Remote sensing of multidimensional canopy structure of global forests in human-dominated landscapes

Forests are one of the most active terrestrial ecosystems on Earth, especially intact forests, which possess high integrity and biodiversity of flora and fauna. Climate change and human activities are considered crucial environmental factors affecting forests. However, there remains significant uncertainty regarding the universal impact of these environmental factors on the multidimensional structure of global forests and how they will shape future forest structure and functionality. This study utilized a substantial amount of satellite data from the GEDI lidar satellite and multispectral MODIS satellite to quantify forest canopy structure density. It successfully delineated the spatial distribution patterns of the multidimensional canopy structure of global forests, focusing on analyzing the influence of human activity on the structural density of global forests, protected forests, and intact forests. Additionally, it analyzed the relative importance concerning human activities, climate, and other environmental factors. Based on this analysis, the study further investigated the differences in the spatial distribution patterns of multidimensional canopy structure in naturally regrowing forests and plantation forests under various human management types. It also implicated the impact of establishing protected areas and excluding human disturbances on forest ecosystem functioning like carbon storage. This research, from a satellite remote sensing perspective, notably revealed that human pressures extend even into forests traditionally believed to be protected and of higher integrity. It contributes to significant corrections regarding prevailing notions about the driving factors behind forest degradation. Moreover, it underscores the critical importance of better management and sustainable maintenance of protected forests, intact forests, and naturally regrowing forests for restoring and safeguarding forest ecosystem functioning.