Influence of Time since Fire and Micro-Habitat Availability  on Terricolous Lichen Communities in Black Spruce  (Picea mariana) Boreal Forests

Yves Bergeron,Saliha Zouaoui,Catherine Boudreault,Pierre Drapeau

doi:10.3390/f5112793

Abstract

Terricolous lichens are an important component of boreal forest ecosystems, both in terms of function and diversity. In this study, we examined the relative contribution of microhabitat characteristics and time elapsed since the last fire in shaping terricolous lichen assemblages in boreal forests that are frequently affected by severe stand-replacing fires. We sampled 12 stands distributed across five age classes (from 43 to >200 years). In each stand, species cover (%) of all terricolous lichen species and species richness were evaluated within 30 microplots of 1 m2. Our results show that time elapsed since the last fire was the factor that contributed the most to explaining terricolous lichen abundance and species composition, and that lichen cover showed a quadratic relationship with stand age. Habitat variables such as soil characteristics were also important in explaining lichen richness. These results suggest that the presence of suitable substrates is not sufficient for the conservation of late-successional terricolous lichen communities in this ecosystem, and that they also need relatively long periods of times for species dispersal and establishment.

Highlights

In eastern Canadian black spruce (Picea mariana) boreal forests, terricolous lichens belonging to the genus Cladonia tend to be progressively replaced by feather mosses as time since the last stand replacing fire increases [1,2,3]
This study addresses a fundamental question for forest ecosystem management: is it stand age or stand characteristics that have the most influence on lichen species composition and abundance? Our results indicate that the time elapsed since the last fire was the factor that contributed the most to explaining terricolous lichen abundance and species composition
130-year age classes, and from high cover of caribou lichens associated with the youngest (Cladonia arbuscula and C. mitis) and oldest (C. rangiferina and C. stellaris)age classes

Summary

Introduction

In eastern Canadian black spruce (Picea mariana) boreal forests, terricolous lichens belonging to the genus Cladonia tend to be progressively replaced by feather mosses as time since the last stand replacing fire increases [1,2,3]. As a result of this process, old forests (>200 years) are often paludified and relatively unproductive compared with younger stands because the organic layer is a poor substrate for tree growth compared with mineral soil [17]. These relatively unproductive uneven-aged forests are known to host a rich liverwort flora [18] and a high abundance of epiphytic lichens [19], but their suitability for terricolous lichens is still poorly investigated

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Discussion

Conclusion