Testing novel applications of satellite imagery developed by the COPERNICUS mission for tracking Ailanthus altissima impacts on invaded ecosystems in a Mediterranean island

Invasive alien plants (IAPs) impact ecosystems through occupying vacant phenological or functional niches and disrupting ecosystem functioning. The Copernicus mission delivers free remote sensing data, facilitating cost-effective and timely ecological monitoring of invaded areas. This study deploys multispectral (Sentinel-1) and thermal (Sentinel-3) Copernicus satellites to characterize ecophysiological and biophysical parameters inside areas invaded by the invasive tree Ailanthus altissima in Sardinia. Furthermore, it examines the ecophysiological and biophysical alterations in the native vegetation caused by its invasion. We mapped 176 invaded and surrounding areas using aerial orthophotos, dividing them into a 20 x 20 m grid. We classified only the homogeneous cells in native vegetation classes following the second level of Carta della Natura and in invaded cells. After, we calculated a subset of not correlated spectral indices proxy of leaf chlorophyll and carotenoid content, of productivity and canopy biomass, of leaf water content, of soil features, and of daily evapotranspiration. We analyzed the monthly trends of invaded areas and the seasonal alterations of native vegetation using linear mixed models, followed by two-way ANOVA and Tukey’s post-hoc test. Our results highlighted the potential of Copernicus mission in capturing the temporal trends of ecophysiological and biophysical spectral parameters in the areas affected by A. altissima invasion. Furthermore, summer season resulted as the most affected by alterations due to A. altissima, in particular for higher productivity and canopy biomass, for greater leaf water content, for lower leaf carotenoid content, for lower bare soil presence compared to native vegetation.