In 1998 various claims began to be made in forestry circles in British Columbia that our forests were growing faster than previously thought. This paper was commissioned by the New Perspectives Forestry Society to find out if there was any substance to these claims.
A Report Prepared by
O. R. Travers, R.P.F.
for the New Perspectives Forestry Society
June 20, 2000
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"Study how a society uses its land and you can come to pretty reliable conclusions as to what its future will be."
E. F. Schumacher
"(P)lanning and practices do not yet protect many of the important environmental forest resources. Implementation of the Code is still incomplete and unfinished four and one-half years after it became law." He warned that: "British Columbia faces serious repercussions if it is unable to demonstrate that wildlife, scenic and recreational values, and biodiversity are protected in forestry operations."
Keith Moore, Chair, BC Forest Practices Board, 1997-1999
ABSTRACT
In 1998 various claims began to be made in forestry circles in British Columbia that our forests were growing faster than previously thought. This paper was commissioned by the New Perspectives Forestry Society to find out if there was any substance to these claims. Upon close examination, it was determined by the Ministry of Forests researchers, that a systematic error had been discovered in a key planning tool, the site index curves. The research confirmed that in some of our forests - those where a site index had been classified in an old growth forest - the new forest on the same site was actually higher than indicated. When the corrected site indices were put into a yield prediction model, the projected rate of growth was higher than previously believed.
Since the New Perspectives Forestry Society is very interested in the management of forests for all values, the scope of this paper was expanded to discuss whether this discovery would help or hinder the establishment of Sustainable Forest Management (SFM) in B.C. Since SFM is based on a much broader concept of sustainability, than the Forest Service Simulation Model used to carry out timber supply analyses, the overall conclusion of this assessment is negative. The only way that higher site indices, and consequently a higher future timber supply would assist the implementation of SFM in BC, is if any increase in the availability of timber were to be "shared " amongst all forest values. Since this is not current practice, and any increase in timber supply today is seen simply as an increase in management flexibility to increase the volume of timber available for today’s licensees to cut, the Old Growth Site Index (OGSI) corrections will likely be a further obstacle to establishing SFM. In worst case scenario the OGSI corrections could be used where they do not apply, and projected timber supply could be increased without any valid technical reason. For SFM is to be successfully implemented there must be a good fit between the carrying capacity of the forest and the amount of timber needed to sustain all values. Some recommendations for achieving SFM are made.
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Table of Contents
Introduction
The Role of the "Base Case" in Setting the Rate of Logging
Correcting an Error in Old Growth Site Indices
Possible Sources of Bias in the OGSI Site Index Corrections
What the OGSI Research Confirmed
Will More Accurate Site Indices Alone Deliver SFM?
Will OGSI Hinder or Help SFM ?
Strategic Management - How to Achieve SFM
Summary
Conclusions
Recommendations
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I. Introduction
Over ninety percent of British Columbia’s forests are publicly owned. Hence their sustainable management to produce a wide range of goods and services is a topic of major interest and concern for all citizens. Between 1990 and 2000 the concepts and methods used to produce these benefits have been changing, and two ideas with potentially opposite consequences have emerged.
The first is international in scope and is known by many as forestry’s contribution to sustainable development – the concept of Sustainable Forest Management (SFM). As international observers will recall, sustainable development was defined in 1987 by the World Commission on Environment and Development as "Development that meets the needs of the present without compromising the ability of future generations to meet their own needs."
Previous definitions of sustainable forestry concentrated on the timber resource, with forest management narrowly focussed on the "sustained yield" of timber. In contrast, the intent of SFM is to manage for a much broader range of resource values such as water supply, soils and cultural sites, as well as timber. As a consequence SFM requires a much broader perspective by forest managers and more complete understanding of the relationship between the actions they take, the forest conditions created by those actions, and the forest values created and influenced by those actions at all spatial and temporal scales.
The second idea is made in B.C. It is the claim and assertion that our forests are growing faster than we previously thought. On July 6, 1998 the provincial government released the results of the Old Growth Site Index (OGSI) study which began in 1994, was completed in 1998, and cost Forest Renewal BC more than $6.4 million. On this occasion, then Minister of Forests, David Zirnhelt said:
" British Columbia's forests are growing faster than forecast,
... there is cause for optimism for future timber supplies,
Second growth forests are reaching maturity sooner and with a greater volume than previously thought,
This will have a positive impact on the forest industry."
Taken together, what does this mean for BC’s forests? Is it possible to manage for a broader array of values as promised by SFM, while at the same time increasing the rate of cut? Moreover, if BC’s forests are indeed growing faster than previously believed, is the best use of this increase to bolster short term timber supplies, or is it needed to provide management flexibility to conserve other values such as wildlife, water and recreation? Will application of the OGSI site index correction equations help or hinder achievement of SFM?
II. The Role of the "Base Case" in Setting the Rate of Logging:
To begin to provide answers these questions it is necessary to understand the administrative process used by the BC Chief Forester for determining allowable annual cuts (AAC’s) and the statutory framework in which it resides. Allowable cuts for Tree Farm Licences and Timber Supply Areas are set by the Chief Forester in accordance with Section 8 (7) of the Forest Act:
Section 8(7)
In determining an allowable annual cut under this section the chief forester, despite anything to the contrary in an agreement listed in section 12, must consider
(a) the rate of timber production that may be sustained on the area, taking into account
(i) the composition of the forest and its expected rate of growth on the area
In considering the factors that must be addressed in determining AAC under section 8, the Chief Forester is assisted by forecasts of timber supply supported by a data package that includes information on the land base inventory, timber growth and yield, and current management practices. A series of timber supply forecasts is produced using this data set and simulated by a computer model (FSSIM). For example, in the 1999 Strathcona TSA timber supply analysis, the Chief Forester stated:
"Each forecast is based on the same set of data, and reflects different decline rates, starting harvest levels, and trade-offs between short- and long-term harvest levels. From this range of forecasts, one is chosen which attempts to avoid excessive changes from decade to decade and significant timber shortages in the future, while ensuring the long-term productivity of forest lands. This is known as the "base case" forecast, which forms the basis for comparison when assessing the effects of uncertainty on timber supply."
Since the base case represents only one in a number of theoretical forecasts, with significant "error and noise" in the data, the base case forecast is not an AAC recommendation. Rather, it is only one possible forecast of timber supply, whose validity depends not only on the accuracy of the data but also on the assumptions in the FSSIM computer simulation.
The Chief Forester examines the degree to which all the assumptions in the base case forecast are realistic and current. He then considers the extent to which the theoretical estimates of future timber supply must be adjusted to better reflect current management practices, especially by the Forest Practices Code. The Chief Forester cautions however, that timber supply analyses are but one important input to an AAC determination. Again, in the Strathcona TSA the Chief Forester said:
"…the AAC determination itself is not a calculation but a synthesis of judgement and analysis in which various uncertainties and potential current and future social, economic and environmental risks are assessed. Depending upon the outcome of these considerations, the AAC determined may or may not coincide with the base case forecast."
The is consistent with the Chief Forester’s guidelines for selecting an AAC, which are:
to maintain the current AAC – if possible;
if not possible, to find the maximum harvest possible, consistent with other criteria;
to maintain a gradual decline to the long term harvest level - if possible; and
to avoid dropping significantly below the long–term harvest level – if possible.
The Chief Forester’s discretion is also constrained by a letter from former Minister of Forests Andrew Petter which stated that:
"…any decrease in allowable cut at this time should be no larger than necessary to avoid compromising long – run sustainability."
Regrettably, the Minister did not define what he meant by long run sustainability.
To illustrate what this means in practice, the Chief Forester recently exercised his judgement in setting the AAC in the Strathcona TSA as follows:
" For the Strathcona TSA, the BCFS analysis indicated that maintaining the current AAC would cause serious future declines in timber supply. To avoid such declines in the BCFS base case projection, an initial harvest level of 1 456 621 cubic meters per year was chosen, which was about 210 000 cubic metres below the current AAC of 1 665 745 cubic meters. …This projected harvest level declined for three decades at a rate held constant at 12 percent per decade, to a mid-term level of about 940 000 cubic metres per year. After five decades at this level, the projected harvest rose to a steady long-term level of 1 088 250 cubic metres per year."
The intent of this rationale is to "avoid excessive changes in AAC from decade to decade and significant timber shortages in the future, while ensuring the long-term productivity of the forests." Whether this actually achieves SFM is further discussed below.
III. Correcting an Error in Old Growth Site Indices
Site index is the independent variable that drives Ministry of Forests growth prediction models in a timber supply analysis. Hence a systematic error in classifying site index could over or underestimate timber supply. The Ministry of Forests explains:
" Site index is used in timber supply planning to predict future stand volume. Site index is used in silviculture to help make sound decisions about management options such as reforestation, spacing, pruning, fertilization and commercial thinning. Site index is used in forest inventory to describe site quality and to update inventory data bases.
Site indices are determined from information collected during inventory and silviculture surveys. Correct estimates of site index are essential to good forest management. They allow the chief forester to determine an appropriate level of timber harvest for a given area. They allow forest managers to predict the outcome of a particular forest practice."
In British Columbia, growth estimates for young forests on Crown land have historically been derived from site indices measured in old-growth stands – because they are the forests present in much of B.C. Some British Columbia foresters have asserted - for some time - this method underestimates site index and therefore underestimates the predicted growth rate of young forests. To assess the merits of this argument, between 1994 and 1997, the Ministry of Forests, funded by Forest Renewal BC, assessed the validity of these assertions on the ground. Albert F. Nussbaum, one of the Ministry of Forests researchers doing this work, provided some early observations:
"Mounting evidence and foresters perceptions suggest that the site index of British Columbia's old-growth (total age > 140 years) stands are being underestimated. Regional plot studies confirmed that site indices were being underestimated for western hemlock (Tsuga heterophyla (Raf.) Sarg. (Nigh and Love 1997) and Lodgepole pine (Pinus contorta Dougl. ex loud. var. latifolia Engelm.) (Goudie 1996) with the results being similar to Alberta (Udell and Dempster 1987). The potential impacts of underestimating site indices on forest level planning decisions warranted a province - wide study to develop site index adjustments, or corrections, for application after the harvest of old-growth stands."
Some of the factors that may lead to underestimates of site index in old growth forests were listed by Alfred Nussbaum et. al. These are:
"Suppression or repression in the top height trees which result in the trees not expressing the growth potential of the site.
Bias in the height-breast age model used to estimate old growth site index.
Top damage in the top height trees, which causes the measured growth to under-represent the true height growth.
Death of the best top height trees; i.e. the trees that best express the potential productivity of the site, which leaves less suitable trees being chosen as top height trees,
Other biotic factors such as infestations and disease."
Mr. Nussbaum concluded:
"Regional studies support perceptions that site indices, the measure of forest site productivity in British Columbia, are underestimated in old -growth stands. When old-growth (total age > 140 years) stands regenerate following harvest, site index estimates generally rise. Data came from paired plots installed in old growth stands and adjacent logged and regenerated (LAR) stands of the same productivity. Site index was estimated for both the old-growth and LAR plots and comparisons were made ... Correction equations and application guidelines are provided. The results of this study should be useful in forest level planning until more reliable methods of estimating site index become available for old-growth stands."
The conclusion of the research is clear and generally not disputed - a technical error was found in the conventional polymorphic site index curves used to estimate site index in old growth stands. To correct this error, the forest researchers developed site index equations for correcting this error in future timber supply planning.
IV. Possible Sources of Bias in the OGSI Site Index Corrections
The Ministry of Forests researchers were cautious. Potential sources of bias in their OGSI site index correction equations were carefully noted as follows:
Bias in the growth intercept methods.
The growth intercept model may give biased LAR (logged and regenerated) plot site index estimates.
Some forest researchers do not think it is sound practice to estimate site index in stands less than one-half of the reference age. In the base case of site index (at 50 years), these researchers would try to estimate site index in stands less than 25 years. Stands in the OGSI study were accepted for site index estimation as low as eleven years. In addition, the researchers had difficulty finding paired plots because old growth is commonly logged soon after the green-up age occurs in immature stands.
Improper matching of the old-growth and LAR plots with respect to site productivity.
Comparisons of the site index of old growth to the LAR plot would be invalid if plots of different site productivity were paired.
Bias in the growth intercept model development technique.
This source of potential bias is possible because the trees selected for stem analysis are not the same as site trees, on average, in the past. The OGSI site index correction equations deal with this bias, if any exist, in the height-age model.
There is potential bias in the application of the OGSI site index correction equations if:
- the results are applied to a population that is different from the sample population;
- inventory estimates of the old growth site index are different from the paired plot estimates of old growth site index.
The Ministry of Forests cautions that the OGSI site index correction equations, should be used :
Only in forests similar to the old-growth polygons that provided the data used to develop the site index correction equations.
Be restricted to the range of site indices sampled in the old-growth stands;
This is a most important qualifier. Not applying it can lead to erroneous results. As noted in the Chief Forester’s AAC Rationale in the 1999 timber supply analyses in the Mid Coast TSA, when the site index corrections were used to adjust site indices of all the old growth, it appeared the remaining old growth had a higher site index, than those already logged. This is obviously false, as the better forest sites are always logged first.
Be monitored in logged and regenerated stands over time to ensure they match the corrected site index estimates.
V. What the OGSI Research Confirmed
All tree growth predictions are prophetic because they presume to predict the future. In the final analysis, no prophecy is perfect, and therefore all growth predictions are imperfect. While past tree growth can be measured accurately, prediction of future tree growth can only be done with uncertainty.
Consequently many claims about increased tree growth by advocates of OGSI can be readily dismissed.
First, the OGSI study says nothing whatsoever about the health of the future forest (as claimed by certain advocates)
Second, the error identified by the OGSI project was in the site index method for classifying site quality, not in any observed change in the growth rate of the forest.
The research determined only that trees were growing faster than previously believed (emphasis added). That does not, however, mean our new forests are actually growing faster. It only means the method for classifying site index was in error. Correcting an estimate of site index will not change the past growth rate of the forest, or what growth will occur in the future. What the OGSI site index equations do is correct an error in the site index classification at 50 years - either by moving projections "forward" to age 50 for young stands, or "backwards" to age 50 for old stands. In other words, the old site index curves were too conservative, and therefore our ASSUMPTIONS about predicted future tree growth will be greater than before.
VI. Will More Accurate Site Indices Alone Deliver SFM?
Will the OGSI site index corrections, in themselves, ensure SFM? The short answer is not likely. OGSI has to do with correcting an error in the method (i.e. a procedure). SFM is a concept (i.e. an idea). OGSI would only improve SFM if there were a good fit between the concept and the method of managing the forest for all values.
The Ministry of Forests defines timber supply as:
"... the rate at which timber is made available for harvesting. It is a measure of the potential flow of logs out of the forest. Timber supply is not the same as the inventory, or amount of timber in the forest.
... As part of the Timber Supply Review, timber supply analyses assess how current forest management practices will affect the supply of wood available for harvesting over time. They also examine how timber supply may be affected by changes in management practices and uncertainties about forest inventory and growth."
In practice, what the timber supply analyst does is to predict a base case of timber supply for 250 years, and then test its sensitivity to changes in the factors used to define the base case in each TSA or TFL. The Ministry of Forests is very careful to state:
"The Timber Supply Review should not be confused with land use planning processes, such as land and resource management plans or local resource use plans, whose purposes are to identify and make decisions about resource values, land use, and management in designated areas."
In this method, what the future forest may look like is not known. This would require a long-term forest management plan to create a forest with a desired structure, function and composition. To recap:
A timber supply analysis is not a SFM plan:
The timber supply analysis is firmly bounded around the problem of maintaining timber supply and not on ensuring desired future forest condition which could sustain all forest values
Timber supply analyses are not a real forecast of what WILL happen. They are a linear extrapolation that assumes the future will be an extension of the past;
Timber supply analyses are not a forecast of what SHOULD happen to minimize risks and maintain options for SFM.
Within this framework, when OGSI is applied in the timber supply forecasts, it will not improve management for all forest values. It is too narrowly focussed to do that.
VII. Will OGSI Hinder or Help SFM ?
It is generally recognized by analysts there is considerable "error and noise" in the data available to conduct timber supply analyses. While OGSI site index corrections will increase the rigor of the method for conducting timber supply analysis, it has little relevance to SFM. As Henry David Thoreau said, it will be "Improved means for unimproved ends." To focus on improving the rigor (the accuracy) of timber supply analyses, without changing the concept, improved SFM will not occur. In fact more accurate information may not even be all that important. Even "perfect knowledge" about the present can not accurately predict the future.
To practice SFM, what forest managers must do is to balance a range of management objectives, and not focus solely on timber. This "better" approach will mean that:
decision making will be expanded to allow increased opportunities for public participation;
the range of forest values that are managed will be expanded to include biodiversity, forest health, wildlife habitat and so on;
the focus will be first on the ecosystem and landscape level, and second on the stand and forest level;
the management orientation will change from a narrow focus on short-term economics, to an ecosystem concept that includes humans.
To achieve SFM the "problem of forest management" will be much more broadly defined by the application of new concepts and methods. More rigor in the management tools, alone, will not achieve SFM. In fact, it could even become an additional obstacle.
VIII. Strategic Management - How to Achieve SFM
The term Sustainable Forest Management is amongst the numerous phrases like "integrated use", "shared vision" and "world class" that have value but become useless when they fade into jargon. It is easy to tell when an idea has descended to this level, because the words are said automatically – almost as a substitute for thinking or saying something more meaningful. SFM, unless well defined and implemented, will meet the same fate.
There is a simple way to deal with this problem – ask the speaker what the words really mean. For example, in 1995 the Province of B.C. embraced SFM as a term and equated it with the Forest Practices Code. In 1998, the Code was "streamlined". Since 1999, independent third party certification has become the focus of SFM in BC. Have any of these recent approaches challenged the concepts and/or the methods of conventional timber supply analysis? None, so far, because the timber supply model:
Is still focussed on maintaining the flow of timber for as long as possible and then to decline with a scheduled falldown in timber supply. SFM in contrast, is focussed on maintaining the forest in a condition that can sustain all forest values, including timber supply:
Assumes the future can be predicted, when in fact this is impossible. Even re-determining AAC’s every five years does not resolve this matter. A better approach is to prepare for the future with plans that maintain options and minimize risks;
Assumes the desired equilibrium (i.e. balance) between human use and the forest should be in the distant future between growth rate and cutting rates. In fact what is needed in the present and the future is a balance between the carrying capacity of the forest and the resource use impacts being imposed on it.
SFM represents a divergence from the status quo. This means the existing organizational structure, management methods and other human resource processes must also change to match this change in direction. If there is no real change, and there has not been to date on the most important issues like the rate of cut, there will be no real movement towards SFM.
This is not a matter of saying things that sound nice. It is about doing the things that are necessary to advance a strategy of moving towards SFM. Structure follows strategy. While the right structure does not guarantee results, the wrong structure will block results and neutralize the best-intentioned efforts.
IX. Summary
Without a strategic intent to achieve the desired outcomes of SFM, and an effective organizational structure to implement it, apparent increases in forest growth by the OGSI site index corrections could become counter productive. Apparent increases in projected timber supply from higher site indices, could be used solely by forest managers to justify accelerated cutting of late successional forests - already in short supply in many areas of BC. It would be a much wiser and more equitable course of action to share the apparent increases in AAC by using some of the additional projected growth to help protect late successional forests and other non-timber values in the short run, and improving the SFM of all ecological, economic and social values in the longer run. The Forests Ministry has demonstrated it has been prepared to improve one of its planning methods, it is now time to improve its most resource management important concept – sustainability.
X. Conclusions
The OGSI Site Index corrections in themselves will mean little improvement to SFM in B. C. In keeping with Henry Thoreau’s quotation in the 1800's, this would be another example of "Improved means, for unimproved ends." In fact OGSI could become another obstacle.
SFM is about more than producing outputs (i.e. direct products such as timber) of the various resources. It is also a matter of sustaining the outcomes (i.e. consequences of an activity or output) that people. SFM when done well does not attempt to predict the future, but instead prepares for the future by maintaining options and minimizing risks;
The OGSI project has improved the Ministry of Forest’s ability to more accurately predict tree growth - by correcting an error in the site index curves. There is no evidence however that actual tree growth has changed at all. OGSI provides no evidence that present growth rates are any different than old growth forests were in the past;
The effect of OGSI is to correct the estimates of predicted future growth rates in an upward direction. While this direction is known, the magnitude of the increased tree growth is not;
If the apparent OGSI increases are administered without a strategy to implement SFM with a supporting organization, the consequences will likely be counter productive. Given that allowable cuts are already in excess of the long-run sustained yield, any increase in annual cut will accelerate the depletion of old-growth timber. If this apparent increase is only interpreted as more "flexibility" to allocate AAC to existing licensees, (and this appears to be current practice) it would accelerate the reduction in the forest’s capacity to sustain a wide range of forest values. Therefore OGSI will become another obstacle to SFM.
XI. Recommendations
Continue to implement the OGSI study findings within the guidelines prescribed by the Ministry of Forests’ researchers. This will ensure that timber supply analysts use these findings in the manner in which they were intended.
Improve the capacity to manage the "big picture" of SFM by implementing the principles and process of strategic management to manage for outcomes ( i.e., desired impacts) as well as outputs of the various resource values. Ensure the organizational structure of government is consistent with this strategy and desired outcomes and outputs – to ensure the effective delivery of SFM.
Interpret the timber supply base case analyses within the strategic context of desired SFM outcomes. Strive to ensure a good fit between both.
Ecologically - define the growing stock of the forest in terms of its structure, function, and composition at all temporal and spatial scales. Economically - describe the trees in the forest in terms of its quantity, distribution, and quality. This will ensure consistency with the SFM Criteria and Indicators as approved by the Canadian Council of Forest Ministers.
Distribute any quantifiable increases in timber supply attributed to OGSI site index corrections to enable SFM of all values in a Provincial Forest. This would provide more equity in the short run, and increased SFM for all forest values - ecological, economic and social - in the long run.
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NOTES
1 Ministry of Forests, 1998. Old Growth Site Index Study Completed. July 6, 1998 Press Releases 1998:059
2 Pedersen, L. September 7,1995. Timber Supply in B.C. – Now and in the Future. A presentation to the Forest Sector Strategy Committee.
3 Petter, A. July 28, 1994. Letter to John Cuthbert, Chief Forester, outlining the social and economic objectives of the Crown pursuant to Section 7 of the Forest Act.
4 Pedersen. L. July 1995. Bulkley Timber Supply Area; Rationale for AAC Determination. B.C. Ministry of Forests, B.C. p.8
5 Site Productivity Working Group. 1996. Site Index. A Growing Issue. Ministry of Forests, Forest Industry, and UBC Faculty of Forestry.
6 Nussbaum, Albert F. 1998. Site Index Adjustments for Old Growth Stands Based on Paired Plots. Ministry of Forests Working Paper 37. 21 pp.
7 Nussbaum, Albert F. 1998. Site Index Adjustments for Old Growth Stands Based on Paired Plots. Ministry of Forests Working Paper 37. 21 pp.
8 Ministry of Forests. No date. Timber Supply Analysis in British Columbia. Timber Supply Branch.
9 Ministry of Forests. No date. Timber Supply Analysis in British Columbia. Timber Supply Branch.
10 Nadler, George and Shozo Hibino. 1990. Breakthrough Thinking. Prima Publishing.
11 Province of British Columbia. 1995. British Columbia’s Sustainable Forest Management. International Relations Unit, Ministry of Forests
12 Chandler, Alfred D. Jr. 1962. Strategy and Structure. Cambridge, N] Massachusetts.
13 Canadian Council of Forest Ministers. 1997. Criteria and Indicators of Sustainable Forest Management in Canada Canadian Forestry Service