Large proportion of wood dependent lichens in boreal pine forest are confined to old hard wood

Abstract

Intensive forest management has led to a population decline in many species, including those dependent on dead wood. Many lichens are known to depend on dead wood, but their habitat requirements have been little studied. In this study we investigated the habitat requirements of wood dependent lichens on coarse dead wood (diameter [10 cm) of Scots pine Pinus sylvestris in managed boreal forests in central Sweden. Twenty-one wood dependent lichen species were recorded, of which eleven were confined to old (estimated to be [120 years old) and hard dead wood. Almost all of this wood has emanated from kelo trees, i.e. decorticated and resin-impregnated standing pine trees that died long time ago. We found four red-listed species, of which two were exclusive and two highly associated with old and hard wood. Lichen species composition differed significantly among dead wood types (low stumps, snags, logs), wood hardness, wood age and occurrence of fire scars. Snags had higher number of species per dead wood area than logs and low stumps, and old snags had higher number of species per dead wood area than young ones. Since wood from kelo trees harbours a specialized lichen flora, conservation of wood dependent lichens requires management strategies ensuring the future presence of this wood type. Besides preserving available kelo wood, the formation of this substratum should be supported by setting aside P. sylvestris forests and subject these to prescribed burnings as well as to allow wild fires in some of these forests.

Forest biodiversity, ecosystem functioning and the provision of ecosystem services

“…For instance, species with poor dispersal abilities, such as epiphytic lichens or small arboreal rodents, suffer significant declines in fragmented landscapes (Jönsson et al 2017 1 ; Santaniello et al 2017;Linnell et al 2017), while the diversity of forest specialist plants in plantation forests is positively influenced by proximity to natural woodland patches providing opportunities for colonisation (Coote et al 2013). Similarly, the amount of natural forest strongly influences the distribution of birds and bats because it provides a significant part of foraging and roosting requirements at the landscape scale (Burgar et al 2015;Lindenmayer et al 2015).…”

Consequences of bioenergy wood extraction for landscape-level availability of habitat for dead wood-dependent organisms

“…One explanation for our outcome may be that old resinimpregnated pine wood occurred in the study landscape. It constitutes one of the most important substrates for dead wooddependent lichens in boreal forests (Santaniello et al, 2017). In the present study, this type of wood occurred in any dead wood category, while earlier studies have been conducted in landscapes that have been more intensively managed for a longer time, where such wood is absent.…”

Rapid legacy‐dependent succession of lichen assemblages after forest fires: Insights from two boreal regions

“…Importantly, ‘fire‐dependent’ species like Carbonicola anthracophila and C. myrmecina , which exclusively inhabit fire‐scarred wood and bark (Bendiksby & Timdal, ; Santaniello et al., ), seem to need the longest period for successful colonization (P. Lõhmus, unpubl. obs).…”

“…The forest models included time since fire (old vs recent burns), while the recent-burn models included the incidence of harvesting (forests vs cut stands). Only statistically significant models or factor sets are shown Importantly, 'fire-dependent' species like Carbonicola anthracophila and C. myrmecina, which exclusively inhabit fire-scarred wood and bark (Bendiksby & Timdal, 2013;Santaniello et al, 2017), seem to need the longest period for successful colonization (P. Lõhmus, unpubl. obs).…”