Canadian Forest Service Publications

The impact of Calamagrostis canadensis on soil thermal regimes after logging in northern Alberta. 1991. Hogg, E.H.; Lieffers, V.J. Canadian Journal of Forest Research 21(3): 387-394.

Year: 1991

Issued by: Northern Forestry Centre

Catalog ID: 11210

Language: English

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Abstract

The grass Calamagrostiscanadensis (Michx.) Nutt. often forms a dense growth after logging in the boreal forest region of western Canada. Mowing treatments were applied experimentally to examine the effects of C. canadensis shoot biomass and litter on soil thermal regimes. In unmowed sites with heavy accumulations of shoot biomass and litter (768 g•m-2), thawing of soil in the spring was delayed by up to 1 month compared with sites subjected to frequent mowing. Mean soil temperature from May to August at the 10-cm depth averaged 3.8 °C warmer in mowed plots than in unmowed plots. Mowing also caused a three- to four-fold increase in the diurnal variation in soil temperature. Based on the results from different mowing treatments, it appeared that the presence of standing dead C. canadensis shoots and litter was more important than living biomass in producing cold soils. Undisturbed sites dominated by Epilobiumangustifolium L. (fireweed), which does not form a persistent litter layer, had warmer soils than unmowed C. canadensis sites. Cold soils could partly explain the poor growth of conifer seedlings that often occurs after planting in grass-dominated boreal sites.