Abstract Detail

Bryological and Lichenological Section/ABLS

Simpson, Michael [1], Dale, DR. M.R.T. [1].

Does substrate affect the potential for establishment of boreal feather mosses after forest fire?.

The rarity of boreal feather mosses for several years after a forest fire is believed to be due to their low dispersal ability and hostile environmental conditions. However, their establishment will also depend o­n the suitability of available substrates. Substrate chemistry, physical structure and water-holding capacity influence plant growth. After a forest fire, substrate pH can be relatively high. Low severity fires leave char o­n the forest floor that does not retain moisture and is nutrient-poor. Even mineral soil dries rapidly in burned sites. Forests where feather mosses are abundant have low exposure, comparatively high humidity, nutrient-containing throughfall, and an acidic humus substrate beneath the moss carpet. I compared the growth of 3 sizes of vegetative fragment (branches, shoot tips and mulch) from 2 feather mosses, Schreber's moss (Pleurozium schreberi) and knight's plume (Ptilium crista-castrensis), o­n 3 burned substrates (ash, burned mineral soil and burned moss) and o­n humus from an undisturbed stand. The initial mean pH of the substrates was: burned moss 4.3, humus 4.6, mineral soil 5.6 and ash 9.0. In a growth chamber, 12 replicates of each fragment-size/species/substrate combination were watered weekly to keep them moist. Another 12 replicates were watered bi-weekly. After 95 days in the high moisture treatment, over half of all Pleurozium branches had new shoots o­n all substrates except ash, and Pleurozium fragments had produced protonemata in 9 humus and 12 burned moss replicates. o­nly o­ne Ptilium branch had new shoots. In the low moisture treatment, o­nly Pleurozium fragments produced growth, and most frequently o­n mineral soil, which rarely dried out. These results suggest that burned substrates do not inhibit shoot production o­n Pleurozium fragments under adequate hydration. Ptilium fragments, however, might be less effective propagules. My research addresses outstanding question concerning post-fire succession in economically important coniferous boreal forests.

1 - University of Alberta, Department of Biological Sciences, CW 405 Biological Sciences Building, Edmonton, Alberta, T6G 2E9, Canada

Keywords:
succession
Pleurozium schreberi
Ptilium crista-castrensis
post-fire substrates
boreal forest.

Presentation Type: Paper
Session: 51-2
Location: Magpie (Cliff Lodge)
Date: Wednesday, August 4th, 2004
Time: 1:15 PM
Abstract ID:54