Soils of the - Agriculture and Agri-Food Canada

PALISADE SOILS (PA)
Location and Extent : Palisade soils are relatively common at the upper elevations in the mountainous ,
northern part of the map area . About 190 ha of pure map units and 3630 ha of soil complexes dominated b y
Palisade soils are mapped . The complexes are mostly with Sayres, Dennett and Whonnock soils and Talus and
Rock Outcrop land types .
Topography and Elevation : Palisade soils are usually very steeply sloping with some variation to extremel y
sloping . Slope gradients are in excess of 30 percent and elevations range upwards from 800 m above sea level .
Parent Material and Texture : Palisade soils have developed from moderately coarse textured, ston y
colluvial deposits at least 1 m deep and overlying mostly bedrock or sometimes, compact glacial till . The soi l
surface consists of mostly well-decomposed organic forest litter up to 25 cm thick . The upper mineral soi l
material varies from gravelly loam to gravelly sandy loam and grades to gravelly sandy loam or gravelly loam y
sand with increasing depth . Coarse fragment content varies from about 30 to 50 percent in the upper part of th e
mineral soil to between 50 and 80 percent below 100 cm .
Soil Moisture Characteristics : Palisade soils are moderately well drained . They are moderately to rapidly
pervious and have moderate to low water holding capacity and moderate surface runoff . Telluric downslop e
seepage is usual below about 100 cm depth during snowmelt and heavy rains .
General Soil Description : Palisade soils generally have from 15 to 25 cm of organic forest litter on the soi l
surface which consists mainly of black to very dusky red, friable, well-decomposed material . This is underlai n
by a 5 to 10 cm thick, grayish-brown or gray, friable, strongly leached, sandy layer which, in turn, is abruptl y
underlain by a dark brown to very dusky red, friable, weakly structured, loamy or sandy zone about 50 cm thick .
This zone grades to about 50 cm of brown to dark brown, friable, sandy material containing common, reddish o r
yellowish mottles in the lower part . Under this is massive, firm, olive-brown or grayish-brown, gravelly, un -
weathered colluvial parent material that contains variable amounts of reddish mottles . Angular gravel, stones ,
cobbles and boulders occupy about 30 to 50 percent (by volume) of the upper mineral soil and increase t o
between 50 and 80 percent in the lower depths . Soil reaction is extremely acid in the upper 100 cm, the n
decreases to very strongly or strongly acid . Soil classification is Orthic Ferro-Humic Podzol .
Commonly Associated Soils : Sayres, Dennett, Whonnock and Golden Ears soils and Rock Outcrop an d
Talus land types are usually closely associated with Palisade soils . Whonnock and Golden Ears soils differ fro m
Palisade soils by having developed from glacial till and contain strongly cemented subsoil layers . Also ,
Whonnock soils are imperfectly drained . Sayres soils differ from Palisade soils by being underlain by bedroc k
within 100 cm of the surface while Dennett soils consist of 10 cm or more of organic material over bedrock . Th e
Talus land type differs by consisting of actively accumulating colluvial debris while the Rock Outcrop land typ e
consists either of exposed bedrock or bedrock covered by less than 10 cm of mineral or organic soil .
Vegetation : Unlogged areas of Palisade soils support old-growth coniferous forests consisting mostly of
Pacific silver fir, mountain hemlock and yellow cedar with a relatively dense ericaceous shrub layer and soi l
surface moss cover. In the lower part of the soils' elevational range some western hemlock and western re d
cedar are intermixed . Rooting depth is essentially unrestricted . Most roots, however, are concentrated in th e
upper 100 cm .
General Land Use Comments : (1) Very steep slopes preclude any use of Palisade soils for agriculture . (2 )
Steep slopes and potentially unstable conditions also preclude urban and related development . (3) Fores t
growth is moderate, limited mainly by the adverse climatic conditions present at the high elevations in whic h
Palisade soils are found . Potential annual wood production by western hemlock and Pacific silver fir is estimate d
to be between 6 and 8 m 3/ha . Palisade soils appear relatively stable under presently forested conditions bu t
logging road construction will likely make the steeper areas relatively unstable, particularly if high cut slopes are
produced and adequate culverting is not installed to control seepage and runoff .
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