An automated Google Earth Engine application for detecting the impacted area of treeless boreal peatland restoration – A tool for practitioners and decision-makers

Abstract

Remote sensing (RS) methods are recognized as a potential solution for the increasing need to monitor peatland changes after restoration, but practical monitoring tools are lacking. To address this gap, our objective is to (1) test which optical satellite variables can be used for detecting hydrological restoration impact in treeless boreal peatlands, (2) develop a user-friendly Google Earth Engine (GEE) application based on the results, and (3) demonstrate its usage in practice. Firstly, by utilizing data from 24 peatland restoration sites in Finland, we used Mann-Whitney U test and Kruskal-Wallis test to determine which optical variables calculated from Sentinel-2 and Landsat 8–9 satellite imagery can be used as indicators for surface wetness changes after peatland restoration. The results from statistical tests indicated that near-infrared (NIR) and shortwave infrared (SWIR) bands were the most effective in detecting the impact. Secondly, we incorporated the NIR and SWIR bands into the GEE application to indicate the location and magnitude of restoration impact. The developed application uses a direct input from the openly available satellite imagery archives and requires only a few inputs from the user for the case-specific analysis, making it user-friendly. The application calculates cloudless and representative satellite image mosaics and uses change detection for the situations before and after restoration to show the hydrological restoration impacts spatially. The application provides researchers, stakeholders, decision-makers, and practitioners with limited technical experience the possibility to use satellite imagery for assessing restoration impacts in open or sparsely treed peatlands in boreal landscapes.