Forests

Su, Jianxiao;Yu, Mengyao;Zhang, Xueting;Xu, Jiali;Gao, Jie

doi: 10.3390/f16030381pmid: N/A

The forest root-shoot ratio (R/S) is an important indicator of the structure and function of forest ecosystems. It reflects the adaptive strategies of plants to environmental changes, and its pattern of change along the latitudinal gradient is of great significance for understanding the response of forest ecosystems to environmental changes. Although numerous studies have addressed the relationship between climate, soil conditions, and the ratio of below-ground biomass to above-ground biomass (R/S) at the local scale, the pattern of R/S variations along the latitudinal gradient in different types of forests, as well as the dominant factors, remain unclear. This study, based on field surveys and literature collected from 2005 to 2020 on 384 planted forests and 541 natural forests in China, investigates the patterns of forest root-shoot ratio variation along latitudinal gradients in planted and natural forests. The study demonstrated a positive correlation between forest R/S ratio and increasing latitudinal gradients across different forest types, including planted and natural forests (p < 0.001). The results demonstrated a negative correlation between R/S in both planted and natural forests and mean annual temperature, annual precipitation and soil phosphorus content. Conversely, a positive correlation was observed between R/S and soil nitrogen content and soil pH. It can be observed that plantation forests are more susceptible to alterations in forest factors than natural forests. Latitudinal patterns can not only directly affect the R/S of planted and natural forests, but also affect forest R/S by influencing climate and forest factors and the interactions of the factors together. Our study distinguishes the pattern of R/S changes along the latitudinal gradient in planted and natural forests and its influencing factors. These findings are important for understanding the pattern changes in different forest ecosystems and provide a theoretical basis for efficiently guiding forest management.

Ma, Haoyang;Yang, Banghui;Wang, Ruirui;Yu, Qiang;Yang, Yaoyao;Wei, Jiahao

doi: 10.3390/f16030382pmid: N/A

The precise prevention and control of forest pests and diseases has always been a research hotspot in ecological environmental protection. With the continuous advancement of sensor technology, the fine-grained identification of discolored tree crowns based on UAV technology has become increasingly important in forest monitoring. Existing deep learning models face challenges such as prolonged training time and low recognition accuracy when identifying discolored tree crowns caused by pests or diseases from airborne images. To address these issues, this study improves the Faster-RCNN model by using Inception-ResNet-V2 as the feature extractor, replacing the traditional VGG16 feature extractor, aiming to enhance the accuracy of discolored tree crown recognition. Experiments and analyses were conducted using UAV aerial imagery data from Jilin Changbai Mountain. The improved model effectively identified discolored tree crowns caused by pine wood nematodes, achieving a precision of 90.22%, a mean average precision (mAP) of 83.63%, and a recall rate of 92.33%. Compared to the original RCNN model, the mAP of the improved model increased by 4.68%, precision improved by 10.11%, and recall improved by 5.23%, significantly enhancing the recognition performance of discolored tree crowns. This method provides crucial technical support and scientific basis for the prevention and control of forest pests and diseases, facilitating early detection and precise management of forest pest outbreaks.

Lee, Min-Woo;Han, Gyu-Il;Kim, Young-Soo;Kim, Seong-Bin;Heo, Tae-Im

doi: 10.3390/f16030383pmid: N/A

This study was conducted to classify the types of degraded land in the Taebaeksan region within the Baekdudaegan mountain range in Korea using image analysis and to assess the degree of degradation through a detailed survey of each type. Based on the findings, candidate tree species for restoration and strategies for land rehabilitation were proposed. The analysis identified 1589 degraded sites, classified into nine types of degradation. Using the Self-Organizing Map (SOM) method, these sites were further categorized into six environmental types. A survey was conducted on 25 degraded sites (encompassing 73 specific locations) in the Taebaeksan region, revealing that the sites fell into seven out of nine degradation categories: grassland, agricultural land, forest roads, ranches, cemeteries, logging sites, and abandoned quarries. The excluded categories were buildings and military facilities. A more focused survey was conducted on the 73 largest sites across the degradation types, with a reference ecosystem selected based on topographic analysis and succession processes. Diagnostic evaluations identified logging sites and severely degraded areas as the most urgent priorities for rehabilitation. Candidate tree species for restoration were proposed for each degradation type and environmental condition, based on ecological importance and reference ecosystem characteristics. This study provides a comprehensive assessment of degradation types following ecological restoration procedures and offers valuable baseline data for selecting restoration species and designing restoration strategies in conjunction with reference ecosystem studies.

Song, Cheng;Li, Zechen;Dai, Yingcheng;Liu, Tian;Li, Jianjun

doi: 10.3390/f16030384pmid: N/A

The forests in China’s temperate semi-arid region play a significant role in water conservation, carbon storage, and biodiversity protection. An accurate estimation of their aboveground biomass (AGB) is crucial for assessing key ecological characteristics, such as forest carbon storage capacity, biodiversity, and ecological productivity. This provides a scientific basis for forest resource management and ecological conservation in this region. In this study, we extract 17 features related to the dominant species (Larix gmelinii and Betula platyphylla), including 7 vegetation indices derived from remote sensing data, 14 indices from 7 satellite bands, and 3 forest site characteristics. We then analyze the correlations between the AGB and these features. We compare the performance of AGB estimation models using linear regression (LR), polynomial regression (PR), ridge regression (RR), Support Vector Regression (SVR), Extreme Gradient Boosting (XGBoost), and random forest regression (RFR). The results show that for Larix gmelinii, the Landsat 8 bands TM4 and TM7 have a greater degree of correlation with the AGB than the other features, while for Betula platyphylla, bands TM3 and TM4 show a greater degree of correlation with the AGB, and elevation has a weaker correlation with the AGB. Although the linear regression (LR) demonstrates certain advantages for AGB estimation, particularly when the AGB values range from 40 to 70 t/ha, the RFR outperforms in overall performance, with estimation accuracies reaching 85% for Betula platyphylla and 89% for Larix gmelinii. This study reveals that both the species and environmental characteristics may significantly influence the selection of the remote sensing features for AGB estimation, and the choice of algorithm for model optimization is critical. This study innovatively extracts the features related to the dominant species in temperate forests, analyses their relationships with environmental factors, and optimizes the AGB estimation model using advanced regression techniques, offering a method that can be applied to other forest regions as well.

Wang, Yujun;He, Mingjun;Han, Feifei;Liang, Chengxiang;Fu, Wenyi;Qian, Siyu;Zeng, Xinglin;Yun, Yingke;Yi, Xiangui

doi: 10.3390/f16030385pmid: N/A

Prunus cerasoides D.-Don is a rare winter-blooming species and a distinctive and potential germplasm resource for cherry blossoms. We have characterized the mitochondrial genome (mitogenome) of P. cerasoides and acquired a monocyclic molecule measuring 421,258 bp. A total of 58 unique genes were annotated, comprising 36 protein-coding genes, 19 tRNAs, and three rRNAs. In the mitochondrial genome of P. cerasoides, we detected 86 simple sequence repeats, 727 dispersed repeats, and 21 tandem repeats. We detected 456 RNA editing sites from 34 unique protein-coding genes, leading to the cytosine to uracil transitions. Collinear analysis revealed that the mitogenome of P. cerasoides is quite conservative among species of the subgenus Cerasus. Moreover, our study detected 26 segments of plastid genomic DNA that had transferred from the plastome to the mitogenome. Six genes were found to be completely transferred from these fragments. The maximum likelihood phylogenetic analysis utilizing the mitogenomes of 29 distinct Rosaceae species supports the classification of P. cerasoides into separate branches. Comprehending the mitochondrial genomic characterization of P. cerasoides is crucial for elucidating its genetic foundation and offers insights into evolutionary relationships within the Prunus species.

Mu, Yali;Yu, Zhihan;Cheng, Haotian;Yang, Hongqiang

doi: 10.3390/f16030386pmid: N/A

Forests, with their ecosystem services capabilities, play a critical role in absorbing carbon dioxide from the atmosphere, positioning forest carbon sinks as important components of China’s strategy to achieve carbon neutrality. However, due to the spatial correlation inherent in forest carbon sink dynamics, the development of these sinks cannot be fully segmented by region. Due to the interconnected nature of forest ecosystems, carbon sink growth exhibits regional interactions rather than isolated developments, necessitating a transregional perspective to comprehensively understand carbon sinks in China. This study derives a spatial effect model to analyze carbon sink growth and assess the transregional spillover effects of forest carbon sink growth. The analysis is based on panel data from 26 provinces in China from 2003 to 2021. The results show that the forest carbon sink growth in one province is often influenced by the neighboring regions, highlighting significant transregional spillover effects. Policies, e.g., Carbon Emission Trading (CET), and forest management practices like tending were found to positively influence the local forest carbon sink growth and generate substantial positive spillover effects in the neighboring provinces. Our results indicate that the total effect of the implementation of the CET policy leads to a 3% increase in carbon sink growth across the 26 provinces in China over the study period from spatial DID estimation. In contrast, urbanization and the increasing value-added services associated with economic growth negatively impact forest carbon sink growth both locally and in neighboring regions. These findings underscore the necessity of a coordinated national strategy to enhance forest carbon sinks, integrating both direct and indirect regional effects. Aligning economic development with carbon sink goals will enable China to effectively balance environmental and economic priorities. Policy recommendations are provided to improve CET mechanisms and foster regional collaboration for sustainable forest management.

Peng, Lingxiao;Sun, Yongyu;He, Zhenmin;Li, Xiangfei;Luo, Zhifeng;Zhou, Shan;Ou, Zhaorong

doi: 10.3390/f16030387pmid: N/A

Trunk sap flow is essential for assessing plant water use efficiency and adaptation, yet the mechanisms underlying drought resistance and water utilization strategies in dry and hot valleys remain poorly understood. This study investigates the sap flow dynamics of four tree species (Albizia kalkora, Diospyros dumetorum, Terminalia franchetii, and Acacia auriculiformis) in a dry and hot valley using Granier’s thermal diffusion probe method. The aims were to analyze interspecific differences and their response mechanisms to environmental factors using a fitted model of sap flow density and transpiration variables, supplemented by Pearson’s and Mantel’s tests. The results showed that (1) the trunk sap flow of each tree species is significantly higher in the wet season than in the dry season. (2) In the dry and wet seasons, the average trunk sap flow rates were in the order Albizia kalkora > Diospyros dumetorum > Terminalia franchetii > Acacia auriculiformis. (3) The correlation between environmental factors and trunk sap flow was in the order photosynthetically active radiation > atmospheric temperature > saturated water vapor pressure difference > relative humidity > wind speed. (4) Deciduous plants demonstrated stronger water-conducting capacities than evergreen plants and native plants exhibited better drought resistance than introduced plants. (5) Acacia auriculiformis and Albizia kalkora were identified as rainfall-sensitive plants, while Diospyros dumetorum and Terminalia franchetii were rainfall-insensitive. By optimizing species selection based on water use efficiency, rainfall sensitivity, and environmental conditions such as light and temperature, this research contributes to enhancing the stability and resilience of ecosystem restoration in arid regions.

Zhao, Chongsheng;Liu, Jiaxin;Zhu, Fangwei;Wang, Shuguang

doi: 10.3390/f16030388pmid: N/A

Foliar fertilization, an effective strategy for enhancing crop yields, is relatively uncommon in bamboo cultivation. To investigate the impact of potassium fertilizer applied directly to bamboo leaves, we applied K2CO3 on the fresh leaves of 1-year-old Neosinocalamus affinis culms. The results indicated that potassium fertilization significantly promoted leaf growth and development, evidenced by thicker leaf and epidermal and mesophyll cells and increased areas of bulliform and fusoid cells. Additionally, the chlorophyll content rose, while the moisture levels declined. Notably, the soluble sugar, starch, and non-structural carbohydrate (NSC) contents in the leaves also increased. Further analysis of the sugar metabolism revealed that the exogenous potassium application boosted the activities of key enzymes involved in sucrose metabolism, including soluble acid convertase (SAI), cell wall invertase (CWI), sucrose synthase (SuSy), and sucrose phosphate synthetase (SPS). The foliar application of K2CO3 also promoted starch synthesis in the leaves by elevating the activities of ADPG pyrophosphorylase (AGPase), soluble starch synthase (SSS), and granular-bound starch synthase (GBSS), while simultaneously diminishing the activities of starch phosphorylase (STP), α-amylase, and β-amylase. Moreover, the targeted application of K2CO3 significantly reduced the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2) and significantly enhanced the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), thereby improving the stress resistance of bamboo leaves. This study suggested that the foliar application of potassium fertilizer promoted leaf growth, enhanced bamboo’s sugar metabolism and storage, and increased the stress resistance of bamboo leaves.

Mandziuk, Agnieszka;Bijak, Szymon;Łukawska, Irena;Radomska, Justyna;Studnicki, Marcin;Parzych, Stanisław

doi: 10.3390/f16030389pmid: N/A

Forest areas have recently become increasingly popular for physical activity in society, especially among niche sports enthusiasts. We analysed the attitude of the specific social group of cross-country skiers in Poland to pay for recreation in forest areas using their Willingness-To-Pay (WTP) and Willingness-To-Accept (WTA) declarations, which was endorsed by classification and regression tree (CART) analysis. In January–March 2023, we surveyed 50 (in a pilot study) and 255 (in the main survey) cross-country skiers, of whom 117 declared both their WTP and WTA amounts. The investigated explanatory variables included gender, age, education, residency, employment in the forestry sector, and respondents’ income or engagement in skiing. The average WTP and WTA values equalled PLN 68.6 ± 46.4 and PLN 81.3 ± 59.0/person, respectively. Despite apparent differences in the distribution of the declared WTP and WTA amounts, their medians differed only insignificantly. We found a significant correlation only between the WTP value and respondents’ income per capita, and between WTP and WTA. The CART models showed that WTP and WTA levels depended primarily on the frequency of skiing, with higher values declared by less frequent visitors. At the current respondent income level, the expenses for skiing were related the most to the respondents’ age and the frequency of skiing. In the case of increased income, they were related mostly to the respondents’ age and place of residence. The research provides practical information for forest managers in the field of recreational access to forests for people who spend their time actively in forests.