Shedding light on arctic-alpine plants: the understudied photobiological responses in the context of climate change.

Arctic-alpine plant populations can be found across latitudinal, altitudinal, micro-topographical and abiotic gradients within the tundra biome, thus experiencing unique combinations of microclimatic niches, geological substrates and light environments. Rising temperatures have been the focus in arctic-alpine research, yet the interest in photic barriers and spectral light requirements is rising in current research. Although ecotypic differences across latitudes and altitudes have been observed and circadian activity under continuous light has been investigated, arctic-alpine photobiology is critically understudied despite its eco-physiological relevance. Experimental studies considering light among the abiotic factors, either for its relevance for photosynthesis or as a potential cue regulating phenology, are not only scarce but they also showcase marked heterogeneity in terms of experimental designs, with only few studies offering comparisons among populations. We argue that arctic-alpine plant species are fitting photobiological research targets thanks to their realized niches and ecological relevance.