DOI: 10.5061/dryad.5tb2rbpjb
title: Community dynamics of lignicolous lichens on standing deadwood in a 275-year chronosequence

description: Dead trees provide discrete habitat patches in which patch quality changes
 gradually due to wood decomposition. Although in most cases these patches
 persist for not more than a few decades, in some ecosystems deadwood
 decomposition and the consequent change in habitat patch quality can be a
 centuries-long process, potentially leading to dynamics of
 deadwood-associated communities taking place over a similar time scale. We
 studied the dynamics of lignicolous lichen communities on snags in
 near-natural European boreal forests. We surveyed lichens on 331 Pinus
 sylvestris snags and obtained their year of death with dendrochronological
 methods. The snags comprised a chronosequence of 275 years in time since
 tree death. Most lichen species (86 %) displayed an association with
 either fresh, intermediate or long-standing snags, with only few species
 occurring at a similar rate throughout the chronosequence. Thus, the
 habitat patches provided by snags were indicated to be characterized by a
 sequence of colonizations by and extinctions of lichen species with
 differing niches. Accordingly, community composition was closely connected
 to time since tree death. Associations with long-standing snags were most
 frequent (46 % of species), and consequently, species richness increased
 with time since tree death – approximately a 2.5-fold increase from 20 to
 90 years from death – but increased no further beyond 90 years since
 death. Several obligate lignicoles occurred only on long-standing snags
 indicating their dependence on this specific type of deadwood. Our
 findings show that time since tree death is a primary determinant of the
 species composition and richness of lignicolous lichens on snags. Thus,
 lignicolous lichen communities are intrinsically linked with snag dynamics
 that occur over centennial time scales in boreal forests. Lignicolous
 lichen diversity is dependent on long-persisting standing deadwood that
 typically occurs only in natural forests.
description: # Community dynamics of lignicolous lichens on standing deadwood in a
 275-year chronosequence Dataset DOI:
 [10.5061/dryad.5tb2rbpjb](https://doi.org/10.5061/dryad.5tb2rbpjb) ##
 Description of the data and file structure This file contains lignicolous
 lichen community data from 331 snags (standing dead trees) that were
 located in three near-natural forest landscapes in Finland.  The surveyed
 snags were located in 94 plots of 0.28 ha, and they represent a randomized
 sample of the decorticated snags of the plots. The year of death of the
 trees was estimated with dendrochronological crossdating. All lichens were
 surveyed on the lowest two meters of the snags. ### Files and variables
 #### File: SnagLichens_Data.xlsx **Description:** Presence-absence
 community data of lichens on the surveyed snags. Each row corresponds to
 one surveyed snag. ##### Variables * Landscape: The study landscape the
 tree was located in (Kuusamo/Lieksa/Salamanperä) * TreeSpComp: The tree
 species composition of the plot the tree was located in
 (Pine-dominated/pine-spruce mixture) * DBH: Diameter at breast height (mm)
 * TSD: Time since death (years) * Sp_richness: Total number of observed
 species * Specialists: Number of specialists of long-standing snags * Rest
 of the columns: Presence-absence of species observed in this study ##
 Code/software MS Excel, Google Sheets, or similar spreadsheet editor
 software.