HARVESTING TO REGENERATE A NATURAL FOREST IN THE MANITOBA ...

HARVESTING TO REGENERATE A NATURAL FOREST
IN THE MANITOBA MODEL FOREST, CANADA

Dr. James Ehnes
Forest Ecologist, ECOSTEM Ltd. & Research Scholar, University of Winnipeg, Manitoba
495B Madison Street, Winnipeg, Manitoba, Canada, R3J 2J1, [email protected]

Abstract – The Manitoba Model Forest is operationalizing the overall goal for sustainable forest management: maintain
forest ecosystem health while harvesting timber (after CCFM 1992). Timber harvest guidelines that approximate the effects
of a large wildfire were developed for spatial scales that span from the operating area (landscape design guidelines) down to
the site (operator and regeneration guidelines). Guidelines are being tested in four large scale harvest trials. A long-term
monitoring program is being established and follow-up research includes testing indicators of sustainable forest management.

Introduction develop and test harvest guidelines that approximate the
effects of a large wildfire. A large wildfire is an event that
The overall goal for sustainable forest management affects spatial scales that span from thousands of hectares
adopted by the Canadian Council of Forest Ministers is to down to a square meter. The harvest analogues are scales
“maintain and enhance the long-term health of our forest that include the operating area down to the site. Thus, the
ecosystems, for the benefit of all living things both focus of this project is the development of landscape
nationally and globally, while providing environmental, design guidelines for an operating area and cut-block
economic, social and cultural opportunities for the benefit guidelines for operators and regeneration.
of present and future generations” (CCFM 1992). We
summarize this goal to: “Maintain forest ecosystem health This project is also developing and testing indicators
while harvesting timber”. of sustainable forest management, establishing a long-
term monitoring program, and developing procedures and
What Is Forest Ecosystem Health? According to the guidelines that cover most aspects of environmentally
Canadian Criteria and Indicators of Sustainable Forest friendly logging practices. This paper presents our first
Management, forests are healthy when we conserve approximation of what it means to affect an operating area
natural biological diversity, maintain ecosystem condition like a large wildfire in eastern Manitoba.
and productivity, conserve soil and water resources and
maintain contributions to global ecological cycles (CCFM Operational Goals
1995).

How do we keep boreal forests healthy? The The development of operational goals is the first step in
approach adopted by this project is to learn from nature. operationalizing the overall goal of sustainable forest
Plants and animals of the boreal forest are adapted to management. By applying the natural disturbance
frequent disturbance. The natural disturbance approach approach to what is meant by forest ecosystem health, we
tries to keep forests healthy by trying to affect the forest come up with the following operational goals for logging:
like natural disturbances. In eastern Manitoba, the natural
forest is mostly shaped by large wildfires. (A) In cut-blocks, minimize the:
(1) Differences in the ways that logging and wildfire
Project Background – initially affect plants, soils and soil organisms;
(2) Time required for a cut-block to look, feel and
The Manitoba Model Forest and Pine Falls Paper operate like a natural forest {an area is called a
Company wanted to undertake a project that would divergent site during the time when it is not like a
include operational implementation and could be natural forest of the same age}.
completed in four years. It was expected that any project
involving natural disturbance guidelines would entail (1) (B) Throughout the region, maintain:
research to fill gaps, (2) analysis of data and the literature, (1) The total area of divergent sites low enough for
(3) translation of information into planning and the regional ecosystem to absorb;
operational guidelines, (4) education of participating (2) Soil fertility at every site that is not a permanent
stakeholders and the public, (5) operator training, (6) road;
operational trials, (7) follow-up research, and (8) ongoing (3) Healthy populations of rare native species that are
adaptation. sensitive to disturbance;
(4) All rare native ecosystems that are sensitive to
Since large wildfires are the dominant type of natural disturbance;
disturbance in the region, the Model Forest decided to (5) Water quantity and quality.

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Even though the project’s focus is on spatial scales the layout of cut-blocks, retention areas and roads in the
spanning from the site to the operating area, it was operating area (Ehnes 2000a).
necessary to develop regional (i.e. an area of about
1,000,000 ha) operational goals. In our approach, Cut-Block Guidelines
sustainability is assessed at the regional rather than the
operating area scale based on ranges of natural variability Cut-block guidelines were developed based on
(Miller and Ehnes in press). research from about 1,000 sample plots in the region
(Ehnes 1998, Ehnes 2000c) and a literature review.
These operational goals are summarized for the
public by the statement: A harvested area should look, Within most burn patches, fire usually is hot enough
feel and operate like a natural forest as quickly as possible to kill the exposed parts of all plants. The recovering burn
after harvesting. patch is even-aged and initially made up of fire tolerant
species. Within these same burn patches, fire burns just
Landscape Design Guidelines long and hot enough to create an excellent seedbed but
not to kill roots or buried seeds. Thus, initial post-fire
Affecting a landscape like wildfire means placing composition is heavily influenced by pre-fire
cut-blocks and retention areas in the same places that fire composition, the seed bank and species with propagules
would leave them. It also means keeping roads and other that disperse quickly over large distances (e.g.
activities out of the places that fire usually skips over Marchantia polymorpha, Polytrichum spp.).
(Ehnes 2000a).
Fire rejuvenates coniferous forests. Fire creates very
To determine what a large wildfire disturbs and what good growing conditions for the plants that are commonly
it leaves in eastern Manitoba, we (1) examined fire history found in the forest. The natural decline in soil fertility is
records and (2) mapped and analyzed six large wildfires arrested and nutrient availability increases. Fire releases
with a combined area of 75,000 ha. Two wildfires were seeds in the cones of some kinds of plants and stimulates
selected from 1955, 1976 and 1983. the sprouting of some dormant buried seeds.

Many of the wildfires that grow beyond 200 ha There are some large initial differences between
become larger than 5,000 ha. An operating area should be wildfire and timber harvesting that cannot be eliminated
at least 1,000 ha. by a natural disturbance approach (Ehnes 2000c). Our
goal is to achieve convergence of post-fire and post-
About 71% of wildfire event area is disturbed. A harvest successional pathways as quickly as possible. To
large wildfire burns almost all upland area in path of the operationalize this goal, ecological objectives for cut-
headfire. Single or small clumps of residual trees are rare blocks were established trying to meet the ecological
and occur mainly at the perimeter of the fire. Large fires objectives through a combination of modified cutting, site
usually jump over large bogs and fens. preparation and regeneration practices (Ehnes 2000a).

A large wildfire creates a landscape with vegetation The modified cutting practices include:
of three ages: 1) Clear-cutting with retention of post-fire pioneer tree
(1) 0 years on most of the upland area and about half of
species:
the densely treed wetlands; a) Leave scattered merchantable jack pine and black
(2) Time since previous fire (mean ≅ 70 years) on about
spruce trees (retention trees) at a density equal to
half of the densely treed wetlands. It seems that many 5% of typical mature density for the macro-site
of the treed wetlands that are skipped in one fire, type (e.g. 70 stems/ ha on shallow mineral soils).
burn in the next one; This meets several of the ecological objectives.
(3) >120 years on the balance of shallow water table b) Leave aspen and birch standing except on harvest
trails. This helps to minimize suckering and
wetlands. sprouting.
c) Eliminate balsam fir, white spruce and tamarack
What a large wildfire disturbs is largely related to either by cutting them down, knocking them
macro-site type and distance from headfire. Operating down or killing them during post-harvest
area disturbance and retention percentages were silviculture. This retards a shift in overstory
established for each macro-site type and for location composition towards fire intolerant species and
relative to fire perimeter. The percentage of an operating outbreaks of insects and diseases.
area (at least 1,000 ha) harvested is determined by 2) Scatter slash.
applying the disturbance percentages to the area 3) Leave snags standing where possible.
distribution of macro-site types within the operating area.
Step-by-step design guidelines take the planner through

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4) Avoid trampling black spruce seedlings and saplings. operational protocols to support sustainable forest
5) Disturb only the duff layer of the soil. management. In the spirit of adaptive management,
6) Avoid rutting and compaction. harvest guidelines are being modified as new information
7) Avoid sensitive ecosystems. is generated by the project. Further details on this project
8) Pile wood inside the cut-block boundary. are available by visiting the Manitoba Model Forest
website (http://www.manitobamodelforest. net/).
These cutting guidelines are being tested in two trial
areas of about 1,300 ha each. One area has winter access Acknowledgements and Disclaimer
only while the other has year round access. In a cut-to-
length system, the cutting guidelines are implemented on Advice on project design and implementation was
shallow mineral soils by cutting on designated trails 12m provided by Armand Boulet, Stan Boutin, David Burton,
apart and leaving a retention tree every 12 m on one side Ian Corns, James Fraser, Vince Keenan, Karen Palidwor,
of the trail. In a cut and skid operation using chainsaws, Derek Sidders, Bill Snell, Tim Swanson, Ilkka Vanha-
the logger starts at the east end of the cut-block and leaves Majamaa, Mike Waldram, Mike Weber, Richard
retention trees on a 12 x 12m spacing. Westwood and Deirdre Zebrowski. Logistical and in-kind
support was provided by Pine Falls Paper Co., Manitoba
Successful trials were completed on Pine Falls Paper Conservation and their employees. In-kind support was
Company’s Forest Management License with both the provided by Pine Falls Paper Co., Manitoba Conservation,
Company’s cut-to-length and contracted cut-and-skid Alberta Pacific Forest Industries and ECOSTEM Ltd..
operations. Project funding was provided by the Manitoba Model
Forest, Pine Falls Paper Co., the Canadian Forest Service
No matter what the machine operators do during and EcoAction 2000.
harvesting, there will still be some big differences
between the effects of logging and fire. Site preparation Most of the material in this paper has been taken
and assisted tree regeneration are critical to regenerating from project reports.
something like a natural forest. Thus far we have tested
two methods of mechanical site preparation in the trial The results and conclusions in this paper are those of
area accessible only in the winter. Water-filled shark fin the author and no official endorsement by the Manitoba
barrels were used on half of the area harvested in the first Model Forest, the Canadian Forest Service, Pine Falls
year. The ecological objectives for duff reduction and Paper Co. or Manitoba Conservation is intended or should
mineral soil exposure were not met due to snow and frost. be inferred.
A Donaren disc trencher was used in the second year with
better results. We are seeking provincial approval to test References
prescribed burning in the other half of the winter trial
area. Prescribed burning has not been used as a method of CCFM (Canadian Council of Forest Ministers). 1992.
site preparation in Manitoba. Drag chains with spikes will Canada forest accord. Forestry Canada. Ottawa.
be used in the summer harvest area this fall.
CCFM (Canadian Council of Forest Ministers). 1995.
Rapid regeneration of typical post-fire species Defining sustainable forest management: a
maintains site fertility and native biodiversity. Canadian approach to criteria and indicators.
Regenerating vegetation captures nutrients released by Natural Resources Canada, Canadian Forest
decomposition before they are leached from the site. A Service, Ottawa.
dense jack pine canopy in the shrub layer eliminates
atypical species within 10 years of the fire. For these and Ehnes, J. 1998. The influences of site conditions, age and
other reasons, the target density for year 3 tree disturbance by wildfire or winter logging on the
regeneration is 75% of typical pre-fire density for the species composition of naturally regenerating
macro-site type (25,000 to 60,000 stems/ ha). boreal plant communities and some implications
Monitoring, Indicators and Technology Transfer for community resilience. Ph.D. thesis,
Department of Botany, University of Manitoba.
Our success at maintaining forest ecosystem
health is being monitored at permanent sample plots Ehnes, J. W. (ECOSTEM Ltd.). 2000a. Maintaining forest
established in the harvest trial areas and a recent wildfire. ecosystem health while harvesting timber by
Intensive scientific research on ecosystem recovery at a harvesting in ways that help harvested areas
subset of these plots is being conducted to improve our look, feel and operate like a natural forest as
understanding of how these ecosystems respond to fire soon as possible: guidelines for landscape design
and harvesting. Concurrently, we are developing and and cut-block operations- second iteration.
testing indicators of sustainable forest management, Manitoba Model Forest Project # 98–2-49,
developing operator and planner guides and modifying Manitoba Model Forest, Pine Falls, Manitoba.

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Ehnes, J. W. (ECOSTEM Ltd.). 2000b. What does a large
wildfire disturb and what does it leave in the
eastern two-thirds in the Manitoba Model Forest.
Manitoba Model Forest Project # 98–2-49,
Manitoba Model Forest, Pine Falls, Manitoba.

Ehnes, J. W. (ECOSTEM Ltd.). 2000c. Post- fire changes
in the composition and structure of woody
material in the Manitoba Model Forest. Manitoba
Model Forest Project # 98–2-49, Manitoba
Model Forest, Pine Falls, Manitoba.

Miller, P. and Ehnes, J. W. In press. Can Canadian
approaches to sustainable forest management
maintain ecological integrity? In Ecological
integrity: integrating environment, conservation
and health. Edited by David Pimental, Laura
Westra and Reed Noss. Island Press.

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