0572-B3
G. D. Sutherland, K.A. Campbell and B.B. Bourgeois 1
Maintaining sufficient representation of ecosystems in managed landscapes is widely considered a key component of a sustainable forest management strategy. Based on regional standards for forest sustainability, this analysis illustrates methods for assessing both rarity of ecosystems and their ecological condition. Using Lignum Ltd's Innovative Forestry Practices Agreement (IFPA) as a study area, reserves were delineated based on management practices and constraints. Reserves were then assessed based on: (1) their rarity (irreplaceability) at several spatial scales, and (2) the vulnerability of ecological values to forest management, using a comparative approach. Approximately 50% of ecosystems in the management unit were found to be rare by one or more of the three criteria of size, relative representation and provincial rarity. Proposed reserves defined using current management practices appeared to be of acceptable ecological condition and improved representation for all of the rare ecosystems, given the limits of available data. Refinement of reserve design techniques using finer-scale vegetation data and stricter criteria for identifying critical management zones (e.g. riparian) could help improve long-term representation of vulnerable ecosystems in Lignum's IFPA.
Worldwide, the concept of sustainability has become a dominant paradigm in forest management (Mendoza and Prabhu 2000). Since the United Nations Conference on Environment and Development (UNCED) in 1992, several processes (e.g., the Montreal C&I process) are underway to develop and implement criteria and indicators for defining, evaluating and monitoring best forest management practices.
The conceptually straightforward desire to sustain biodiversity by conducting renewable resource management is difficult in practice (MacNally et al. 2002). Large gaps in our understanding of biodiversity and species' requirements make it challenging to determine: (1) existing patterns of ecological process and function; (2) ecological baselines; and (3) trade-offs in human-managed landscapes. In addition, the resources needed to gather ecological data, undertake planning, and conduct on-the-ground management and monitoring usually are limited.
Ensuring the adequate distribution of whole ecosystems and natural disturbance processes is the most feasible approach to managing for individual species. An important step towards protecting biodiversity and achieving sustainable forest management (SFM) is to maintain representative ecosystems at all scales across a landscape. This can be achieved by including the representation of all ecosystems in a protected reserve network. Using ecosystems as surrogates for biodiversity (MacNally et al. 2002), representation also acts as an indicator of biological richness. Consequently, SFM assessment standards, such as those of Forest Stewardship Council (FSC), require adequate representation of ecosystems and their processes to be maintained on a managed landbase at all spatial scales.
Certification of SFM is provided by a number of organizations worldwide. The most common certification standards used in Canada are: the International Organization for Standards (ISO) 14001, Canadian Standards Association (CSA), Sustainable Forestry Initiative (SFI), and FSC. In British Columbia (BC), development of SFM standards is increasingly related to FSC Standards.
The general assessment framework of FSC is comprised of principles, criteria, and indicators for SFM. The goals of forest stewardship are specified in principles, criteria specify a means of determining if the principle is being fulfilled, and verifiers describe measurable targets for criteria. Target levels of indicators are defined by a desirable range of variation that ensures the maintenance of natural processes on the land base (Kneeshaw et al. 2000).
This project evaluated the contribution of forest reserves within the Lignum Innovative Forest Practices Agreement (IFPA) management unit towards achieving current ecological standards for SFM. In particular, Principle 6 of FSC-BC focused the analysis:
Forest management shall conserve biological diversity and its associated values, water resources, soils, and unique and fragile ecosystems and landscapes, and, by so doing, maintain the ecological functions and the integrity of the forest. (FSC-BC, July 2002)
The Lignum IFPA is a large and complex forest management unit covering approximately 610,000 hectares in the central interior of BC, extending over several forest tenures, First Nations territories, communities, agricultural units, and numerous tourism resorts (Figure 1). The IFPA was formed in 1997 as part of a government-industry initiative to test new and innovative forestry practices. Lignum's IFPA vision is to sustain the ecological integrity of forest ecosystems while maintaining long-term profitability within the context of a range of economic, social, and cultural opportunities for all generations.
The IFPA Forestry Plan follows an ecosystem management planning approach to develop strategies that maintain ecosystem function and supply a range of desired products and services. These strategies incorporate landscape dynamics and ecosystem assessments to build an understanding of natural disturbance patterns as a basis for conserving biodiversity and assessing ecosystems for their wildlife habitat and timber suitability. Lignum has attained certification from both ISO 14001 and SFI and has been awaiting development of BC Regional Standards before resuming certification efforts under FSC.
Goals for sustainability are best achieved through actions carried out at the forest management unit where policy is implemented as on-the-ground activities (Wright et al. 2002). The Lignum IFPA provides an opportunity to test the integration of SFM policy (provincial and regional standards to protect biodiversity) and operational practices.
A reserve network was identified on the IFPA consisting of existing reserves, plus reserves that result from management practices and operational constraints. The reserve network was constructed in a sequence of three increments based on the level of management constraint in each reserve ecosystem (Figure 2).
Figure 1 Location of the Lignum IFPA
Figure 1. Lignum's IFPA (top map) and its location in British Columbia, Canada (bottom map).
The first (most-constrained) increment included long-term reserves (e.g., old-growth management areas) where reserves had defined boundaries, were legally protected, had specific objectives, and had minimal human disturbance. The second increment added to increment 1, short-term reserves (e.g., patches retained for wildlife objectives) that met the above criteria but would be harvested within one rotation. Increment 3 (least-constrained) added to reserves in increment 2, defacto reserves that had some harvesting constraints applied (e.g., ungulate winter range where crown closure is maintained), and therefore provided some additional habitat and biodiversity values.
Figure 2. Distribution of reserves (long-term, short-term and defacto) across the IFPA.
One way to define ecosystems is by the communities of organisms they contain. Given the uncertainties regarding the presence and distribution of most species, this is not usually practical. An alternative is to utilize broadly defined ecosystems or combinations of ecosystems as ecosystems of biological diversity (e.g., Franklin 1993; Margules and Pressey 2000).
This analysis used the hierarchical Biogeoclimatic Ecosystem Classification (BEC) system developed in BC (Meidinger and Pojar 1991), which is based on broad vegetation, soil and climate features. BEC divides the province of BC into fourteen major zones on the basis of broad climate, soil and vegetation features. These zones are subdivided into subzones based on major climatic differences, and further subdivided into variants according to geographic location. In this assessment, BEC variants were used as surrogates for ecosystem types (Table 1).
Table 1. Ecosystem definitions in the IFPA derived from the Biogeoclimatic Ecosystem Classification system (see Meidinger and Pojar 1991).
BEC variant |
Definition |
Atp |
Alpine Tundra parkland |
BGxh3 |
Bunchgrass very dry hot |
BGxw2 |
Bunchgrass very dry warm6,7 |
ESSFwc3 |
Engelmann Spruce Subalpine Fir wet cold1,3 |
ESSFwk1 |
Engelmann Spruce Subalpine Fir wet cool1,3 |
ICHwk4 |
Interior Cedar Hemlock wet cool8,9 |
IDFdk3, IDF dk4 |
Interior Douglas-fir dry cool7 |
IDFxm |
Interior Douglas-fir very dry mild4,5,7 |
IDFxw |
Interior Douglas-fir very dry warm4,5,7 |
MSxk |
Montane Spruce very dry very cool4,5 |
MSxv |
Montane Spruce very dry very cold4,5 |
SBSdw1, SBS dw2 |
Sub-boreal Spruce dry warm2,4,5,7 |
SBPSxc |
Sub-boreal Pine Spruce very dry cold2,4,5,7 |
SBPSmk |
Sub-boreal Pine Spruce moist cool4,5,7 |
Dominant tree species
Four analysis criteria were used to assess the contribution of proposed reserves to achieving current SFM standards for ecosystems on the Lignum IFPA:
If a high proportion of an ecosystem's area occurs in the IFPA as compared to the province or region, then the IFPA has a high opportunity to protect against possible loss. Opportunity for protection was determined by comparing the area of each ecosystem in the IFPA to the area of that ecosystem defined regionally and provincially. A high opportunity for protection was designated for ecosystems falling above the 12% threshold recommended in BC's Protected Area Strategy.
Potential conservation concerns increase with increasing rarity of ecosystems (Rabinowitz et al. 1986). Here, rarity was defined by the size of each ecosystem, the representation of ecosystems in the IFPA relative to the province, and the overall representation of the ecosystem provincially as follows:
Size - Ecosystems were considered rare if their area was < 10% of the total IFPA area.
Representation in the IFPA relative to the province - Classes were defined based on whether the ecosystem was:
To achieve representation of all ecosystems, classes 1 and 3 are of high priority to protect in reserves. Ecosystems in class 2 should also be represented in reserves whenever possible to ensure local representation. It is desirable to maintain ecological representation of class 4 ecosystems in reserves, but it is not a priority.
Overall representation provincially - An arbitrary 5% provincial representation guideline was used to identify a threshold of provincial rarity.
Representation of ecosystems was determined by two methods and compared between reserve increments. First, the total reserve area of each ecosystem was compared to the amount of protected area required by FSC-BC. Second, over- or under- represented ecosystems were identified by assuming that ecosystems should be represented in proportion to their occurrence in BC.
Seven indicators of ecological condition evaluated the similarity between forest conditions in the reserves and the average value for that indicator in each ecosystem. The indicators described site characteristics (average site index), forest structure and composition (average height, % of forest > 140 years old, % leading species, crown closure) and landscape distribution of different seral stages (early, mid, and late with age class divisions between stages dependent on the particular ecosystem type).
Lists of threatened or endangered species and/or communities were examined to identify ecosystems of particular concern for biodiversity and wildlife habitat (BC Conservation Data Centre 2002).
The IFPA had relatively high opportunity to protect two ecosystems: the IDFdk3 (>20% of the provincial total), and the IDFdk4 (> 12% of the provincial total).
Four ecosystems were both rare in the IFPA and elsewhere in the province (BGxw2, BG xh3, ICHwk4, IDFxw) (Figure 3). These ecosystems are high priority to protect in reserves on the IFPA. Five ecosystems were relatively rare on the IFPA, but more common in the province (SBSdw1, MSxv, MSxk, ESSFwk1, and ESSFwc3). These ecosystems should also be included in reserves to ensure local representation. However, because of their relatively similar ecology, some flexibility between ecosystems in the same BEC subzones is possible. Finally, several ecosystems were locally common (IDFdk3, IDFdk4, IDFxm, SBPSmk, SBPSxc, SBSdw2) and were relatively common elsewhere. Overall, ten ecosystems met at least one of our definitions of geographic rarity.
The reserve increments (in particular the long-term increment) improved the relative representation of all ten rare ecosystems. For example, a higher percent of IDFxw and BGxh3 were captured in reserves than the proportional area of these ecosystems in the entire IFPA. Five of these ecosystems (ICHwk4, ESSFwc3, ESSFwk1, MSxv, and SBSdw1) are slightly under-represented even with the reserves.
The FSC-BC minimum criteria for protected areas were not met for seven of the fifteen ecosystems (excluding ATp) (Figure 4). The threshold was exceeded for the two ecosystems with high opportunity for protection. Amount of reserves in the four rare ecosystems also surpassed the threshold, three in the long-term reserve increment (the most constrained reserves). The remaining ecosystem (ICHwk4) did not meet the threshold in any of the reserve increments.
Based on the above criteria (opportunity for protection, rarity, representation), improvements to the protection of ICHwk4, SBSdw1, MSxv, ESSFwc3 and ESSFwk1 in should be considered. These ecosystems not only were rare, but also were under-represented in the reserves as compared to the IFPA, and to FSC-BC criteria.
Most reserve increments appeared unbiased in terms of productivity (site index and average tree height), captured a greater proportion of mature and old forest , and included a greater proportion of Douglas-fir and lesser proportion of lodgepole pine than on the IFPA. These findings were consistent for all 6 under-represented ecosystems. Most ecosystems containing threatened or endangered species are adequately represented in reserves, with the exception of SBPSmk (one listed species).
The Lignum IFPA is an ecologically diverse and complex area. Reserves defined using present land-use management practices appeared to improve representation for ecosystems that were rare or that ranked as having a high opportunity for protection. Reserves adequately captured ecological values in each ecosystem, although inventory data were limited in their ability to describe ecological conditions accurately. Ecosystems requiring closer examination were ICHwk4, MSxv, ESSFwc3, and ESSFwk1.
Figure 3. Patterns of rarity and commonness among BEC variants (ecosystems) in the IFPA compared with provincial patterns. Note the log-log scale on axes.
Figure 4. Representation of BEC variants in the reserve increments as a percentage of the total area of that variant in the IFPA- FSC-BC requirements.
One of the primary values of this analysis was to prioritize ecosystems for inclusion in reserves. Many authors suggest ranking under-represented ecosystems according to their `irreplaceability' or rarity (Margules and Pressey 2000) and `vulnerability' or risk of being impacted by management (Dunn et al. 1999, Margules and Pressey 2000). Margules and Pressey (2000) propose assigning the highest priority to those areas ranking high for both irreplaceability and vulnerability.
In this analysis, definitions of geographical rarity at several scales were used to assess irreplaceability while indicators of ecological condition were used to assess vulnerability. Results showed that five ecosystems ranked highly for future reserve zones, largely on the basis of their irreplaceability. Opportunities exist to improve protection (and hence representation): the rarest ecosystems by definition are small in area and additional reserves will have minimal impact on other goals such as timber harvesting. Representation of rare ecosystems should be improved now, rather than in the future, because management activities could result in irrecoverable declines in both abundance and condition of the ecosystems.
The analysis was a conservative estimate of the relative vulnerabilities of ecosystems, in part because the BEC system is relatively coarse2. In general, this analysis would be best applied as part of a hierarchical approach, either with multiple ecosystem classification schemes (Faith et al. 2001, MacNally et al. 2002), or by incorporating other management actions such as protection of key habitat elements outside of reserves on the managed landscape (Franklin 1993, Bunnell 1999).
The reserves created in this analysis satisfied many of the FSC-BC (July 2002) criteria for protected reserves. In particular, the reserves captured rare and unique ecosystems, as well as rare and endangered species. While not all ecosystems met FSC-BC criteria for minimum protected areas, many of the rare ecosystems did.
The proposed reserve network did not meet certain critical FSC-BC criteria and verifiers. In particular, the riparian buffers generated for our analysis were insufficient according to FSC-BC criteria (which sets a minimum buffer size of 1 ha/km). Some of the shortfalls in meeting FSC-BC standards were the result of data availability and accuracy. First, forest inventory data for many of the IFPA forest ecosystems (especially interior Douglas-fir stands) are poor in estimating critical stand attributes (i.e., stand age, height, crown closure), and other important attributes were unavailable (e.g., downed wood, snag densities). Second, many stands are more diverse in tree species of high biodiversity value (e.g., deciduous species) than was apparent in standard inventories. Third, disturbance histories of stands in the IFPA area are complex, involving different disturbance regimes, as well as historical selection harvesting in some stands.
This analysis did not explicitly evaluate ecosystem connectivity, forest interior, or wildlife habitat. These three concepts are often difficult to measure and interpret ecologically in the ecosystems present in the IFPA (Bunnell 1999, Bunnell et al. 1999). Consultations with Lignum, as well as local ecologists, and wildlife biologists will enable appropriate measures and evaluation criteria for these to be developed in the future.
In future, the development of a fully FSC-BC compliant reserve network can be achieved by bringing together people and information. Lignum has developed an ecosystem management planning methodology, which involves coarse- and fine- filter approaches to defining and managing for biodiversity and habitat. This information, when used in conjunction with this analysis of protected reserves, will be critical in both the development of and agreement upon a comprehensive reserve network by Lignum staff, as well as local ecologists, foresters, and biologists.
The results from this analysis will be valuable to Lignum in establishing new or alternative operational practices and policies around reserve protection. Reserves can be added or redefined to address specific issues (e.g., endangered species) and to better meet reserve objectives (e.g., protection of riparian functions). Analyses of this type provide a scientific basis for negotiating old-growth management areas to improve ecosystem protection. In addition, the analysis is a starting point for designing alternative management regimes to safeguard or improve ecological condition on the IFPA. Refinement of the reserve network on Lignum's IFPA will not only help ensure sustainability of ecosystem functions over time but will act as a significant example of successful SFM certification in British Columbia.
This project was supported by Lignum Ltd. and Forest Renewal BC. We thank Doug Williams and Melissa Hadley of Cortex Consultants Inc. and staff of Lignum Ltd.: Dave Conly, John Gooding, Shawn Meisner, Tyler Mitchell and Dave Peterson. Thanks also to personnel of B.C. Ministries of Forests, Sustainable Resource Management and Water, Land and Air Protection.
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1 Cortex Consultants Inc. Suite 3a-1218 Langley St., Victoria, B.C. CANADA, V8W 1W5. [email protected]; Website: www.cortex.ca
2 At the time of this analysis, alternative datasets for classifying ecosystems (such as terrestrial ecosystem mapping) were not available for the study area.