soil and hydrology

Careful Logging – Partial Cuts

Soil and Hydrology

Concerns Significance What are the Standards? How am I assessed? BMP’s

With support from Forest Research Partnership (Canadian Ecology Centre, Tembec, MNR, CFS) and MTCU

Al Corlett, R.P.F., Forestry Consultant


Soil and Hydrology

Erosion

Rutting


Soil and HydrologyAquatic ValuesSoil Compaction


Soil and Hydrology


Concerns –compaction

heavy equipment at wrong time or place, leading to—

Soil and Hydrology


Soil and Hydrology

Compaction H2O & nutrients can’t

move thru soil as easilyMore surface run-off,

especially if ruttedIncreased moisture

retention – longer to dry


Soil and Hydrology

Compaction soil stays cool longer in the springtime,

shortened growing season and delaying silviculture


Concerns –

compaction reduced growth

- even for light traffic

increased dieback

Soil and Hydrology


Soil and Hydrology

Compaction – influenced by: Texture, ground pressure / vibration, but

most important – moisture contentMost severe, medium to fine textured

soils, especially during wet periods greatest at 60-100% of soils’ water

holding capacity Consequences – lowland sites


Soil and Hydrology

Compaction – influenced by:

# of passes – the first few count!After average 2.5

trips, densities within 10% of the max


Concerns – effects can last a long time

Soil and Hydrology

32 years: 25% of area still heavily compacted (> 1.2 gm/cc)

(Wert, Thomas 1981)

Up to 18 years(Hatchell & Ralston 1971)

40 years on severely compacted areas

(Perry 1964)


Concerns: Erosion movement of soil particles by wind, water,

gravity

Higher risk: steep or long slopes, unstable road cut/fill sands and silts, shallow soil over bedrock,

water crossings

Soil and Hydrology


Soil and Hydrology

Concerns: Erosionsoil movementsedimentation into fish habitat


Concerns: Erosion smothering of root systems, reduced growth rate mortality

Soil and Hydrology


Soil and Hydrology


Concern: Rutting wet soils –very prone to rutting/compaction fine textured soils more susceptible than

coarse textured mineral soils. but very fine sands and fine sands may be

susceptible when wet. soils with lots of coarse fragments (e.g.,

stony tills or outwash) are less prone

Soil and Hydrology


Concern: Ruttingespecially bad in the spring and fall when soils are saturated

making re-use of trails difficult – more trails needed next time

Soil and Hydrology


Soil and Hydrology

Where are the issues? steep slopes rocky ridges long slopes complex terrain,

water courses treed lowlands


Risk of damage:•reduced when soil frozen•Increased risk – spring snowmelt, above normal rainfall

Soil and Hydrology


Standards: Rutting standards / BMP’s vary

by district, but under development

evidence – 20cm leads to major, long-term, localized damage.

how much total coverage is acceptable?

Soil and Hydrology


Standards: Rutting Caution: re-using

severely rutted old trails – may put you out of compliance before you even start!

If productivity issue –

re-use If hydrological – re-locate

Soil and Hydrology


BMP’s: Planning – all stages set clear objectives related to forest health regulate the timing of harvest according to

season / site condition (switch to winter harvest if a lot of wetland in the block)

good trail design and planning before the cut

have contingency areas

Soil and Hydrology


BMP’s: Landings use maps, field

information to locate landings

use existing landings (and trails) if appropriate

non-productive sites

Soil and Hydrology


BMP’s: Landings don’t bulldoze (cut

woody veg at ground level)

surface with chips / stone, aggregate if it will stabilize surface

Soil and Hydrology


BMP’s: Landings

To reduce compacted area –

keep as small as possible

pile material as high as safety permits

Soil and Hydrology


BMP’s: Landings gently sloping

(less than 8%, but not flat)

outside AOC’s

Soil and Hydrology


BMP’s: Landings locate so skidding

traffic doesn’t cross natural drainage

locate so water won’t flow in or out where roads or trails enter

Soil and Hydrology


BMP’s: Landings locate to promote

skidding & forwarding down-hill

Soil and Hydrology


BMP’s: Trail Management Minimize sections where water may

be difficult to drain or divert. grades >10%, long unbroken grades, long flat stretches, stretches that are straight up or

downhill that still require ditches

Soil and Hydrology


BMP’s: Trail Management stay out of AOCs, wet areas,

floodplains, outcrops, gullies, sensitive areas (watercourses, seasonal ponds, seeps, poorly drained areas)

Soil and Hydrology


BMP’s: Trail Management stick to coarser soils (sandy or higher

coarse fragments / gravelly), avoid silts and clays

run trails parallel to contours, run upslope trails along ridge crest

Soil and Hydrology


BMP’s: Trail Management avoid locating skid trails on moderate to

steep slopes (it is the gradient of the trail that is critical, not the hillside slope)

winch wood off areas with slopes >30% reach onto slopes with feller/buncher,

place piles at top or bottom of slope

Soil and Hydrology


BMP’s: Trail Management forwarding downhill is preferred (downhill

= favourable grade, uphill = adverse grade recommended grades for primary trails:

<10% adverse (up to 20% OK for short adverse pitches. E.G. 100-200 feet uphill, if straight and level before pitch) – use a clinometer

Soil and Hydrology


BMP’s: Trail Management pre-plan (walk the block

1st to locate wetlands & other sensitive sites)

orient trails away from wetlands, toward dry ground

place tops in wet areas

Soil and Hydrology


BMP’s: Trail Management during dry periods,

operate on low-lying areas with sufficient ground strength first

move to better drained sites when it gets wet

Soil and Hydrology


BMP’s: Trail Management when possible, reach

into wet areas to fell, and

pile bunches on dry ground for easy access by forwarder

Soil and Hydrology


BMP’s: Trail Management in winter, prepare roads

and trails ahead of time so that they are frozen

work wetter areas early in the day while still cold

Soil and Hydrology

Note: 7.5 cm. soil frost to support small equipment, 15 cm. for large


BMP’s: Trail ManagementRisk of unfrozen soils – little frost before snowfall soils are dry temperatures above

freezing lower slopes, wetter

sites

Soil and Hydrology


BMP’s: Trail Management Postpone logging if soil

at 30cm depth will hold a cast

too late if water can be squeezed from a handful of soil, if ruts deep, or if water seeps into ruts

Soil and Hydrology


BMP’s: Trail Management

where roads / trails must be located across contours, use runoff ditches to reduce velocity and magnitude of runoff

Soil and Hydrology


BMP’s: Trail Management drop load, winch across

trouble spots reduce weight of

forwarder forwarders – back-up trail

on short runs rather than having to turn around in the bush

Soil and Hydrology


BMP’s: Trail Management stabilizing exposed soil

wood chips, waste wood, bark mulch lasts several seasons, 2-6” depth,

slopes less than 4:1 (not in areas of concentrated water flow)

gravel low slope, little concentrated flow

Soil and Hydrology



hay or straw mulchone or two seasons, 2

bales for 30’X30’ areaon steep slopes,

anchor with netting or twine

Soil and Hydrology



stabilizing exposed soil hay or straw mulch

trench 10cm deep, width of bale,

Sloped up 10 cmabove original

ground level

Stake

Hay Bales

TwineFlow

Embed in 10cm deep trench

45cm mindepth intoground

Soil and Hydrology



stabilizing exposed soil single row – no

gaps, backfill on uphill

side

Sloped up 10 cmabove original

ground level

Stake

Hay Bales

TwineFlow

Embed in 10cm deep trench

45cm mindepth intoground

Soil and Hydrology



stabilizing exposed soil vegetation

permanently stabilize disturbed areas

Soil and Hydrology




best on slopes less than 4:1

Soil and Hydrology




rake, grade, remove debris, smooth site

Soil and Hydrology




apply seed spring, fall or after rain

Soil and Hydrology




mulch on dry or erodible soils or if seeded in summer

Soil and Hydrology




no vehicles until well established

Soil and Hydrology



water bars installed to move water off trail (before

it reaches an AOC)

Soil and Hydrology



stabilizing exposed soil water bars

at least 6-12” deep, 6-12” high, 20-30o to the trails, cross drainage grade of 2%

Soil and Hydrology



Recommended Spacing of Water Bars

% Grade Distance between Water Bars (m)

5 3810 2420 1430 1140 9

Soil and Hydrology

soil and hydrology

Documents

prone soil

soils water

fine textured soils

shallow soil

ruttingwet soils

fine sands

water crossingssoil

long slopes