Soil factors influencing

moisture & productivity:

Overview, soil descriptions, and

landscape processes

Chuck Bulmer and Brian Wallace

21 April 2017 Dry Belt Fir workshop, Vernon

“advancing management of multiple values in the dry belt fir, and

maintaining dry belt fir stands over the long term””

Outline • Soils of the Dry Fir Forests in the

Okanagan • physiography, geological origin, parent

materials, soil development

• Sources of information • Soils of BC website distribution

• Soil Information Finder Tool

• Other mapping efforts

• Perspectives on changing

information needs

Dry fir: • Elevations to ca

900m in the north

and as high as

1200+ in the south

• Mostly confined to

the valley walls and

plateau edges in the

north, and up on to

the plateau in the

south

Vernon area: • Elevations up to ca

800-1200m in the

north and as high as

1200+ in the south

• Higher on south

facing slopes

Steep slopes: • Slope in degrees

• Many parts of area

with the dry fir

forests are along

the walls of the

Okanagan Valley

Geology: • Mosaic of rock

types, not related to

topography

• Residual soil

materials and

colluvium inherit

rock characteristics

• ‘Local’ glacial tills

retain similarity

• Transported valley

sediments - no

Soil texture and plant

available water

Parent

material: • Tills on the plateau

• Water-deposited

materials in the

valley bottom

• Colluvium on the

slopes

• Rock, organics in

lesser amounts

Soil types: • Grass land soils in

the valley; south

aspect

• Forest soils in

uplands: Brunisols

and Luvisols,

depends on texture

• Poorly drained soils

(Gleysol) and fresh

deposits (Regosol)

close to the rivers

The effect of aspect S:

Chernozem Brunisol

Kelowna

area: • Elevations a bit

higher than Vernon

• Mostly confined to

the valley walls in

the north, and up on

to the plateau in the

south

Steep slopes: • Slope in degrees

• Many parts of area

with the dry fir

forests are along

the walls of the

Okanagan Valley

Geology: • Mosaic of rock

types, not related to

topography

• Residual soil

materials and

colluvium inherit

rock characteristics

• ‘Local’ glacial tills

retain similarity

• Transported valley

sediments - no

Parent

material: • Tills on the plateau

• Water-deposited

materials in the

valley bottom

• Colluvium on the

slopes

• Rock, organics in

lesser amounts

Soil types: • Grass land soils in

the valley; south

aspect

• Forest soils in

uplands: Brunisols

and Luvisols,

depends on texture

• Poorly drained soils

(Gleysol) and fresh

deposits (Regosol)

close to the rivers

Dry fir: • Elevations to ca

800m in the north

and as high as

1200+ in the south

• Mostly confined to

the valley walls in

the north, and up on

to the plateau in the

south

Steep slopes: • Slope in degrees

• Especially near

Keremeos the valley

sides are very steep

Geology: • Mosaic of rock

types, not related to

topography

• Residual soil

materials and

colluvium inherit

rock characteristics

• ‘Local’ glacial tills

retain similarity

• Transported valley

sediments - no

Parent

material: • Tills on the plateau

• Water-deposited

materials in the

valley bottom

• Colluvium on the

slopes

• Rock, organics in

lesser amounts

Soil types: • Grass land soils in

the valley; south

aspect

• Forest soils in

uplands: Brunisols

and Luvisols,

depends on texture

• Poorly drained soils

(Gleysol) and fresh

deposits (Regosol)

close to the rivers

Sources of

soil info: • Search “soils info

BC”

• http://www.env.gov.bc.ca/e

sd/distdata/ecosystems/

(kmz files for google earth)

• Soil Information Finder

tool Web mapping

Deepa Filatow MoE Kelowna

View soil data in Google Earth:

View soil data in Google Earth:

View soil data in SIFT:

View soil data in SIFT:

View soil data in SIFT:

Sources

25 m soil map

for the

Okanagan Basin

Scott Smith

Ag Agri-Food

Canada,

Summerland

Erosion and

redistribution • Erosion is an

ongoing process,

but operates slowly

in vegetated soils

• Greatly accelerated

after fire, when soil

is exposed

• Dry landscapes can

experience severe

soil loss

Erosion and redistribution • There is only a thin veneer of soil over many

hillslopes in the Okanagan landscape

Conclusions • Diverse origins and ecosystems

have created different soils

• Soil texture is connected to geology

/ rock type.

• Aspect affects water balance and

vegetation outcomes

• Steep slopes are common

• Ongoing redistribution of soil

materials through landscape

evolution

• Water, solar energy, drive important

processes of productivity

Extras

Soil Water Balance Inputs = snow and rain

Outputs =

• evaporation

• transpiration

• runoff

• storage

More water loss from

transpiration?

• Fine textured (clay) soils allow greater water movement

toward the surface from deeper layers.

• It takes about 15 days with little rain to dry the top 5 to 10

cm of an exposed mineral surface to the permanent wilting

point.

• If there is no vegetation, the soil at the 15 to 20 cm depth

will still be moist.

Spittlehouse and Stathers. 1990. Seedling microclimate.

Soil water dynamics after harvest

Frost and tree seedlings

• Radiation frost occurs on calm, clear nights when the ground

surface cools to <0°C. Bare soil reduces this risk while grassy

vegetation increases the risk.

• Advection frost occurs when cool air flows or is blown

(advected) onto a site.

• Radiation and advection frosts often occur at the same time.

Perspective: • Need to use

information to

keep it ‘alive’

• Knowledge

may not ever

really be

‘lost’, it may

just need to

be refreshed

• Experience

• Competition for moisture between grass and tree

seedlings

• Intensity of site prep and the timing of seedling

planting after harvest will likely influence the success

of the new forest

Conclusions