More than just a plant: cushion plants as biodiversity protectors in high mountains of Siberia

The Siberian cushion plants have been little studied. This research aimed to reveal their morphological and ecological features as enabling them to survive and to protect biodiversity in a changing environment. The research was conducted in the Altai Mountains, Russia, at 1750–4000 m a.s.l. The temperature of cushion plants, the surrounding air and soil were studied. Substrate samples from cushions and topsoil were taken and analysed. Indices of hydrolytic acidity, loss on ignition and percentage of humus, phosphorus and nitrogen were taken into account in soil analysis. Bryophytes and vascular plants inhabiting cushions were studied. Fifty-four cushion plant species were classified into six morphological types based on the cushion skeleton construction and divided into ‘obligate’ and ‘facultative’ cushion plants. The temperature inside the cushions is much more stable, than that of their environment. Accumulation of organic matter within the cushions and in the sphere of their vital functions represents a process of local primary soil formation and makes cushion plant communities indifferent to the ground quality. The functional features of the cushion plants allow them to occupy high-mountain habitats and to be the centres of communities including other plants and animals, which can be found in an extreme environment only within or near the cushions, increasing the biological diversity of the alpine mountain zone