Analysis of Forest Soils
Four types of forested landscapes are found throughout Canada: Organic, Luvisolic, Brunisolic, and Podzolic.
Organic soils occur where water accumulates to such a degree that decomposition of organic matter by microorganisms is suppressed or essentially eliminated, and layers of organic material (commonly called peat) build up over time. The remaining three orders are found in better drained forest landscapes and at the broadest level their distribution is controlled by the nature of the parent material and by climate.
Soils of the Luvisolic order are dominant in forested landscapes underlain by tills derived from underlying sedimentary rocks or on clayey lacustrine deposits. Because the glacial materials have a sedimentary rock origin they are relatively high in clay and in base cations such as calcium and magnesium. The diagnostic feature of Luvisolic soils is a textural contrast between the A and the B horizon – the Ae horizon has less clay than the Bt horizon. Because of the high base cation content these soils typically have neutral or alkaline pH values although some acidic Luvisols are found, especially in eastern Canada.
Soils of the Brunisolic and Podzolic orders are found in the same basic parent material type and differ primarily in terms of soil moisture available for soil-forming processes. They are both forested soils found primarily on sandy parent materials in areas underlain by igneous rocks, most prominently on the Canadian Shield, but are also found in other regions on sandy glacio-fluvial deposits. Podzolic soils are dominant on sandy deposits in ecozones or parts of ecozones where the mean annual precipitation is above about 700 mm. At mean annual precipitation levels below this Brunisolic soils are found on the same types of sandy deposits, most notably through NW Ontario and the Canadian Shield in the Prairie provinces. Coniferous-dominated plant communities are the major vegetation type found on both types of soils.
Organic soils occur where water accumulates to such a degree that decomposition of organic matter by microorganisms is suppressed or essentially eliminated, and layers of organic material (commonly called peat) build up over time. The remaining three orders are found in better drained forest landscapes and at the broadest level their distribution is controlled by the nature of the parent material and by climate.
Soils of the Luvisolic order are dominant in forested landscapes underlain by tills derived from underlying sedimentary rocks or on clayey lacustrine deposits. Because the glacial materials have a sedimentary rock origin they are relatively high in clay and in base cations such as calcium and magnesium. The diagnostic feature of Luvisolic soils is a textural contrast between the A and the B horizon – the Ae horizon has less clay than the Bt horizon. Because of the high base cation content these soils typically have neutral or alkaline pH values although some acidic Luvisols are found, especially in eastern Canada.
Soils of the Brunisolic and Podzolic orders are found in the same basic parent material type and differ primarily in terms of soil moisture available for soil-forming processes. They are both forested soils found primarily on sandy parent materials in areas underlain by igneous rocks, most prominently on the Canadian Shield, but are also found in other regions on sandy glacio-fluvial deposits. Podzolic soils are dominant on sandy deposits in ecozones or parts of ecozones where the mean annual precipitation is above about 700 mm. At mean annual precipitation levels below this Brunisolic soils are found on the same types of sandy deposits, most notably through NW Ontario and the Canadian Shield in the Prairie provinces. Coniferous-dominated plant communities are the major vegetation type found on both types of soils.