|
|
|
Socio-Economic
Montage
|
Potential of Partial
Cutting Silvicultural Systems to Affect Stand Productivity and Wood
Flow
|
Authored by: Ivan
Listar, R.P.F.
Prepared for: Ministry
of Forests
March 1998
Location of Publication:
"Columbia Basin Trust Collection"
Ministry of Forests, Nelson, BC
|
Recent Timber Supply Reviews indicate
significant reductions in both short and long term wood supply.
Additional reductions are anticipated with the implementation
of the Forest Practices Code (FPC) and the approved Kootenay
Boundary Land Use Plan (KBLUP). The Allowable Annual Cut
(AAC) for the Nelson
Forest Region has been reduced from 6.3 million to
5.5 million m3 per year, representing a loss of 13 percent.
Implementation of the FPC and the KBLUP are anticipated to
reduce the AAC to between 4.7 and 5.2 million cubic metres.
Two major factors contributing to the reduction are green-up/adjacency
rules and integrated resource management objectives such as
biodiversity, wildlife habitat and visual quality.
At present, clearcutting is the
predominant silviculture system currently practiced throughout the
Nelson Forest Region (62.7% of the area harvested), followed by
seedtree (20.8%), single tree selection (6.7%), group selection
(5.7%), and shelterwood (4.1%). The KBLUP Implementation Strategy
Task Force is considering partial cutting tactics that could positively
influence the wood flow in the region without negatively affecting
the Long Run Sustainable Yield. It is speculated that partial cutting
systems may be able to address these management factors and improve
wood supply in the short term because of increased flexibility in
harvest scheduling. The goal of this paper is to provide some guidance
for implementing an increase in partial cutting without undue risk
of disease, regeneration failure and loss of Mean Annual Increment
(MAI).
The objectives of this project were
to:
 |
To identify "low
risk" timber types and stand conditions for partial
cutting silviculture systems;
|
|
To evaluate the effects of
various partial cutting regimes and levels of Armillaria
on stand productivity;
|
|
To provide general partial
cutting guidelines and management strategies for both silviculturists
and modellers; and,
|
|
To evaluate the effects of
partial cutting "low risk" timber types on wood
flow in the Boundary and Cranbrook Forest Districts. |
A more balanced mixture of clearcutting
and partial cutting silviculture systems is recommended. The choice
of system is not limited to one of the classical models, but may
include variants that take advantage of current stand conditions
to meet management, biological and social objectives. An increase
in the amount of area harvested annually in the Nelson Forest Region
using low risk partial cutting silvicultural systems is also recommended.
Other recommendations include:
|
Partial cutting prescriptions
should consider: a) suitability as determined by silvicultural,
regeneration and forest health characteristics of the stands;
b) maximization of MAI, and; c) wood flow in the management
unit. Group selection and small patch clearcuts, followed
by shelterwood systems offer the most flexibility with the
lowest risks to regenerating stands. The choice of silviculture
system, site preparation techniques and stand tending activities
should all contribute to maximizing the yield and the reduction
of risk to Armillaria.
|
|
District Managers should examine
the historic use of partial cutting and expand their programs
where applicable and as necessary in constrained areas, minimizing
risk through root rot surveys and attention to the principles
of MAI maximization. Partial cutting should focus on low risk
approaches involving Armillaria-resistant species and inoculum
removal. Group selection and small patch clearcuts are strongly
favoured for lowering risk.
|
|
Regional silviculture systems
staff should assume a training and extension function and
devote adequate staff time to providing formal and and "tailgate"
workshops, conducting case studies and publishing a series
of example silviculture prescriptions (SP's) that develop
partial cutting expertise in the Nelson Forest Region.
|
|
In order to maximize MAI in
a partially cut stand, we must know the level of Armillaria
infection. Recent trials with the present survey systems indicate
that the systems cannot differentiate between different Armillaria
infection levels. This must be corrected at the provincial
level by the Forest Health Section to ensure that SP's can
be correctly developed.
|
|
The regional forest pathology
program should ensure that: a) the Armillaria root disease
SOP is finalized with the assistance of the regional soil
scientist, site preparation coordinator, incremental silviculturist
and the provincial pathologist; b) a regional database is
developed for root rot and soil disturbance surveys so that
the MAI implications of root disease and pushover logging
can be modeled; and, c) the development of the ROTSIM
root disease model is supported during the development of
PROGNOSIS.
|
|
Use FSSIM
as a screening tool to determine if there is or is not an
effect of partial cutting on wood flow. If there is no negative
effect, then other forest estate models, which can accommodate
partial cutting, should be used to demonstrate the effects.
|
There is potential to meet the demand
for partial cutting in some timber types in constrained areas while
still meeting adjacency and other management objectives. Although
there is a general consensus that Armillaria is present throughout
the Nelson Forest Region, the fact that Armillaria exists in a stand
will not preclude that stand from being harvested and managed. The
presence of Armillaria however, will dictate the management options
available on that site.
LINK TO DEFINITIONS:
1. LOW RISK
"Low risk" refers to biological suitability and high probability
of harvesting and regeneration success while minimizing the negative
effects of Armillaria root disease.
2. PROGNOSIS
A stand growth model used to develop partial cutting growth curves.
It is able to simulate tree growth in a manner that incorporates
the stand dynamics that result from a mixture of tree species and
partial harvests. It is also able to incorporate the effects of
Armillaria root disease and its responses to stand entry.
3. ROTSIM
A root disease extension module for PROGNOSIS.
4. FSSIM (Forest Service Simulation)
A forest estate simulation model that is designed to work with clearcut
harvest projections and is not well able to project stand entries
with partial removals.
|
|
