A review of reindeer lichen (Cladonia subgenus Cladina) linear growth rates

Richard Troy Mcmullin,Sean Rapai

doi:10.7557/2.40.1.4636

Abstract

Cladonia subgenus Cladina (the reindeer lichens) can be a dominant part of terrestrial ecosystems worldwide. They are particularly abundant in arctic-alpine and boreal regions, where they are a primary food source for woodland caribou/reindeer in winter months. Determining the growth rates of reindeer lichen is important for understanding and managing lichen regeneration following disturbances such as timber harvesting, mining, grazing, and wildfire. Regeneration and rehabilitation rates can be calculated with greater accuracy when growth rates are well understood. We provide a summary of 17 studies from 6 countries that determined the linear growth rates of three reindeer lichen groups, Cladonia arbuscula/mitis (mean = 4.7 mm/yr.), C. rangiferina/ C. stygia (mean = 5.1 mm/yr.), and C. stellaris (mean = 4.8 mm/yr.). We use linear growth rates as a proxy for over-all growth and biomass. Variables found to influence lichen growth rates are also discussed, which include light, moisture, temperature, air pollution, acid rain, precipitation, snow accumulation, substrate, age of individuals, and type of disturbance. These results can assist land managers in developing more accurate strategies for restoring lichens in disturbed areas.

Highlights

Cladonia subgenus Cladina is a group of fruticose lichens that are richly branched and lack an outer cortex (Brodo et al, 2001; Smith et al, 2009)
We provide a summary of 17 studies from 6 countries that determined the linear growth rates of three reindeer lichen groups, Cladonia arbuscula/mitis, C. rangiferina/ C. stygia, and C. stellaris
In Canada, multiple populations of woodland caribou are listed on Schedule 1 of the federal Species at Risk Act, which means the number of individuals is declining and they are at risk of extinction or extirpation (SARA, 2019)

Summary

Introduction

Cladonia subgenus Cladina (the reindeer lichens) is a group of fruticose lichens that are richly branched and lack an outer cortex (Brodo et al, 2001; Smith et al, 2009). Reindeer lichens are the primary winter food source for woodland caribou (Rangifer tarandus caribou; Bergerud & Nolan, 1970; Eriksson et al, 1981; Newmaster et al, 2013; Thompson et al, 2015). They are an important component of the winter diet of reindeer (Rangifer tarandus) in Russia (Andreev, 1977) and Scandinavia (Skogland, 1984; Kumpula, 2001), where reindeer have an important economic and cultural role as livestock in northern regions (Sandström, 2003; Rangifer, 40, (1) 2020. Since reindeer lichens are a major part of the winter diet of woodland caribou (Bergerud & Nolan, 1970; Newmaster et al, 2013; Thompson et al, 2015), they are an essential component in restoring caribou winter habitat (Duncan, 2015; Rapai et al, 2017; Rapai et al, 2018)

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