Wood anatomical analysis of Swiss willow (Salix helvetica) shrubs growing on creeping mountain permafrost

Permafrost and related landforms (rockglaciers) are widespread phenomena in alpine geosystems. In the context of changing environments due to the significant warming, there is a need for thorough monitoring and analyzing the complex responses of these cryospheric geosystems. Here, the first-time application of wood anatomical methods in this context is presented in order to investigate whether rockglacier movement is reflected in varying cell structures of plants growing on top of the rockglaciers.In order to determine the influence of ground movements (by permafrost creep) and their influence on the conductive elements within roots of plants, wood-samples were taken from active and inactive rockglaciers in the Turtmann Valley, southern Swiss Alps. Since the occurrence of trees is limited altitudinally, the investigation was restricted to Swiss willow shrubs (Salix helvetica) frequently growing in permafrost areas above the timberline in the European Alps. This rather new approach concentrates on general vessel size differences as a result of mechanical stresses. The comparison of vessel sizes in roots of Swiss willow shrubs growing on active and inactive permafrost bodies depicts differences within the roots, which are related to the activity status of the respective rockglacier creep.