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Forests, Volume 14, Issue 8 (August 2023) – 180 articles

Cover Story (view full-size image): This study presents a method of tree species classification using individual tree metrics derived from a three-dimensional point cloud via unmanned aerial vehicle laser scanning (ULS). In this novel approach, we evaluated the metrics of 1045 trees using a generalized linear model (GLM) and random forest (RF) techniques to automatically assign individual trees into either a coniferous or broadleaf group. We evaluated several statistical descriptors, including a novel approach using the Clark–Evans spatial aggregation index (CE), which indicates the level of clustering in point clouds. A comparison of classifiers that included and excluded the CE indicator values demonstrated their importance for improved classification of the individual tree point clouds. The overall accuracy when including the CE index was 94.8% using a GLM approach and 95.1% using an RF approach. View this paper
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15 pages, 7789 KiB  
Article
Identification and Characterization of the AREB/ABF/ABI5 Gene Family in Sandalwood (Santalum album L.) and Its Potential Role in Drought Stress and ABA Treatment
by Xiaojing Liu, Renwu Cheng, Yu Chen, Shengkun Wang, Fangcuo Qin, Dongli Wang, Yunshan Liu, Lipan Hu and Sen Meng
Forests 2023, 14(8), 1691; https://doi.org/10.3390/f14081691 - 21 Aug 2023
Viewed by 1185
Abstract
AREB/ABF/ABI5 (ABA-responsive element-binding protein/ABRE binding factors and ABA INSENSITIVE 5) transcription factors are involved in regulating the expression of ABA (abscisic acid)-related genes and improving plant adaptability to environmental stress. To explore the influence of AREB/ABF transcription factors on santalol synthesis, we conducted [...] Read more.
AREB/ABF/ABI5 (ABA-responsive element-binding protein/ABRE binding factors and ABA INSENSITIVE 5) transcription factors are involved in regulating the expression of ABA (abscisic acid)-related genes and improving plant adaptability to environmental stress. To explore the influence of AREB/ABF transcription factors on santalol synthesis, we conducted a genome-wide analysis of the AREB gene family in sandalwood, identified 10 SaAREB genes, and divided them into five subfamilies. We found that all SaAREB genes encoded unstable hydrophilic proteins and the subcellular localization prediction of SaAREBs was that they are located in the nucleus. AREB/ABF genes belong to the bZIP-A subfamily and we found that the 10 AREB proteins all contained bZIP (basic region leucine zipper) and four potential phosphorylation sites (RXXS/T). According to the collinearity analysis results, four of the SaAREB genes were involved in two fragment duplication events. Through qRT-PCR (real-time fluorescence quantitative PCR), we explored the expression profile of SaAREB in different tissues; the effects of ABA treatment and drought treatment on AREB transcription factors were predicted. From the expression of different tissues, we found that SaAREB1 not only responded to prolonged drought but also was highly expressed in stems. Moreover, SaAREB3, SaAREB7, and SaAREB8 specifically respond to ABA treatment. Based on RNA-seq (RNA sequencing) data, we found that SaAREB6 and SaAREB8 were highly expressed in the sapwood and transition regions. Regarding SaCYP736A167, as a key gene in santalol synthesis, its promoter contains the most ABRE cis-reactive elements. These results provide a basis for further analysis of the role of the Santalum album L. (S. album) ABRE/ABF/ABI5 genes in the formation of santalols. Full article
(This article belongs to the Special Issue Abiotic Stress in Tree Species)
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17 pages, 4239 KiB  
Article
Response of the Radial Growth of Woody Plants in the West Siberian Plain and Adjacent Mountainous Territories to the Characteristics of the Snow Cover
by Nikolay I. Bykov, Anna A. Shigimaga and Natalia V. Rygalova
Forests 2023, 14(8), 1690; https://doi.org/10.3390/f14081690 - 21 Aug 2023
Viewed by 752
Abstract
The dependence of the width of annual rings of woody plants on the characteristics of the snow cover is analyzed in various natural zones of the West Siberian Plain and adjacent mountainous areas: the maximum depth and water reserve for the entire winter [...] Read more.
The dependence of the width of annual rings of woody plants on the characteristics of the snow cover is analyzed in various natural zones of the West Siberian Plain and adjacent mountainous areas: the maximum depth and water reserve for the entire winter period and for individual months, the dates of disappearing, establishment, and duration of the occurrence of a stable snow cover. It has been shown that the role of the depth and water content of snow cover for the radial growth of trees is differentiated by geographical location. On the plain, it intensifies in the forest-tundra and dry steppe. The response of radial growth to snow cover in the upper and lower parts of the forest belt is often the opposite. Dates of establishment of stable snow cover are more important for tree growth compared to dates of disappearance. Dates of disappearance of stable snow cover are more significant in the southern regions than in the northern ones. The value of the duration of the period with stable snow cover for tree growth is higher in the southern regions. Full article
(This article belongs to the Special Issue Climate and Tree Growth Response: Advances in Plant Sciences)
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27 pages, 57145 KiB  
Article
Identification of Bird Habitat Restoration Priorities in a Central Area of a Megacity
by Yuncai Wang, Xinghao Lu, Ruojing Wang, Yifei Jia and Junda Huang
Forests 2023, 14(8), 1689; https://doi.org/10.3390/f14081689 - 21 Aug 2023
Viewed by 1251
Abstract
Rapid global urbanization has caused habitat degradation and fragmentation, resulting in biodiversity loss and the homogenization of urban species. Birds play a crucial role as biodiversity indicators in urban environments, providing multiple ecosystem services and demonstrating sensitivity to changes in habitat. However, construction [...] Read more.
Rapid global urbanization has caused habitat degradation and fragmentation, resulting in biodiversity loss and the homogenization of urban species. Birds play a crucial role as biodiversity indicators in urban environments, providing multiple ecosystem services and demonstrating sensitivity to changes in habitat. However, construction activities often disrupt urban bird habitats, leading to a decline in habitat quality. This paper proposes a framework for prioritizing habitat restoration by pinpointing bird hotspots that demand attention and considering the matching relationship between bird richness and habitat quality. Shanghai represents a typical example of the high-density megacities in China, posing a significant challenge for biodiversity conservation efforts. Utilizing the random forest (RF) model, bird richness patterns in central Shanghai were mapped, and bird hotspots were identified by calculating local spatial autocorrelation indices. From this, the habitat quality of hotspot areas was evaluated, and the restoration priority of bird habitats was determined by matching bird richness with habitat quality through z-score standardization. The results were as follows: (1) Outer-ring green spaces, large urban parks, and green areas along coasts or rivers were found to be the most important habitats for bird richness. Notably, forests emerged as a crucial habitat, with approximately 50.68% of the forested areas identified as hotspots. (2) Four habitat restoration types were identified. The high-bird-richness–low-habitat-quality area (HBR-LHQ), mainly consisting of grassland and urban construction land, was identified as a key priority for restoration due to its vulnerability to human activities. (3) The Landscape Shannon’s Diversity Index (SHDI) and Normalized Difference Vegetation Index (NDVI) are considered the most significant factors influencing the bird distribution. Our findings provide a scientifically effective framework for identifying habitat restoration priorities in high-density urban areas. Full article
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15 pages, 2727 KiB  
Article
Comparison of Machine Learning Methods for Estimating Leaf Area Index and Aboveground Biomass of Cinnamomum camphora Based on UAV Multispectral Remote Sensing Data
by Qian Wang, Xianghui Lu, Haina Zhang, Baocheng Yang, Rongxin Gong, Jie Zhang, Zhinong Jin, Rongxiu Xie, Jinwen Xia and Jianmin Zhao
Forests 2023, 14(8), 1688; https://doi.org/10.3390/f14081688 - 21 Aug 2023
Cited by 3 | Viewed by 1298
Abstract
UAV multispectral technology is used to obtain leaf area index (LAI) and aboveground biomass (AGB) information on Cinnamomum camphora (C. camphora) and to diagnose the growth condition of Cinnamomum camphora dwarf forests in a timely and rapid manner, which helps improve [...] Read more.
UAV multispectral technology is used to obtain leaf area index (LAI) and aboveground biomass (AGB) information on Cinnamomum camphora (C. camphora) and to diagnose the growth condition of Cinnamomum camphora dwarf forests in a timely and rapid manner, which helps improve the precision management of Cinnamomum camphora dwarf forests. Multispectral remote sensing images provide large-area plant spectral information, which can provide a detailed quantitative assessment of LAI, AGB and other plant physicochemical parameters. They are very effective tools for assessing and analyzing plant health. In this study, the Cinnamomum camphora dwarf forest in the red soil area of south China is taken as the research object. Remote sensing images of Cinnamomum camphora dwarf forest canopy are obtained by the multispectral camera of an unmanned aerial vehicle (UAV). Extreme gradient boosting (XGBoost), gradient boosting decision tree (GBDT), random forest (RF), radial basis function neural network (RBFNN) and support vector regression (SVR) algorithms are used to study the correlation and estimation accuracy between the original band reflectance, spectral indices and LAI and AGB of Cinnamomum camphora. The results of this study showed the following: (1) The accuracy of model estimation based on RF is significantly different for different model inputs, while the other four models have small differences. (2) The accuracy of the XGBoost-based LAI model was the highest; with original band reflectance as the model input, the R2 of the model test set was 0.862, and the RMSE was 0.390. (3) The accuracy of the XGBoost-based AGB model was the highest; with spectral indices as the model input, the R2 of the model test set was 0.929, and the RMSE was 587.746 kg·hm−2. (4) The XGBoost model was the best model for the LAI and AGB estimation of Cinnamomum camphora, which was followed by GBDT, RF, RFNN, and SVR. This research result can provide a theoretical basis for monitoring a Cinnamomum camphora dwarf forest based on UAV multispectral technology and a reference for rapidly estimating Cinnamomum camphora growth parameters. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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14 pages, 4552 KiB  
Article
Habitat Suitability of Pine Wilt Disease in Northeast China under Climate Change Scenario
by Jue Wang, Jifeng Deng, Wenfeng Yan and Yanan Zheng
Forests 2023, 14(8), 1687; https://doi.org/10.3390/f14081687 - 21 Aug 2023
Cited by 3 | Viewed by 1105
Abstract
Pine wilt disease (PWD), caused by Bursaphelenchus xylophilus, is one of the most severe forest diseases worldwide. PWD causes devastating disasters to Chinese pine trees, seriously threatening forestry production and the forest ecological environment, and causes economic losses of over ten billion [...] Read more.
Pine wilt disease (PWD), caused by Bursaphelenchus xylophilus, is one of the most severe forest diseases worldwide. PWD causes devastating disasters to Chinese pine trees, seriously threatening forestry production and the forest ecological environment, and causes economic losses of over ten billion yuan per year to China. Previous studies have shown that the spread of PWD is closely related to climate factors. Today, PWD is spreading rapidly owing to abnormal climate changes. In order to provide a reference for controlling the spread of PWD in China, in this study, we accurately assessed the risk of the continued spread of PWD in Northeast China; a correlative species distribution model (MaxEnt) (RM = 1, AUC = 0.9904) was used to evaluate China’s climate suitability for PWD. The effects of climate factors on the spread of PWD in Northeast China were studied using Liaoning Province as an example by analyzing the relationship between the changes in average precipitation, average temperature, average relative humidity, average vapor pressure deficit, average wind speed, average sunshine duration and the area of the PWD epidemic over the past five years. These results suggest that with the change in climate, the areas suitable for PWD have expanded, and certain previously unsuitable areas for its distribution have become suitable. Temperature and precipitation were found to play key roles in the occurrence and damage of PWD, and hot and arid conditions favored the spread of PWD. It is recommended that for areas within the suitable range of PWD but not yet epidemic areas, quarantine should be strengthened to prevent the further spread of PWD. In addition, special attention should be paid to epidemic areas with high temperatures and arid while the monitoring of PWD should be strengthened to achieve the early detection and timely treatment of infected epidemic trees. Our results indicate that PWD undoubtedly poses a major threat to Northeast Chinese pine species if climate change proceeds as projected. In the future, more attention should be paid to monitoring the northward spread of PWD, and further studies should consider meteorological data forecasts, which could facilitate timely control measures. Full article
(This article belongs to the Special Issue Global Biogeography and Invasion Risk of Forest Pathogens)
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18 pages, 4344 KiB  
Article
Effects of Myo-Inositol on NaCl Stress in Tamarix ramosissima: Insights from Transcriptomics and Metabolomics
by Haijia Li, Yunlong Fan, Huanchao Zhang and Yahui Chen
Forests 2023, 14(8), 1686; https://doi.org/10.3390/f14081686 - 21 Aug 2023
Cited by 1 | Viewed by 998
Abstract
NaCl stress adversely affects plant growth. Tamarix ramosissima Ledeb (T. ramosissima), a halophyte, thrives in saline-alkali areas. Myo-inositol, a lipid-soluble compound, is crucial for stress response, but its role in mitigating NaCl damage remains underexplored. We analyzed transcriptome sequencing and [...] Read more.
NaCl stress adversely affects plant growth. Tamarix ramosissima Ledeb (T. ramosissima), a halophyte, thrives in saline-alkali areas. Myo-inositol, a lipid-soluble compound, is crucial for stress response, but its role in mitigating NaCl damage remains underexplored. We analyzed transcriptome sequencing and metabolites in T. ramosissima roots under NaCl stress at various intervals (0 h, 48 h, and 168 h). We identified ten Myo-inositol oxygenase-related genes. Nine of these genes, linked to metabolic pathways involving Myo-inositol, showed differential expression. Myo-inositol accumulation increased over time, suggesting its role as an osmotic regulator and reactive oxygen species (ROS) scavenger. This accumulation likely shields T. ramosissima from NaCl-induced osmotic and oxidative damage. Notably, Unigene0002140 and Unigene0095980, associated with Myo-inositol oxygenase, appear to regulate Myo-inositol accumulation and correlate significantly with its levels. We hypothesize they are key genes in controlling Myo-inositol levels, warranting further study. This research illuminates the role of Myo-inositol oxygenase-related genes in T. ramosissima roots combating NaCl stress, offering insights for selecting salt-tolerant tree species. Full article
(This article belongs to the Section Genetics and Molecular Biology)
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12 pages, 2537 KiB  
Article
Ecological Stoichiometry of N and P across a Chronosequence of Chinese Fir Plantation Forests
by Juan Cao, Wende Yan, Taimoor Hassan Farooq, Xiaoyong Chen, Jun Wang, Chenglin Yuan, Yaqin Qi and Khalid Ali Khan
Forests 2023, 14(8), 1685; https://doi.org/10.3390/f14081685 - 21 Aug 2023
Cited by 2 | Viewed by 903
Abstract
Ecological stoichiometry is crucial in understanding nutrient dynamics and its impact on plant growth and development at various ecological scales. Among the different nutrients, nitrogen (N) and phosphorus (P) have been widely recognized as key elements regulating substance transport, energy utilization, and ecosystem [...] Read more.
Ecological stoichiometry is crucial in understanding nutrient dynamics and its impact on plant growth and development at various ecological scales. Among the different nutrients, nitrogen (N) and phosphorus (P) have been widely recognized as key elements regulating substance transport, energy utilization, and ecosystem conversion. The N:P ratio in plants serves as a sensitive indicator of ecological processes, reflecting the availability and balance of these nutrients. Therefore, studying the ecological stoichiometry of N and P is essential for accurately assessing soil fertility and site productivity, particularly in forest ecosystems with low-fertility soils. In this study conducted in Huitong, Hunan province, southern China, the contents of N and P, as well as the N:P ratios, were investigated in plant-soil systems across four different aged stands of Chinese fir forests (3-, 8-, 18-, and 26-year-old stands). The results revealed varying concentrations of N and P in soils and foliage across the different plantations. Soil N concentrations increased by approximately 4%, 30%, and 22% in 8-, 18-, and 26-year-old plantations compared to the 3-year-old plantation. Soil P concentration was significantly higher in 8-, 18-, and 26-year-old plantations compared to the 3-year-old plantation. The average soil N:P ratio followed the order of 3-year-old plantation > 18-year-old plantation > 26-year-old plantation > 8-year-old plantation. Regarding foliage, both N and P contents exhibited a similar pattern across the different aged leaves, with current-year-old leaves having higher concentrations than 1-year-old, 2-year-old, and 3-year-old leaves in all four Chinese fir plantations. The study further established relationships between soil and foliage nutrient ratios. Soil N:P ratio was positively correlated with soil N content but negatively associated with soil P content. The foliage N:P ratio also showed a significant negative correlation between leaf N and foliage P content. These findings suggest that soil nutrient conditions improved with the aging of Chinese fir plantations, mainly due to increased inputs of above- and below-ground litter. Overall, this study provides valuable insights into the ecological stoichiometry of N and P in Chinese fir plantations, offering a scientific basis for sustainable forest management practices in southern China. Full article
(This article belongs to the Special Issue Soil Biogeochemical Cycling of Nutrients in Forest)
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16 pages, 3034 KiB  
Article
The Construction of a High-Density Genetic Map for the Interspecific Cross of Castanea mollissima × C. henryi and the Identification of QTLs for Leaf Traits
by Xibing Jiang, Yanpeng Wang, Junsheng Lai, Jian Wu, Conglian Wu, Weiyun Hu, Xiaolong Wu and Bangchu Gong
Forests 2023, 14(8), 1684; https://doi.org/10.3390/f14081684 - 20 Aug 2023
Viewed by 922
Abstract
Chinese chestnut is an economically and ecologically valuable tree species that is extensively cultivated in China. Leaf traits play a vital role in the photosynthetic capacity, chestnut yield, and quality, making them important breeding objectives. However, there has been limited research on constructing [...] Read more.
Chinese chestnut is an economically and ecologically valuable tree species that is extensively cultivated in China. Leaf traits play a vital role in the photosynthetic capacity, chestnut yield, and quality, making them important breeding objectives. However, there has been limited research on constructing high-density linkage maps of Chinese chestnut and conducting quantitative trait loci (QTL) analyses for these leaf traits. This knowledge gap has hindered the progress of selection in Chinese chestnut breeding. In this study, we selected a well-established interspecific F1 population, consisting of Castanea mollissima ‘Kuili’ × C. henryi ‘YLZ1’, to construct comprehensive genetic maps for chestnut. Through the use of a genotyping-by-sequencing (GBS) technique, we successfully created a high-density linkage map based on single-nucleotide polymorphisms (SNPs) from the F1 cross. The results showed that 4578 SNP markers were identified in the genetic linkage map, and the total length was 1812.46 cM, which was distributed throughout 12 linkage groups (LGs) with an average marker distance of 0.4 cM. Furthermore, we identified a total of 71 QTLs associated with nine chestnut leaf traits: chlorophyll b content (chlb), stomatal conductance (Gs), leaf area (LA), leaf dry weight (LDW), leaf fresh weight (LFW), leaf length (LL), leaf width (LW), petiole length (PL), and specific leaf weight (SLW). These QTLs were identified based on phenotypic data collected from 2017 to 2018. Notably, among the 71 QTLs, 29 major QTLs were found to control leaf area (LA), leaf dry weight (LDW), and leaf width (LW). The high-density genetic mapping and QTL identification related to leaf traits in this study will greatly facilitate marker-assisted selection (MAS) in chestnut breeding programs. Full article
(This article belongs to the Special Issue Functional Genomics of Forest Trees)
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15 pages, 4123 KiB  
Article
Leaf Plasticity of the Subtropical Evergreen Tree Phoebe bournei Increases with Ontogeny in Response to Sun and Shade
by Xin-Bei Li, Cheng-Cheng Liu, Jia-Xin Chen, Meng-Meng Zhang, Jun-Hong Zhang, Zai-Kang Tong and Qi Yang
Forests 2023, 14(8), 1683; https://doi.org/10.3390/f14081683 - 20 Aug 2023
Cited by 2 | Viewed by 795
Abstract
Variation in shade tolerance is a primary mechanism driving succession in subtropical forests. However, little attention has been given to ontogenetic variation in light tolerance of late succession tree species such as Phoebe bournei. To investigate the differences in adaptive strategies between [...] Read more.
Variation in shade tolerance is a primary mechanism driving succession in subtropical forests. However, little attention has been given to ontogenetic variation in light tolerance of late succession tree species such as Phoebe bournei. To investigate the differences in adaptive strategies between seedlings and saplings in response to sun and shade, we systematically studied the physiological and morphological leaf plasticity of P. bournei and how these variables are influenced by ontogeny. This study provided experimental evidence that leaf plasticity increases with the ontogeny of juvenile P. bournei adapting to the changing light resources. Investment in leaf construction increased with age and light resources in the evergreen P. bournei, as shown by leaf mass per unit area (LMA). Six-month-old seedlings lacked the adjustment of stomatal conductance (gs) and stomatal density responding to sun and shade. For seedlings, maintaining high gs under sun conditions increased stress risk instead of carbon gain. However, the leaves of 2-year-old saplings accumulated more soluble sugars and showed lower stomatal conductance and higher stomatal density under the sun than under shade conditions. The nonphotochemical quenching of sun leaves increased with plant age, indicating that the photoprotective capacity was enhanced with ontogeny. The leaf plasticity increasing along the ontogeny of juvenile P. bournei may contribute to the adaptation from shade to sun. Our study provides new insights into understanding the influence of ontogeny on shade responses of late succession trees in subtropical forests. Full article
(This article belongs to the Special Issue Adaptive Mechanisms of Tree Seedlings to Adapt to Stress)
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22 pages, 21504 KiB  
Article
Comparing the Impact of Urban Park Landscape Design Parameters on the Thermal Environment of Surrounding Low-Rise and High-Rise Neighborhoods
by Sihan Xue, Liang Yuan, Kun Wang, Jingxian Wang and Yuanfeng Pei
Forests 2023, 14(8), 1682; https://doi.org/10.3390/f14081682 - 19 Aug 2023
Cited by 2 | Viewed by 1116
Abstract
Scientific and reasonable planning of urban forests is crucial to mitigate the UHI effect and create a comfortable local climate. This study focused on maximizing the synergistic effect of landscape design parameters (i.e., Landscape Shape Index (LSI), Percentage of Green Area (PGA), Park [...] Read more.
Scientific and reasonable planning of urban forests is crucial to mitigate the UHI effect and create a comfortable local climate. This study focused on maximizing the synergistic effect of landscape design parameters (i.e., Landscape Shape Index (LSI), Percentage of Green Area (PGA), Park Area (PA), and Percentage of Water Area (PWA)) through orthogonal experimental design and numerical simulation to improve the regulation of the thermal environment of urban parks in the surrounding blocks. For the neighborhood of low-rise buildings, the influence of PGA was the most significant in the morning with a contribution rate of 50.43%, while PWA was the most influential during midday and evening, with contribution rates of 73.02% and 52.30%, respectively. In contrast, PA was the most influential in the morning with a contribution rate of 62.11% for the high-rise building neighborhood, while the impact of PWA was the most significant in the midday with a contribution rate of 43.99%. In addition, the contribution of PA and PWA played vital roles at night. This study proposed combinations of landscape design parameters for urban parks that met the requirements of two types of neighborhoods, which would help guide the planning and construction of urban forests. Full article
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15 pages, 4156 KiB  
Article
The Broken Chloroplast Gene Clusters in Gymnosperms Exhibit Elevated Substitution Rates
by Jingyao Ping, Xiaona Zhong, Ting Wang and Yingjuan Su
Forests 2023, 14(8), 1681; https://doi.org/10.3390/f14081681 - 19 Aug 2023
Cited by 1 | Viewed by 919
Abstract
Plant chloroplast (cp) gene clusters consist of genes arranged closely together on the cp genome. These genes are organized in operon structures and participate in cotranscription, typically exhibiting conservation. Broken gene clusters have been observed in gymnosperms. In order to investigate whether the [...] Read more.
Plant chloroplast (cp) gene clusters consist of genes arranged closely together on the cp genome. These genes are organized in operon structures and participate in cotranscription, typically exhibiting conservation. Broken gene clusters have been observed in gymnosperms. In order to investigate whether the substitution rates and selection pressure of associated genes are affected following the disruption of gene clusters, the cp genomes of 80 species (78 gymnosperms and 2 outgroups) were analyzed. A phylogenetic analysis was conducted using 58 shared genes to examine the evolutionary rates and selection pressure of genes associated with gene clusters and protein-coding genes in Sciadopitys verticillata. The results demonstrate that S. verticillata exhibited the highest number of rearrangements compared to the Cycas revoluta genome. Four gene clusters (rps2, psbB, rpoB, and petL clusters) in S. verticillata were disrupted, while rps2 in Callitris rhomboidea experienced disruption. Significantly increased evolutionary rates were observed in 12 out of 18 gene cluster-related genes in S. verticillata. Following disruption, S. verticillata and C. rhomboidea exhibited an increase in gene cluster-related genes, particularly rps2, and higher selection pressure on both rps2 and atpA genes compared to other species. Furthermore, among the 58 genes shared by S. verticillata, the evolutionary rates of 36 genes increased, and the selection pressure on 13 genes exceeded that of other species. These results indicate an increased substitution rate of gene clusters in S. verticillata and C. rhomboidea. The large-scale rearrangement and elevated substitution rates of the cp genome in S. verticillata were revealed. This study sheds light on the heterogeneity of cp genome evolution in gymnosperms. Full article
(This article belongs to the Section Genetics and Molecular Biology)
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12 pages, 1687 KiB  
Article
Physiological Response to Low Temperature of Four Genotypes of Cyclocarya paliurus and Their Preliminary Evaluation to Cold Resistance
by Zanpei Zhang, Yueying Gu, Qianxing Mao and Ji Wang
Forests 2023, 14(8), 1680; https://doi.org/10.3390/f14081680 - 19 Aug 2023
Cited by 1 | Viewed by 1297
Abstract
Cyclocarya paliurus is a versatile tree species with immense potential for development, as it combines edible, medicinal, and ornamental functions. Low temperature is one of the important abiotic factors that affect plant survival and flourishing but their response mechanism to low temperature is [...] Read more.
Cyclocarya paliurus is a versatile tree species with immense potential for development, as it combines edible, medicinal, and ornamental functions. Low temperature is one of the important abiotic factors that affect plant survival and flourishing but their response mechanism to low temperature is not yet clear. In this study, we utilized annual shoots of four genotypes of C. paliurus, namely T2, W10, M31 and S12, as materials. The physiological responses of annual shoots of C. paliurus to low temperature stress were elaborated by determining and comparing indicators related to cold resistance, such as relative electric conductivity, semi-lethal low temperature, malondialdehyde, soluble sugar, soluble protein, proline, superoxide dismutase and peroxidase. The contents of malondialdehyde, proline, soluble protein and peroxidase activities were not only correlated with the treatment temperature but also related to the genotypes. Osmotic substance (soluble sugar, soluble protein and proline) contents and antioxidant enzyme activities (peroxidase and superoxide dismutase) of the four genotypes showed a trend of increasing and then decreasing with the five decreasing temperatures. Furthermore, a comprehensive evaluation of cold resistance was performed by using a combination of principal component analysis and membership function, with the cold resistance ranked as W10 > M31 > S12 > T2. Results from this study would provide some references for extending the plantation areas. Full article
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17 pages, 16812 KiB  
Article
Remote Sensing Identification and the Spatiotemporal Variation of Drought Characteristics in Inner Mongolia, China
by Xiaomin Liu, Sinan Wang and Yingjie Wu
Forests 2023, 14(8), 1679; https://doi.org/10.3390/f14081679 - 18 Aug 2023
Viewed by 966
Abstract
In the context of global warming, timely and accurate drought monitoring is of great importance to ensure regional ecological security and guide agricultural production. This study established the Drought Severity Index (DSI), based on the potential evapotranspiration (PET), evapotranspiration (ET) and normalized difference [...] Read more.
In the context of global warming, timely and accurate drought monitoring is of great importance to ensure regional ecological security and guide agricultural production. This study established the Drought Severity Index (DSI), based on the potential evapotranspiration (PET), evapotranspiration (ET) and normalized difference vegetation index (NDVI) data from 2001 to 2020, to compensate for the low accuracy of drought spatial and temporal evolution due to the uneven distribution of stations. The DSI index was established to reveal the spatial and temporal variation of droughts in Inner Mongolia in the past 20 years, using trend analysis, gravity shift and geographic probes, and to explore the influence of different factors on the DSI. The results were as follows. (1) The results showed that the spatial distribution of DSI in Inner Mongolia during 2001–2020 had strong spatial heterogeneity, and generally showed distribution characteristics of drought in the west and wet in the east. In addition, the changes in DSI all exhibited a rising tendency, with the highest tendency in deciduous broadleaf forests (DBF) and the lowest tendency in grassland (GRA). (2) The center of gravity of wet, normal and arid areas showed a migration trend from northeast to southwest, with migration distances of 209 km, 462 km and 826 km, respectively. (3) The four combinations of temperature and elevation, temperature and slope, temperature and land use, and temperature and rainfall contributed the most. The results obtained in this study are important for the scheduling of ecological early warnings and drought prevention and control. Full article
(This article belongs to the Special Issue Global Change and Forest Plant Community Dynamics)
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15 pages, 6413 KiB  
Article
Variations in Microbial Residue and Its Contribution to SOC between Organic and Mineral Soil Layers along an Altitude Gradient in the Wuyi Mountains
by Yiming Sun, Xunlong Chen, Anna Zhong, Shijie Guo and Houxi Zhang
Forests 2023, 14(8), 1678; https://doi.org/10.3390/f14081678 - 18 Aug 2023
Viewed by 942
Abstract
Microbes are crucial components of soil, and their residue carbon plays a significant role in the formation and stabilization of soil carbon pools. However, current research on microbial residue carbon has predominantly focused on surface soils, with limited studies on deep soils. The [...] Read more.
Microbes are crucial components of soil, and their residue carbon plays a significant role in the formation and stabilization of soil carbon pools. However, current research on microbial residue carbon has predominantly focused on surface soils, with limited studies on deep soils. The patterns of variation along soil profiles and their controlling factors remain unclear. Therefore, this study aimed to investigate the soils from different elevations in the Wuyi Mountains, specifically focusing on the organic layers (0–10 cm) and mineral layers (30–40 cm). Amino sugars were utilized as biomarkers for the microbial residue, and the RDA (redundancy analysis) method was employed to analyze the patterns of microbial residue carbon in different soil layers and to identify the factors that control them. The results indicate that there are significant differences in the microbial residue carbon content and its contribution to soil organic carbon (SOC) between the different soil layers. Specifically, between the organic layer and the mineral layer, the microbial residue carbon content exhibited an increasing trend, whereas its contribution to SOC decreased. This finding suggests that soil layer type has a notable impact on microbial residue carbon content and its contribution to SOC. Moreover, fungal residue carbon content was found to be higher than bacterial residue carbon content in both soil layers. However, the ratio of fungal residue carbon to bacterial residue carbon gradually decreased between the organic layer and the mineral layer. This implies that although fungal residue carbon remains dominant, the contribution of bacterial residue carbon to the soil carbon pool increases as the soil transitions to the mineral layer. The total soil carbon content, elevation, and C/N ratio exhibited positive correlations with fungal and bacterial residue carbon, indicating their significant roles in the accumulation of microbial residue carbon in soils. Notably, elevation emerged as a key regulating factor in the accumulation of microbial residue carbon, explaining 85.8% and 67.9% of the variations observed in the organic layer and the mineral layer respectively. These research findings contribute to a better understanding of the soil carbon cycling process and its mechanisms, providing a scientific basis for developing strategies to enhance soil carbon sequestration by manipulating micro-organisms. Full article
(This article belongs to the Special Issue Adaptive Mechanisms of Tree Seedlings to Adapt to Stress)
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10 pages, 1898 KiB  
Article
A Comparative Study of Methods Recording Beekeeping Flora
by Vasilios Liolios, Dimitrios Kanelis, Maria-Anna Rodopoulou and Chrysoula Tananaki
Forests 2023, 14(8), 1677; https://doi.org/10.3390/f14081677 - 18 Aug 2023
Viewed by 685
Abstract
The knowledge of beekeeping flora of an area and of each plant’s provision is crucial for beekeepers to plan their hive transfers when practicing nomadic beekeeping. Thus, in the present study, we evaluated the use of pollen traps as a means of identifying [...] Read more.
The knowledge of beekeeping flora of an area and of each plant’s provision is crucial for beekeepers to plan their hive transfers when practicing nomadic beekeeping. Thus, in the present study, we evaluated the use of pollen traps as a means of identifying beekeeping plants in target areas, assessing their pollen percentage contributions and estimating their flowering seasons. The results were compared with the classical field observation method, widely used for flora recording. In total, 98.8% of the plants were recognized by using pollen traps and 89.4% from observations in the field, while for 73% there was found an agreement between population size (Wittig Scale) and Pollen Contribution Scale (PCS). The results showed that pollen traps can be helpful tools not only for defining the presence or absence of a beekeeping plant, but also for providing important information regarding the population size of a taxon of major beekeeping importance in the area surrounding the apiary. Finally, the estimation of the flowering season and its maximum point can be accurately predicted by using pollen traps on plants of beekeeping interest. Full article
(This article belongs to the Section Forest Biodiversity)
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17 pages, 1538 KiB  
Article
Leisure Involvement, Leisure Benefits, and Subjective Well-Being of Bicycle Riders in an Urban Forest Park: The Moderation of Age
by Wenguang Geng, Qian Wan, Hongyu Wang, Yushunan Dai, Lisheng Weng, Meng Zhao, Ying Lei and Yumin Duan
Forests 2023, 14(8), 1676; https://doi.org/10.3390/f14081676 - 18 Aug 2023
Cited by 3 | Viewed by 1172
Abstract
The prominence of participating in outdoor leisure activities has gained significance in individuals’ lives as a result of the rapid growth of the economy and the rise in available leisure time. The present study employed structural equation modeling to examine the relationships among [...] Read more.
The prominence of participating in outdoor leisure activities has gained significance in individuals’ lives as a result of the rapid growth of the economy and the rise in available leisure time. The present study employed structural equation modeling to examine the relationships among leisure involvement, the three distinct dimensions of leisure benefits (physiological benefits, psychological benefits, and social benefits), and subjective well-being of bicycle riders. Moreover, the moderating effect of age was also investigated. A field survey was undertaken within an urban forest park, Nanjing City, Jiangsu Province, China, in order to gather data, resulting in the collection of 512 questionnaires that were deemed usable. The results suggest that leisure involvement has a significant and positive impact on bicycle riders’ physiological, psychological, and social benefits, as well as their overall subjective well-being. The subjective well-being of individuals is positively influenced by the physiological, psychological, and social benefits. Additionally, the results of the analysis on the moderating effects suggest that age significantly moderates the relationships between leisure involvement and leisure benefits. The present study also addresses the theoretical and practical implications, limitations, and potential avenues for future research. Full article
(This article belongs to the Special Issue Forest Ecosystem Services and Landscape Design - Series II)
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1 pages, 624 KiB  
Correction
Correction: Wang et al. Predicting Soil Saturated Water Conductivity Using Pedo-Transfer Functions for Rocky Mountain Forests in Northern China. Forests 2023, 14, 1097
by Di Wang, Jianzhi Niu, Yubo Miao, Tao Yang and Ronny Berndtsson
Forests 2023, 14(8), 1675; https://doi.org/10.3390/f14081675 - 18 Aug 2023
Viewed by 598
Abstract
The authors wish to make the following corrections to their paper [...] Full article
25 pages, 7469 KiB  
Article
Seasonal Variation and Soil Texture-Related Thinning Effects on Soil Microbial and Enzymatic Properties in a Semi-Arid Pine Forest
by Cristina Lull, Ricardo Gil-Ortiz, Inmaculada Bautista and Antonio Lidón
Forests 2023, 14(8), 1674; https://doi.org/10.3390/f14081674 - 18 Aug 2023
Cited by 5 | Viewed by 1283
Abstract
Thinning is a practice that reduces competition for available soil resources, thereby promoting vegetation growth and affecting soil, which is involved in important ecosystem processes. Soil quality is directly influenced by various aspects such as ground cover, regional climate, and local microclimate, which [...] Read more.
Thinning is a practice that reduces competition for available soil resources, thereby promoting vegetation growth and affecting soil, which is involved in important ecosystem processes. Soil quality is directly influenced by various aspects such as ground cover, regional climate, and local microclimate, which can further be modified by forest thinning. In this study, the effect of tree thinning and climate on microbiological and enzymatic soil properties was investigated in an Aleppo pine (Pinus halepensis M.) forest more than a decade after silvicultural treatments. The treatments included were clear-felling (100% of mean basal area (BA) removed), moderate thinning (60% BA removed), and control (no thinning). Soil organic carbon (SOC), water-soluble organic carbon (WSOC), basal soil respiration (BSR), microbial biomass carbon (MBC), soil enzymes (β-glucosidase, acid phosphatase, urease, and dehydrogenase), general soil characteristics, soil temperature and humidity, and precipitation were compared seasonally for over two years by analysis of variance and multivariate analysis. Results showed that the effect of 60% thinning improved soil microbial and enzymatic soil properties with variable results, mainly depending on soil organic matter content and soil texture. SOC, WSOC, and MBC were highly correlated with BSR and enzymatic activities. The main reason for the observed differences was water availability, despite a large seasonal variation. In conclusion, microbial activity was strongly affected by soil characteristics and climate, which in turn were influenced by the silvicultural treatments applied. Moderate thinning can be used as a useful practice to improve soil quality in the Mediterranean area. Full article
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14 pages, 4433 KiB  
Article
Tree Health Condition in Urban Green Areas Assessed through Crown Indicators and Vegetation Indices
by Luis Manuel Morales-Gallegos, Tomás Martínez-Trinidad, Patricia Hernández-de la Rosa, Armando Gómez-Guerrero, Dionicio Alvarado-Rosales and Luz de Lourdes Saavedra-Romero
Forests 2023, 14(8), 1673; https://doi.org/10.3390/f14081673 - 18 Aug 2023
Cited by 2 | Viewed by 1485
Abstract
The urban environment induces stress on trees and its impact can be identified by observing the condition of the crown. The aim of this study is to correlate the variables of crown density (Cdn), crown transparency (Ctr) and dieback (Cdie) with the following [...] Read more.
The urban environment induces stress on trees and its impact can be identified by observing the condition of the crown. The aim of this study is to correlate the variables of crown density (Cdn), crown transparency (Ctr) and dieback (Cdie) with the following vegetation indices: the normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), blue-normalized difference vegetation index (BNDVI), green-normalized difference vegetation index (GNDVI), green–red vegetation index (GRVI) and red–green–blue vegetation index (RGBVI) of the crowns of trees located in urban green areas, as well as chlorophyll fluorescence (Fv/Fm) as an indirect indicator of the overall tree health condition. A total of 549 trees were evaluated, represented in 24 families, 36 genera and 53 species; the variables had average values of 67.96% for Cdn, 35.19% for Ctr and 1% for Cdie. Correlations were found between Fv/Fm, NDVI and BNDVI. NDVI and BNDVI correlated with variables such as Cdn and Ctr, mainly in species such as Ligustrum lucidum, Jacaranda mimosifolia and Fraxinus uhdei. Therefore, it is possible to evaluate the tree health condition of trees in urban green environments through the identification of unfavorable conditions at the crown level by using vegetation indices for some of the species studied. Full article
(This article belongs to the Special Issue Urban Forestry Measurements)
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21 pages, 17573 KiB  
Article
Extraction of Pine Wilt Disease Regions Using UAV RGB Imagery and Improved Mask R-CNN Models Fused with ConvNeXt
by Zhenyu Wu and Xiangtao Jiang
Forests 2023, 14(8), 1672; https://doi.org/10.3390/f14081672 - 18 Aug 2023
Cited by 4 | Viewed by 1225
Abstract
Pine wilt disease (PWD) is one of the most concerning diseases in forestry and poses a considerable threat to forests. Since the deep learning approach can interpret the raw images acquired by UAVs, it provides an effective means for forest health detection. However, [...] Read more.
Pine wilt disease (PWD) is one of the most concerning diseases in forestry and poses a considerable threat to forests. Since the deep learning approach can interpret the raw images acquired by UAVs, it provides an effective means for forest health detection. However, the fact that only PWD can be detected but not the degree of infection can be evaluated hinders forest management, so it is necessary to establish an effective method to accurately detect PWD and extract regions infected by PWD. Therefore, a Mask R-CNN-based PWD detection and extraction algorithm is proposed in this paper. Firstly, the extraction of image features is improved by using the advanced ConvNeXt network. Then, it is proposed to change the original multi-scale structure to PA-FPN and normalize it by using GN and WS methods, which effectively enhances the data exchange between the bottom and top layers under low Batch-size training. Finally, a branch is added to the Mask module to improve the ability to extract objects using fusion. In addition, a PWD region extraction module is proposed in this paper for evaluating the damage caused by PWD. The experimental results show that the improved method proposed in this paper can achieve 91.9% recognition precision, 90.2% mapping precision, and 89.3% recognition rate of the affected regions on the PWD dataset. It can effectively identify the distribution of diseased pine trees and calculate the damage proportion in a relatively accurate way to facilitate the management of forests. Full article
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17 pages, 2743 KiB  
Article
Microwave Treatments and Their Effects on Selected Properties of Portuguese Pinus pinaster Aiton. and Eucalyptus globulus Labill. Wood
by Fernando Júnior Resende Mascarenhas, Alfredo Manuel Pereira Geraldes Dias, André Luis Christoforo, Rogério Manuel dos Santos Simões and André Eduardo Palos Cunha
Forests 2023, 14(8), 1671; https://doi.org/10.3390/f14081671 - 18 Aug 2023
Cited by 1 | Viewed by 1005
Abstract
The most widespread wood species in the Portuguese forest and the most widely utilized are maritime pine (Pinus pinaster) and eucalyptus (Eucalyptus globulus Labill). In the case of eucalyptus, except for the pulping sector, it might have limited usage due [...] Read more.
The most widespread wood species in the Portuguese forest and the most widely utilized are maritime pine (Pinus pinaster) and eucalyptus (Eucalyptus globulus Labill). In the case of eucalyptus, except for the pulping sector, it might have limited usage due to drying issues and low permeability. Microwave (MW) treatment is a technology that has been used to improve wood species’ permeability. Therefore, the present paper aimed to evaluate the MW treatment of both Portuguese wood species and to investigate the effects of different MW treatments on wood’s density, water uptake capability, modulus of rupture (MOR), and modulus of elasticity (MOE). Using small clear wood specimens, two MW powers were used, 700 and 1200 W, and the samples were submitted to successive MW cycles of 2 min till they reached the required dryness. The results showed that each wood species had a different behavior during the MW drying in terms of drying rate, supply, and consumption of energy. In general, with the increase in MW power, the densities of both species decreased and the water uptake increased, as a possible indicator that a certain level of microstructural damage might have occurred. Regarding the mechanical properties of MW-treated maritime pine and eucalyptus wood specimens, under the harshest conditions (MW power of 1200 W), MOR and MOE were reduced compared with the wood sample without MW treatment. Full article
(This article belongs to the Special Issue Wood Quality and Mechanical Properties)
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18 pages, 2265 KiB  
Article
Identifying the Internal Coupling Coordination Relationship of Forest Ecological Security and Its Spatial Influencing Factors
by Jiehua Lyu, Zhe Sun, Tingyu Yang, Bin Zhang and Xiuting Cai
Forests 2023, 14(8), 1670; https://doi.org/10.3390/f14081670 - 18 Aug 2023
Viewed by 904
Abstract
Forest ecological security is an important guarantee for national security and the healthy development of forestry. Existing research has been limited to the comprehensive evaluation and obstruction factors of forest ecological security, and this study innovatively analyzes internal coordination of forest ecological security [...] Read more.
Forest ecological security is an important guarantee for national security and the healthy development of forestry. Existing research has been limited to the comprehensive evaluation and obstruction factors of forest ecological security, and this study innovatively analyzes internal coordination of forest ecological security and its spatial influencing factors in order to enhance the internal coordination of the forest ecosystem and promote the coordinated improvement of regional forest ecological security. Firstly, the forest ecological security in China from 2006 to 2020 was evaluated. On this basis, the coupling coordination degree of forest ecological security (FESD) was calculated, and its influencing factors and spatial spillover effects were analyzed using the spatial econometric model. The results show that: (1) most of China’s provincial forest ecological security is at a critical and relatively safe level, and shows a trend of gradual improvement; (2) FESD in 25 provinces, represented by Guangxi, is in the acceptable range and is constantly improving; and (3) annual mean temperature, urbanization rate, completed forestry investment, and forest pest control have been positive influences on FESD. Forest population density, per capita GDP, and investment in environmental governance have significant negative influences. In addition, completed forestry investment, annual mean temperature, urbanization rate, forest population density, and forest pest control have significant spillover effects on FESD. Therefore, in the process of forest ecological management, it is necessary to further strengthen investments in forestry and pest control, and to pay more attention to the interaction between regions. Full article
(This article belongs to the Section Forest Ecology and Management)
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17 pages, 14892 KiB  
Article
Mapping Land Use and Land Cover Classes in São Paulo State, Southeast of Brazil, Using Landsat-8 OLI Multispectral Data and the Derived Spectral Indices and Fraction Images
by Yosio E. Shimabukuro, Egidio Arai, Gabriel M. da Silva, Tânia B. Hoffmann, Valdete Duarte, Paulo R. Martini, Andeise Cerqueira Dutra, Guilherme Mataveli, Henrique L. G. Cassol and Marcos Adami
Forests 2023, 14(8), 1669; https://doi.org/10.3390/f14081669 - 18 Aug 2023
Cited by 1 | Viewed by 1954
Abstract
This work aims to develop a new method to map Land Use and Land Cover (LULC) classes in the São Paulo State, Brazil, using Landsat-8 Operational Land Imager (OLI) data. The novelty of the proposed method consists of selecting the images based on [...] Read more.
This work aims to develop a new method to map Land Use and Land Cover (LULC) classes in the São Paulo State, Brazil, using Landsat-8 Operational Land Imager (OLI) data. The novelty of the proposed method consists of selecting the images based on the spectral and temporal characteristics of the LULC classes. First, we defined the six classes to be mapped in the year 2020 as forest, forest plantation, water bodies, urban areas, agriculture, and pasture. Second, we visually analyzed their variability spectral characteristics over the year. Then, we pre-processed these images to highlight each LULC class. For the classification, the Random Forest algorithm available on the Google Earth Engine (GEE) platform was utilized individually for each LULC class. Afterward, we integrated the classified maps to create the final LULC map. The results revealed that forest areas are primarily concentrated in the eastern region of São Paulo, predominantly on steeper slopes, accounting for 19% of the study area. On the other hand, pasture and agriculture dominated 73% of all São Paulo’s landscape, reaching 39% and 34%, respectively. The overall accuracy of the classification achieved 89.10%, while producer and user accuracies were greater than 84.20% and 76.62%, respectively. To validate the results, we compared our findings with the MapBiomas Project classification, obtaining an overall accuracy of 85.47%. Therefore, our method demonstrates its potential to minimize classification errors and offers the advantage of facilitating post-classification editing for individual mapped classes. Full article
(This article belongs to the Special Issue Mapping Forest Vegetation via Remote Sensing Tools)
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16 pages, 6267 KiB  
Article
The Impact of Nitrogen Application on Leaf and Root Functional Traits of Davidia involucrata Saplings
by Mei Liu, Jiahao Wen, Wenjuan Xu, Yamei Chen and Zhiliang Ma
Forests 2023, 14(8), 1668; https://doi.org/10.3390/f14081668 - 18 Aug 2023
Cited by 1 | Viewed by 1055
Abstract
Understanding the effects of nitrogen (N) deposition on plant functional traits can provide insights into their adaptation strategies. We conducted an N application experiment (0, 5, 10, 15 g N m−2) with potted saplings of the endangered species Davidia involucrata and [...] Read more.
Understanding the effects of nitrogen (N) deposition on plant functional traits can provide insights into their adaptation strategies. We conducted an N application experiment (0, 5, 10, 15 g N m−2) with potted saplings of the endangered species Davidia involucrata and examined 24 functional traits of both leaves and roots. We found that N application increased the leaf morphological traits, except for a significant decrease (by 19.2%–27.0%) in specific leaf area (SLA). Compared to the control treatment, N application significantly increased the specific root surface area (SRA), specific root length (SRL), and root tissue density (RTD) by 9.2%–20.1%, 20.2%–47.9%, and 30.8%–46.4%, respectively, while root diameter was conservative and insensitive to N application. Additionally, N application had contrasting effects between leaf and root carbon, N, and phosphorus contents and their stoichiometry. SRL, SRA, and RTD were positively correlated with most leaf photosynthetic traits, but negatively correlated with SLA. Moreover, root biomass and root chemical traits were also tightly correlated with leaf photosynthetic traits and chemical traits. These results suggest that N application may trigger a resource-conservative strategy for leaves but a nutrient-acquisitive strategy for roots. Future N deposition combined with other practices, such as simultaneous P fertilizer application, can be effective for the scientific conservation of D. involucrata populations in their natural habitats. Full article
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20 pages, 1096 KiB  
Article
The Effect of Carbon Sink Afforestation Projects on China’s Forest Product Export Trade: Empirical Evidence from Chinese Microenterprises
by Xiaoxin Gao and Caihong Zhang
Forests 2023, 14(8), 1667; https://doi.org/10.3390/f14081667 - 18 Aug 2023
Viewed by 995
Abstract
Forestry carbon sinks are an important measure for enabling China to cope with global climate change and realize its “double carbon” goal. Carbon sink afforestation projects (CSAPs) are a type of forestry carbon sink projects, and the question of whether China’s forest products [...] Read more.
Forestry carbon sinks are an important measure for enabling China to cope with global climate change and realize its “double carbon” goal. Carbon sink afforestation projects (CSAPs) are a type of forestry carbon sink projects, and the question of whether China’s forest products with an export orientation can adapt to the requirements of high-quality development is important for balancing the relationship between emissions reduction and development. We use the micro-data of forest product export enterprises provided by the China Customs Database and construct a difference-in-difference (DID) model to investigate the impact of CSAPs on China’s forest product export and its heterogeneity. The results show that CSAPs significantly increase the export scale of China’s forest products. CSAPs lead to significant heterogeneity regarding the forest product export scale in relation to regions, production factor intensity, trade pattern, enterprise ownership, and export destination countries. We further find that although the implementation of CSAPs significantly reduces the export types of forest products, it significantly promotes an increase in the export price and the expansion of the export quantity of forest products, and it optimizes the export structure of forest products to some extent. The “Belt and Road” initiative (BRI) has played a significant positive role in regulating the expansion of the forest product export scale with CSAPs. The implementation of CSAPs reduces the risk of termination of trade relations among forest product export enterprises and extends the export duration. The conclusions provide implications for policy makers and managers of forest product enterprises. Full article
(This article belongs to the Section Forest Economics, Policy, and Social Science)
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22 pages, 8818 KiB  
Article
Unveiling the Diversity of Bangka Island’s Mangroves: A Baseline for Effective Conservation and Restoration
by Suci Puspita Sari, Nico Koedam, Aditya Pamungkas, Muhammad Rizza Muftiadi and Frieke Van Coillie
Forests 2023, 14(8), 1666; https://doi.org/10.3390/f14081666 - 17 Aug 2023
Cited by 1 | Viewed by 1359
Abstract
The current state of the mangrove ecosystem on Bangka Island requires urgent attention from the local government to protect, restore, and conserve the remaining mangrove areas. Hence, this study endeavors to assess the species composition of mangroves on Bangka Island, examining their correlation [...] Read more.
The current state of the mangrove ecosystem on Bangka Island requires urgent attention from the local government to protect, restore, and conserve the remaining mangrove areas. Hence, this study endeavors to assess the species composition of mangroves on Bangka Island, examining their correlation with edaphic factors and shedding light on the zonation pattern within the region. We examined species composition, edaphic factors, and zonation patterns along 20 m × 100 m transects perpendicular to the waterfront at 22 sampling sites distributed across Bangka Island. Our findings revealed the presence of 21 mangrove species from ten families, including two mangrove associates. Among the documented species, the Rhizophoraceae family exhibited the highest floristic abundance with nine species. Edaphic factors (soil texture, pore-water salinity, N-total, P, and K) significantly influenced mangrove species composition (p < 0.05). However, these factors explained only 37.2% of the overall variability, suggesting additional factors contribute to the diverse zonation and composition of mangroves on Bangka Island. This study has relevant implications for the conservation and management of mangroves on Bangka Island. By gaining insight into the specific site’s floristic composition, overall richness, and distribution, our findings can guide effective conservation and restoration strategies by understanding the factors shaping mangrove composition. Full article
(This article belongs to the Special Issue Biodiversity, Health, and Ecosystem Services of Mangroves)
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14 pages, 4815 KiB  
Article
Distribution of Genes and Microbial Taxa Related to Soil Phosphorus Cycling across Soil Depths in Subtropical Forests
by Hao Lv, Jie Yang, Siwen Su, Yue Liu, Jie Feng, Yuxiang Sheng, Ting Wang, Jinwen Pan, Li Tang, Liang Chen, Shuai Ouyang and Guangjun Wang
Forests 2023, 14(8), 1665; https://doi.org/10.3390/f14081665 - 17 Aug 2023
Cited by 2 | Viewed by 1456
Abstract
Although many studies have focused on the roles of soil microbes in phosphorus (P) cycling, little is known about the distribution of microbial P cycling genes across soil depths. In this study, metagenomic sequencing was adopted to examine the differences in the abundance [...] Read more.
Although many studies have focused on the roles of soil microbes in phosphorus (P) cycling, little is known about the distribution of microbial P cycling genes across soil depths. In this study, metagenomic sequencing was adopted to examine the differences in the abundance of genes and microbial taxa associated with soil P cycling between organic and mineral soil in subtropical forests. The total relative abundance of inorganic P solubilizing genes was the highest, that of P starvation response regulating genes was second, and organic P mineralizing genes was the lowest. The soil organic carbon concentration, N:P ratio, and available P concentration were higher in the organic soil than the mineral soil, resulting in abundances of organic P mineralizing genes (appA and 3-phytase), and inorganic P cycling genes (ppa), whereas those of the inorganic P cycling genes (gcd and pqqC) and the P starvation response regulating gene (phoR) were higher in mineral soil. The four bacteria phyla that related to P cycling, Proteobacteria, Actinobacteria, Bacteroidetes, and Candidatus_Eremiobacteraeota were higher in organic soil; conversely, the three bacteria phyla (Acidobacteria, Verrucomicrobia, and Chloroflexi) and archaea taxa were more abundant in mineral soil. Therefore, we concluded that the distribution of genes and microbial taxa involved in soil P cycling differed among soil depths, providing a depth-resolved scale insight into the underlying mechanisms of P cycling by soil microorganisms in subtropical forests. Full article
(This article belongs to the Special Issue Application of Microbes in Landscape Restoration)
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15 pages, 1425 KiB  
Article
Effect of Temperature, Seed Size, Sowing Depth, and Position on Seed Germination and Seedling Growth of Bauhinia retusa Roxb. and Bauhinia variegata L.
by Neeraj Yadav, Vinod Prasad Khanduri, Bhupendra Singh, Chatar Singh Dhanai, Manoj Kumar Riyal, Deepa Rawat, Taufiq Ahmad and Munesh Kumar
Forests 2023, 14(8), 1664; https://doi.org/10.3390/f14081664 - 17 Aug 2023
Cited by 1 | Viewed by 1417
Abstract
In urban forestry plantations are implemented in different cities of the world for social and environmental benefits. Bauhinia retusa and Bauhinia variegata are important species and to be used as large-scale plantation programs in urban forestry which might solve or mitigate urban, social, [...] Read more.
In urban forestry plantations are implemented in different cities of the world for social and environmental benefits. Bauhinia retusa and Bauhinia variegata are important species and to be used as large-scale plantation programs in urban forestry which might solve or mitigate urban, social, and environmental issues such as improving the physical & mental health of residents, food and nutrition security, increasing urban biodiversity, cooling the neighboring, preventing soil erosion, flooding, and mitigating greenhouse gas emissions and air pollution. The present study was conducted with the aim of producing quality planting material for B. retusa and B. variegata in the nursery for afforestation programs. Seeds of B. retusa and B. variegata were collected from the natural habitats to assess seed germination and seedling growth. Seeds were stored in different types of containers at room temperature and later on exposed to 15, 20, and 25 °C in seed germinator. Seeds were further sown in polythene bags according to the seed size, seed coat color, seed sowing depth, the orientation of seeds, and the result of the emergence of seedlings, their growth, and biomass were estimated. A two-way analysis of variance was calculated to estimate the variation among the studied parameters. Results revealed that a constant 25 °C temperature was considered best for seed germination of both the Bauhinia species. Polybags were found the most suitable for storing the Bauhinia seeds among the storage containers. The seedling emergence and growth were maximum in yellow color and large seeds. In B. retusa, seedling emergence, and growths were the maximum in seeds sown at a horizontal position and in B. variegata at an upright position. Seedling emergence, length, and biomass were recorded the maximum when seeds of B. retusa were sown at 4 cm depth and B. variegata seeds were sown at 2 cm depth. The study recommends that the yellow color seed that has to be sown at 2 cm to 4 cm depth with upright and horizontal positions is considered best for the production of quality planting stock of both studied Bauhinia species. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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20 pages, 16523 KiB  
Article
Spectral Analysis, Biocompounds, and Physiological Assessment of Cork Oak Leaves: Unveiling the Interaction with Phytophthora cinnamomi and Beyond
by Rui Guerra, Rosa Pires, António Brázio, Ana Margarida Cavaco, Gabriela Schütz and Ana Cristina Coelho
Forests 2023, 14(8), 1663; https://doi.org/10.3390/f14081663 - 17 Aug 2023
Viewed by 1067
Abstract
The cork oak tree (Quercus suber L.) symbolizes the Montado landscape in Portugal and is a central element in the country’s social and economic history. In recent decades, the loss of thousands of cork oaks has been reported, revealing the ongoing decline [...] Read more.
The cork oak tree (Quercus suber L.) symbolizes the Montado landscape in Portugal and is a central element in the country’s social and economic history. In recent decades, the loss of thousands of cork oaks has been reported, revealing the ongoing decline of these agroforestry ecosystems. This emblematic tree of the Mediterranean Basin is host to the soil-born root pathogen Phytophthora cinnamomi, an active cork oak decline driver. In this framework, the early diagnosis of trees infected by the oomycete by non-invasive methods should contribute to the sustainable management of cork oak ecosystems, which motivated this work. Gas exchange and visible/near-infrared (400–1100 nm) reflectance spectroscopy measurements were conducted on leaves of both control and P. cinnamomi inoculated plants. These measurements were taken at 63, 78, 91, 126, and 248 days after inoculation. Additionally, at the end of the experiment, biochemical assays of pigments, sugars, and starch were performed. The spectroscopic measurements proved effective in distinguishing between control and inoculated plants, while the standard gas exchange and biochemistry data did not exhibit clear differences between the groups. The spectral data were examined both daily and globally, utilizing the PARAFAC method applied to a three-way array of samples × wavelengths × days. The separation of the two plant groups was attributed to variations in water content (4v (OH)); shifts in the spectra red edge; and structural modifications in the epidermal layer and leaves’ mesophyll. These spectral signatures can assist in the field identification of cork oaks that are interacting with P. cinnamomi. Full article
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18 pages, 3554 KiB  
Article
A Statistical Approach to Macrofungal Diversity in a Mediterranean Ecosystem of the Iberian Peninsula Dominated by the Holm Oak (Quercus ilex L. subsp. ballota (Desf.) Samp.)
by Abel Fernández-Ruiz, José Luis Vicente-Villardón, José Sánchez-Sánchez, Prudencio García-Jiménez, Sergio Sánchez-Durán and David Rodríguez-de la Cruz
Forests 2023, 14(8), 1662; https://doi.org/10.3390/f14081662 - 17 Aug 2023
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Abstract
The fungal biodiversity associated with a stable plant community appears to vary from year to year. To analyse the annual behaviour in the formation of fruiting bodies, a statistical study of the data obtained for 4 years (2009–2012) in an apparently undisturbed Mediterranean [...] Read more.
The fungal biodiversity associated with a stable plant community appears to vary from year to year. To analyse the annual behaviour in the formation of fruiting bodies, a statistical study of the data obtained for 4 years (2009–2012) in an apparently undisturbed Mediterranean ecosystem dominated by the holm oak (Quercus ilex L. subsp. ballota (Desf.) Samp.), located in the Midwest of the Iberian Peninsula, was carried out. These data were related to the main meteorological variables. The 150 species collected showed a significant annual, monthly, and weekly difference in their fruiting during the collection period. All this implies a variation in the annual fungal fruiting which can modify the moment of when maximum peaks of fruiting appear, their duration, and the number of species that compose them. In addition, the results make it possible to establish an annual behaviour pattern, with sporocarp formation throughout the year and four fruiting groups (two of them in the dry season). They also allow for inferring a possible response to climate change, with a delay in the fruiting of the autumn-winter group and earlier fruit bearing in the winter-spring group. Full article
(This article belongs to the Special Issue Fungal Dynamics and Diversity in Forests)
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