The Role of Ecological Factors in Distribution and Abundance of Terrestrial Orchids

Abstract

Distributed throughout the continents, terrestrial orchids are known for their great species richness and specificity in relation to pollinators and mycorrhizal symbionts. Moreover, a large number of them are rare and sensitive to environmental changes. This chapter is mainly focused on the terrestrial orchids of Europe and reviews the major environmental factors affecting the patterns of their distribution, abundance, and richness (elevation, latitude, longitude, area size, climatic factors, geological substrates, soil characteristics, vegetation types, effects of disturbance), as well as the significance of mycorrhizal fungi and pollination systems. Some new data, especially regarding the responses of orchids to climate change and their occurrence on specific geological and soil substrates and vegetation types, are presented. Although the distribution and abundance of terrestrial orchids are associated with the joint effects of most of the examined factors, some factors have emerged as crucial, especially on the northern and southern borders of their distribution. Furthermore, the role of environmental factors depends largely on the belowground strategies of orchids. The chapter highlights the importance of exploring the level of specialization of orchids with respect to habitat conditions as an important basis for their conservation.