Conclusions

This review has examined the remote sensing of grassland biodiversity and functional traits with a focus on recent technological and methodological developments. Advances in UAV technology have accelerated the increase in grasslands surveys featuring very high spatial resolutions, with 3D components and increasingly employing multispectral and hyperspectral sensors. As UAV technology continues to improve and become more accessible through cheaper costs and automated flight controls, and survey and processing methods mature, UAVs are likely to become a standard tool in grassland surveys. UAV surveys can also bridge the gap between ground-based fieldwork and satellite remote sensing, as well as providing ground truthing for spaceborne data, potentially refining the seemingly inconsistent relationship between spectra variation and biodiversity. This can aid in the development of satellite remote sensing methods and allow the scaling of biodiversity and functional trait surveys from discrete points to site-wide and national surveys.