Soils of the - Agriculture and Agri-Food Canada

POIGNANT SOILS (PT)
Location and Extent : Poignant soils occur in the eastern part of the map area, mainly along the lowe r
mountain slopes adjacent to the Fraser Valley . About 2630 ha of soil complexes dominated by Poignant soils ar e
mapped ; the complexes are usually with Lonzo Creek and Cannell soils .
Topography and Elevation : Poignant soils are steeply to extremely sloping ; most slope gradients ar e
between 30 and 70 percent. Elevations range from about 20 to 600 m above sea level .
Parent Material and Texture : The parent material of Poignant soils is a medium to moderately coars e
textured, stony, mixture of silty eolian deposits and colluvium . 'The deposits are deeper than 1 m and overli e
bedrock . Surface textures vary from gravelly silt loam to gravelly sandy loam, the subsurface is mostly gravell y
sandy loam or gravelly loam while the subsoil varies from gravelly sandy loam to gravelly loamy sand . Stones ,
cobbles, and sometimes boulders are common throughout the soil .
Soil Moisture Relationships : Poignant soils are well drained . They are rapidly pervious and have moderat e
to low water holding capacity and moderate to slow surface runoff . Temporary telluric seepage occurs in som e
areas along the surface of the underlying bedrock after heavy rain .
General Soil Description : Poignant soils generally have up to 10 cm of variably decomposed organi c
forest litter on the soil surface . This is underlain by about 20 cm of reddish-brown to dark brown, friable, weakl y
structured, silty to loamy material containing variable amounts of fine, spherical concretions and usually 30 t o
60 percent coarse fragments (gravel, stones and cobbles) . This zone then grades into about 30 cm of friable t o
loose, yellowish-brown to brown, sandy or loamy material containing between 40 and 70 percent coars e
fragments . Under this, in turn, is 50 cm or more of loose, gravelly and stony colluvium which overlies bedrock or ,
occasionally, glacial till . Soil reactions vary from very strongly or strongly acid in the upper soil to medium or
slightly acid in the lower subsoil . Soil classification is usually Orthic Humo-Ferric Podzol although smal l
inclusions of Orthic Dystric Brunisol also occur in areas that are somewhat unstable .
Commonly Associated Soils : Lonzo Creek, Cannell and Eunice soils and Rock Outcrop land type usuall y
are closely associated with Poignant soils . Lonzo Creek soils differ from Poignant soils by consisting of 20 to 5 0
cm of silty aeolian material over glacial till . Cannell soils differ by being underlain by bedrock within 100 cm o f
the surface while Eunice soils differ by being composed of 10 cm or more of organic material over bedrock . Th e
Rock Outcrop land type consists either of exposed rock or rock covered by less than 10 cm of mineral or organi c
material .
Vegetation : The usual vegetation on Poignant soils is second-growth forest that includes coast Douglas-fir ,
some western red cedar and western hemlock, red alder, vine and bigleaf maple and a variable shrub cover .
Rooting, except for limitations imposed by stoniness, is essentially unrestricted down to the underlyin g
bedrock .
General Land Use Comments : (1) Excessive slopes and stoniness make Poignant soils unsuitable fo r
agricultural use . (2) Excessive slopes, relative shallowness to bedrock and potential instability also mak e
Poignant soils unsuited for urban uses . (3) Forest growth is moderate, limited somewhat by low water holdin g
capacity and resultant droughty conditions during most growing seasons . Poignant soils are frequently closel y
intermingled with soils of differing character making them difficult to manage individually. Estimated annual
wood production by coast Douglas-fir is about 6 .5 to 9 m 3/ha .
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