Editorial for the Special Issue 'SAR for Forest Mapping II'

Abstract

As vital natural resources, forests are of extreme importance for all living beings on our planet. They play a key role in controlling climate change; represent essential sources of energy (e.g., biomass), food, jobs, and livelihoods; and serve as a natural habitat to a large variety of animal species, which is essential for biodiversity preservation. Forest ecosystems are constantly shaped and changed by physical and biological disturbances, and eventual regeneration processes. As an example, forest degradation is currently occurring at an alarming rate, and it often occurs due to illegal anthropogenic activities such as logging and fires. Sensitive environments have been irreversibly damaged, with critical environmental and economic consequences at regional as well as global scales. Precise and efficient assessment and monitoring of forest resources, treatments, and recreational opportunities are therefore of crucial importance in order to develop early warning systems. In this scenario, synthetic aperture radar (SAR) remote sensing represents a unique technique to provide high-resolution images independently of daylight and in almost any weather conditions. In the past few decades, SAR imaging has demonstrated its suitability for forest mapping applications. The combination of polarimetric, interferometric, and/or tomographic information further increases its capabilities and its products' accuracy. This Special Issue consists of nine research papers, which investigate several aspects related to forest parameter estimation and retrieval using SAR-based methods, such as the mapping of forest cover, above-ground biomass (AGB), and growing stem volume (GSV), as well as forest height inversion, forest structure characterization, the estimation of phenological changes, and damages in drought-affected forests using SAR data time series. All the methods proposed in these papers were validated using real SAR data and benchmarked with state-of-the-art approaches, thus comprehensively demonstrating the theoretical and practical contributions of the research.