Alpine lichen-dominated heaths: ecology, effects of reindeer grazing, and climate change. A review

Abstract

Lichens are important forage for reindeer during winter, making evaluation of lichen biomass important for reindeer population management. Lichen heaths have a scattered distribution at high latitudes and altitudes in Fennoscandia. During the last few decades, their decrease has been attributed to reindeer grazing and trampling as well as climate change. Some consider this decrease to be the result of competition from vascular plants. However, we believe that this is a far too simple an explanation. In many studies the most important factor - deep soils with long-lasting frost - has not been considered. As a result, anticipated long-term effects of climate change and grazing should be reconsidered. Lichens have no roots, and therefore, environmental and edaphic conditions have limited direct effects on lichen abundance. Vascular plants live in contact with two different environments; the atmosphere and the rhizosphere, and ecological factors within both affect them. It is imperative to know which environmental factors increase the possibility of maintenance and development of extensive lichen heaths. In this review, we use current ecological knowledge to discuss the ecology of alpine lichen heath distribution and possible reasons for their decline, both at present and in the future.