Ministry of ForestsResearch Program

L A N D M A N A G E M E N T H A N D B O O K

47

Silviculture Prescription Data C

ollection Field Handbook

Silviculture Prescription DataCollection Field Handbook

Interpretive Guide for DataCollection, Site Stratification,and Sensitivity Evaluation forSilviculture Prescriptions

2000

Silviculture Prescription DataCollection Field HandbookInterpretive Guide for DataCollection, Site Stratification,and Sensitivity Evaluation forSilviculture Prescriptions

M. Curran, I. Davis, and B. Mitchell

Ministry of ForestsResearch Program

ii

Canadian Cataloguing in Publication Data

Main entry under title:Silviculture prescription data collection field handbook : interpretive

guide for data collection, site stratification, and sensitivity evaluationfor silviculture prescription

(Land management handbook ; )

Includes bibliographical references: p.isbn ---

. Forests and forestry - British Columbia - Planning. . Forest manage-ment - British Columbia - Planning. I. Ministry of Forests. Research Branch.II. Series.

sd391.s54 2000 634.9´5´09711 c00-960278-x

Prepared byM. Curran, I. Davis, and B. MitchellforB.C. Ministry of ForestsResearch Branch Yates StreetVictoria, BC

Copies of this Land Management Handbook may be obtained,depending on supply, from:

Crown Publications Fort StreetVictoria, BC

() -

http://www/crownpub.bc.ca

For more information on Forestry Division publications, visit our web site athttp://www/for.gov.bc.ca/hfd/pubs/index.htm

© Province of British ColumbiaWhen using information from this or any Research Program report,please cite fully and correctly.

SOIL HORIZONS

At a suggested minimum, record either Ah or Ae, andB, C, and R horizons (Figure ). Recording otherhorizon designations, as shown below, is optional.Determine mineral soil horizons primarily by changesin colour, texture, and coarse fragments. Use thepresence of carbonates (effervescence with acid),compacted layers, gleying, and mottles for furtherdifferentiation. Indicate, on the table provided forsoil horizon descriptions, the depth of your soil pit incentimetres. This can be important for future refer-ence. See item , “Soil Classification/Association,”for some management interpretations of commonsoil orders.

29. HORIZON• A horizon – Determine if the A horizon is Ah or

Ae and provide the depth of the A horizon incentimetres. If the A horizon is absent or less than. cm deep, record depth as less than . cm.

Ah: a surface mineral horizon containing anaccumulation of organic matter. Usually darkercoloured than the underlying horizons; oftenlooks like garden/potting soil, and some-times called “topsoil.” The Ah layer willusually dominate the nutrient pool of thesite and can influence the humus formclassification and the Forest Floor Displace-ment Hazard rating.

Ae: a surface or near-surface mineral horizon with most of theorganic material, clays, and soluble materials leached out. Usually lightercoloured than the underlying horizons; appearing “bleached” or “ashy.”(Ahe has properties of both, often has a “salt and pepper” appearance, orlighter/greyer than a “classic” topsoil).)

• B horizon – A mineral horizon with an accumulation or enrichment ofclay, sesquioxides (iron and aluminum), or organic matter. If changes ina texture, coarse fragment, or calcium carbonate content occur withinthis horizon, it is useful to provide the description for each layer (Bm,Bmk, etc.). More detailed horizon descriptors for the B horizon mightinclude the following:

Bf: iron and aluminum enriched; reddish brown to reddish colour.(Bhf if also high in organic matter).

Bt: clay accumulation; underlies a coarser-textured horizon (e.g., Ae);often blocky structure; clay coatings may be visible.

figure 19 Schematic soilprofile (cm).

29. Horizon FS 39A

Bg: fluctuating water table or restricted drainage; often a bluish grey(gleyed) matrix with reddish mottles and granular structure.

Bm: weakly modified layer not showing the distinct characteristicsof the above-mentioned B layers; yellowish brown to slightly reddishbrown.

BC: transitional between B and C horizons.

• C horizon – An unweathered soil parent material.

• R horizon, Bedrock – This is consolidated bedrock that is too hard tobreak with the hand or to dig with a shovel.

• Horizon modifiers – For any of the mineral soil horizons describedabove, use the following modifiers:

k: used with any horizon to indicate presence of carbonates (fizz withacid); most often used with B and m (e.g., Bmk) or C (see carbonatesunder item ).

g: used with any horizon to indicate a fluctuating water table; usuallybluish grey soil matrix with prominent reddish mottles.

j: used with any horizon to denote a weak expression of the suffix itmodifies.

• Organic soil – Organic horizons develop mainly from mosses, sedges,rushes, and woody materials under poor drainage conditions. Theycontain more than % organic matter.

Of: fibric, poorly decomposed (i.e., large amounts of well-preservedfibre are readily identified as to botanical origin).

Om: mesic, moderately decomposed (i.e., fibre is partly altered)Oh: humic, well decomposed (i.e., plant residues that for the most

part have been transformed into humic materials). Folisols are anorganic soil found on rock or skeletal material. Record layers within aFolisol as L, F, or H under forest floor depth (item ).

30. DEPTH (cm)Provide the average range of depth of each of the horizons in centimetresfrom mineral soil top ( cm) to bottom (e.g., Ae – cm; Bm, – cm). Ifthe A horizon is absent or less than . cm deep, do not record, or recorddepth as less than . cm. Indicate depth and thickness of organic soilhorizons in the same way as for mineral soils.

If the bottom of the BC horizon is not reached in the soil pit and you haveenough soil disturbance hazard information, record as greater than the soilpit depth (e.g., BC –+ cm). Likewise, indicate if the C horizon cannot bereached (e.g., “not found at cm”); otherwise record the observed depth orrange (e.g., C –+ cm).

30. DepthFS 39A

31. TEXTURESoil texture refers to the relative proportions of the sand, silt, and clay parti-cles within a soil. Each has distinctive properties and a particular “feel,”allowing a person to estimate the proportions in a sample of soil by handtexturing. Texture can be estimated very roughly from a dry sample. Claymaterials are very hard; loam and silt materials are slightly hard to soft; andsand materials are loose grained. To be more precise, use the moist sampleprocedure for hand texturing, provided here, or given in the regional eco-logical field guide.

Table outlines the general implications of soil texture for forestmanagement.

Determine the soil texture for each horizon according to the relativeamounts of sand, silt, and clay particles less than mm in size. If twotextures exist for one horizon, separate them into two horizons (e.g., Bm,Bm). If the texture varies in one horizon (e.g., SL to SCL), record the codeas “SL / SCL.” Use the keys in this handbook (Table , Figure ) to improveyour estimate. The texture triangle and keys in the regional ecological fieldguides may also help.

Note: The distinction between fine sandy loam and coarser sandy loamis important for forest management and necessary in the determinationof soil disturbance hazards.

32. PLASTICITYWhile hand texturing samples from each mineral soil horizon, also deter-mine its soil plasticity. Plasticity is the ability to change shape under theinfluence of an applied stress, and to retain the new shape after removal ofthe stress. Different soil plasticity requires different forest managementconsiderations, especially when contemplating the soil’s ability to withstandground-based operations.

Use the following method to determine soil plasticity.

Thoroughly work water into the texture sample. Adjust the moisture con-tent by rolling the sample in your hand or on a flat surface to reduce mois-ture, or by adding more water, until you can roll the smallest diameter for a cm long roll (also referred to as a worm). Determine the plasticity classbased on the criteria found on page .

31. Texture FS 39A

table 2 General implications of soil texture for forest managementa

a■

= m

ajor

pro

blem

s, ▲

= c

once

rn, ●

= m

ay b

e a

con

cern

, ❍ =

no

con

cern

b

Dep

endi

ng

on s

ite

con

diti

on

Gen

eral

imp

licat

ion

s o

f so

il te

xtur

e fo

r fo

rest

man

agem

ent

Oth

er im

port

ant

site

fact

ors

to c

onsi

der

in a

ddit

ion

to

text

ure

(ve

geta

tion

can

infl

uen

ce a

s w

ell)

:

Surf

ace

eros

ion

Com

pact

ion

Ava

ilabl

e n

utr

ien

ts Sl

ope

Stab

ility

Ava

ilabl

e w

ater

Clim

ate

Slop

e %

Slop

e le

ngt

h/u

nif

orm

ity

Coa

rse

frag

men

ts So

il m

oist

ure

Soil

laye

rs/d

epth

Soil

stru

ctu

re Se

epag

e

Clim

ate

Coa

rse

frag

men

ts So

il st

ruct

ure

Soil

moi

stu

re Fo

rest

floo

r de

pth

Coa

rse

frag

men

ts O

rgan

ic m

atte

r So

il de

pth

Seep

age

Clim

ate

(lea

chin

g) U

nfa

vou

rabl

e su

bstr

ate

Clim

ate

Slop

e %

Slop

e le

ngt

h/c

onti

nu

ity

Soil

laye

rs So

il de

pth

Soil

moi

stu

re B

edro

ck fe

atu

res

Seep

age

Clim

ate

Slop

e %

Slop

e po

siti

on C

oars

e fr

agm

ents

Org

anic

mat

ter

Soil

moi

stu

re So

il de

pth

/lay

ers

Seep

age

31. TextureFS 39A

Text

ure

Surf

ace

eros

ion

(soi

l det

ach

abili

ty)

Com

pact

ion

/R

utt

ing

Ava

ilabl

en

utr

ien

tsSl

ope

stab

ility

Ava

ilabl

e w

ater

LS o

r S

� s

ever

e on

ste

ep s

lope

s❍

� (

� o

r �

)b�

dry

rav

ellin

g ca

n b

e se

vere

on

ste

ep s

lope

s�

ver

y po

or

SL�

very

ste

ep s

lope

s�

�

or�

� d

ry r

avel

ling

on s

teep

slo

pes

� p

oor

Fin

e SL

� s

ever

e on

all

slop

es�

��

can

flow

�

L�

mod

erat

ely

stee

p�

��

�

SiL

or S

i�

all

slop

es�

❍�

can

flow

/slu

mp

❍

SCL

��

ver

y h

igh

❍�

can

flow

/slu

mp

�

CL

��

ver

y h

igh

❍�

can

flow

/slu

mp

�

SiC

L�

(�

)b�

ver

y h

igh

❍�

can

flow

/slu

mp

�

SC❍

� v

ery

hig

h❍

� c

an fl

ow/s

lum

p�

C❍

� v

ery

hig

h❍

� c

an fl

ow/s

lum

p�

SiC

❍ (

�)b

� v

ery

hig

h❍

� c

an fl

ow/s

lum

p�

table 3 Guide for approximating soil texture class using hand texturing(modified from Cariboo Research Section)

a Loam is a textural class exhibiting physical properties intermediate between those ofsand, silt, and clay.

b Fine sandy loam is fine grainy; medium sandy loam is medium grainy; and coarse sandyloam is coarse grainy.

31. Texture FS 39A

Graininess

Stickiness

Non-grainy (20%sand)

Slightly grainy(20−50%sand)

Grainy(50−80%sand)

Very grainy (80% sand)

Very sticky> 40% clay

siltyclay

clay sandyclay

—

Sticky25−40%clay

silty clayloam

clay loam sandy clayloam

—

Slightlysticky< 25% clay

silt loamor silt

loama sandy loam

fineb

medium coarse

—

Non-sticky< 10% clay

— — — loamy sandor sand

Fine fractionseparate

Diameter range(mm) Properties

Clay < 0.002 Very hard when dry; feels smoothand is very sticky when wet; feelssmooth when placed between teeth

Silt 0.002–0.05 Slightly hard to soft when dry;powder is floury when dry; feelsslippery and slightly sticky when wet;silt cannot be seen or felt as grainsbetween thumb and forefinger, butcan be felt as a fine grittiness whenplaced between teeth

Sand

Fineb

Medium

Coarse

0.05–2.00

0.05–0.25

0.25−0.50

0.50–2.00

All visible soil particles are sand;loose grains when dry; grainy whenfelt between thumb and forefinger;non-sticky when wet

Procedure for Hand Texturing

. Obtain a small handful of soil, crush it in the hand, and remove coarse fragments(particles > mm in diameter).

. Gradually add water to the soil and work it into a moist putty with a soil knife orfingers. The correct moisture content is important. If the putty flows with the force ofgravity, then it is too wet. If it crumbles when rolled, then it is too dry. It should havethe consistency of a filler putty.

. Determine the stickiness of the soil putty by working it between the thumb andforefinger, pressing and then separating the digits. Estimate clay content in this way(clay limits below are approximate):

Very sticky: Soil putty adheres strongly to both digits and stretches distinctly beforebreaking (> % clay).

Sticky: Soil material adheres to both digits and stretches slightly before breakingwhen digits pulled apart (–% clay).

Slightly sticky: Soil material adheres to only one of the digits and comes off the otherrather cleanly. The soil does not stretch appreciably when digits separated (< %clay).

Non-sticky: Practically no soil material adheres to the thumb and forefinger (< %clay).

. Determine the graininess of the soil putty by rubbing it between thumb andforefinger. Estimate sand content in this way (sand limits below are approximate):

Non-grainy: Little or no grain detected (< % sand).

Slightly grainy: Some grain detected, but non-grainy material (silt and clay) domi-nant (–% sand).

Grainy: Sand detected as the dominant material. Some non-grainy material detectedbetween sand grains (–% sand).

Very grainy: Only material detected is sand. Little or no non-grainy material present(greater than % sand).

. After stickiness and graininess are determined, use the hand texturing table as anapproximate guide to the textural class of the soil. Use the textural triangle for a moreaccurate determination of the textural class.

table 3 Continued

31. TextureFS 39A

figure 20 Key for estimating soil texture in the field (adapted from Lloyd etal. 1990 and Walmsley et al. 1980).

Key

fo

r es

tim

atin

g s

oil

text

ure

in t

he

fiel

d, a

lon

g w

ith

so

il te

xtur

e tr

ian

gle

31. Texture FS 39A

* *

HC

C

SiC

LC

LSC

SCL SL

LSS

Si

SiL

SiC

L

100 90 80 70 60 50 40 20 1030 0

100

9080

7060

5040

2010

300

Perc

ent

sand

Percent clay

figure 20 Continued

Soil

text

ure

tria

ngle

31. TextureFS 39A

*Si

lt fe

els

slip

pery

or

soap

y w

hen

wet

; fin

e sa

nd

feel

s st

iffe

r;lik

e gr

indi

ng

com

pou

nd

or fi

ne

san

dpap

er. F

ine

san

dy

loam

mea

ns

the

soil

con

tain

s

% o

r m

ore

fin

e or

ver

y fi

ne

san

d,or

mor

e th

an

%

fin

e an

d ve

ry fi

ne

com

bin

ed.

Code Plasticity (ability to change shape)

NP Nonplastic – a roll cm long and mm thick cannot beformed.

SP Slightly plastic – a roll cm long and mm thick can beformed, but cannot support its own weight when dangledfrom the thumb and forefinger.

P Plastic – a roll cm long and mm thick can be formed, butcannot support its own weight when dangled from thethumb and forefinger.

VP Very plastic – a roll cm long and mm thick can supportits own weight when dangled from the thumb andforefinger.

“Soil plasticity” as defined in the Canadian System of Soil Classification(Day ), provides a better framework for communicating soil behaviourat differing moisture levels, than do soil textural classes. Textural classes arenot very diagnostic when predicting how a soil will behave mechanically at agiven moisture level because:

• some texture classes have a very large range in clay content (e.g., –%for silt loam);

• during the lab analysis to determine texture, soil samples are cleanedof some behavior influencing minerals (e.g., organic matter, calcareousmaterial, and iron and aluminum oxides); and

• clays can contain a number of different clay minerals (with distinctcohesive properties such as plasticity and stickiness) that behavedifferently to mechanical forces.

Using soil plasticity classes will not alter the soil compaction hazardfor a site, but highlights those soil conditions that are more likely tolead to compaction and rutting.

Table outlines the general implications of soil plasticity for forestmanagement.

33. COARSE FRAGMENTS PERCENT AND SIZEEstimate the percentage of coarse fragments (> mm) by volume (tothe closest %) within each horizon using the visual estimation key(see Figure ). Indicate the size of coarse fragments (CF) by type, asfollows:

Type of CF (Code) Diameter range

Gravels (G) – mmCobbles (C) – mmStones (S) > mm ( cm)

32. Plasticity FS 39A

Note: Texture and coarse fragment content at various depths in thesoil profile are required to complete different hazard ratings in varioussections on the plot card. Therefore, be sure to complete all soil disturb-ance hazard ratings while you are at the soil pit.

34. COLOUR / MOISTURE

ColourDescribe the colour of all mineral soil horizons. Light, medium, or darkare common descriptors. Examples of alternative descriptors include: (W)white, (G) grey, (Y) yellow, (Br) brown, (R) reddish or rust, (RB) reddishbrown, or (Bl) black.

Colour is useful for interpreting the relative amounts of organic matter inthe mineral soil, for classifying soils, and for prescribing topsoil handling andother soil rehabilitation operations. Light-coloured soils (e.g., white, lightgrey, yellow) are low in organic matter; medium-coloured soils (brown) aremoderate in organic matter content; dark-coloured soils (e.g., black, darkbrown, dark red) are high in organic matter.

MoistureDescribe the moisture content of the soil horizon at the time of sampling as(D) dry, (M) moist, or (W) wet. Indicate the moisture content using thefollowing definitions for the condition of loose soil squeezed in the hand.

34. Colour / MoistureFS 39A

table 4 General implications of soil plasticity for forest management a, b

Nonplastic Slightly plastic Plastic Very plastic

Compaction � � � �

Rutting � (� if too dry) � � �

Ease of rehab � � � �

Slope stability � (� dry ravel) � � �

Surface erosion � � � �

Available nutrients � or � � (can be �) � �

Available water � or � � (can be �) � �

a ■ = major problems, ▲ = concern, ● = may be a concern, ❍ = no concernb See Table for other important site factors.

Dry: Will not form a cast; powdery dry or hard.

Moist: Forms a cast, but surface does not glisten when shaken or squeezed.

Wet: Forms a cast; surface glistens when shaken or squeezed (i.e., a film ofwater is visible).

Knowing the moisture content at the time of field sampling can help withplanning seasonal soil operations and understanding site growth-limitingfactors.

35. ROOTING DEPTH (cm)Measure and record the distance (in centimetres) from the top of the min-eral soil to the depth below which the abundance of roots decreases to a fewfine and very fine roots (i.e., three or fewer per . × . cm surface). Inshallower soils, this is usually to the bottom of the B horizon, or to a restric-tive layer. This information may prove useful for rehabilitation plans.

Fine roots are – mm thick; very fine roots are less than mm thick.

36. DRAINAGERecord the drainage class of the plot as rapidly, well, moderately well, imper-fectly, poorly, or very poorly drained. See Table and Figure for drainagedefinitions.

37. SEASONAL SOIL FACTORS (dates: dry, wet, frozen, snow)

Use the moisture descriptor (item ) to help calibrate the seasonal soilfactors. Where seasonal conditions alter the operability or stability of thesoils, describe the factor (e.g., moisture content, degree of frost, snow cover)and provide the applicable season(s) (e.g., late summer to early fall). Con-sult the Regional Soil Scientist or District Earth Scientist regarding localinterpretations and experience with equipment trafficability. Some prelimi-nary interpretations are provided in Curran ().

Consider the following factors during your data collection.

• Soil moisture conditions – Indicate the season in which you would expectthe top cm of the mineral soil to be dry or wet. Local experience andknowledge is important. If you are unsure of the season(s), use questionmarks. Dry does not have to be “powder dry.”

Practical experience, tempered with information from regional ecologicalfield guides, can assist the assessment. For example, the climate descrip-tion pages for biogeoclimatic subzones in the Nelson Region field guide

FS 39A34. Colour / Moisture

Drainage class Definition Mottling / gleying Other

Rapidly drained Soil moisture contentseldom exceeds fieldcapacity in any horizonsexcept immediately afterwater additions

None Often coarsetexturedor shallow tobedrock;normally occurson steep slopes

Well drained Soil moisture content doesnot normally exceed fieldcapacity for a significantpart of the year in anyhorizon (except possiblythe C)

Usually none or≥ 1m depth

Often mediumtextured;no seepage

Moderately welldrained

Soil moisture exceeds fieldcapacity for a small, butsignificant period of theyear

Often faintlymottled in lowerB and C horizons

Often medium tofine textured;seasonal seepage

Imperfectlydrained

Soil moisture exceeds fieldcapacity in subsurfacehorizons for moderatelylong periods during theyear

Distinctlymottled in B andC horizons

Soils aregenerally gleyedsubgroups ofmineral soilorders

Poorly drained Soil moisture contentexceeds field capacity in allhorizons for a large part ofthe year

Usually stronglygleyed

Soils generally ofGleysolic orOrganic orders

Very poorlydrained

Free water remains at thesurface (or within 30 cm)for most of the year

Usually stronglygleyed

Soils generally ofGleysolic Order(peaty phase) orOrganic order

table 5 Soil drainage class (adapted from B.C. Ministry of Forests 1983;Agriculture Canada 1987)

figure 21 Generalized drainage patterns and drainage classes for soils asinfluenced by slope position. Note that drainage classes mayvary for a given slope position according to soil texture andcoarse fragment content.

36. DrainageFS 39A

(Braumandl and Curran ) provide interpretations of seasonal soilconditions, ranging from the driest to the wettest site series (e.g. “soilsdry out for short to non-existent time periods”). An appendix containsfurther definitions of the time periods and depths. These interpretationsare valuable because practical experience may be swayed by events suchas “El Nino” winters.

In making an interpretation, it is important to observe how the soilbehaves under moist and wet hand manipulation during hand texturing.Hand tests serve to mimic the forces applied to the soil by machine traffic(i.e., the combined forces of compression, shearing, and some vibra-tion). Recognize that greatest compaction occurs under “moist” soilwetness, and wetter soils will rut; equipment is best kept to designatedtrails under these conditions. Local experience is important, see Curran() for more information. Wet soil consistency, particularly how“plastic” the soil behaves (item ), provides an important basis for theharvesting strategies outlined in Curran ().

• Frozen ground – Indicate the typical winter depth of soil freezing forundisturbed soil (exposed surfaces freeze much deeper) and enter theseason(s) between which you would expect this condition to prevail.(Refer to climate information provided in the regional ecosystem fieldguide.)

One common misinterpretation is that soils remain frozen undersnowpack. In the southern Interior of British Columbia and elsewhere,the soil is seldom frozen once a snowpack is over 30 cm deep; actualfrozen depth will vary with snow density, layering, and temperatures.

Note: Many soils in the province do not remain frozen for very long. Assoon as any snow cover accumulates, or warm weather melts the snowcover, the soil starts to thaw.

• Snowpack – Indicate the typical winter snowpack depth and condition(granular or compressible), and enter the season(s) between which youwould expect it to prevail.• Granular: snow that does not pack or consolidate easily (powdery to

sugary or grainy; does not make a good snowball)• Compressible: snow near 0ºC (water films present) that packs and

consolidates well (makes a good snowball)

The regional ecosystem field guides supply some climatic information in thedescriptions of climate or absolute moisture regimes.

37. Seasonal Soil Factors FS 39A

38. UNFAVOURABLE SUBSTRATESRecord the presence of any unfavourable substrates by indicating “Y” for yes.Record the depth at which this substrate begins. If exposed or present, thesesubstrates may produce unfavourable growing conditions for the new cropof trees.

Types of unfavourable substrates include the following:

Seepage (mottles/gleying): A condition indicative of excess soil water andtherefore reduced soil aeration. A gleyed soil matrix (dull yellowish, blue, orolive colour) indicates a permanent water table; orange-coloured mottlingindicates a fluctuating water table. The level of water during the dry periodof the year approximates the level of a permanent water table.

Note: Consider only for subhygric, hygric, and subhydric sites, asdetermined by vegetation (site series). Indicate whether the seepage youobserve is seasonal rather than permanent. Record the depth from whichwater seeps into the soil pit. Keep in mind that, in many cases, water willfill a pit many hours after digging. It is unlikely that this depth of waterwill truly indicate the depth of the water table on certain sites.

Unfavourable subsoils: Includes subsoil conditions that produceunfavourable growing conditions when exposed by displacement.Unfavourable subsoils include:

• Carbonates: In arid and semi-arid areas (e.g., PP, IDF zones), soildevelopment is limited by moisture, and salts (including lime) that havenot been leached out of the developing soil profile. Even in humid areaswith limestone-derived parent materials, calcium carbonate (lime) hasoften not been weathered and leached out of the profile. The resulting“calcareous horizons” in the soil has an unfavourable (alkaline) soil pH,especially for conifer nutrition. Often, these calcareous soils exhibit awhite coating on coarse fragments or contain powdery white deposits(i.e., free lime). The presence of free lime is demonstrated by a fizz whenfine soil particles (< mm in diameter) are in contact with % HCl(hydrochloric acid, also known as muriatic acid). To make a %solution of HCl, dilute muriatic acid of known strength. Be sure to readinstructions before diluting muriatic acid with water—it may bedangerous if improperly mixed. Buy muriatic acid at a builders’ supplyor hardware store.

Note: Record the depth at which % hydrochloric acid forms a lowfoam on fine soil particles (not just coarse fragments); this is referred toas a “moderately strong effervescence.”

38. Unfavourable SubstratesFS 39A

• Water-restricting layer: A substrate that restricts the downward flowof water, but not necessarily root growth. A water-restricting layer mayindicate the presence of certain soil hazards. This substrate includesimpermeable, dense, very compact or cemented layers (i.e., soils that arehard to dig with a shovel); bedrock; or a permanent water table (see“Seepage” above).

• Bt or dense parent material: Bt refers to a B horizon enriched with clay.To restrict root growth, a Bt horizon must be at least cm thick. Denseparent materials may include soils that are hard to dig with a shovel.Dense parent materials may include compact glacial till, and compactsilty- or clay-textured glaciolacustrine deposits (see “Water-restrictinglayer” above).

• Sands / gravels: Any materials with a sand (S) or loamy sand (LS) texturehave very little silt and clay, and hence little nutrient or water-holdingcapability (less of a concern in wettest biogeoclimatic subzones). Theseunfavourable substrates commonly occur in glaciofluvial or recent fluvialdeposits, but may also be derived from other parent materials.

• Fragmental (> % CF): Any soils with more than % coarse fragmentcontent (i.e., fragments > mm diameter). These soils can restrictrooting volume, and moisture and nutrient availability to plants.

Root-restricting layer: A substrate that restricts the downward growth ofroots. It may include a layer of bedrock, or comprise impermeable, verycompact or cemented layers, or a permanent water table.

For any restrictive layers identified, describe the specific type of restrictivelayer, such as bedrock, compact glacial till, compact silty- or clayey-glacio-lacustrine deposits, compact marine deposits, dense clay-enriched horizons,cemented horizons, etc. If seepage is apparent, indicate whether it is perma-nent or seasonal (e.g., fluctuating water table).

For further descriptions, refer to Hazard Assessment Keys for Evaluating SiteSensitivity to Soil Degrading Processes Guidebook.

OPTIONAL SOILS INFORMATION

items to may be useful for specific reasons noted under each item.

39. LANDFORM / PARENT MATERIALUse the diagrams in Figures and , and the key in Figure , toidentify the landform (parent material). Describe the parent materialas: (O) organic, (R) bedrock, (C) colluvial, (M) morainal, (F) fluvial,

38. Unfavourable Substrates FS 39A

(FG) glaciofluvial, (W) marine, (D) weathered bedrock, (L) lacustrine, or(E) eolian. The type of landform can be further described as: (b) blanket,(v) veneer, (f) fan, (t) terrace, (p) plain, or (c) cone (see Table ).

figure 22 Cross-sectional diagram of interior valley landforms (originalhand sketch by Greg Utzig for B.C. Ministry of Forests, Nelson).

figure 23 Cross-sectional diagram of interior plain/plateau landforms(original hand sketch by Greg Utzig for B.C. Ministry of Forests,Nelson).

39. Landform / Parent MaterialFS 39A

figure 24 Key to the identification of parent materials (from Braumandland Curran 1992, adapted from Lloyd et al. 1990).

Key

to

th

e id

enti

fica

tio

n o

f p

aren

t m

ater

ials

39. Landform / Parent Material FS 39A

figure 24 Continued

39. Landform / Parent MaterialFS 39A

table 6 Summary characteristics of parent materials and landformsSu

mm

ary

char

acte

rist

ics

of

par

ent

mat

eria

ls a

nd

lan

dfo

rms

39. Landform / Parent Material FS 39A

table 6 Continued

39. Landform / Parent MaterialFS 39A

This information is important for interpreting instability, particularly wheninterpretation is based on experience in a local area.

Various other references (e.g., Keser ; Ryder and Howes ; Howes andKenk ; and regional ecological field guides) will help you identify andclassify landforms.

40. SOIL CLASSIFICATION / ASSOCIATIONIdentify and classify soils to the Soil Order (e.g., Podzol, Gleysol) and GreatGroup (e.g., Humo-Ferric Podzol) level. Figure contains the necessaryclassification information. See also the Canadian System of Soil Classification(Agriculture Canada ). Knowledge of local soil classification may behelpful in making management interpretations and may be needed forherbicide permit application.

If available, add the soil association. Locate this information in a soil maplegend or report, and record by soil association name (e.g., Wycliffe SoilAssociation). Knowledge of the local soil associations and associatedlandforms is useful for the prescription process and communicating localexperience.

Some general interpretations for soil orders follow.

• Organic soils – Very cold, wet soils; includes Humisols, Mesisols,Fibrisols, and Folisols; very sensitive to disturbance; for Folisols, theforest floor is extremely important; sometimes this is the only soil on thesite, and therefore very sensitive.

• Chernozems – Grassland soils; grasses compete intensely for water;usually droughty, may have summer frosts; often calcareous at depth.

• Gleysols – Cold, wet soils; shallow rooting; windthrow problemscommon. For Luvic Gleysols, see also Luvisols, below.

• Luvisols – Usually dense “clay pan” at depth (unfavourable subsoil);often very high compaction hazard; may have suspended water tableand associated windthrow, cold soil, and slope stability problems; maybe calcareous at depth.

• Podzols – Occur in humid climates (wet belts or ESSF zone); if thick Ae(e.g., > cm), may be very acidic and nutrient-poor.

• Brunisols – Less developed soil; more alkaline ones (e.g., Melanic orEutric Brunisols) are often calcareous at depth. If Brunisols found onsteep slopes where Podzols are expected, see Regosols, below.

• Regosols – Younger soils, either from extreme climates (e.g., desert-like), or (more commonly) recently deposited or exposed parentmaterial (e.g., floodplains, old landslides). If found on steep slopeswhere more developed soils are expected, evaluate slope stabilityconcerns even if not obvious (see item , “Indicators of PotentialSlope Instability”).

39. Landform / Parent Material FS 39A

41. SURFACE ORGANIC MATTER / SOIL CHARACTERISTICSDescribe the organic matter on the surface of the forest floor and calculatethe percent cover of exposed boulders, rock outcrops, and mineral soil.

This information is useful when selecting harvesting and site preparationequipment. Coarse woody debris can limit the use of some site preparationequipment. The presence of large amounts of exposed mineral soil may beimportant in site preparation and planting decisions, as well as assessmentsof the sensitivity or significance of the forest floor.

Assess and consider the importance of organic matter and associated nutri-ents and biology. On some sites, preserving organic matter levels should beconsidered in the SP (e.g., in grass-dominated open-growing stands in drierbiogeoclimatic zones, such as BG, PP, IDF, and MS). Coarse woody debris isan important source of forest floor organic matter; it provides sites fornitrogen fixation and critical water storage.

• Coarse woody debris – Note whether it is standing or down, sound orrotten. Is snag preservation important for wildlife? If so, note how muchis recommended.

• Rotting wood – This is partially or completely incorporated into theforest floor. Record the quantity present and consider its importance.In drier ecosystems, much of the organic matter in the forest floor comesfrom coarse woody debris. Note any recommendations.

• Exposed soil or rock – Note whether the forest floor is naturallydiscontinuous. If so, determine the Forest Floor Displacement Hazard.Will boulders, sand, or rock outcrops limit equipment operations? Inaddition, will natural disturbances create enough planting or regenera-tion opportunities?

42. COARSE FRAGMENT BEDROCK / LITHOLOGYNote the general rock type(s) of the coarse fragments or bedrock (e.g.,granite). Using the key provided (Figure ), describe the crystal size, hard-ness, and colour (from a fresh face on the rock). If available, use local bed-rock keys and geology information.

Some bedrock types can indicate problems—for example, serpentine andphyllites, as well as some shales and schists, are often unstable; phyllitesweather readily to clays; and areas of limestone and calcareous siltstone aredifficult to revegetate. In the “Indicators of Potential Slope Instability”section (item ), note whether important lithological or bedrock featuresare present that may affect forest management activities (e.g., beddingplanes that are similar to the general slope angle, or extensive fracturing andweathering). These features can potentially affect the stability of the slope,or the stability of road cuts and fills.

42. Coarse Fragment Bedrock / LithologyFS 39A

figure 25 Soil classification key to the Great Group level (adapted fromLloyd et al. 1990).

Soil

clas

sifi

cati

on

key

to

th

e G

reat

Gro

up le

vel

40. Soil Classification / Association FS 39A

figure 25 Continued

40. Soil Classification / AssociationFS 39A

figure 26 Key to the identification of rocks (adapted from B.C. Department ofMines and Petroleum Resources 1970) (Continued on next page).

42. Coarse Fragment Bedrock / Lithology FS 39A

Key

to

th

e id

enti

fica

tio

n o

f ro

cks

figure 26 Continued

42. Coarse Fragment Bedrock / LithologyFS 39A