Restoring for Old Growth Characteristics
Aging a Forest to Create Old Growth Characteristics
Most southern Ontario old growth was removed by logging, fire and settlement between mid-1700’s and early 1900’s.
New forests cover much of s. Ontario.
New forest less diverse than old mixed hardwood.
Now provides habitat for fewer species.
Forest will become old-growth on its own
100 y for deciduous trees, longer for conifer
Trees will die and fall
Return energy and nutrients to soil
OM will build
Will retain moisture
Will create a moist old growth environment
For faster results
Cut holes in canopy
Rebuild rich layer of decaying OM
Protect wildlife trees
Complex, multi-layered structure
Trees of all ages and sizes
Several canopy layers
Trees like pines that poke through canopy
Periodically, make clearings in ½ to 2% of parcel
> 50 m from edge and from other clearings
Small gaps (6-10 m) (remove 2-3 mature trees)
Encourages growth of shade-tolerant spp.
Larger gaps (10-50 m)
Encourage mid-tolerant spp. like oaks, white ash, white pine
Large openings (>50 m)
Favor intolerant spp. like poplar, birch, black cherry
Only makes sense in large parcels
To regenerate shade tolerant spp., choose sites where saplings of shade-tolerant spp. are present.
If you have unplanned treefall, create a gap by cutting several neighbor trees.
Protect uncommon trees from harvest
Such as long-lived conifers.
Pits and mounds
In natural forests
Provide range of moisture conditions
Expose mineral soil needed by some seeds
Decaying root masses create rich habitat
Dig depressions and mound up the spoil
Let declining trees fall naturally
In natural forests
Adds OM and nutrients to soil
Provides germination sites for some spp.
Leave 10 fallen logs per ha
>2 m long, >60 cm diam.
Cut sequentially to get age classes
Allow brush and leaves to decompose
Protect litter and herbaceous plants from livestock
When logging, localize activity on few skid trails
Log in winter and skid on snow trails
Wildlife trees (mast trees, cavity trees)
Leave 6 living cavity trees per ha
> 25 cm dbh
At least one > 50 cm dbh
Choose some of softer wood
Choose some that live longer, some that die early
Leave as many as possible
At least 5 per ha, some > 50 cm dbh
Create snags by girdling
Dead conifers stand longer
Aim for diversity of snag ages
Nut, fruit trees
7 per ha
> 50 cm dbh
3 per ha
Leave one cluster of three per 4 ha (pines, hemlocks, spruce)
Protect as seed source
U.S. Forest Service recommends variable-density thinning for conifer plantations
Thin to different densities in ¼ to 1 acre patches
Leave ¼ to ½ acre unthinned areas
Create small gaps < ¼ acres
Small gaps allow in light but do not increase windthrow
In young plantations, small gaps will encourage the growth of herbs, shrubs and understory trees, and, large open-grown trees
In un-thinned or lightly-thinned areas, shade tolerant trees like hemlocks will grow.
Natural disturbances will continue to occur, adding to landscape diversity
Allowing natural disturbances to create old-growth features
Pits and mounds
Will take over a century in New England
Legacy tree protection
Never harvested; perhaps 25-50% of canopy trees
Reduced harvest of other trees continues
Produces large trees, canopy, snags, big logs
USFS Southern Region completed a report in 1997:
“Guidance for Conserving and Restoring Old-Growth Forest Communities in National Forests in the Southern Region”
Old growth characterized by:
Variation in tree size and spacing
Accumulations of dead fallen and standing trees
Decadence (broken or deformed tops and root decay)
Multiple canopy layers
Canopy gaps and understory patchiness
Three levels of old growth recognition
Existing old growth
Criteria: age, disturbance, basal area, tree size
Future old growth
Allocations of wilderness or backcountry which will be managed to become old growth
Possible old growth
Stands meeting one or more minimum old growth criteria
Southwestern forests are characterized as “frequent fire” systems.
Large trees and a modest amount of large dead material (standing or down) are one characteristic.
High density of trees is not a characteristic of uneven-aged old growth stands adapted to frequent, low-intensity fires.
Stands are usually composed of shade-intolerant pines that need the creation of openings every decade or so to produce uneven-age stands.
One approach is to achieve a target basal area (10-18 m2/ha)
Most large, old trees are retained
Some trees retained in all diameter classes
Ponderosa pine dominates
ome Pseudotsuga, Abies
Some dead; historical fires kept it at low levels
Natural and prescribed fire
Improvement cutting (removal of Doug fir)
Sanitation cutting (removal of diseased trees)
Cutting to allow new age classes
Carry out restoration over long periods of time