DOI: 10.5061/dryad.k0p2ngf7f
title: Date Creek Lichen colonization data

description: Conservation of epiphytic lichens in managed forest landscapes relies on
 understanding limitations to their dispersal and establishment after
 harvesting. A hot-spot for cephalo- and cyanolichens, the Kispiox inland
 temperate rainforest of British Columbia, Canada, is an example of where
 forest managers seek silviculture options that allow for forest harvesting
 to continue, while also conserving threatened species. To characterize
 colonization of these lichens (including the nationally-threatened
 Nephroma occultum and Lobaria retigera), we quantified thalli on
 25-year-old regenerating spruce trees at varying distances from forest
 edges in logged openings of different sizes surrounded by mature (160
 years) or old-growth (≥350 years) forest. This dataset records colonies
 observed along with the tree they were observed on and their size. The
 second dataset has information about each opening that was sampled.
description: We sampled 213 trees at varying distances from the forest canopy
 edges. For clearcuts and large gaps with a transect length ≥ 100m, we
 sampled one tree every 10 m until 50 m, then every 25 m afterwards. For
 gaps with transects 50 - 70 m we sampled a tree every 10 m. For smaller
 gaps, we sampled five equally-distributed trees along the transect. For
 the smallest gaps (transect &lt; 15 m) we sampled the best-colonized
 trees along the transect (up to 5 trees per opening). In general, we used
 a 20 m<sup>2</sup> search zone for large openings (5 m × 2 m
 on either side of transect) at each transect distance to select the tree
 with the best cephalo- and cyanolichen colonization, though for small
 openings, this search zone was smaller. At each tree,
 all cephalo- and cyanolichens &gt; 0.1 cm<sup>2 </sup>were
 counted and measured on branches below 1.5 m. To allow for efficiencies in
 data collection, the common species were only recorded on the three
 branches with the best lichen colonization. We used a 1 cm × 1 cm wire
 grid to estimate the surface area of each lichen thallus. The grid was
 placed on top of each lichen and the grid cells or fractions of grid cells
 occupied by the lichen were estimated. This approach gave a repeatable
 method of measuring thallus area compared to more subjective visual
 estimates of lichen loading. The same person measured all lichens to
 decrease measurement error. Taxonomically difficult specimens, as well as
 voucher specimens from each site, were examined in the lab. Nomenclature
 follows Esslinger (2019).    Using likelihood methods
 and Akaike’s Information Criterion (AIC) in a multiple alternate
 hypothesis framework (Burnham and Anderson 2002, Canham and Uriarte 2006),
 we examined the relationship between various measures of abundance per
 sample tree (total number of thalli, number of species (richness), number
 of thalli of each taxon) and distance from the closest forest edge along a
 north-south bearing (model 1). We also examined three additional effects
 on lichen colonization: age of the surrounding forest (model 2), size of
 the logged opening (model 3), and position within the opening (distance
 from north vs. south edge) (model 4). We also compared the models to a
 null model, which estimated lichen abundance as a simple mean multiplied
 by the tree size effect. The model with the lowest AIC
 value was considered to have the most support from the data. When models
 differed by AIC values (ΔAIC) less than 2, the more parsimonious (fewer
 parameters) model was considered superior. A simulated annealing algorithm
 (likelihood package; Murphy 2015) in the statistical software R v. 3.5.1
 calculated maximum-likelihood estimates and approximate 95% support
 intervals for the parameters in each model after 40,000–100,000 iterations
 (Goffe et al. 1994; R Development Core Team 2018).
description: Column header descriptions: TU - The treatment
 unit from the Date Creek Research Forest where the data were collected,
 with the additional clear-cuts given the codes B6 and C4
 Gap and NewGap - The gap numbers from the Date Creek Research
 Forest where the data were collected Tree.distance_m -
 The distance in meters from North to South along the transect through each
 gap DBH_cm - The diameter of the tree at 1.3 m high
 where the lichens were observed on in cm Branch_vs_Tree
 - Branch means the species was searched for on the three best branches of
 a tree, Tree means the species was searched for on the whole tree
 everywhere lower than 1.5 m high Species - 7 digit code
 for species name Area_cm - estimated surface area in
 cm<sup>2</sup> of each lichen thallus CC_YN
 - Y for opening is the size of a clear-cut (&gt;1 ha) and N for
 smaller openings Size - estimated size of opening in
 m2 NS line - distance from north to south edge of
 opening in m EW line - distance from east to west edge
 of opening in m Paula NS length - distance from north
 to south edge of opening in m remeasured by Paula during lichen
 study SurroundingStandAge - whether surrounding
 unharvested forest for each opening is better described as mature (~165
 years) or old growth (350+ years) at the beginning of the experiment in
 1992 Notes - comments on area and how calculated for
 different openings