Abstract Questions Shrub encroachment has been observed in many alpine and arctic environments and is expected to significantly alter these ecosystems. Mapping these processes with remote sensing is a powerful tool for monitoring purposes. Thus, we test the distinctiveness of the reflectance signature of target species relative to their co-occurring shrub species using uni- and multivariate analyses for an alpine ecosystem. We ask: (i) is it possible to differentiate shrub species with a unique growth form by their reflectance signature; (ii) which of the tested multispectral sensors produces the best separation; and (iii) how are the results affected by the timing of data acquisition in the vegetation period? Location Kazbegi district, Central Greater Caucasus, Georgia. Method We analysed three shrub ( Betula litwinowii , Rhododendron caucasicum , Hippophae rhamnoides ) and one tall forb ( Veratrum lobelianum ) species occurring in the sub-alpine to alpine belt The vegetation of 52 relevés was analysed using non-metric multidimensional scaling and indicator species analysis. From field spectrometric data we simulated multispectral sensor bands ( IKONOS , Quickbird 2, RapidEye, WorldView-2) directly taken from the target species. We analysed the reflectance signature in RapidEye data from June and September. For all data sets we calculated the Jeffries-Matusita distance ( JMD ) as a separation measure and tested the reflectance signature of the single bands for differences. Results Betula litwinowii and V. lobelianum always co-occurred in our data. A high abundance of B. litwinowii could also be found in the Rhododendron cluster and vice versa, whereas the Hippophae cluster was more homogeneous. Simulated bands showed good overall separation ( JMD 1.58–2.00) of the target species. The separation increased with the increase of number of bands and inclusion of the red edge band. There was a general trend in which the reflectance from satellite images produced a lower separation ( JMD 1.20–1.55) than the simulations, with the best separation in the late vegetation period. Conclusion Our results showed the possibility to spectrally separate encroaching shrub species with a unique growth form in a high-mountain environment using simulated multispectral data and satellite imagery.