Forest Parameter Extraction and Ecological Applications with UAV-Based Remote Sensing Techniques

A special issue of Forests (ISSN 1999-4907). This special issue belongs to the section "Forest Inventory, Modeling and Remote Sensing".

Deadline for manuscript submissions: 31 July 2025 | Viewed by 4101

Special Issue Editors


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Guest Editor
School of Geographical Sciences, Southwest University, Chongqing 400700, China
Interests: UAV-based remote sensing of environment; LiDAR-based remote sensing of forest ecology
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
College of Geography and Environmental Science, Henan University, Kaifeng 475004, China
Interests: vegetation phenology; ecosystem carbon cycle; climate change; ecological monitoring; remote sensing and GIS applications
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Department of Forestry, Guangxi University, Nanning 530004, China
Interests: forest spatial structure diversity; LiDAR and 3D forest; forest growth modeling

Special Issue Information

Dear Colleagues,

Forest parameter extraction, particularly in the context of precision forestry and ecosystem management, has long been a crucial area of research. Traditional methods of forest inventory, such as field surveys, are labor-intensive and time-consuming, and sattelite-based remote sensing is often limited in spatial and temporal coverage. With the advancement of unmanned aerial vehicles (UAVs) and onboard sensors, there has been a paradigm shift in forest monitoring capabilities. The onboard sensors loaded on UAVs or drones can acquire high-precision data, including RGB, multispectral, hyerspectral, and point cloud data, and so on, enabling more detailed and accurate forest parameter extraction, ecological modelling, and applications.

This Special Issue aims to provide a platform for researchers and practitioners to showcase the latest advances in forest parameter extraction and ecological applications using UAV-acquired data, and works on the integration of deep learning techniques in processing UAV-acquired data are the most encouraged. The scope of this Special Issue includes, but not limited to:

  • Automated extraction of individual and stand-level parameters from UAV-acquired data;
  • Integration of optical and LiDAR data for improved forest parameter estimation;
  • Methods for handling large-scale and complex UAV datasets;
  • Assessment of the accuracy and uncertainty of deep learning-based forest parameter estimates;
  • Applications of deep learning in precision forestry, forest management, and ecosystem services;
  • Novel deep learning architectures for forest segmentation and classification.

This Special Issue seeks to showcase high-quality papers that present cutting-edge research in the field of forest parameter extraction using UAV-acquired data. The types of papers that are particularly encouraged include the following:

  1. Methodological Developments: papers that propose novel deep learning algorithms or network architectures specifically designed for forest parameter extraction from UAV-derived data. These may include improvements in feature extraction, classification accuracy, or computational efficiency.
  2. Case Studies: studies that demonstrate the application of deep learning techniques to real-world forest monitoring scenarios, highlighting their practicality, accuracy, and potential for operational use. Case studies should provide detailed descriptions of the data acquisition, preprocessing, and analysis steps, as well as an evaluation of the results.
  3. Comparison Studies: papers that compare and contrast different deep learning methods or data sources (e.g., optical vs. LiDAR) for forest parameter extraction. These studies can provide valuable insights into the strengths and limitations of various approaches and data sources, and help guide future research directions.
  4. Review Articles: comprehensive reviews of the current state-of-the-art in deep learning for forest parameter extraction and ecological applications using UAV-acquired data. These articles should synthesize existing research, identify key challenges and opportunities, and suggest future research directions.
  5. Technical Reports: reports on technical advancements or best practices related to UAV data acquisition, preprocessing, or management that are essential for supporting deep learning-based forest parameter extraction.

In summary, this Special Issue aims to bring together researchers from diverse backgrounds, including remote sensing, forestry, computer vision, and machine learning, to share their latest findings and foster collaboration in the exciting field of forest parameter extraction and ecological application combining UAV-acquired data and deep learning techniques.

Prof. Dr. Jiayuan Lin
Dr. Haoming Xia
Dr. Hongxiang Wang
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Forests is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • forest parameter extraction
  • unmanned aerial vehicle (UAV) or drone
  • remote sensing
  • convolutional neural network (CNN)
  • deep learning
  • tree classification
  • forest inventory
  • precision forestry

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Published Papers (3 papers)

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Research

24 pages, 14176 KiB  
Article
Optimizing Multidimensional Spectral Indices and Ensemble Learning Methods for Estimating Nitrogen Content in Torreya grandis Leaves Based on UAV Hyperspectral
by Xiaochen Jin, Liuchang Xu, Hailin Feng, Ketao Wang, Junqi Niu, Xinyuan Su, Luyao Chen, Hongting Zheng and Jianqin Huang
Forests 2025, 16(1), 40; https://doi.org/10.3390/f16010040 - 29 Dec 2024
Cited by 1 | Viewed by 852
Abstract
Ensuring sufficient nitrogen intake during the early growth stages of Torreya grandis is crucial for improving future fruit yield and quality. Hyperspectral remote sensing, enabled by unmanned aerial vehicle (UAV) platforms, provides extensive spectral information on forest canopies across large areas. However, the [...] Read more.
Ensuring sufficient nitrogen intake during the early growth stages of Torreya grandis is crucial for improving future fruit yield and quality. Hyperspectral remote sensing, enabled by unmanned aerial vehicle (UAV) platforms, provides extensive spectral information on forest canopies across large areas. However, the potential of combining multidimensional optimized spectral features with advanced machine learning models to estimate leaf nutrient stress has not yet been fully exploited. This study aims to combine optimized spectral indices and ensemble learning methods to enhance the accuracy and robustness of estimating leaf nitrogen content (LNC) in Torreya grandis. Initially, based on full-band spectral information, five spectral transformations were applied to the original spectra. Then, nine two-band spectral indices and twelve three-band spectral indices were optimized based on published formulas. This process created a total of 27 spectral features across three dimensions. Subsequently, spectral features of varying dimensions were combined with multiple linear regression (MLR), decision tree regression (DTR), random forest (RF), and eXtreme Gradient Boosting (XGBoost) to train base estimators for ensemble models. Using a stacking strategy, various modeling combinations were experimented with, resulting in the construction of 22 LNC estimation models. The results indicate that combining two-band and three-band spectral features can more comprehensively capture the subtle changes in the nitrogen status of Torreya grandis, with the optimized spectral index mNDVIblue (555, 569, 572) showing the highest correlation with LNC at −0.820. In the modeling phase, the base estimators used MLR, RF, and XGBoost, while the meta estimator employed MLR’s stacking model to achieve the highest accuracy and relatively high stability on the validation set (R2 = 0.846, RMSE = 1.231%, MRE = 3.186%). This study provides a reference for the efficient and non-destructive detection of LNC or other phenotypic traits in large-scale economic forest crops using UAV hyperspectral technology. Full article
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20 pages, 4073 KiB  
Article
Individual Tree Crown Detection and Classification of Live and Dead Trees Using a Mask Region-Based Convolutional Neural Network (Mask R-CNN)
by Shilong Yao, Zhenbang Hao, Christopher J. Post, Elena A. Mikhailova and Lili Lin
Forests 2024, 15(11), 1900; https://doi.org/10.3390/f15111900 - 28 Oct 2024
Viewed by 1654
Abstract
Mapping the distribution of living and dead trees in forests, particularly in ecologically fragile areas where forests serve as crucial ecological environments, is essential for assessing forest health, carbon storage capacity, and biodiversity. Convolutional neural networks, including Mask R-CNN, can assist in rapid [...] Read more.
Mapping the distribution of living and dead trees in forests, particularly in ecologically fragile areas where forests serve as crucial ecological environments, is essential for assessing forest health, carbon storage capacity, and biodiversity. Convolutional neural networks, including Mask R-CNN, can assist in rapid and accurate forest monitoring. In this study, Mask R-CNN was employed to detect the crowns of Casuarina equisetifolia and to distinguish between live and dead trees in the Pingtan Comprehensive Pilot Zone, Fujian, China. High-resolution images of five plots were obtained using a multispectral Unmanned Aerial Vehicle. Six band combinations and derivatives, RGB, RGB-digital surface model (DSM), Multispectral, Multispectral-DSM, Vegetation Index, and Vegetation-Index-DSM, were used for tree crown detection and classification of live and dead trees. Five-fold cross-validation was employed to divide the manually annotated dataset of 21,800 live trees and 7157 dead trees into training and validation sets, which were used for training and validating the Mask R-CNN models. The results demonstrate that the RGB band combination achieved the most effective detection performance for live trees (average F1 score = 74.75%, IoU = 70.85%). The RGB–DSM combination exhibited the highest accuracy for dead trees (average F1 score = 71.16%, IoU = 68.28%). The detection performance for dead trees was lower than for live trees, which may be due to the similar spectral features across the images and the similarity of dead trees to the background, resulting in false identification. For the simultaneous detection of living and dead trees, the RGB combination produced the most promising results (average F1 score = 74.18%, IoU = 69.8%). It demonstrates that the Mask R-CNN model can achieve promising results for the detection of live and dead trees. Our study could provide forest managers with detailed information on the forest condition, which has the potential to improve forest management. Full article
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16 pages, 5428 KiB  
Article
Estimation and Spatial Distribution of Individual Tree Aboveground Biomass in a Chinese Fir Plantation in the Dabieshan Mountains of Western Anhui, China
by Aimin Chen, Peng Zhao, Yuanping Li, Huaidong He, Guangsheng Zhang, Taotao Li, Yongjun Liu and Xiaoqin Wen
Forests 2024, 15(10), 1743; https://doi.org/10.3390/f15101743 - 2 Oct 2024
Viewed by 1035
Abstract
Understanding aboveground biomass (AGB) and its spatial distribution is key to evaluating the productivity and carbon sink effect of forest ecosystems. In this study, a 123-year-old Chinese fir forest in the Dabieshan Mountains of western Anhui Province was used as the research subject. [...] Read more.
Understanding aboveground biomass (AGB) and its spatial distribution is key to evaluating the productivity and carbon sink effect of forest ecosystems. In this study, a 123-year-old Chinese fir forest in the Dabieshan Mountains of western Anhui Province was used as the research subject. Using AGB data calculated from field measurements of individual Chinese fir trees (diameter at breast height [DBH] and height) and spectral vegetation indices derived from unmanned aerial vehicle (UAV) remote sensing images, a random forest regression model was developed to predict individual tree AGB. This model was then used to estimate the AGB of individual Chinese fir trees. Combined with digital elevation model (DEM) data, the effects of topographic factors on the spatial distribution of AGB were analyzed. We found that remote sensing spectral vegetation indices obtained by UAVs can be used to predict the AGB of individual Chinese fir trees, with the normalized difference vegetation index (NDVI) and the optimized soil-adjusted vegetation index (OSAVI) being two important predictors. The estimated AGB of individual Chinese fir trees was 339.34 Mg·ha−1 with a coefficient of variation of 23.21%. At the local scale, under the influence of elevation, slope, and aspect, the AGB of individual Chinese fir trees showed a distribution pattern of decreasing from the middle to the northwest and southeast along the northeast-southwest trend. The effect of elevation on AGB was influenced by slope and aspect; AGB on steep slopes was higher than on gentle slopes, and the impact of slope on AGB was influenced by aspect. Additionally, AGB on north-facing slopes was higher than on south-facing slopes. Our results suggest that local environmental factors such as elevation, slope, and aspect should be considered in future Chinese fir plantation management and carbon sink assessments in the Dabieshan Mountains of western Anhui, China. Full article
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