Habitat associations of red-listed epiphytic lichens in Finland

Abstract

The Finnish red list shows that the epiphytic lichen flora of Finnish forests is highly threatened and declining steeply. Red lists provide limited information on the habitat associations of threatened species, which could be relevant in informing management and conservation measures. We used documented empirical data and expert assessments to determine for each red-listed (IUCN categories Near Threatened, NT; Vulnerable, VU; Endangered, EN; Critically Endangered, CR; Regionally Extinct, RE) epiphytic lichen species of Finland the following key habitat associations: host tree species, substrate type, habitat type, geographical distribution, preferred microclimate, and minimum required forest and tree age. The most important host tree species were Picea abies (L.) H. Karst. and Populus tremula L. Other tree species of high importance included Sorbus aucuparia L. and Salix caprea L. One fourth of red-listed epiphytic lichens were primarily lignicolous. Most species required old-growth forests (required by 41% of species) or old trees (52%), but many species required only mature forests (36%) or trees (35%). The microclimatic preferences of most red-listed epiphytic lichens consisted of high or intermediate light availability and humidity. Most species whose status had deteriorated were dependent on deciduous trees. The continuous availability of old deciduous trees (especially Populus, Salix and Sorbus) requires special attention in both managed and protected forests. Red-listed epiphytic lichens would be aided by increased forest protection or transitioning to less intensive management regimes.

Time-lag effects of habitat loss, but not fragmentation, on deadwood-dwelling lichens

“…We assume that the observed stronger effect of past habitat amount on red-listed than nonred-listed species was not due to a difference in the time lag itself, but simply to stronger effects of landscape habitat amount in general on red-listed species. Red-listed lichen species are typically more specialized to old forest habitats (Nirhamo et al 2023), while non-red-listed species are more likely to occur even in the matrix (young forests) if suitable deadwood substrates are available. Therefore, the amount Page 13 of 16 111…”