Terrestrial lichen data for Saskatchewan, Canada

Increased fire activity due to climate change may impact the successional
dynamics of boreal forests, with important consequences for caribou
habitat. Early successional forests have been shown to support lower
quantities of caribou forage lichens, but geographic variation in, and
controls on, the rates of lichen recovery have been largely unexplored. In
this study, we sampled across a broad region in northwestern Canada to
compare lichen biomass accumulation in ecoprovinces, including the
Saskatchewan Boreal Shield, the Northwest Territories Taiga Shield and
Northwest Territories Taiga Plains, divided into North and South. We
focused on the most valuable Cladonia species for boreal and barren ground
caribou: Cladonia mitis and C. arbuscula, C. rangiferina and C. stygia, C.
stellaris and C. uncialis. We developed new allometric equations to
estimate lichen biomass from field measurements of lichen cover and
height; allometries were consistent among ecoprovinces, suggesting
generalizability. We then used estimates of lichen biomass to quantify
patterns of lichen recovery in different stand types, ecoprovinces, and
with time following stand-replacing fire. We used a hurdle model to
account both for the heterogeneous nature of lichen presence
(zero-inflation), and the range of abundance in stands where lichen was
present. The first component of the hurdle model, a generalized linear
model (GLM), identified stand age, stand type and ecoprovince as
significant predictors of lichen presence. With a logistic growth model, a
measure of lichen recovery (time to 50% asymptotic value) varied from 28
to 73 years, dependent on stand type and ecoprovince. The combined
predictions of the hurdle model suggest the most rapid recovery of lichen
biomass across our study region occurred in jack pine in the Boreal Shield
(30 years), while stands located in the Taiga Plains (North and South)
required a longer recovery period (approximately 75 years). These results
provide a basis for estimating future caribou habitat that encompasses
some of the large variation in fire effects on lichen abundance and
vegetation types across the range of boreal and barren ground caribou in
North America.