Canadian Forest Service Publications
Soil parent material may control forest floor properties more than stand type or stand age in mixedwood boreal forests. 2004. Lamarche, J.; Bradley, R.L.; Paré, D.; Légaré, S.; Bergeron, Y. Écoscience 11(2): 228-237.
Issued by: Laurentian Forestry Centre
Catalog ID: 39530
Availability: PDF (request by e-mail)
Soil quality in the boreal mixedwood forest depends to a certain extent on the chemical, biochemical, and microbial properties of the forest floor. Given that forest floors are composed mainly of decomposing plant detritus, forest composition (i.e., stand type) should play a key role in determining soil quality. Stand age is also expected to control certain forest floor properties, due to the balance in the amount and quality of substrates introduced into, and lost from, the forest floor during stand development. Finally, mineral parent material should also be related to some forest floor properties, by controlling site nutrient capital which may affect litter quality. In order to compare the relative effects of these three factors, forest floor material was collected in the Abitibi region of northwestern Québec, from replicated (n = 3) treatment plots comprising a factorial array of three stand types (spruce/fir, aspen, and paper birch), three stand ages (57, 78-85, and 131 y-old), and two parent materials (clay and till). Forest floor samples were compared on the basis of 18 variables depicting I) chemical properties, ii) base cation status, iii) nitrogen cycling, and iv) microbial properties. All three sampling factors exerted a significant effect on some of the measured forest floor properties, but parent material has a significant effect on twice the number of forest floor properties as did stand type or stand age. Besides exerting an effect on nutrient capital, we propose that parent material also affects cation exchange capacity and unsaturated hydraulic conductivity, which in turn influence litter quality and ecosystem productivity. Our results suggest, therefore, that a detailed classification of mineral parent materials might be a useful basis for interpreting and predicting soil quality in the mixedwood boreal forest.