DIVISION S-5—SOIL GENESIS, MORPHOLOGY,AND CLASSIFICATION

Landform-Soil-Vegetation-Water Chemistry Relationships, Wrigley Area, N.W.T.:I. Morphology, Classification, and Site Description1

M. E. WALMSLEY AND L. M. LAVKULicn2

ABSTRACT

Five landforms occurring in the intermittent permafrostregion of the Mackenzie Valley are described. The five land-forms, consisting of distinct soil and vegetative characteristicsoccur on a transect from the 1170 m ASL (above sea level)position at the summit of Cap Mountain, Wrigley area, N.W.T.,to approximately 500 m ASL at the base of the slope. Two soilsmeet the requirement of a histic epipedon. An area of stonestripe and stone ring formation was encountered at approxi-mately 1000 m ASL and an extensive area of lichen-coveredpolygonal bogs occurred at approximately 500 m ASL. The soilsare described in relation to environmental factors and theprocesses of cryoturbation causing intermittent horizons arediscussed.

Additional Index Words: alpine soils, toposequence, soil-landform relationships, boreal forest soils, arctic vegetation.

A LTHOUGH it is often reported that there is a dearth of-Tx knowledge with respect to northern development espe-cially concerning environmental factors, much informationis available regarding environmental factors in the BorealForest regions of Canada (Roberts-Pichette, 1972). Muchof this information, however, is indirect for much of north-ern Canada as it is often extrapolated from areas not di-rectly within the areas of concern, e.g., the MackenzieValley. In this light, a study was conducted to illustrate therelationships between soil, vegetation, landform, and waterchemistry in the intermittent permafrost region of the Mac-kenzie Valley my means of a transect from the 1170 mASL of Cap Mountain, to the 500 m ASL position at thebase of the mountain.

STUDY AREA

The study area is located within the northern part of the In-terior Plains containing the Mackenzie Plain, east of the Mac-kenzie Mountains (Fig. 1). Climatically, the study area is northof the summer limit of permafrost (Brown, 1970). The area hasa climate that is considered subarctic (Brandon, 1965), typifiedby cool, short summers with temperatures above 10C. The long,cold winters have led to considerable ice buildup in some of thedifferent terrain types in the Wrigley area. Table 1 presents a

1 Contribution from the Dept. of Soil Science, Univ. of BritishColumbia, Vancouver, V6T IW5, Canada. Financial support wasreceived from the Canada Dept., Indian and Northern Affairsunder the Arctic Land Use Research Program (ALUR). Re-ceived 15 Mar. 1974. Approved 5 Nov. 1974.2 Research Associate and Associate Professor respectively,Dep. of Soil Sci., The Univ. of British Columbia, Vancouver 8,B.C.

summary of the climatic parameters. A 10-year average is givenfor the mean maximum and minimum temperatures whereas a25-year average is given for the remaining parameters. Thegeology of the area has been documented by the publicationsof Craig (1965), Hume (1954), Stott (1960) and Douglas andNorris (1960). The entire lowland area has been covered bya continuous mantle of glacial and postglacial deposits. Exten-sive areas of organic terrain are common throughout this region(Lavkulich, 1970; 1971; 1972).

The study area is located on the southeast slope of CapMountain, a dominant physiographic feature of the landscapein the Wrigley area. Geographically, the transect extended froma semiflat alpine meadow area at the top of Cap Mountain(1170 m ASL) to an area of stone stripe and stone ring forma-tion at approximately 1000 m ASL which further extended intoa rocky area consisting mainly of broken rock fragments andcolluvium at 800 m ASL. From this area, the transect extendedto the foot of the slope which consisted of an extensive area ofcoalescing fans, dissected in certain locations by erosional drain-age channels flowing down the mountain slope. The coalescingfan area located between 700 and 550 m ASL, gradually ex-tended into a small forest of stunted Picea mariana whichabruptly merged with an area of lichen-covered polygonal bogsat approximately 500 m ASL.

RESULTS AND DISCUSSION

The study area is schematically presented in Fig. 2. Dueto the remoteness of the area, no data was available regard-

Beaufort Sea

ATKINS...POINT*\ Amundsen Gulf

IAYOGIAK ^^^^LV

NORTHWEST

FORT GOOD HOPE

TERRITORIES

ALBERTA

Fig. 1—Geographic location of study area, Wrigley, N.W.T.

84

WALMSLEY & LAVKULICH: LANDFORM-SOIL-VEGETATION-WATER CHEMISTRY RELATIONSHIPS: I. 85

Table 1—Selected climatic data of the Wrigley area

Month

JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember

MeanMaximum

-27.0-20.2-11.3

3.2

13.620.622.520.211.30.9

-21.8

TernMean

Minimum

-34.8-29.8-23. 1

9.90.67.19.67.00.3

-5.8-22.2-26.3

perature

Maximum

-9.9-7.43.3

13.323.728.730. 828.320.312.6-1.8

-10.8

Minimum

-45.1-43.1-36.7-23.0

7.0-0.3

1. 8-1.16.0

-18.6-35.2-42.4

with freezingtemperature

312831271410.31.6

10283031

Total

1.951.250.981.522.303.605.034.783.322.702.122.10

Precipitation

with 0. 01or more

10.98.67.66.87.09.1

10.79.38.49.2

10.79.3

Snowfall

19.512.510.013.54.80.00.00.03.5

20.822.520.0

ing soil temperatures or air movement patterns. From siteobservations, it is believed that windswept conditions pre-vail at the summit of the mountain as well as on the slope.This has the effect of causing the soil to freeze early in thefall and warm fairly rapidly in the spring. As a result thisarea was locally more arid than the other sites, with soiltemperatures closely paralleling air temperature patterns.The coalescing fan area at the base of the slope is believedto be less windswept and covered by a considerable depthof snow in winter, as indicated by numerous examples ofkrummholz vegetation. This has the effect of causing themean soil temperatures to be higher during the wintermonths than the corresponding air temperature. Dependingon the duration of the snowpack in this area, the mean soiltemperatures will remain lower than mean air temperaturesduring the spring months. Similar to the areas at the top ofthe mountain, the polygonal bog area is considered to begenerally windswept with the exception that large drifts of

snow will accumulate within the scattered clumps of treesdotting the landscape in this area. As mentioned above, thiswill result in a rapid cooling of the ground as winterapproaches and subsequently a rapid warming during thespring. The presence of a thick, insulating mat of organicmaterial on this landform coupled with these climatic char-acteristics is considered conducive for polygonal groundformation (Britton, 1957).

Each of the five landforms was described and character-ized. Within each landform a modal soil pit was selected.The pedons were examined in the field using standard tech-niques. Bulk samples were taken of each major horizonand returned to the laboratory for processing and analyses.Depths and horizonations are those recorded in the fielddescription. The following is a description of each landformproviding profile descriptions, major vegetation and obser-vational field data.

40-

PergelicCryofibrist

LANDFORMS

I. Alpine Meadow

EC. Stone Stripe and Stone Ring

m. Colluvial Slope

EL. Coalescing Fan

3C. Polygonal Bog

EL

20-

cm

0-

20-

40-

m

Horizon

^^j|l,l TT-rr'l c

ELEVATION ABOVECAP MOUNTAIN SEA LEVEL (meters)

r 1200

1100

1000

900

800

700

- 600

- 500

frozen

PergelicCryohemist

Lithic

Cryochrept

Pergelic

Cryochrept

TypicCryaquept

Fig. 2—Schematic representation of a toposequence of soils and their relationship to the landform units in the Wrigley area, N.W.T.

86 SOIL SCI. SOC. AMER. PROC., VOL. 39, 1975

Alpine Meadow Area: Pergelic Cryohemist

This very poorly drained soil occurs on a 2% slope. Theregolith is a calcareous glacial till and loess mixture. Bed-rock in the area is dominantly sandstone and quartzite.

Hori-zon

OiDelOe2

Depth,cm

0-1111-23

23 +

DescriptionDark brown (10 YR 4/3, moist); pH 3.0Dark brown (7.5 YR 3/2, moist); pH 4.3Very dark grayish brown (10 YR 3/2, moist);pH4.3

The alpine meadow consists of a very poorly drained areasurrounding a small alpine lake (tarn). The organic mate-rial, frozen at approximately 30 cm is dissected by drainagelines forming a polygonal pattern, resultant from the wind-swept and locally arid nature of this area. A histic epipedonhas developed in this environment with the dominant soilbeing a Pergelic Cryohemist according to the Soil Taxon-omy of the USDA (1968). Ecologically, the area is typifiedby a well developed shrub layer consisting of Betula glan-dulosa, Salix spp., Salix reticulata and Potentilla fruticosa.The predominant species in the rich herb layer are Dryassp., Lupinus arcticus, Anemone parviflora, Pediculariskanei, Saxifraga bronchialis, Aconitum columbianum andArnica sp. Feathermosses (Hylocomium splendens, Pleu-rozium schreberi and Ptilium crista-castrensis) and lichens(Cetraria cuculata and Alectoria octocruka) are abundant.

Stone Stripe Area: Pergelic Cryochrept

These moderately well drained soils occur on 10 to 15%slopes on gently undulating colluvial fans. The regolith isa mixture of calcareous loamy glacial till and colluvium.Each of the four sample sites on this landform is describedconsecutively below (see Fig. 3).

Hori-zonAl

B21

B22

B23

Hori-zon

Al

Ob

Depth,cm0-3

3-23

23-38

38-48

48+

Depth,cm0-4

4-12

SlTEl

DescriptionBlack (5 Y 2/2, moist; 7.5 YR 3/2, dry);sandy clay; weak granular structure; veryturfy; pH 5.1; clear smooth boundary.Brown (10 YR 5/3, moist); clay loam;moderate fine subangular blocky structure;friable; pH 6.3 gradual irregular boundary.Grayish brown (10 YR 5/2, moist); clayloam; moderate coarse blocky structure;friable; pH 6.3; gradual irregular boundary.Grayish brown (2.5 Y 5/2, moist); clay loam;moderate very coarse subangular blockybreaking to moderate fine subangular blockystructure; friable; pH 5.9; gradual wavyboundary.Dark brown (10 YR 3/3, moist); clay loam;coarse subangular blocky structure; firm;pH 6.8; clear wavy boundary.

SITE 2

DescriptionDark reddish brown (5 YR 2/2, moist);sandy clay loam; weak granular structure;turfy; pH 5.9; clear wavy boundary.Dark brown (7.5 YR 3/2, moist); pH 6.4;gradual irregular boundary.

B21

B22

C

Hori-zon

Al

B21

B22

C

Hori-zon

Al

B21

B22

C

12-22

12-22

47 +

Depth,cm

0-10

10-20

20-29

29 +

Depth,cm0-3

3-13

13-23

23 +

Brown (10 YR 5/3, moist); clay loam;moderate fine subangular blocky structure;friable; pH 6.3; clear smooth boundary.Brown (10 YR 5/3, moist); clay loam;moderate coarse subangular blocky structure;firm; pH 5.8; gradual wavy boundary.Olive gray (5 Y 5/2 moist); clay loam;moderate fine subangular blocky structure:firm; pH 7.1; abrupt smooth boundary.

SITES

DescriptionGrayish brown (2.5 Y 5/2, moist); clay loam;weak granular structure; turfy; pH 5.6; clearsmooth boundary.Grayish brown (2.5 Y 5/2, moist); clay;moderate fine subangular blocky structure;firm; pH 5.8; gradual irregular boundary.Grayish brown (2.5 Y 5/2, moist); clayloam; moderate coarse blocky structure;friable; pH 5.8; gradual wavy boundary.Olive brown (2.5 Y 4/4, moist); clay loam;coarse subangular blocky structure; firm; pH6.2 clear wavy boundary.

SITE 4

DescriptionDark reddish brown (5 YR 3/2, moist); sandyclay loam; weak granular structure; turfy;pH 4.7; clear smooth boundary.Dark brown (10 YR 3/3, moist); clay loam;weak fine blocky structure; friable; pH 5.1;gradual wavy boundary.Dark grayish brown (10 YR 4/2, moist); clayloam; moderate medium blocky structure;friable; pH 5.8; gradual wavy boundary.Grayish brown (10 YR 5/2, moist); clayloam; fine subangular blocky structure; firm;pH 6.4; clear wavy boundary.

An ochric epipedon has developed in this environmentwith a light brown mineral surface horizon formed fromthe accumulation and decomposition of shrubs and herbs.The soils from the four sampling sites described for thisarea are classified as Pergelic Cryochrepts. Due to the vari-ability present in the developed soils in this area, a cross-sectional profile through a stone ring is presented in Fig. 3.Ground frost had caused a large amount of mixing and con-voluting of the soil horizons. Figure 3 illustrates two areasin the solum where organic material has been incorporatedinto the profile, described as Ob horizons. Both of theseareas are located on either side of the stone ring, indicatingdownward as well as inward movement of material underthe stone ring area with a subsequent upward movement ofcoarser material. Inspection of the soils developed in thisarea indicates some differences in the morphology of thesoils developed under the stone rings and the soils devel-oped under the depressions between the stone rings. The Alhorizon developed under the stone ring has a low organicmatter content compared with the Al horizons developedin the areas between the stone rings. Such a situation is in-dicative of both a more intensive biological activity in thearea between the stone rings as well as greater cryoturbationunder the stone ring area, causing a considerable movementof mineral material into this zone. An indication of thedepth to which the most extensive amount of cryoturbation

WALMSLEY & LAVKULICH: LANDFORM-SOIL-VEGETATION-WATER CHEMISTRY RELATIONSHIPS: I. 87

SiteI

Site2

20 -i

Site3

Stone Stripe

Site4

100 200 300

HORIZONTAL DISTANCE ( c m )Fig. 3—Cross-sectional profile through stone stripe area, illustrating sampling sites.

may be effective is given by the location of the B21 horizon.Just as the depth of the Ob horizons were approximately 5to 10 cm below the surface of the depressions between thestone rings, the B21 horizon is at approximately the samedepth. This suggests a depth of approximately 15 cm for themaximum zone of extensive cryoturbation.

The dominant vegetation on the stone rings and the stonestripes which run parallel to the slope is somewhat differentin comparison to the meadow unit discussed previously. Inthis area Vaccinium sp. was dominant whereas Betulaglandulosa was dominant in the meadow unit. The stonestripes and stone rings had abundant Dryas sp. and gen-erally the same herbs as the lush meadow unit but with lessground coverage.

Colluvial Slope Area: Lithic Cryochrept

This moderately well drained soil occurs on a 25 to 30%slope of the undulating colluvial slope east and down slopeof the stone stripe area. The underlying regolith is a mixtureof coarse textured colluvial material and calcareous loamyglacial till overlying noncalcareous shale bedrock.

Hori-zon

OAl

Alb

B2

C

R

Depth,cm2-00-4

4-6

6-16

16-24

24+

DescriptionDark brown (7.5 YR 3/2, moist); pH 6.4.Very dark brown (10 YR 2/2, moist); sandyloam; weak granular structure; pH 6.2; clearsmooth boundary.Very dark grayish brown (10 YR 3/2, moist);sandy clay loam; weak granular structure; pH6.2; gradual wavy boundary.Grayish brown (2.5 YR 5/2, moist); clayloam; moderate fine subangular blocky struc-ture; friable; pH 6.8; gradual irregularboundary.Grayish brown (2.5 Y 5/2, moist); clay loam;coarse subangular blocky structure; firm; pH6.6; clear wavy boundary.Noncalcareous shale bedrock.

With the exception of extensive cryoturbic proccesses,the soil developed on this landform is similar to that of thestone stripe area. An ochric epipedon has also developed

and the soil is classified as a Lythic Cryochrept. Continualdownslope movement of shattered bedrock and unconsoli-dated material in this environment has altered the profilein a certain manner. The presence of a buried Al (Alb)is indicative of the large amount of downslope movementtypical of this area. Such gravitational processes have alsoresulted in shallow profile development in comparison tothe soils developed in the stone stripe area.

Ecologically, the rocky units were dry areas which werebeing invaded by Dryas sp., Lupinus arcticus, Oxytropismaydelliana, Saxifraga bronchialis, Polytrichum juniper-inum, Cetraria cuculata and Cetraria tilesii.

Coalescing Fan Area: Typic Cryaquept

This poorly drained soil occurs on a 7% slope of thegently undulating coalescing fan south of the stone stripearea. The regolith consists of a mixture of colluvial andalluvial material composed of shattered noncalcareous shalebedrock.

Hori-zon

O

Bg

BC

C

Hori-zon

011012Of

Depth,cm

20-0

0-11

11-19

19 +

DescriptionVery dark brown (10 YR 2/2, moist); pH5.9.Brown (10 YR 5/3, moist); sandy loam, finesubangular blocky structure; slightly sticky;pH 6.4; diffuse irregular boundary.Reddish brown (5 YR 4/3, moist); loamysand; structureless; nonsticky; pH 6.6; diffuseirregular boundary.Dark reddish gray (5 YR 4/2, moist); loamysand; structureless; nonsticky; pH 6.4; diffuseirregular boundary.

Depth,cm Description

0-20 Dark brown (7.5 YR 4/4, moist); pH 2.6.20-35 Dark brown (7.5 YR 4/2, moist); pH 2.5.

35+ Same as above but frozen.

Pedologically, the area is characterized by Typic Crya-quept soils in the more depressional areas and by organicsoils, developed on the hummocks of the slightly undulatingtopography. Geomorphically, the area consists of large

88 SOIL SCI. SOC. AMER. PROC., VOL. 39, 1975

coalescing colluvial fans extending from the base of themountain. The slope of the land varies from 5 to 10% andin aerial extent ranges from approximately 8 to 10 km inlength and 1 to 2 km in width. As a result of the finelybedded red shale bedrock of the slope area, the materialis under constant movement during the summer and fallmonths. Consequently, the area is quite unstable in termsof engineering uses such as road or pipeline construction.

The dominant vegetation of this area is visually strikingas a result of the vast expanse of krummholz trees and lowshrub vegetation. The authors believe this area to be inun-dated with a large amount of snow during the wintermonths, blowing off from the nearby mountains and slopes.Consequently, the trees in the area were extremely stuntedor krummholz in nature, caused by the weight of the deepsnow. Dominantly, the vegetation consists of scattered,krummholz Picea glauca with a shrub layer consisting ofBetula glandulosa, Vaccinium sp., Salix reticulata, Salixspp., Rhododendron lapponicum, Vaccinium vitis-idaeaand Arctostaphylos rubra. Typical herbs are Dryas sp., To-fielda sp., Lupinus arcticus and Pedicularis kanei. Thefeathermosses Hylocomlum splendens, Dicranum sp., To-menthypnum nitens and Dicranum undulatum are abun-dant, with the lichens Cladina arbuscula and Cetraria cucu-lata present.

Polygonal Box Area: Pergelic Cryofibrist

This very poorly drained soil occurs on nearly level to-pography with slopes of 0 to 2%. The regolith is composedof sphagnum moss species at different stages of decomposi-tion, frozen at 35 cm.

Hori- Depth,zon cm Description

011 0-20 Dark brown (7.5 YR 4/4, moist); pH 2.6.012 20-35 Dark brown (7.5 YR 4/2, moist); pH 2.5.Of 35+ Same as above but frozen.

The lichen-covered bog or peat polygon (Tarnocai,1970) has polygonal cracks outlined in the bogs with poly-gons 15 to 20 m in diam. These cracks or fissures are ofvariable width (1-3 m) and sunk about 0.5 m below thesurrounding terrain.

Vegetatively, the area is characterized by a shrub layerof < 1 m in height. The species consisted of Betula glandu-losa Ledum decumbens, Andromeda polifolia, Vacciniumvitis-idaea, and Rubus chamaemorus. The dominant sphagnais Sphagnum fuscum while approximately 80% of theground was covered by lichen species consisting of Cladinaalpestrus, Cetraria cuculata, Cladina rangiferina and Cla-dina mitis.

In summary, the five landforms described appeared dis-tinctly different pedologically as well as ecologically butwhen considered collectively were component ecosystemsforming a part of the major ecosystem characteristic of thispart of the Boreal Forest region of Canada (Rowe, 1959).Gross climatic regimes dominate the characteristics of thephysical environment in this region. The cold temperature

associated with each of the five landforms caused not onlya limited biological breakdown of organic matter but alsoincreased the physical weathering of rock material due tointense freeze and thaw cycles. Soil formation on mineralsites is shallow and highly retarded by mixing of soil hori-zons as a result of cryoturbation. The subangular blockystructures and friable consistencies reflect the high permea-bility and low clay mineral contents of these soils illustratingthe low level of chemical weathering. Organic matter hasaccumulated to variable depths at certain locations in thisregion and tended to modify the effect of climate. Theorganic material accumulated in the alpine meadow studyarea was at a higher stage of decomposition than was theorganic material located on the polygon bog study area. Theelevation of the sites and the distribution of snow hasaffected the distribution of permafrost and the types ofvegetative species. Each of these factors has contributed toa higher degree of biological activity at the alpine meadowsite.

ACKNOWLEDGMENTS

Sincere appreciation is extended to the Department of Indianand Northern Affairs, Ottawa, for financial assistance throughthe Arctic Land Use Research (ALUR) program. The viewsexpressed are those of the authors and not necessarily those ofthe Department.