Greenwood Lake Conservation Reserve Tuesday, 2nd June, 2020 
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Contact Address
Greenwood Lake Advisory Committee c/o

Dr. Willard Carmean
Professor Emeritus

Faculty of Natural
Resources Management,
Lakehead University

955 Oliver Road,
Thunder Bay, Ontario,
Canada P7B 5E1

     (807) 343-8110
Old Growth White Pine

Origin of White Pine Forest

White pine needs a "bit of a break" to take root and grow. Generally the seeds and seedling do best on nutrient rich soils, and in areas having moderate shade and reduced competition for other plants.

  • Fire often provides the ideal "break" for white pine. Fire can reduce or eliminate the competition from an existing forest stand releasing nutrients stored in trees and litter. If white pine seed take root after a burn, and if seedlings escape competition, the trees stand a good chance of long term success.
  • "Gap regeneration" is a forestry term used to describe gaps in the forest canopy where disease or wind may have killed or downed occasional large trees. These small openings provide the break white pine seedlings need to take root and prosper.
  • White pine may be able to take root and grow under the canopy of a poorly stocked hardwood or mixedwood forest found on dry sites. When the short-lived hardwoods die, white pine in the understory may be able to claim the upper canopy.
  • Abandoned agricultural fields provide openings where white pine seedlings can take root.

Declined Area of White Pine

  1. reduced seed source
  2. widely spaced seed years
  3. hardwood competition
    • reduced wildfire
  4. disease as instects
    • white pine blister rust
    • white pine weevil

Natural Regeneration of White Pine

A few scattered old white pine trees often remain in forest landscapes, but these lone pines usually are surrounded by dense stands of trembling aspen, white birch, spruce, and balsam fir. Thses dense mixedwood stands usually provide too much competition for establishment of relatively shade-intolerant white pine seedlings. However, white pine could be regenerated beneath these lone pines if the competing hardwoods and conifers were harvested just before a good pine seed year; scarification or prescribed burning could provide a good seed bed for white pine seedling. Such white pine regeneration must be protected and released just as we protect and release planted trees.

White pines often become established in the understory of poorly stocked, less vigorous aspen and birch forests found on shallow, gravelly or coarse textured soils. Removal or thinning of such poor hardwood forests could release understory white pine seedlings and saplings. A partial harvesting of overstory pine (shhelterwood cutting) has been used to regenerate white pine seedlings in the understory of white pine stands found on coarse textured soils.

Planting White Pine

Planting is needed in suotable areas that lack a natural seed source fo white pine; thses might be areas where white pine never occurred or where pine has been lost due to fire, harvesting and competition from hardwoods. For such areas white pine can be planted just as we plant spruce, jack pine or red pine; for old growth purposes, plantings could have irregular shaped boundaries and trees could be planted randomly instead of in rows. As with other conifer plantings, site preparation and tending might be needed. White pine plantations probably would be most successful on drier soils having relatively little competing vegetation and where blister rust hazard is relatively low. White pine also could be planted in the understory of poorly stocked slow growing aspen and birch stands on shallow, gravelly, or coarse textured soils. Hardwoods on such soils grow slowly, have sparse crowns and are short lived thus releasing understory planted or natural white pine. Such poor hardwood stands also provide some shading that lessens white pine weevil infestation.

General Description

The southern third of this 811 ha (1,004 ac.) Reserve is a fully stocked old growth white pine forest estimated to be about 300 years old. Many of the largest pines are more than 1 m (3.3 ft.) in diameter and more than 40 m (131 ft.) tall. Yellow birch and red maple reach the northern limits of their range in this area with occasional trees occurring under the pine canopy together with balsam fir, black spruce and white spruce.

In the northern part of the reserve white pines are less numerous and the forests are mixed stands of black spruce, white spruce, balsam fir, trembling aspen, white birch and white ceder. Interspersed throughout these mixedwood stands are individual trees and groups of white pine and occasional red pine.

The Reserve is located on a stony glacial moraine left by the receding glaciers about 10,000 years ago. Soils vary in depth and broad uplands are enriched with a surface slit loam layer deposited by wind or water following glacial retreat. Lower slopes have stony boulder layer and low depressions have organic soils often stocked with pure black spruce stands.

A network of walking trails provides access for research and education as well as nature appreciation. These trails are intended for foot traffic only; downed logs, rock outcrops, boulder fields and peat bog are barriers discouraging unwanted use by motorized vehicles. We cordially invite you to explore and enjoy the diversity and complexity of this old growth forest as well as the geologic diversity of upland moraines, lowland peat bogs, and the shoreline of Greenwood Lake.

History and Status

Old growth white pine forests were once common in the southern Ontario, eastern Canada and in the northeastern United States. The tall pines became the masts of sailing ships and the beams and lumber of world commerce. These magnificent old growth white and red pine forests are now rare in Ontario.

Old growth stands of white and red pine south of thunder Bay and west to Kenora were harvested in the early 1900's. But the remote and inaccessible Greenwood Lake forest lay just beyond reach of axe and saw. In the 1970's access roads approached Greenwood Lake and foresters with the Ontario Ministry of Natural Resources and Great Lakes Forest Products (now Bowater Inc.) recognized the unique character of this forest and recommended its protection.

This 811 ha (2,004 ac.) Reserve is on Crown Land and is excluded from the Dog River-Matawin Forest licensed to Bowater Thunder Bay Woodlands. The forest was indetified in the provincial old growth initiative and was officially recognized as a Provincial Conservation Reserve in 1995. Timber harvesting and mining are not permitted, ensuring that the area remains undisturbed and suitable for research and educational purposes. A committee composed of representatives from Lakehead University, Thunder Bay Field Naturalists, The Ontario Ministry of Natural resources and Bowater Thunder Bay Woodlands oversees the research and educational activities of the forest.

White Pine Blister Rust

Introducer to North America from Europe around 1908, white pine blister rust is now a serious disease affecting young white pine. To avoid or minimize damage from blister rust foresters will generally:

  • avoid planting white pine in areas that are high hazard micro-sites for blister rust such as lower slopes and depressions where dew and humidity favour germination of blister rust spores on needles of white pine.
  • reduce understory vegetation to increase wind movement and lessen dew accumulation.
  • prune lower branches of young white pine where blister rust infection is more common.
  • frequently inspecct young trees and prune rust infected twigs and branches.
  • encourage research that will provide resistant strains of white pine.

White Pine Weevil

White pine weevil is a major insect pest because weevil larvae attack the leaders (terminal shoots) of young trees. The loss or danage of the leader cause forking, multiple leaders, lost growth, unsightly and poor quality trees. Management practices that can avoid or minimize excessive weevil damage include:

  • avoil plantingwhite pine in areas that have high weevil hazard.
  • plant at high densities thus favouring development of terminal leaders.
  • use early pruning to remove infected leaders as well as favouring a lateral branch as a new leader.
  • use insecticidies to protect white pine leaders from weevils.
  • plant white pine in the understory of poorly stocked and slow growing white birch and trembling aspen stands where weevil hazard is low.
  • use early thinning that removes damaged trees and favours well formed domainant trees.

The Role of Fire

The large white pine trees at Greenwood Lake are simliar in age and size. Their uniform age and size suggests that a stand replacing fire, over 300 years ago provided the "breal" that eventually created the forest we see today. Fire scars are not noticeable on the boles (trunks) of the large white pine and this absence of scars suggests that intense fire has not occurred since the white pine forest was established.

The fire that burned this area around 1700 created ideal openings for successful white pine regeneration. The thick bark and long limb-free boles of older white pines make them more resistant to fire than smaller thin-barked trees. Seeds from surviving large white pine trees or seeds from trees bordering the burn blew into these openings. Many fast growing pine seedlings eventually dominated competing hardwoods and other conifers to create the uniform old growth white pine forest of today.

A small but intense wildfire occurred in August, 1991 in the southeast part of teh Reserve, along a portion of the orange trail. Lightning struck a standing dead white pine snag. Dry weather and an accumulation of dead balsam fir killed by spruce budworm created ideal conditions for a very hot burn. Fortunately, a nearby fire crew extinguished the fire and limited the burn to about 5 hectares. This small burned area provides a "natural laboratory" for the study of white pine regeneration following fire. Rseults from permanment quadrats within the burn indicate that:

  • most of the large white pine within the burned area were killed due to crown scorch; intense heat from convection currents consumed or serverely scorched needles of the trees;
  • white pine seeds from trees bordering the burn produced a continued regeneration of scattered new white pine seedlings; black spruce and balsam fir seedlings as well as regrowth of white birch and trembling aspen sprouts also occurred;
  • white pine seedlings beneath the dense clumps of birch and aspen were growing slowly due to severe competition but free-to-grow sight year-old white pine seedlings in opening between clumps were as much as 3 m (9.8 ft.) tall;
  • small amounts of white pine blister rust and white pine weevil infestations were present.

Studies of the permanent quadarts will continue to help answer the following questions:

  • how many of the established white pine seedlings will survive the dense hardwood competition?
  • will there be enough dominant free-growing white pine seedlings to form a new white pine forest or will a mixedwood forest develop with a few scattered pines mixed with many hardwood and conifer species?
  • will this mixedwood forest eventually evolve into a white pine forest when the short-lived hardwoods succumb to disease and insects?

Stand and Landscape Diversity

In biological terms "diversity" means wealth. An area with a variety of habitats, different forest species (forest composition) and different features (forest structure) will support a richer abundance and variety of plant and wildlife.

Forest Composition

The colour aerial photograph mosaic (centre panel) shows the diverse composition of habitats and forest types within the Reserve. Significant habitats include several small lakes, peat bogs, black spruce stands in lowland areas, mixedwood forests in the nortern part of the Reserve, and well stocked almost pure old growth pine forests in the southern part.

Forest Structure

Imagine the forest as a "layered" community. Each layer provides home and sanctuary for different plants, animals and birds. A forest with many layers will have an abundance and diversity of live. The layers (or structure) of the old glowth white pine forest at Greenwood Lake include:

  • a dominant almost pure white pine canopy formsthe uppermost layer of the forest;
  • a lower canopy consists of white spruce, black spruce, balsam fir, and occasional white birch, yellow birch and red maple;
  • a shrub layer primarily mountain maple and beaked hazel;
  • standing dead snags and fallen logs at different stages of decomposition are common and provide habitats for a vaariety of birds, animal, and species.

Old Growth White Pine for the Future

Most old growth white pine forests had their beginning following wildfire. The magnificent long-lived pines found in Greenwood Lake are now near the end of their successional path; it started with natural regeneration and then progressed through sapling, pole size trees, and mature forests before reaching the old growth stage now found at Greenwood Lake. This successional path will eventually end in the death of these old pines due to old age, disease, insects, or wind. White pine does not regenerate well in the understory of dense forest stands, so eventually these old trees will die and a new forest of different tree species will emerge.

Sustaining old growth white pine in the forest landscape requires efforts at all stages of their life cycle -- regeneration, mid-age and old-age. Practices are needed that will regenerate white pine, so that they can become the old growth forests of the future. Prectices also are needed that will avoid or minimize damage from white pine blister rust and white weevil.