The fate of hydnoid fungi in The Netherlands and Northwestern Europe

Changes in frequency of sporocarps of hydnoid fungi in The Netherlands since 1950 are analysed using several methods. All 22 native species show a significant decrease from 1950 onwards. For 12 species associated with Fagus and Quercus a partial recovery since 1998 is demonstrated. Among 10 species associated with Pinus nine have become extinct and no recovery is observed so far. Changes in conservation status of all species are described. The causes of changing frequencies are discussed, being mainly related to amounts of deposited nitrogen. The different reactions of symbionts of deciduous and coniferous trees are explained. The status of hydnoid fungi in The Netherlands is compared with the situation in Belgium, Germany and Sweden.