How Agriculture Affects Lichen Vegetation in Central Switzerland

Abstract

The results from several floristic and bioindication projects in Central Switzerland (1986–1998), focusing on the effects of agriculture, particularly from nitrogen and agrochemical emissions, are summarized. The abundance of nutrienttolerant lichen species and the decreased occurrence of nitrophytic lichens are both correlated with agricultural land use and high atmospheric deposition. The impact could be demonstrated not only by the distribution patterns of nutrient-tolerant species, but also by the high N content of lichens such as Physcia caesia. Positive growth response of Cetraria islandica to application of mineral nutrients and increased CO₂ in open-top chambers at high altitudes was also observed. The methods and a survey of the results from studies conducted within the framework of the lichen research programme of the Natural History Museum of Lucerne are presented here. A discussion of the issues shows the need for further studies concerning the influence of introduced nutrients on the biodiversity of lichens.