Forest Land Cover Mapping at a Regional Scale Using Multi-Temporal Sentinel-2 Imagery and RF Models

Abstract

Over the last several decades, thanks to improvements in and the diversification of open-access satellite imagery, land cover mapping techniques have evolved significantly. Notable changes in these techniques involve the automation of different steps, yielding promising results in terms of accuracy, class detection and efficiency. The most successful methodologies that have arisen rely on the use of multi-temporal data. Several different approaches have proven successful. In this study, one of the most recently developed methodologies is tested in the region of Galicia (in Northwestern Spain), with the aim of filling gaps in the mapping needs of the Galician forestry sector. The methodology mainly consists of performing a supervised classification of individual images from a selected time series and then combining them through aggregation using decision criteria. Several of the steps of the methodology can be addressed in multiple ways: pixel resolution selection, classification model building and aggregation methods. The effectiveness of these three tasks as well as some others are tested and evaluated and the most accurate and efficient parameters for the case study area are highlighted. The final land cover map that is obtained for Galicia has high accuracy metrics (an overall accuracy of 91.6%), which is in line with previous studies that have followed this methodology in other regions. This study has led to the development of an efficient open-access solution to support the mapping needs of the forestry sector.

Identification of Silvicultural Practices in Mediterranean Forests Integrating Landsat Time Series and a Single Coverage of ALS Data

“…Further research is recommended to assess the importance of this criterion when fusing methods are applied. Reference [71] applied the fusion techniques based on the percentage of votes to create a forest land cover map, and achieved higher accuracies, but they did not test our FUSION approach.…”

Analyzing the Evolution of Land-Use Changes Related to Vegetation, in the Galicia Region, Spain: From 1990 to 2018

“…The altitude in Galicia ranges from sea level to nearly 2000 m and the topography includes plains as well as mountain areas with steep valleys [31,32]. Galicia has two types of climate according to the Köppen-Geiger classification, the Csb (Mediterranean-Oceanica climate) and the Csa (Mediterranean climate) [33].…”

Automatic Identification of Forest Disturbance Drivers Based on Their Geometric Pattern in Atlantic Forests

“…The forest disturbance map of Galicia was obtained through the comparison of three consecutive annual land cover maps, specifically those corresponding to 2018, 2019 and 2020. The annual land cover maps were obtained according to the multitemporal approach described in Alonso et al [53]. This approach was specifically designed to optimize the results considering the singularities of the Galician forest sector.…”

“…The last step is the aggregation of the 12 maps of a given year in a final map. This step was performed using the plurality voting decision criteria [53]. In that way, one aggregated map is obtained for every analyzed year.…”