we delineated spatial optimization zones for VEQI. The results indicate that the VEQI exhibits a trend of transitioning from low values in urban centers to high values in suburban and rural areas. Over 20 years, the average VEQI of the study region ranged from 10.85% to 94.94%. Slope, DEM, and vegetation type were identified as significant drivers of VEQI, while precipitation, temperature, and nighttime light were considered secondary factors. Notably, areas in Hunan, Jiangxi, and Hubei provinces, especially the western part of Hunan, were pinpointed as spatial optimization regions. This research not only enhances the understanding of vegetation’s ecological quality in the urban agglomeration of the middle reaches of the Yangtze River but also provides scientific insights for the protection and management of vegetation. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
13 pages, 3722 KiB  
Article
Temporal Variations in Enzymatic and Non-Enzymatic Antioxidant Activity in Silver Birch (Betula pendula Roth.): The Genetic Component
by Vaida Sirgedaitė-Šėžienė, Ieva Čėsnienė and Dorotėja Vaitiekūnaitė
Forests 2024, 15(7), 1262; https://doi.org/10.3390/f15071262 - 19 Jul 2024
Viewed by 101
Abstract
Betula pendula Roth. (silver birch) is a pioneer species in the Northern Hemisphere forests. It plays a significant role in various ecosystems, human industries, and biodiversity. Taking all this into account, understanding the genetic diversity within B. pendula populations is crucial for fully [...] Read more.
Betula pendula Roth. (silver birch) is a pioneer species in the Northern Hemisphere forests. It plays a significant role in various ecosystems, human industries, and biodiversity. Taking all this into account, understanding the genetic diversity within B. pendula populations is crucial for fully exploiting their potential, particularly regarding their production of phenolic compounds and antioxidants. We tested the non-enzymatic and enzymatic antioxidant activity in seven silver birch half-sib family leaves. Spectrophotometric data from leaf extracts showed that there was a significant variation between families in terms of total phenol content (TPC) and antioxidant enzyme (superoxide dismutase, peroxidase (POX), catalase, glutathione reductase, and ascorbate peroxidase) levels. The data were gathered during two consecutive seasons, resulting in a variance in antioxidant production, which generally increased in the tested families during the second year (except for POX) as opposed to the first vegetative season. For example, SOD levels increased in the second year by 15% to 243% and TPC increased by 46%–189%, depending on the half-sib family. A more thorough study of this variation should prove beneficial in various research fields, ranging from climate change to cosmetics. Full article
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17 pages, 5108 KiB  
Article
Spatial Pattern and Environmental Driving Factors of Treeline Elevations in Yulong Snow Mountain, China
by Chuan Lin, Lisha Yang, Ruliang Zhou, Tianxiang Zhang, Yuling Han and Yanxia Wang
Forests 2024, 15(7), 1261; https://doi.org/10.3390/f15071261 - 19 Jul 2024
Viewed by 118
Abstract
The southwestern region of China is a global biodiversity hotspot. Understanding the environmental mechanisms behind treeline formation in high-altitude areas is crucial for predicting ecosystem changes, such as the upward movement of the treeline due to climate warming and the disappearance of high-altitude [...] Read more.
The southwestern region of China is a global biodiversity hotspot. Understanding the environmental mechanisms behind treeline formation in high-altitude areas is crucial for predicting ecosystem changes, such as the upward movement of the treeline due to climate warming and the disappearance of high-altitude rocky beach and shrub ecosystems. Globally, observations show that growing seasonal temperatures at treelines are typically 6–7 °C, but trees do not always reach the predicted elevations. Spatial heterogeneity exists in the deviation (Dtreeline) between actual treeline elevation and the thermal treeline; however, the main driving factors for Dtreeline in many areas remain unclear. This study uses Yulong Snow Mountain as an example, employing machine learning methods like Support Vector Machine (SVM) to precisely identify actual treeline elevation and Extreme Gradient Boosting Tree (XGBoost) to explore the main environmental factors driving the spatial heterogeneity of Dtreeline. Our research found that (1) more than half of the treelines deviated from the thermal treeline, with the average elevation of the thermal treeline (3924 ± 391 m) being about 56 m higher than the actual treeline (3863 ± 223 m); (2) Dtreeline has a complex relationship with environmental factors. In addition to being highly correlated with temperature, precipitation and wind speed also significantly influence the treeline in this region; and (3) the influence of individual variables such as precipitation and wind speed on the spatial variation of Dtreeline is limited, often nonlinear, and involves threshold effects. This knowledge is essential for developing comprehensive protection strategies for Yunnan’s high-altitude ecological systems in response to climate warming. Furthermore, it plays a significant role in understanding the changes in biological communities and the response of high-altitude areas to climate change. Full article
(This article belongs to the Section Forest Ecology and Management)
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18 pages, 3283 KiB  
Article
Soil Organic Carbon in Mid-Atlantic Region Forest Soils: Stocks and Vertical Distribution
by Daniel J. Colopietro and Ray R. Weil
Forests 2024, 15(7), 1260; https://doi.org/10.3390/f15071260 - 19 Jul 2024
Viewed by 112
Abstract
Over a period of 10 years, 418 forested plots within the US National Capital Region parks were visited for morphological descriptions and to inventory carbon (C) stocks. Samples were collected from organic horizons, the loose leaf litter, and, using a hand auger, from [...] Read more.
Over a period of 10 years, 418 forested plots within the US National Capital Region parks were visited for morphological descriptions and to inventory carbon (C) stocks. Samples were collected from organic horizons, the loose leaf litter, and, using a hand auger, from each mineral horizon to a depth of 1 m. Soil C concentration was determined using high-temperature combustion, and organic carbon (OC) stocks were then calculated for each master horizon. Soil bulk density (Db) was determined using the core method for O and A horizons. For deeper mineral horizons, a strong linear relationship between NRCS SSURGO representative values and measured Db values averaged according to soil series (R2 = 0.75) was observed. Thus, the NRCS SSURGO representative Db values were used for mineral horizons below the A horizon. An average of 0.5 ± 0.0 kg C m−2 was contained in the loose leaf litter. For plots with O horizons, the organic layer contained 2.9 ± 0.3 kg C m−2. An average of 4.6 ± 0.2 kg C m−2 was stored in the A horizon, down to an average lower boundary of 18.8 cm. The mineral horizons below the A horizon averaged 8.5 kg C m−2. In these forested soil profiles, 52.8% of the TOC is found below the A horizon and 18.0% of the TOC is in the organic horizons. The predictive strength of the thickness of and SOC in the A horizon was also evaluated in terms of explaining and predicting TOC in the profile and in the subsoil. The thickness and SOC in the A horizon explained 54% of the variation in TOC stock; however, it was a poor predictor of OC stored in the subsoil (R2 = 0.04). This study demonstrates the importance of deeper sampling to encompass more of the rooting depth when investigating SOC stocks. Full article
(This article belongs to the Section Forest Soil)
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13 pages, 2574 KiB  
Article
Energetic Features of Hardwood Pellet Evaluated by Effect Size Summarisation
by Rodolfo Picchio, Rachele Venanzi, Vincenzo Civitarese, Aurora Bonaudo, Angela Lo Monaco and Francesco Latterini
Forests 2024, 15(7), 1259; https://doi.org/10.3390/f15071259 - 19 Jul 2024
Viewed by 132
Abstract
High-quality pellets are typically produced from coniferous sawdust. However, achieving comparable quality from alternative feedstocks, such as broadleaf wood, often necessitates pre-treatments or additives. Yet, within the framework of small-scale pellet production, local forest enterprises may lack the resources for such treatments and [...] Read more.
High-quality pellets are typically produced from coniferous sawdust. However, achieving comparable quality from alternative feedstocks, such as broadleaf wood, often necessitates pre-treatments or additives. Yet, within the framework of small-scale pellet production, local forest enterprises may lack the resources for such treatments and usually produce pellets from the whole trees, including branches, leaves and tops. This can have an impact on the quality of the pellets obtained in this manner. To be classified as high-quality pellets (A1 class), the specific features of the pellet must be higher or fall below the thresholds specified in the EN ISO 17225 standard. In this study, we developed an alternative statistical approach to evaluate pellet quality in comparison to the constant thresholds reported in the technical standard. We applied such an approach to evaluate the quality of pellets produced from the broadleaved species common in the Mediterranean forestry, including European beech (Fagus sylvatica L.), Turkey oak (Quercus cerris L.), Eucalyptus (clone Eucalyptus camaldulensis x C. bicostata), and Poplar clone AF6. In particular, we focused on three variables that are generally the most troublesome for the production of high-quality pellets from the broadleaved species, namely bulk density, ash content, and lower heating value. We found that the beech pellets showed satisfactory bulk density (average effect size of −1.2, with no statistical difference in comparison to the standard’s threshold) and ash content (average effect size of about −5 and significantly lower than the standard’s threshold), but the heating value was significantly lower than the threshold required by the standard (average effect size of about −3). Conversely, other investigated species exhibited notable deficiencies, with turkey oak pellets displaying acceptable heating values. We found a significant improvement in ash content and heating value with increasing stem age within the same species thus suggesting that material derived from thinning interventions might be preferable over coppice-derived biomass for high-quality pellet production. We suggest that future research on the topic should focus on investigating pellets produced from blends of beech and turkey oak biomass. We further recommend a wider application of the proposed statistical approach, considering that it is clear and easy to interpret, and allows for a statistical comparison of the obtained values against the requirements of the technical standard. Full article
(This article belongs to the Special Issue Novelties in Wood Engineering and Forestry—2nd Edition)
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16 pages, 3080 KiB  
Article
Interactive Effects of Salinity and Hydrology on Radial Growth of Bald Cypress (Taxodium distichum (L.) Rich.) in Coastal Louisiana, USA
by Richard H. Day, Andrew S. From, Darren J. Johnson and Ken W. Krauss
Forests 2024, 15(7), 1258; https://doi.org/10.3390/f15071258 - 19 Jul 2024
Viewed by 108
Abstract
Tidal freshwater forests are usually located at or above the level of mean high water. Some Louisiana coastal forests are below mean high water, especially bald cypress (Taxodium distichum (L.) Rich.) forests because flooding has increased due to the combined effects of [...] Read more.
Tidal freshwater forests are usually located at or above the level of mean high water. Some Louisiana coastal forests are below mean high water, especially bald cypress (Taxodium distichum (L.) Rich.) forests because flooding has increased due to the combined effects of global sea level rise and local subsidence. In addition, constructed channels from the coast inland act as conduits for saltwater. As a result, saltwater intrusion affects the productivity of Louisiana’s coastal bald cypress forests. To study the long-term effects of hydrology and salinity on the health of these systems, we fitted dendrometer bands on selected trees to record basal area increment as a measure of growth in permanent forest productivity plots established within six bald cypress stands. Three stands were in freshwater sites with low salinity rooting zone groundwater (0.1–1.3 ppt), while the other three had higher salinity rooting zone groundwater (0.2–4.9 ppt). Water level was logged continuously, and salinity was measured monthly to quarterly on the surface and in groundwater wells. Higher groundwater salinity levels were related to decreased bald cypress radial growth, while higher freshwater flooding increased radial growth. With these data, coastal managers can model rates of bald cypress forest change as a function of salinity and flooding. Full article
(This article belongs to the Special Issue Coastal Forest Dynamics and Coastline Erosion, 2nd Edition)
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22 pages, 9521 KiB  
Article
Estimation of Leaf Area Index for Dendrocalamus giganteus Based on Multi-Source Remote Sensing Data
by Zhen Qin, Huanfen Yang, Qingtai Shu, Jinge Yu, Li Xu, Mingxing Wang, Cuifen Xia and Dandan Duan
Forests 2024, 15(7), 1257; https://doi.org/10.3390/f15071257 - 19 Jul 2024
Viewed by 138
Abstract
The Leaf Area Index (LAI) plays a crucial role in assessing the health of forest ecosystems. This study utilized ICESat-2/ATLAS as the primary information source, integrating 51 measured sample datasets, and employed the Sequential Gaussian Conditional Simulation (SGCS) method to derive surface grid [...] Read more.
The Leaf Area Index (LAI) plays a crucial role in assessing the health of forest ecosystems. This study utilized ICESat-2/ATLAS as the primary information source, integrating 51 measured sample datasets, and employed the Sequential Gaussian Conditional Simulation (SGCS) method to derive surface grid information for the study area. The backscattering coefficient and texture feature factor from Sentinel-1, as well as the spectral band and vegetation index factors from Sentinel-2, were integrated. The random forest (RF), gradient-boosted regression tree (GBRT) model, and K-nearest neighbor (KNN) method were employed to construct the LAI estimation model. The optimal model, RF, was selected to conduct accuracy analysis of various remote sensing data combinations. The spatial distribution map of Dendrocalamus giganteus in Xinping County was then generated using the optimal combination model. The findings reveal the following: (1) Four key parameters—optimal fitted segmented terrain height, interpolated terrain surface height, absolute mean canopy height, and solar elevation angle—are significantly correlated. (2) The RF model constructed using a combination of ICESat-2/ATLAS, Sentinel-1, and Sentinel-2 data achieved optimal accuracy, with a coefficient of determination (R2) of 0.904, root mean square error (RMSE) of 0.384, mean absolute error (MAE) of 0.319, overall estimation accuracy (P1) of 88.96%, and relative root mean square error (RRMSE) of 11.04%. (3) The accuracy of LAI estimation using a combination of ICESat-2/ATLAS, Sentinel-1, and Sentinel-2 remote sensing data showed slight improvement compared to using either ICESat-2/ATLAS data combined with Sentinel-1 or Sentinel-2 data alone, with a significant enhancement in LAI estimation accuracy compared to using ICESat-2/ATLAS data alone. (4) LAI values in the study area ranged mainly from 2.29 to 2.51, averaging 2.4. Research indicates that employing ICESat-2/ATLAS spaceborne LiDAR data for regional-scale LAI estimation presents clear advantages. Incorporating SAR data and optical imagery and utilizing diverse data types for complementary information significantly enhances the accuracy of LAI estimation, demonstrating the feasibility of LAI inversion with multi-source remote sensing data. This approach offers an innovative framework for utilizing multi-source remote sensing data for regional-scale LAI inversion, demonstrates a methodology for integrating various remote sensing data, and serves as a reference for low-cost high-precision regional-scale LAI estimation. Full article
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18 pages, 7099 KiB  
Article
Variation in Niche and Interspecific Associations across Elevations in Subtropical Forest Communities of the Wuyi Mountains, Southeastern China
by Jintao Hu, Zhaoliang Zheng, Xinyi Wen, Xisheng Hu, Yongming Lin, Jian Li, Jian Ni and Chengzhen Wu
Forests 2024, 15(7), 1256; https://doi.org/10.3390/f15071256 - 19 Jul 2024
Viewed by 137
Abstract
Elucidating changes in the structure and function of plant communities along different elevation ranges will help researchers to analyze the strategies plant communities use in environments and processes influencing niche differentiation. The aims of this paper are to reveal the underlying mechanisms and [...] Read more.
Elucidating changes in the structure and function of plant communities along different elevation ranges will help researchers to analyze the strategies plant communities use in environments and processes influencing niche differentiation. The aims of this paper are to reveal the underlying mechanisms and ecological processes governing the development of subtropical forest ecosystem plant communities. This paper analyzes the forest vegetation of the Wuyi Mountains across the following three elevation ranges: low elevation, mid elevation, and high elevation, spanning from 560 to 2150 m. Twenty and twenty-three dominant tree and shrub layer species, respectively, were identified based on their importance values, and their niches and species associations were further analyzed based on the elevation range. The results showed interspecific associations between tree and shrub species, with the strongest associations observed at mid-elevations. The analysis of niche width and overlap showed that the number of pairs of species with a higher degree of niche overlap decreased with increasing elevation, suggesting that resource use varied at different elevations for both tree and shrub layer species, which may be related to the adaptive capacity of plants at different elevations to the environment and resource use strategies. These findings should contribute to a deeper understanding of the ecological functioning and structural framework of plant communities on Wuyi Mountain. Full article
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15 pages, 2399 KiB  
Article
Range-Wide Assessment of Recent Longleaf Pine (Pinus palustris Mill.) Area and Regeneration Trends
by Kevin M. Potter, Christopher M. Oswalt and James M. Guldin
Forests 2024, 15(7), 1255; https://doi.org/10.3390/f15071255 - 19 Jul 2024
Viewed by 157
Abstract
Longleaf pine (Pinus palustris Mill.) is a conifer historically associated with an open forest ecosystem that extended across much of the coastal plain of the Southeastern United States. It now exists mainly in isolated fragments following the conversion of forests and the [...] Read more.
Longleaf pine (Pinus palustris Mill.) is a conifer historically associated with an open forest ecosystem that extended across much of the coastal plain of the Southeastern United States. It now exists mainly in isolated fragments following the conversion of forests and the long-term disruption of the low-intensity fire regime upon which the species depends. Recent decades have seen efforts to restore longleaf pine forests by government and private landowners. This was reflected in analyses of national forest inventory data during two time periods, ca. 2009–2015 and 2016–2021, that showed increases in the estimated number of longleaf pine trees, the area of the longleaf pine forest type, and the number and area of planted longleaf pine, along with growth in mean plot-level longleaf pine carbon and importance value. At the same time, we found a decrease in the overall forest area containing longleaf pine, manifested across a variety of other forest types. These results point to a dynamic through which forests dominated by longleaf pine are becoming more widespread via restoration, while forests in which the species is a less important component are transitioning to other forest types or land uses. We also detected a decrease over time in the estimated number of longleaf seedlings across most states and forest types and a decline in naturally regenerated longleaf pine. To further assess regeneration trends in longleaf pine, we calculated the estimated proportion of small trees (seedlings and saplings) for the entire species and for seed zone sub-populations. We found a species-wide decrease in the proportion of small trees, from 82.1 percent to 75.1 percent. This reduction was most pronounced along the edges of the species distribution and could indicate less sustainable levels of regeneration in some areas. These results underscore the challenges of facilitating natural regeneration in this important species. Full article
(This article belongs to the Special Issue Longleaf Pine Ecology, Restoration, and Management)
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10 pages, 1653 KiB  
Article
Effects of Forest Bathing on Blood Pressure and Heart Rate in Older Adults in Mexico
by María Guadalupe Garibay-Chávez, Arturo Curiel-Ballesteros, Javier García de Alba-García, Miriam Borja-Arreola, Daniela Moreno-Ramírez and Eliana Santos-Zamora
Forests 2024, 15(7), 1254; https://doi.org/10.3390/f15071254 - 19 Jul 2024
Viewed by 169
Abstract
Currently, in cities in different regions of the world, forest bathing (FB) is considered a practice to promote public health in vulnerable groups, such as the elderly, who have a higher risk of hypertension. This practice has had limited development in Latin American [...] Read more.
Currently, in cities in different regions of the world, forest bathing (FB) is considered a practice to promote public health in vulnerable groups, such as the elderly, who have a higher risk of hypertension. This practice has had limited development in Latin American countries, and therefore, the objective of this study was to evaluate the benefits of forest baths on blood pressure and heart rate in a group of older adults in Guadalajara, Mexico. A program of six sessions was designed, the first to welcome and recognize the natural environment of the urban forest and the other five dedicated to each of the senses (hearing, touch, smell, sight, and taste), using the methodology of the Forest Therapy Hub (FTHub). The type of study was observational (before and after) with a single group, where the participants’ blood pressure and heart rate were evaluated. The results obtained showed significant effects of FB on reduction in high systolic blood pressure and diastolic hypertension before and after FB, with no significance on heart rate. Forest baths can be considered as an alternative strategy to manage the risk of hypertension in older adults, due to their ability to induce relaxation and normalize blood pressure levels. Full article
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19 pages, 8302 KiB  
Article
Evaluating the Impact of Climate Change and Human Activities on the Potential Distribution of Pine Wood Nematode (Bursaphelenchus xylophilus) in China
by Liang Zhang, Ping Wang, Guanglin Xie and Wenkai Wang
Forests 2024, 15(7), 1253; https://doi.org/10.3390/f15071253 - 18 Jul 2024
Viewed by 227
Abstract
Bursaphelenchus xylophilus is a pest that interferes with the health of forests and hinders the development of the forestry industry, and its spread is influenced by changes in abiotic factors and human activities. The potential distribution areas of B. xylophilus in China under [...] Read more.
Bursaphelenchus xylophilus is a pest that interferes with the health of forests and hinders the development of the forestry industry, and its spread is influenced by changes in abiotic factors and human activities. The potential distribution areas of B. xylophilus in China under four shared-economic pathways were predicted using the optimized MaxEnt model (version 3.4.3), combining data from a variety of environmental variables: (1) prediction of natural environmental variables predicted under current climate models; (2) prediction of natural environmental variables + human activities under current climate models; and (3) prediction of natural environmental variables under the future climate models (2050s and 2070s). Meanwhile, whether the niche of B. xylophilus has changed over time is analyzed. The results showed that human activities, precipitation in the driest month, annual precipitation, and elevation had significant effects on the distribution of B. xylophilus. In the current conditions, human activities greatly reduced the survival area of B. xylophilus, and its suitable distribution area was mainly concentrated in the southwestern and central regions of China. Under the influence of climate change in the future, the habitat of B. xylophilus will gradually spread to the northeast. In addition, the ecological niche overlap analysis showed that B. xylophilus in future climate was greater than 0.74. This study provides important information for understanding the ecological adaptation and potential risk of B. xylophilus, which can help guide the decision making of pest control and forest protection. Full article
(This article belongs to the Topic Plant Invasion)
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19 pages, 8480 KiB  
Article
Mapping Characteristics in Vaccinium uliginosum Populations Predicted Using Filtered Machine Learning Modeling
by Yadong Duan, Xin Wei, Ning Wang, Dandan Zang, Wenbo Zhao, Yuchun Yang, Xingdong Wang, Yige Xu, Xiaoyan Zhang and Cheng Liu
Forests 2024, 15(7), 1252; https://doi.org/10.3390/f15071252 - 18 Jul 2024
Viewed by 222
Abstract
Bog bilberry (Vaccinium uliginosum L.) is considered a highly valued non-wood forest product (NWFP) species with edible and medicinal uses in East Asia. It grows in the northeastern forests of China, where stand attributes and structure jointly determine its population characteristics and [...] Read more.
Bog bilberry (Vaccinium uliginosum L.) is considered a highly valued non-wood forest product (NWFP) species with edible and medicinal uses in East Asia. It grows in the northeastern forests of China, where stand attributes and structure jointly determine its population characteristics and individuals’ growth. Mapping the regional distributions of its population characteristics can be beneficial in the management of its natural resources, and this mapping should be predicted using machine learning modeling to obtain accurate results. In this study, a total of 60 stands were randomly chosen and screened to investigate natural bog bilberry populations in the eastern mountains of Heilongjiang and Jilin provinces in northeastern China. Individual height, canopy cover area, and fresh weight all increased in stands at higher latitudes, and shoot height was also higher in the eastern stands. The rootstock grove density showed a polynomial quadratic distribution pattern along increasing topographical gradients, resulting in a minimum density of 0.43–0.52 groves m−2 in stands in the southern part (44.3016° N, 129.4558° E) of Heilongjiang. Multivariate linear regression indicated that the bog bilberry density was depressed by host forest tree species diversity; this was assessed using both the Simpson and Shannon–Wiener indices, which also showed polynomial quadratic distribution patterns (with a modeling minimum of 0.27 and a maximum of 1.21, respectively) in response to the increase in latitude. Structural equation models identified positive contributions of tree diameter at breast height and latitude to shoot height and a negative contribution of longitude to the bog bilberry canopy area. Random forest modeling indicated that dense populations with heavy individuals were distributed in eastern Heilongjiang, and large-canopy individuals were distributed in Mudanjiang and Tonghua. In conclusion, bog bilberry populations showed better attributes in northeastern stands where host forest trees had low species diversity, but the dominant species had strong trunks. Full article
(This article belongs to the Section Wood Science and Forest Products)
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32 pages, 2815 KiB  
Article
Biogeochemical Migration of Some Rare Elements in the “Leaf Debris–Soil” System of the Catenary Landscapes in Tropical Mountainous Forests in Southern Vietnam
by Yaroslav Lebedev, Anna Drygval, Cam Nhung Pham, Roman Gorbunov, Tatiana Gorbunova, Andrei Kuznetsov, Svetlana Kuznetsova, Van Thinh Nguyen and Vladimir Tabunshchik
Forests 2024, 15(7), 1251; https://doi.org/10.3390/f15071251 - 18 Jul 2024
Viewed by 166
Abstract
Expeditionary studies of the functioning of landscapes of mid-mountain monsoon (including fog) forests have been being conducted within the landscape and ecological station in the territory of the Bidoup-Nui Ba National Park and the adjacent Hon Giao since 2018 and are currently underway. [...] Read more.
Expeditionary studies of the functioning of landscapes of mid-mountain monsoon (including fog) forests have been being conducted within the landscape and ecological station in the territory of the Bidoup-Nui Ba National Park and the adjacent Hon Giao since 2018 and are currently underway. One of the research objectives is to clarify the biogeochemical migrations of the material composition of soils in the “leaf debris–soil” system. We have consistently studied natural objects for their material composition as well as the intensity and rate of involvement of chemical elements in physicochemical migration processes in the “leaf debris–soil” system. Our findings indicate an active influx of a select group of examined elements (Se, Pd, Ag, Cd, Sn, Bi), particularly Bi, Pd, Se, and Cd, through the leaf debris and the detachment of aboveground plant organs, warranting their integration into organogenic soil horizons. Subsequently, lateral migration (Pd, Cd, Se) ensues. Slope processes within subordinate landscape facets, in addition to soil moisture and aeration processes, contribute to the subsequent redistribution of elemental volumes introduced into organogenic soil horizons. Full article
(This article belongs to the Special Issue Biogeochemical Cycles in Forests)
14 pages, 1952 KiB  
Article
Trait Assessment of 1122 Populus deltoides Clones: Unveiling Correlations among Growth, Wood Properties, and Disease Susceptibility
by Tianyu Ma and Jing Hou
Forests 2024, 15(7), 1250; https://doi.org/10.3390/f15071250 - 18 Jul 2024
Viewed by 164
Abstract
This study aimed to evaluate the growth, wood properties, disease susceptibility, and sex traits of 1122 Populus deltoides clones to reveal the trait variability and correlations, providing a basis for genetic improvement and breeding. The measurements included the diameter at breast height (DBH), [...] Read more.
This study aimed to evaluate the growth, wood properties, disease susceptibility, and sex traits of 1122 Populus deltoides clones to reveal the trait variability and correlations, providing a basis for genetic improvement and breeding. The measurements included the diameter at breast height (DBH), leaf area, basic wood density (BWD), content of cellulose, hemicellulose, lignin, and disease susceptibility index (DSI). The coefficients of variation ranged 6.91%–41.96%, with the BWD showing the lowest variability. Significant sexual dimorphism was observed, with male clones exhibiting higher DBH and hemicellulose content, and female clones displaying larger leaf areas and greater phenotypic variability. Correlation analysis revealed that the leaf area was positively correlated with the BWD and hemicellulose, and it was negatively correlated with the DBH and lignin; lignin was negatively correlated with cellulose. PCA confirmed these relationships and additionally highlighted a positive correlation between the DSI and DBH. These findings established links between the growth traits and wood properties, enhancing our understanding of trait diversity in P. deltoides and providing insights for breeding strategies to develop high-quality, high-yielding cultivars. Full article
(This article belongs to the Section Wood Science and Forest Products)
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10 pages, 3531 KiB  
Article
Evaluation of the Effectiveness of the Elderly Cognitive and Exercise Forest Therapy Program According to Brain Wave and Autonomic Nervous System Parameters
by Jeong-Woo Seo, Kahye Kim, Seul Gee Kim, Jiyune Yi, Wonsop Shin, Jungmi Choi and Jaeuk U. Kim
Forests 2024, 15(7), 1249; https://doi.org/10.3390/f15071249 - 18 Jul 2024
Viewed by 155
Abstract
The purpose of this study is to more quantitatively identify changes in body function through various bio-signal parameters. (1) Background: Forest therapy is effective in stabilizing cognitive, emotional, cardiovascular, and autonomic nervous systems. In particular, it is necessary to more quantitatively confirm changes [...] Read more.
The purpose of this study is to more quantitatively identify changes in body function through various bio-signal parameters. (1) Background: Forest therapy is effective in stabilizing cognitive, emotional, cardiovascular, and autonomic nervous systems. In particular, it is necessary to more quantitatively confirm changes in body functions through various bio signals. (2) Methods: As a forest therapy program (FTP) for the elderly, it consisted of strength training in the forest, respiratory aerobic exercises, and cognitive function training, and a total of 19 sessions were performed for 12 weeks. The electroencephalography (EEG) and Photoplethysmography (PPG) before and after the program were measured and compared between program participants (FTP group) and non-participants (control group). (3) Results: the FTP group showed increase in the alpha band power in EEG and a decrease in the PRV index, Tad, and Tae after the program compared to the control group; (4) Conclusions: Significant differences occurred in the physiological functioning of the elderly participants after the program. This is a result that can confirm the effectiveness of forest therapy more quantitatively. Forest therapy has a positive effect on mental stress reduction and cardiovascular function. Full article
(This article belongs to the Special Issue Forest Bathing and Smart Devices)
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27 pages, 14689 KiB  
Article
Spatiotemporal Changes in Ecological Quality and Its Response to Forest Landscape Connectivity—A Study from the Perspective of Landscape Structural and Functional Connectivity
by Miaomiao Liu, Guanmin Liang, Ziyi Wu, Xueman Zuo, Xisheng Hu, Sen Lin and Zhilong Wu
Forests 2024, 15(7), 1248; https://doi.org/10.3390/f15071248 - 18 Jul 2024
Viewed by 183
Abstract
Understanding the response of ecological quality (EQ) to forest landscape connectivity is essential to global biodiversity conservation and national ecological security. However, quantitatively measuring the properties and intensities within these relationships from a spatial heterogeneity perspective remains challenging. This study takes the Fujian [...] Read more.
Understanding the response of ecological quality (EQ) to forest landscape connectivity is essential to global biodiversity conservation and national ecological security. However, quantitatively measuring the properties and intensities within these relationships from a spatial heterogeneity perspective remains challenging. This study takes the Fujian Delta region as its case study. The Google Earth Engine platform was employed to compute the remote sensing ecological index (RSEI), the landscape metrics were applied to represent the structural connectivity of the forest landscape, and the minimum cumulative resistance model was adopted to measure the cost distance index representing the functional connectivity of the forest landscape. Then, the spatial correlation and heterogeneity between the EQ and forest landscape connectivity were analyzed based on spatial autocorrelation and geographical weighted regression at three scales (3, 4, and 5 km). The results showed the following: (1) from 2000 to 2020, the overall EQ increased, improving in 37.5% of the region and deteriorating in 13.8% of the region; (2) the forest landscape structural and functional connectivity showed a small decreasing trend from 2000 to 2020, decreasing by 1.3% and 0.9%, respectively; (3) eight forest landscape structural and functional connectivity change modes were detected under the conditions of an improving or degrading EQ based on the change in RSEI and forest landscape structural and functional connectivity; (4) the geographical weighted regression results showed that compared with the forest landscape structural connectivity index, the cost distance index had the highest explanatory power to RSEI in different scales. The effect of forest landscape functional connectivity on EQ is greater than that of structural connectivity. It provides a scientific reference for ecological environmental monitoring and the ecological conservation decision-making of managers. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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15 pages, 3396 KiB  
Article
Variations in the Forest Productivity of Pinus patula Plantations in Tanzania: The Need for an Improved Site Classification System
by Joshua Maguzu, Ulrik Ilstedt, Josiah Zephaniah Katani and Salim S. M. Maliondo
Forests 2024, 15(7), 1247; https://doi.org/10.3390/f15071247 - 18 Jul 2024
Viewed by 252
Abstract
The productivity of forests in sub-Saharan Africa is often summarized into large compartments or site classes. However, the classification of forest productivity levels based on the original site index model in Tanzania and the techniques applied to generate the model did not include [...] Read more.
The productivity of forests in sub-Saharan Africa is often summarized into large compartments or site classes. However, the classification of forest productivity levels based on the original site index model in Tanzania and the techniques applied to generate the model did not include the micro-toposequence variations within compartments. This may create false expectations of wood supply and hinder the estimation of sustainable harvesting processes. This study analyzed variations in forest productivity and the site index in P. patula stands in two forest plantations of Tanzania to assess the applicability and generality of the present site classification system. We used dominant height as a proxy for forest productivity in 48 plots at the Sao Hill forest plantation (SHFP) and 24 plots at the Shume forest plantation (SFP). We stratified the sampling plots in each site class along the soil catena and recorded the elevation, slope, and slope positions (summit, mid, and lower). Our results showed that the site classes did not generally match the previously assigned site classes and the productivity of a given site class varied between the two plantations. We found a consistently higher productivity than that implied by the original site index in SFP, while in SHFP, the productivity was both higher and lower than estimated in different compartments. Both elevations and slope significantly contributed to predicting the productivity variations within site classes. Overall, the results indicate that physiographic factors affect variations in forest productivity within the assigned site classes. We recommend a more comprehensive site productivity assessment that takes into account physiographic variations and hence provides more accurate information for sustainable forest plantation management in Tanzania and in the region at large. Full article
(This article belongs to the Special Issue Forest Growth and Yield under Environmental Changes)
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25 pages, 11649 KiB  
Article
Impact of Conservation in the Futian Mangrove National Nature Reserve on Water Quality in the Last Twenty Years
by Jin Luo, Qiming Huang, Hongsheng Zhang, Yanhua Xu, Xiaofang Zu and Bin Song
Forests 2024, 15(7), 1246; https://doi.org/10.3390/f15071246 - 17 Jul 2024
Viewed by 276
Abstract
Mangroves play a crucial role in improving the water quality of mangrove wetlands. However, current research faces challenges, such as the difficulty in quantifying the impact of mangroves on water quality and the unclear pathways of influence. This study utilized remote sensing imagery [...] Read more.
Mangroves play a crucial role in improving the water quality of mangrove wetlands. However, current research faces challenges, such as the difficulty in quantifying the impact of mangroves on water quality and the unclear pathways of influence. This study utilized remote sensing imagery to investigate the long-term changes in mangrove forests in the Futian Mangrove National Nature Reserve and constructed a water quality index based on water quality data. Finally, structural equation modeling was employed to explore the pathways of influence and quantify the impact effects of mangroves, climate, and water quality. The study findings revealed several key points: (1) The mangrove forests in the Futian Mangrove National Nature Reserve exhibited a trend of expansion towards the ocean during this period. (2) The seasonal and annual characteristics of water quality in Shenzhen Bay indicated a significant improvement in water quality from 2000 to 2020. (3) Mangroves have significant direct and indirect impacts on water quality, which are more pronounced than the effects of climate factors. These findings not only offer insights for the environmental management and conservation of Shenzhen Bay but also provide support for future comprehensive studies on the response relationships between the morphology, species, and physiological characteristics of mangroves and water quality. Full article
(This article belongs to the Special Issue Effect of Mangrove Ecosystems on Coastal Ecology and Climate Change)
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22 pages, 23895 KiB  
Article
Analysis of Spatiotemporal Evolution and Driving Forces of Vegetation from 2001 to 2020: A Case Study of Shandong Province, China
by Dejin Dong, Ziliang Zhao, Hongdi Gao, Yufeng Zhou, Daohong Gong, Huaqiang Du and Yuichiro Fujioka
Forests 2024, 15(7), 1245; https://doi.org/10.3390/f15071245 - 17 Jul 2024
Viewed by 249
Abstract
As global climate change intensifies and human activities escalate, changes in vegetation cover, an important ecological indicator, hold significant implications for ecosystem protection and management. Shandong Province, a critical agricultural and economic zone in China, experiences vegetation changes that crucially affect regional climate [...] Read more.
As global climate change intensifies and human activities escalate, changes in vegetation cover, an important ecological indicator, hold significant implications for ecosystem protection and management. Shandong Province, a critical agricultural and economic zone in China, experiences vegetation changes that crucially affect regional climate regulation and biodiversity conservation. This study employed normalized difference vegetation index (NDVI) data, combined with climatic, topographic, and anthropogenic activity data, utilizing trend analysis methods, partial correlation analysis, and Geodetector to comprehensively analyze the spatiotemporal variations and primary driving factors of vegetation cover in Shandong Province from 2001 to 2020. The findings indicate an overall upward trend in vegetation cover, particularly in areas with concentrated human activities. Climatic factors, such as precipitation and temperature, exhibit a positive correlation with vegetation growth, while land use changes emerge as one of the key drivers influencing vegetation dynamics. Additionally, topography also impacts the spatial distribution of vegetation to a certain extent. This research provides a scientific basis for ecological protection and land management in Shandong Province and similar regions, supporting the formulation of effective vegetation restoration and ecological conservation strategies. Full article
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22 pages, 23929 KiB  
Article
FireYOLO-Lite: Lightweight Forest Fire Detection Network with Wide-Field Multi-Scale Attention Mechanism
by Sha Sheng, Zhengyin Liang, Wenxing Xu, Yong Wang and Jiangdan Su
Forests 2024, 15(7), 1244; https://doi.org/10.3390/f15071244 - 17 Jul 2024
Viewed by 214
Abstract
A lightweight forest fire detection model based on YOLOv8 is proposed in this paper in response to the problems existing in traditional sensors for forest fire detection. The performance of traditional sensors is easily constrained by hardware computing power, and their adaptability in [...] Read more.
A lightweight forest fire detection model based on YOLOv8 is proposed in this paper in response to the problems existing in traditional sensors for forest fire detection. The performance of traditional sensors is easily constrained by hardware computing power, and their adaptability in different environments needs improvement. To balance the accuracy and speed of fire detection, the GhostNetV2 lightweight network is adopted to replace the backbone network for feature extraction of YOLOv8. The Ghost module is utilized to replace traditional convolution operations, conducting feature extraction independently in different dimensional channels, significantly reducing the complexity of the model while maintaining excellent performance. Additionally, an improved CPDCA channel priority attention mechanism is proposed, which extracts spatial features through dilated convolution, thereby reducing computational overhead and enabling the model to focus more on fire targets, achieving more accurate detection. In response to the problem of small targets in fire detection, the Inner IoU loss function is introduced. By adjusting the size of the auxiliary bounding boxes, this function effectively enhances the convergence effect of small target detection, further reducing missed detections, and improving overall detection accuracy. Experimental results indicate that, compared with traditional methods, the algorithm proposed in this paper significantly improves the average precision and FPS of fire detection while maintaining a smaller model size. Through experimental analysis, compared with YOLOv3-tiny, the average precision increased by 5.9% and the frame rate reached 285.3 FPS when the model size was only 4.9 M; compared with Shufflenet, the average precision increased by 2.9%, and the inference speed tripled. Additionally, the algorithm effectively addresses false positives, such as cloud and reflective light, further enhancing the detection of small targets and reducing missed detections. Full article
(This article belongs to the Section Natural Hazards and Risk Management)
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22 pages, 913 KiB  
Review
A Comparative Literature Review of Machine Learning and Image Processing Techniques Used for Scaling and Grading of Wood Logs
by Yohann Jacob Sandvik, Cecilia Marie Futsæther, Kristian Hovde Liland and Oliver Tomic
Forests 2024, 15(7), 1243; https://doi.org/10.3390/f15071243 - 17 Jul 2024
Viewed by 298
Abstract
This literature review assesses the efficacy of image-processing techniques and machine-learning models in computer vision for wood log grading and scaling. Four searches were conducted in four scientific databases, yielding a total of 1288 results, which were narrowed down to 33 relevant studies. [...] Read more.
This literature review assesses the efficacy of image-processing techniques and machine-learning models in computer vision for wood log grading and scaling. Four searches were conducted in four scientific databases, yielding a total of 1288 results, which were narrowed down to 33 relevant studies. The studies were categorized according to their goals, including log end grading, log side grading, individual log scaling, log pile scaling, and log segmentation. The studies were compared based on the input used, choice of model, model performance, and level of autonomy. This review found a preference for images over point cloud representations for logs and an increase in camera use over laser scanners. It identified three primary model types: classical image-processing algorithms, deep learning models, and other machine learning models. However, comparing performance across studies proved challenging due to varying goals and metrics. Deep learning models showed better performance in the log pile scaling and log segmentation goal categories. Cameras were found to have become more popular over time compared to laser scanners, possibly due to stereovision cameras taking over for laser scanners for sampling point cloud datasets. Classical image-processing algorithms were consistently used, deep learning models gained prominence in 2018, and other machine learning models were used in studies published between 2010 and 2018. Full article
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19 pages, 8365 KiB  
Article
Biomass and Carbon Stock Capacity of Robinia pseudoacacia Plantations at Different Densities on the Loess Plateau
by Yawei Hu, Jiongchang Zhao, Yang Li, Peng Tang, Zhou Yang, Jianjun Zhang and Ruoxiu Sun
Forests 2024, 15(7), 1242; https://doi.org/10.3390/f15071242 - 17 Jul 2024
Viewed by 215
Abstract
Forests make an important contribution to the global carbon cycle and climate regulation. Caijiachuan watershed false acacia (Robinia pseudoacacia Linn.) plantation forests have been created for 30 years, but a series of problems have arisen due to the irrationality of the density [...] Read more.
Forests make an important contribution to the global carbon cycle and climate regulation. Caijiachuan watershed false acacia (Robinia pseudoacacia Linn.) plantation forests have been created for 30 years, but a series of problems have arisen due to the irrationality of the density involved at that time. To precisely assess the contribution of R. pseudoacacia plantations with different densities to this cycle, we measured the diameter at breast height (DBH), tree height (H), biomass, and carbon stocks in trees, shrubs, herbs, litter, and soil across different density ranges, denoted as D1 = 900–1400, D2 = 1401–1900, D3 = 1901–2400, D4 = 2401–2900, and D5 = 2901–3400 trees ha−1. In order to achieve the purpose of accurately estimating the biomass, carbon stocks and the contribution rate of each part in different densities of R. pseudoacacia plantations were measured. The results are as follows: (1) Both DBH and H decreased with increasing density, and field surveys were much more difficult and less accurate for H than DBH. Based on the two allometric growth models, it was found that the determination coefficient of the biomass model that incorporated both H and DBH (0.90) closely resembled that of the model using only DBH (0.89), with an error margin of only 0.04%. (2) At the sample scale, stand density significantly affected R. pseudoacacia stem biomass and total biomass. At the individual plant scale, stand density significantly affected R. pseudoacacia organ biomass. Increasing stand densities promoted the accumulation of vegetation biomass within the sample plot but did not improve the growth of individual R. pseudoacacia trees. The stem biomass constituted the majority of the total R. pseudoacacia biomass (58.25%–60.62%); the total R. pseudoacacia biomass represented a significant portion of the vegetation biomass (93.02%–97.37%). (3) The total carbon stock in the sample plots tended to increase with increasing stand density, indicating a positive correlation between density and the carbon stock of the whole plantation forest ecosystem. Hence, in future R. pseudoacacia plantations, appropriate densities should be selected based on specific objectives. For wood utilization, a planting density of 900–1400 trees ha−1 should be controlled. For carbon fixation, an initial planting density of 2900–3400 trees ha−1 should be selected for R. pseudoacacia. This study provides theoretical support for local forest management and how to better sequester carbon. Full article
(This article belongs to the Special Issue Biomass Estimation and Carbon Stocks in Forest Ecosystems—Volume II)
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17 pages, 9721 KiB  
Article
A Spatio-Temporal Analysis of the Frequency of Droughts in Mexico’s Forest Ecosystems
by Leticia Citlaly López-Teloxa and Alejandro Ismael Monterroso-Rivas
Forests 2024, 15(7), 1241; https://doi.org/10.3390/f15071241 - 17 Jul 2024
Viewed by 229
Abstract
Droughts can affect forest ecosystems and lead to soil degradation, biodiversity loss, and desertification. Not all regions of Mexico are affected in the same way, as some areas are naturally more prone to drought due to their geographical location. Therefore, the objective of [...] Read more.
Droughts can affect forest ecosystems and lead to soil degradation, biodiversity loss, and desertification. Not all regions of Mexico are affected in the same way, as some areas are naturally more prone to drought due to their geographical location. Therefore, the objective of this work was to carry out a spatio-temporal analysis of the occurrence of droughts (severe and extreme) in Mexican forest systems, covering the period 2000–2021, and to study the area covered by these events in Mexican forest systems. This analysis was divided into three stages: the classification of land use and vegetation, spatial mapping and the classification of drought intensity, and an analysis of drought frequency and probability in forest systems. The results show that more than 46% of Mexico’s forest area experienced severe and extreme droughts during the 21-year period studied. Broadleaved forests were most affected by severe and extreme droughts, with a frequency of 6 years. The increasing frequency of droughts poses a major challenge to the resilience of forest ecosystems in Mexico, highlighting the need to implement climate change adaptation and forest management measures to protect the country’s biodiversity and natural resources. Full article
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12 pages, 1241 KiB  
Article
Physical and Mechanical Properties of Juvenile Wood of Anadenanthera peregrina (L.) Speg. fromThinning
by Emilly Soares Gomes Silva, Fabricio Gomes Gonçalves, Pedro Gutemberg Alcântara Segundinho, Cleyton Machado Prata Filho, Yonny Martinez Lopez, Izabella Luzia Silva Chaves, Donatian Gustave, Michelângelo Vargas Fassarella and Bruno Miguel Morais Lemos Esteves
Forests 2024, 15(7), 1240; https://doi.org/10.3390/f15071240 - 16 Jul 2024
Viewed by 283
Abstract
Reducing the rotation period through thinning and changing planting spacing can influence the technological properties of wood, with little attention paid to the effects of these variables on the raw material, which limits its processing in the wood sector. This work aimed to [...] Read more.
Reducing the rotation period through thinning and changing planting spacing can influence the technological properties of wood, with little attention paid to the effects of these variables on the raw material, which limits its processing in the wood sector. This work aimed to evaluate the physical and mechanical properties of wood from Anadenanthera peregrina juveniles thinned in three planting spacings (3 m × 3 m, 4 m × 4 m, and 5 m × 5 m). The physical properties in the base-top and pith–shell directions and the mechanical properties of the samples were evaluated. The results indicate better technological properties for wood with larger spacings. The physical properties showed decreasing trends in the base-top direction and increasing trends in the pith-bark direction, with a distinct trend in the degree of collapse. The average basic density of the different planting spacings varied between 0.47 g cm−3 and 0.63 g cm−3. The mechanical properties obtained for the 4 m × 4 m spacing were superior to those of the other spacings. Wood from young A. peregrina is an alternative for industrial processing, as wood from higher planting densities is more suitable for purposes that require resistance and rigidity. Full article
(This article belongs to the Section Wood Science and Forest Products)
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19 pages, 3789 KiB  
Article
Cenostigma pluviosum Tree Stem Growth and Carbon Storage in a Subtropical Urban Environment: A Case Study in Sao Paulo City
by Julia Rodrigues-Leite, Denise Duarte, Astrid Moser-Reischl and Thomas Rötzer
Forests 2024, 15(7), 1239; https://doi.org/10.3390/f15071239 - 16 Jul 2024
Viewed by 313
Abstract
Our aim is to contribute to understanding the role of subtropical trees on carbon storage and CO2 removal in the city of Sao Paulo/Brazil, besides highlighting the surrounding environment implications to sibipiruna trees (Cenostigma pluviosum)’s performance. The case study was [...] Read more.
Our aim is to contribute to understanding the role of subtropical trees on carbon storage and CO2 removal in the city of Sao Paulo/Brazil, besides highlighting the surrounding environment implications to sibipiruna trees (Cenostigma pluviosum)’s performance. The case study was conducted with three trees, one planted on a sidewalk in Pinheiros neighborhood, a highly sealed area, and two in a green area, the Ibirapuera Park. To define the stem basal area growth and its pattern, local measurements were taken over a year and a segmented linear regression model was adjusted. The stem growth dependency on microclimate was tested by a Spearman Correlation. The trees’ active stem growth presented a similar pattern. The soil volumetric water content and soil temperatures were the variables with more impact. The total mean radial stem growth for the IBIRA1 and IBIRA2 trees was 1.2 mm year−1 and 3 mm year−1, while at PIN1 it was 1.3 mm year−1. The total biomass increment in IBIRA1 and IBIRA2 was 4.2 kg C year−1 and 12.8 kg C year−1, while in PIN it was 4.9 kg C year−1 and the removal was 15.3 C year−1, 47.1 kg CO2 year−1 and 17.9 kg CO2 year−1, respectively. The results indicated that the land cover difference implies a significant interference with the promotion of carbon fixation and CO2 removal, demonstrating that planting urban trees in soils with better water storage conditions is more efficient. Full article
(This article belongs to the Special Issue Urban Tree Design and Urban Microclimate—Series II)
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16 pages, 8974 KiB  
Article
Remark: Evaluation of the Habitat and Potential of Taxus chinensis var. mairei in the Jiangnan Hilly Region
by Ruyi Bao, Jiufen Liu, Xiaohuang Liu, Xiaofeng Zhao, Xueqi Xia and Chao Wang
Forests 2024, 15(7), 1238; https://doi.org/10.3390/f15071238 - 16 Jul 2024
Viewed by 230
Abstract
Taxus chinensis var. mairei is an endangered tree species endemic to China; it has important ornamental, timber, and medicinal value. In this work, based on a MaxEnt model, the Jiangnan hilly region was used as the study area, and geographic, climatic, soil, and [...] Read more.
Taxus chinensis var. mairei is an endangered tree species endemic to China; it has important ornamental, timber, and medicinal value. In this work, based on a MaxEnt model, the Jiangnan hilly region was used as the study area, and geographic, climatic, soil, and vegetation data were synthesized to simulate the present area of suitable habitat for T. chinensis; the key environmental factors that constrain its habitat expansion were also explored. Additionally, the potential future distribution of this species under different climate-change scenarios was predicted. The results showed that the six variables making the highest contribution to T. chinensis habitat suitability were the precipitation of the warmest quarter (14.2%), precipitation seasonality variation coefficient (9.1%), aspect (8.2%), altitude (8%), maximum temperature of the warmest month (7.4%), and base saturation (6.6%). Ideal areas have middle elevations, northeastern or northwestern slopes, warmest quarterly precipitation of 508.3–629.2 mm, maximum temperature in the warmest month of 34.6–35.9 °C, and relatively moist soil. The current area of suitable habitat is 6.09 × 105 km2, of which the area of high suitability is 7.56 × 104 km2; this is mainly concentrated in the southwestern part of Hunan, the southwestern part of Jiangxi Province, and the northern part of Zhejiang. Under the SSP2-4.5 climate scenario, the area of high habitat suitability increases; under both the SSP1-2.6 and SSP5-8.5 climate scenarios, the suitable habitat area expands similarly. The direction of the center-of-mass migration of T. chinensis under different climate scenarios is somewhat different from that caused by the uncertainty of human activities and climate warming. This paper clarifies the distribution of suitable habitat and future potential for T. chinensis in the Jiangnan hilly region, providing a theoretical basis for habitat management of this species. Full article
(This article belongs to the Section Forest Ecology and Management)
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14 pages, 6365 KiB  
Article
Spatial Distribution Patterns and Influencing Factors of Dominant Species in Plain Valley Forests of the Irtysh River Basin
by Jihu Song, Zhifang Xue, Bin Yang, Tong Liu, Ye Yuan, Ling Xu and Zidong Zhang
Forests 2024, 15(7), 1237; https://doi.org/10.3390/f15071237 - 16 Jul 2024
Viewed by 259
Abstract
The Irtysh River, which stretches for 633 km, is the second longest river in Xinjiang. The valley forests within its basin are unique forest resources that exhibit crucial ecological functions and form an integral part of China’s “Three North” Shelterbelt Forest Project. However, [...] Read more.
The Irtysh River, which stretches for 633 km, is the second longest river in Xinjiang. The valley forests within its basin are unique forest resources that exhibit crucial ecological functions and form an integral part of China’s “Three North” Shelterbelt Forest Project. However, previous studies mainly focused on individual tributaries or main streams, lacking comprehensive research on the overall river and valley forest resources and their ecological functions. To address this research gap based on comprehensive investigations, this study analyzed the dominant species composition, spatial distribution patterns, and influencing factors of valley forests across various branches of the Irtysh River basin plain. The results revealed the presence of 10 local tree species in the area, with Populus laurifolia, Populus alba, Salix alba, and Betula pendula as the dominant species. However, seedling regeneration was relatively weak. P. laurifolia, P. alba, and S. alba were widely distributed across tributaries and main streams, whereas B. pendula was primarily found in the tributaries. The four dominant species exhibited distinct clustering patterns. The concentration intensity of these dominant species in the main stream of the Irtysh River basin was significantly higher than those in other tributaries, with P. laurifolia showing a lower concentration intensity across the entire basin than the other dominant species. Negative density dependence was the primary biological factor influencing species aggregation intensity, with significant positive effects on P. alba and S. alba and significant negative effects on B. pendula. Among the abiotic factors, elevation had a significant positive effect on the aggregation intensities of P. alba, S. alba, and B. pendula, indicating that these species tend to aggregate more densely at higher elevations. Conversely, slope had a significant negative impact on the aggregation intensities of P. laurifolia, P. alba, and S. alba, suggesting that increasing slope steepness leads to a decrease in the clustering of these species. Similarly, the distance from the river channel had a significant negative effect on the aggregation intensities of S. alba and B. pendula, implying that as the distance from the river increases, the clustering patterns of these species become less pronounced. This study aimed to detail the current state of valley forest resources and their ecological functions, thereby laying a foundation for their effective protection. Full article
(This article belongs to the Section Forest Ecology and Management)
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