Trees Outside Forests (TOFs): A Global Review of Methodological Advances, Limitations, and Framework Innovations

Trees outside forests (TOFs) represent an important natural and anthropogenic resource that contributes significantly to biodiversity conservation, climate resilience, and the protection of forest genetic resources (FGRs). Despite their ecological and socioeconomic importance, TOFs are increasingly declining due to land‐use changes, urbanization, industrial expansion, and climate change. This study aims to (i) synthesize the global evolution and current status of TOFs, (ii) critically review existing approaches for their mapping and assessment, and (iii) propose a robust framework to improve their monitoring and integration into forest management systems. A comprehensive review of literature and National Forest Inventory practices was conducted to evaluate methodologies used for TOF assessment across multiple spatial scales, ranging from national to farm level. The study examines conventional and advanced geospatial techniques, including remote sensing, high‐resolution satellite imagery, and light detection and ranging (LiDAR), highlighting their applications, strengths, and limitations. Particular attention is given to spatial mapping resolutions (1:10,000–1:50,000) and the integration of species, structural, and functional attributes into TOF assessment frameworks. The findings reveal that, despite technological advancements, no universally reliable and standardized method exists for accurately mapping TOFs, primarily due to their dispersed nature and variability across landscapes. To address these challenges, this study proposes a conceptual framework that integrates multitemporal datasets from Sentinel‐1 and Sentinel‐2 with a convolutional neural network (CNN)–based analysis to improve the detection, characterization, and spatial assessment of TOFs. The proposed framework offers a scalable and cost‐effective approach for enhancing mapping accuracy and consistency, with significant implications for National Forest Monitoring Systems, carbon stock estimation, and policy formulation. By strengthening the inclusion of TOFs in forest inventories, this work supports sustainable resource management, improved ecosystem services, and informed decision‐making for climate change mitigation and biodiversity conservation.