Ministry of Environment

 

Strategic Plan for the Use of Prescribed Fire to Restore Ecosystems in the Okanagan Region

 

 

 

 

Submitted by:

B.A. Blackwell and Associates Ltd.

3087 Hoskins Road

North Vancouver, BC

V7J 3B5

 

And

 

R.W. Gray Consulting Ltd.

6311 Silverthorne Road

Sardis, BC

V2R 2N2

 

Submitted to:

 

Robert Stewart

Ecosystem Biologist

102 Industrial Place

Penticton, BC

V2A 7C8

 

March 2006


Executive Summary

The Okanagan Region represents one of the most biologically diverse regions of the Province. Low levels of precipitation, hot summers and mild winters provide a wide range of habitat for species that are unique to both British Columbia and Canada. This biological diversity is under considerable stress from a number of related problems associated with human population growth. Specifically these problems can be summarized as follows:

 

·         Fire suppression has resulted in a change in fire regime (fire frequency and severity) throughout the region. Increasing tree densities and the resultant competition for moisture and nutrients have negatively impacted large areas of open grassland and forest. These changes have impacted forest health throughout the region.

·         Habitats are shrinking, threatening and endangering many species. For example, only approximately 9% of the natural grasslands native to the region remain, due to roads, human development, and orchards.

·         Introduction of exotic species threaten many of the native habitats.

·         Overgrazing has also had a major impact on biodiversity by causing disturbance of soil and native vegetation, and by providing ideal conditions for the invasion and spread of exotic species.

 

While fire suppression is but one of many problems impacting biodiversity and ecosystem health in the region, it probably represents the single most important and spatially extensive issue that managers have the potential to impact. This report: 1) documents a rationale for prioritising prescribed burning as a restoration tool within the region; 2) uses GIS inventories and analysis tools to implement the rationale and spatially identify burn priorities, and; 3) outlines a five year plan to initiate the implementation of the project.

 

Prescribed burn priorities identified during a GIS analysis were field checked in several locations within the study area. For the most part, the results indicated that the algorithm developed to identify restoration priorities met the objectives of a coarse scale analysis. Following the field visit, identified treatment areas were summarized by priority within ownership categories, inside and outside of the Timber Harvesting Land Base (THLB), and by treatment complexity and associated costs.

 

Overall, a total of more than 36,000 ha have been classified as high priority for prescribed burning to facilitate restoration. However, much of this area (26,267 ha) is within the THLB on crown land and may be constrained by other land management objectives. Only 9,734 ha are outside of the THLB. Large areas, both within the THLB (334,152 ha) and outside the THLB (157,508 ha), have been classified as moderate priority for prescribed burning.

 

In addition to prescribed burn priority identification, the report addresses the development of a five-year burning plan, monitoring treated areas, and discusses treatment strategies.


Table of Contents

1.0        Introduction... 1

2.0        Study Area.. 4

3.0        Historic Fire Regime and Fire Regime Departure Layers. 6

4.0        Methods. 7

4.1        Treatment Priority Rating. 9

4.1.1     Historic Natural Fire Regime. 9

4.1.2     Fire Regime Condition Class. 9

4.1.3     Forest Health Factors. 10

4.1.4     GIS Processing. 10

4.2        Treatment Complexity Rating. 11

4.2.1     Fire Regime Condition Class. 11

4.2.2     Wildland Urban Interface. 11

4.2.3     GIS Processing. 12

4.3        Constrained Area. 12

5.0        Results and Discussion... 13

5.1        Field checking the GIS analysis. 13

5.2        Analysis and Mapping Summaries. 17

5.2.1     Distribution of Historic Natural Fire Regimes within the study area. 17

5.2.2     Distribution of Condition Class Within the Study Area. 19

5.2.3     Distributions of Prescribed Burn Priorities Within the Study Area. 21

5.2.4     Distribution of Treatment Complexity Classes Within the Study Area. 23

5.3        Treatment Strategies. 25

5.3.1     Setting Appropriate Objectives. 25

6.0        Monitoring Prescribed Fire.. 30

6.1        Monitoring Fire Behavior. 30

6.2        Vegetation And Forest Structure Monitoring. 31

6.3        General Monitoring for all areas. 32

6.3.1     Response of red and blue listed plants. 32

6.4        Monitoring for specific areas. 32

6.4.1     Forested Area. 32

6.4.2     Grassland Areas. 33

6.4.3     Timing of Measurement 34

6.5        Wildlife Monitoring. 34

6.5.1     Douglas-fir habitats (along slopes and crests of hills) 34

6.5.2     Very open forest 34

6.5.3     Grasslands. 35

6.5.4     Cultivated field.. 35

6.5.5     Aspen copses, Aspen forest, Open Water, Vernal Ponds and Rock or Talus. 35

6.5.6     Shrubland.. 35

6.5.7     Monitoring for mule deer. 36

6.5.8     Monitoring for California bighorn sheep.. 36

7.0        Transition from Old Program Priorities to Newly Identified Priorities. 37

8.0        Five-year Plan... 38

9.0        Recommendations. 39

10.0      Literature Cited.. 1


List of Figures

Figure 1. Study Area Boundary. 5

Figure 2. View of the approximate study area looking north (image sourced from Google EarthÔ) 6

Figure 3. Steps undertaken to identify and prioritize unconstrained areas for ecological restoration treatment. 8

Figure 4. Section of Darke Lake Provincial Park showing interface of park with adjacent private land. Additional overlying layers include: FRCC, UWR, FHF, and OGMAs. 13

Figure 5. Hillslope on the west side of Darke Lake. 14

Figure 6. Landscape view of the east side of Darke Lake. 16

Figure 7. Stand-level view of forest structure on the east side of Darke Lake. 17

Figure 8. Historic natural fire regime within the study area. 19

Figure 9. Condition class within the study area. 21

Figure 10. Treatment Priority Rating within the study area. 23

Figure 11. Treatment Complexity Rating within the study area. 25

Figure 12. Large downed log being consumed in a cool, spring prescribed burn. Most attempts to save these structures, through constructed firebreaks or avoidance firing, are unsuccessful (R. Gray photo). 27

Figure 13. Large diameter, old Douglas-fir killed as a byproduct of thinning young Douglas-fir encroachment (K. Iverson photo). 28

Figure 14. Pitch tubes resulting from a post-prescribed burn infestation of red turpentine beetles in a ponderosa pine. On this particular unit no crown scorch was recorded yet 20% of the mature pine were killed by bark beetles within two years of the burn (R. Gray photo). 29

Figure 15. This site was burned in a 1979 wildfire and “reburned” in 2002 in a subsequent wildfire. The effect of the two fires, especially the second fire which burned through a considerable fuel load of fallen fire-killed trees, was catastrophic (R. Harrod photo). 30

 

List of Tables

Table 1. Rating scale matrix for input coverages to establish Treatment Rating Priority. 10

Table 2. Final Treatment Priority Ratings. 11

Table 3. Rating scale matrix for input coverages to establish Treatment Complexity Ratings. 12

Table 4. Final Treatment Complexity Ratings. 12

Table 5. Area summary of ownership and historic natural fire regimes within and outside of timber harvesting land base for the study area. 18

Table 6. Area summary of ownership and condition class within and outside of the timber harvesting land base for the study area. 20

Table 7. Area summary of ownership and prescribe burn priority rating within and outside of the timber harvesting land base for the study area. 22

Table 8. Area summary of ownership and potential treatment Complexity within and outside of the timber harvesting land base for the study area. 24

 


1.0                           Introduction

Historically in British Columbia, ecosystem restoration (ER) has suffered from the lack of a strategic, integrated approach to planning and operations. Part of this is due to a common debate pitting the management of individual species, be they endangered species or commodity species, against the management of “ecosystems” (Weigand and Everett 1994). The scarcity of year-to-year consistency in funding, coupled with insufficient staff resources to run a program, has also led to a scattered approach to restoration. It is also possible that adequate trained and skilled resources to carry out a modest sized ER program are lacking in most regions.

Currently, ER programs could be described as being “reactive” in nature with treatment units identified by immediate priority and funded out of whatever dollars can be cobbled together. Agency personnel assigned to the task of implementing ER do not have the time or resources for long-range planning, and become little more than contract administrators for a program carried out largely by outside consultants and contractors. The one exception to the rule in BC, at least when it comes to higher level strategic planning, is the Kootenay-Boundary Land-Use Plan (KBLUP), which has taken large steps towards developing a strategic ER program. The KBLUP used the assignment of natural disturbance type 4 (NDT4) ecosystems based on biogeoclimatic ecosystem (BEC) zones. This information was used to guide restoration activities within the management area. NDT4 ecosystems include grassland, shurbland and forested communities that generally experience frequent, low severity fire regimes. Unfortunately, this plan also suffers from many of the same strategic planning shortfalls experienced in other parts of the province. The KBLUP plan has identified, in a coarse way, the target ecosystems for restoration in the NDT4; this could be referred to as “top-down” direction. The “bottom-up” direction of the plan (the local-level, long-term juxtaposition of objectives) is missing. Individual projects are not explicitly linked but appear to be reactionary and “single-species” focused, funding is inconsistent, program monitoring is inadequate, and resources are insufficient. These are “strategic” issues with the plan though from both a spatial sense and an objective-attainment sense.

A solution to the strategic ER planning issue is the development of regional ER programs focused on managing for ecosystem resilience (Wade 1988, Walker 1994) as opposed to managing for a single species. These programs require long-term direction from strategic plans in order to develop activities that will meet long-term landscape level objectives. These programs also require dedicated personnel resources and operations funding. While the latter is not part of this project, addressing the former would certainly provide strong rationale for increased resources to implement the program.

The approach to strategic planning put forward in this report comes from prior experience developing comprehensive ER programs in both the US and BC. In the case of the US southwest, strong cultural connections had to be made within the ER program because of long-standing Apache Indian traditions in land use. In the Squamish Forest District, socio-economic connections had to be made because the primary land-use was timber management. Regardless of the objectives of the overarching land management agency, there are ways to shape and adapt ER to meet strategic ER planning goals. The steps in this process are as follows:

1.      Purpose and Need for Ecosystem Restoration. This may come from pre-existing agency documents that have established goals and objectives for the region. This should include strong scientific rationale for the program (i.e., why, where, when and how). In the Squamish Forest District, extensive historic fire regime and stand structure studies were conducted to provide direction for the restoration program. These studies were designed to determine the historic or natural range of variation (RONV) and how it compared with current ecosystem structure and composition. Unfortunately, there are few Okanagan region studies of this nature; however, several surrogates do exist. Gray and Riccius (1999) in the Merritt area and Gray (2003) in the Sinlahekin Valley in Washington State provide some applicable data, while the coarse-scale historic natural fire regime (HNFR) and fire regime condition class (FRCC) models developed by Blackwell et al. (2003) provide further spatial direction. This foundation information is critical to enabling spatial prioritization of areas further along in the process. Defining the restoration program rationale is also critical for public education purposes. Glaring knowledge gaps in disturbance dynamics and ecosystem responses can be identified here and incorporated into program-level adaptive management and monitoring.

2.      Data Collection, Collation, and Analysis. In this phase the gross area under management, past management activities, pre-existing and future management activities are investigated. Coarse- and fine-filter analysis systems (GIS-based) that will enable identification of future (5-year window) treatment priorities are built in this phase. The gross area of management needs to be reviewed in the context of biogeography (topography, physiography, vegetation characteristics), ownership (public, private), and primary land-use (timber harvesting, wildlife habitat). This becomes one of the key baseline layers for planning the feasibility and costs of various ER strategies. In addition, existing plans for future treatments are reviewed to see how they fit with the new model. There is insufficient funding in the system to discard prior work so every effort must be made to make some use of it. GIS-based filters and queries are used to help dial down to operational units once a hierarchical planning approach (agency goals, objectives and prioritization) has been developed. This stage incorporates the necessary environmental, ecological, and social values in a spatial context. Once individual treatment areas have been identified, further analysis is conducted to address treatment strategies, feasibility of success, risk, and cost. Issues such as down-wind smoke sensitive areas, adjacent area hazards (recent harvest/land clearing slash), adjacent area land-use conflicts (livestock vs native ungulates, etc.) are addressed here.


The Ministry of Environment (MOE) has not traditionally managed ecosystems. They have managed for specific species and/or attributes within ecosystems but they have not systematically planned for the management of ecosystem health (defined as inherent natural diversity and resilience (Wade 1988, Walker 1994) across their jurisdiction. Ecosystem management has been characterized by diffuse, single-focus treatments within a general ecological framework. There is no overarching strategy to manage all ecosystems in a resilient state starting with those in the furthest departed condition.

The Ministry of Forests and Range (MOFR) has not traditionally managed ecosystems either. They have managed for a specific objective (i.e., timber and range) within ecosystems but they have not systematically planned for the management of ecosystem diversity and resilience across their jurisdiction. This has resulted in a dominant objective being managed for in a diffuse way. Management focus is scattered across the landscape in an attempt to answer to social and environmental impacts. Ecosystem health issues abound, attesting to the inadequacy of this approach.

The KBLUP plan could be seen as a compromise strategy between the two. The MOFR emphasis is de-emphasized to a certain degree (reduced stocking standards); ecosystem health can be maintained through repeated disturbance to promote diversity and resilience at the stand level. The MOE single species or habitat attribute emphasis, unfortunately, still prevails as can be seen in how treatments are prioritized. The most ecologically, socially and economically feasible areas are not the first to be treated, instead the prioritization of treatment is determined through the single-species/attribute approach. To make the KBLUP truly successful, the strategy for ecosystem health should shift to a prioritization based on landscape scale forest health factors and treatment funding should compliment and encourage this shift. Although it would be ecologically ideal to treat all areas that are departed from their natural state, social and economic constraints mean that this approach may fail to achieve landscape-level forest health objectives. With limited human and financial recourses, it is arguably more efficient to prioritize treatments first in areas that are less severely departed from their natural state. This ensures that these ecosystems are maintained in a healthy state, potentially enables more area to be treated and allows any remaining resources to be directed to treating more departed ecosystems.

The approach of this plan is to adopt a strategic direction focusing on landscape-scale ecosystem health. While definitions of ecosystem health are prevalent throughout the literature the central tenets are the creation and maintenance of naturally diverse (meaning “native” species) and resilient (elasticity following disturbance) ecosystems (Cairn 1988, Jordan 1988, Everett 1994, Kolb et al. 1994, DellaSala et al. 1995, Gayton 2001). This requires the ability to quantify “health” in a GIS platform. In the dry forest and grassland ecosystems of North America, altered fire regimes are at the core of ecosystem health (Everett 1994, Covington 1995, Fiedler et al. 1995, Rapport and Yazvenko 1995). Fires have either not occurred frequently enough (e.g., historically open ponderosa pine bunchgrass ecosystems), or have occurred too frequently (e.g., cheatgrass invasion areas). Using fire regime condition as a surrogate for ecosystem health, we can build a base layer from which additional data can be added to culminate in a landscape-scale strategy for ecosystem restoration activities.

2.0                           Study Area

The study area encompasses 2,966,765 ha of the Okanagan (Figure 1 and Figure 2). The study area boundary is based on the MOE’s Region 8 (Okanagan) jurisdictional boundary. The boundary’s southern most edge runs along the Canada-US border. The eastern boundary starts between Grand Forks and Rossland, and roughly follows the Columbia Mountain Range to the north. The northern most point of the boundary is Mount Griffin Provincial Park, just below Revelstoke. The western boundary runs down between Merritt and Kelowna and then moves further to the west (to approximately 45 km west of Princeton) before meeting the Canada-US border.

The study area falls predominantly within the Southern Interior Forest Region (RSI). A small portion of the area overlaps with the Coast Forest Region (RCO). Several forest districts overlap with the study area. Within the RSI, these include the Okanagan Shuswap District, the Arrow Boundary District and the Cascades Forest District. A small portion of the RCO’s Chilliwack District overlaps the study area’s southwestern corner.

The terrain and climate within this area is highly diverse. The following biogeoclimatic (BEC) zones define the study area:

·           Interior Douglas-fir             (861,560.7 ha [29.0%]);

·           Englemann Spruce-Subalpine fir (705,588.0 ha [23.8%]);

·           Interior Cedar Hemlock (560,864.5 ha [18.9%]);

·           Montane Spruce (559,649.7 ha [18.9%]);

·           Ponderosa Pine (128,591.2 ha [4.3 %])

·           Alpine Tundra (79,750.5 ha [2.7%]);

·           Bunchgrass (61,938.9 ha [2.1%]); and

·           Coastal Western Hemlock (8,821.2 ha [0.3%]).

 

The study area contains features that were formed by uplifting of the earth’s crust between one and two million years ago. The mountainous areas are made up of folded sedimentary and metamorphic rock, and form part of the Columbia Mountain Chain (consisting of the Purcell Mountains, Selkirk Mountains, Monashee Mountains and Cariboo Mountains). The Interior Plateau, which is to the west of the Columbia Mountains, was also formed by uplifting but was not folded or carved. However, erosion by rivers has resulted in uneven, rolling terrain. The Suhswap Highland, Okanagan Highland, Quesnel Highland, Thompson Plateau, Fraser Plateau and Basin and Nechacko Plateau form the Interior Plateau. Glacial action formed the Okanagan Valley (at the centre of the study area) roughly 10,000 years ago when the ice retreated.

The network of lakes and rivers left behind when the glaciers retreated influences the local climate. Because of the influence of these water-bodies on air currents, the Okanagan Valley tends to experience milder winters than the areas to its north and east. The Okanagan Valley’s climate is described as mild and continental[1]. Summer tends to consist of hot days, cool nights and relatively low humidity. Winters are moderate to cold with cool, humid air. The central part of the valley (Kelowna and Peachland) averages 1,954 hours of sunshine per year and 29.8 cm of rain[2]. The southern part of the valley (Osoyoos and Penticton) is within the northernmost tip of the Great Basin Desert and has the driest climate in Canada (average rainfall of 28.0 cm per year).

Figure 1. Study Area Boundary

Figure 2. View of the approximate study area looking north (image sourced from Google EarthÔ)

3.0                           Historic Fire Regime and Fire Regime Departure Layers

The model outputs for Historic Natural Fire Regime (HNFR) and Fire Regime Condition Class (FRCC) (Blackwell et al. 2003) incorporate the best available knowledge of pre-settlement fire history and the social and ecological consequences of departures in those fire regimes. Data used in the HNFR model includes top-down controls (regional climate), bottom-up controls (local vegetation classification, topography, and physiography), and process metrics from regional stand-level fire history studies. The FRCC model includes stand-level structural elements that impact fire behavior and fire regime characteristics and provides a qualitative assessment of potential fire-related consequences. At their core, these two models assess risk as probability (HNFR) and consequence (FRCC). Risk analysis should form the foundation of any ER program prioritization strategy. Probability and consequence can be configured in any number of ways depending on the management objectives for the land manager. In the case of the Ministry of Environment, a strong program emphasis is placed on managing ecosystem sustainability, diversity, and above all resilience.

The investigation of RONV provides us with the capacity to predict ecosystem component adaptability to the natural disturbance regime. Following a natural disturbance, the ecosystem components that are adapted to the disturbance should exhibit resilience. If they do not respond, it is likely that the characteristics of the disturbance regime (timing, intensity, etc.) have exceeded RONV (Meyer et al. 2005).

Why is RONV important? As a society and as professionals managing on behalf of society, we need to be able to confidently predict the impacts of our actions and the consequences of natural disturbances. The RONV condition provides us with a documented set of parameters based on stand and landscape patterns resulting from disturbance processes. If we choose to manage conditions outside RONV it is our responsibility to predict outcomes and inform managers of potential consequences.

4.0                           Methods

There were three steps undertaken to identify and prioritize unconstrained areas for ecological restoration treatment (Figure 3):

1.                  Develop a Priority Treatment Rating using condition class, historic natural fire regime and forest health factors.

2.                  Develop a Treatment Complexity Rating using wildland urban interface and condition class.

3.                  Combine the Treatment Complexity Rating, Timber Harvesting Land Base (THLB) and Ownership to delineate the least constrained High Priority Treatment areas.

Figure 3. Steps undertaken to identify and prioritize unconstrained areas for ecological restoration treatment.

 

4.1                             Treatment Priority Rating

4.1.1                       Historic Natural Fire Regime

The HNFR layer is a combination of known and predicted fire regime metrics by BEC subzone plus topographic variables that affect fire behavior. A detailed description of how the HNFRs were constructed can be found in Blackwell et al. 2003. In the predictive model HNFR is ranked according to flammability of the dry forest types, which include the Ponderosa Pine and Interior Douglas-fir BEC zones. The most flammable fire regime is HNFR I which includes low elevation, dry ponderosa pine and Douglas-fir forests with grass and/or timber litter as the primary carrier of surface fire. Upslope and on cool aspects at low elevation from HNFR I is the HNFR II fire regimes which are characterized by slightly cooler and moister conditions than HNFR I. Fuelbeds in HNFR II range from grass and timber litter to compacted duff and moss. Further upslope and on cooler aspects is HNFR IV which has a shorter fire season than HNFR I. Fuels here typically ranged from compacted timber litter to heavy loading of timber litter and dead downed trees.

4.1.2                       Fire Regime Condition Class

FRCC is a quantitative measure of fire regime departure from historic conditions. The more fire is removed from a fire regime the more the fire regime changes. This modeling system has as its basis the supposition that fire will eventually return to the fire regime. The more removed fire is, combined with the more frequent fire used to be within the system, the greater the environmental impact. This supposition is in marked contrast to the opinions of some professionals that once an historic fire regime has changed there is little value in considering a move back to historic trends. This professional opinion has its basis in the opinion that fire will not return to the system. The use of this model holds its value in presenting the range of consequences that could occur once fire returns to the system. Once again, the reader is encouraged to review Blackwell et al. 2003 for a detailed description of FRCC.

Applying in a predictive model FRCC can be used to derive two different metrics: a) time-since-disturbance, or b) complexity of treatment. Time-since-disturbance is a qualitative indicator of structural changes to the ecosystem due to the cessation of fire (i.e., increased fuel loading, increased tree density, increased canopy closure, etc.). In Blackwell et al. (2003) FRCC is ranked from furthest departed (longest time-since-disturbance) to least departed. This ranking would identify sites with fuel load, tree density, etc., as the highest priority for treatment.

FRCC can also be used to gauge complexity of treatment, with complexity defined as both complex objectives, and high unit treatment cost. Canopy closure from forest cover inventories is an integral component of FRCC determination. FRCC 1 to 3 indicate increasing time-since-disturbance and increasing canopy closure (i.e., increasing stand density). For example, a stand classified as FRCC 3 in an HNFR I fire regime has missed numerous surface fires and has likely experienced an increase in canopy closure. Ecologically, this may be the most appropriate stand to treat first within the framework of a prioritization model. Obviously with fuels and stand structure significantly departed from RONV these stands are at high risk to adverse impacts from wildfire and/or insects and diseases. Stand-level biodiversity and resilience would be impaired should a natural disturbance occur. However, several issues make this approach difficult to implement. A limited restoration program budget is one significant issue but a greater issue is the need to conduct very intensive pre-burning fuel modification treatments.

The very issues that make FRCC 3 stands good candidates to place at the top of prioritization make them very complex candidates to restore. High stand density, high fuel load, and high canopy closure make these sites very difficult and expensive to treat with prescribed fire alone. In our prioritization model, we have reversed the ranking order for FRCC and have identified FRCC 1 stands as the priority. This is from the perspective of relative complexity of treatment objectives and cost. With a limited annual budget and a small, developing burn program it was felt by the project team that this was a more appropriate approach for this project.

Another ideological reason for taking this approach is to treat FRCC 1 sites as a preventative measure, thus holding FRCC 1 sites from sliding into FRCC 2. This approach is being widely debated amongst our colleagues in the US who wrestle with this conundrum as well. Do we hold off maintaining a site in FRCC 1 because we are concentrating on restoring an FRCC 2 or 3 site? At the end of he day are we any further ahead? We chose to focus efforts on the former – preventing FRCC 1 sites from becoming ingrown.

4.1.3                       Forest Health Factors

Since 1999, the MOFR has carried out aerial overview flights across the majority of forested land in BC to survey forest health (JCH Forest Pest Management 2002). The survey data has been used as a key source to document the Mountain Pine Beetle outbreak and a number of other important forest health agents in BC. The data is composed of pest infestation polygons and points each assigned a specific Forest Health Factor (pest code, damage agent or condition code).

The entire length of record (1999 to 2004) was used in this project. All point infestations were buffered by 100 m. This buffered coverage was then merged with the polygon infestation coverage to create a Forest Health Factor (FHF) coverage for the entire Okanagan Region.

4.1.4                       GIS Processing

Each input coverage (FRCC, HNFR and FHF) was converted into 25 x 25 m raster cells and assigned ratings according to Table 1. Individual ratings for each raster cell were developed on 0 to 10 scales.

Table 1. Rating scale matrix for input coverages to establish Treatment Rating Priority.

Input Coverages

Rating

Fire Regime Condition Class

1

10

2

5

3

0

None

0

Historic Natural Fire Regime

I

10

II

8

IV

5

Others/None

0

Forest Health Factor

Present

10

Absent

0


To create the Treatment Priority Rating, the rating for each raster cell was calculated as a weighted sum of the three input coverages as per the following equation:

(FRCC*0.33) + (HNFR*0.33) + (FHF*0.33) = Treatment Priority Rating

Table 2 shows final Treatment Priority Ratings.

Table 2. Final Treatment Priority Ratings

Rating

Priority

>/= 7.5

High

>/= 5.0 < 7.5

Moderate

>/= 2.5 < 5.0

Low

0 < 2.5

Very Low

4.2                             Treatment Complexity Rating

4.2.1                       Fire Regime Condition Class

FRCC 3 stands are considered the most difficult and costly to treat. See section 4.1.1 for a overview discussion of this issue.

4.2.2                       Wildland Urban Interface

The Wildland Urban Interface (WUI) was used as an indicator of proximity to inhabited areas and was based on structure density from TRIM. All anthological building features were extracted from this data set and buffered such that structural classes could be assigned based on their density on the landscape.

Interface density classes were delineated as follows:

Undeveloped 0-1 structures/km2

Isolated =1-10 structures/km2

Mixed = 10-100 structures/km2

Developed = 100-1000 structures/km2

Urban = > 1000 structures/km2

 

All WUI categories, except undeveloped, were buffered by 1 km. Difficulty to treat increases (i.e, cost, emissions mitigation, etc.) with increasing proximity to WUI and increasing WUI density class.

4.2.3                       GIS Processing

Each input coverage (FRCC and WUI) was converted into 25 x 25 m raster cells and assigned ratings according to Table 3. Individual ratings for each raster cell were developed on 0 to 10 scales.

Table 3. Rating scale matrix for input coverages to establish Treatment Complexity Ratings.

Input Coverages

Rating

Fire Regime Condition Class

3

10

2

8

1

5

None

0

Wildland Urban Interface

 

Urban

10

Developed

9

Mixed

7

Isolated

5

Buffer 1km

5

Underdeveloped/None

0


To create the Treatment Complexity Rating, the rating for each raster cell was calculated as a weighted sum of the two input coverages as per the following equation:

(FRCC*0.5) + (WUI*0.5) = Treatment Complexity Rating

Table 4 shows final Treatment Complexity Ratings.

Table 4. Final Treatment Complexity Ratings

Rating

Priority

>/= 7.5

High

>/= 5.0 < 7.5

Moderate

>/= 2.5 < 5.0

Low

0 < 2.5

Very Low

4.3                             Constrained Area

The Timber Harvesting Land Base, Ownership and Treatment Complexity result were all overlaid spatially to net out the unconstrained High Priority Treatment areas.

5.0                           Results and Discussion

5.1                             Field checking the GIS analysis

Once the initial mapping results were completed in GIS, map outputs of selected areas were created to check the results. Darke Lake Park provides a good example of one of the test areas visited during the field check. The following discussion summarizes some of the issues identified during the field checking process.

Darke Lake Park (Figure 4) and adjacent area provides a good example of the variables that were considered during the development of the prioritization model. This small park lies due west of Summerland in a narrow north-south oriented valley. Many of the planning issues apparent at Darke Lake are similar, if not identical to issues found throughout the Okanagan Region.

Text Box: Photo B, CText Box: Photo AText Box: Private land

Figure 4. Section of Darke Lake Provincial Park showing interface of park with adjacent private land. Additional overlying layers include: FRCC, UWR, FHF, and OGMAs.

As is described in the introduction and methodology sections, we began with two layers: HNFR and FRCC. This area is in FRCC 3, the most departed condition and has stand-level fuels and tree density conditions similar to those pictured in Figure 5. This image is of the landscape at “Photo A” in Figure 4. Tree density is high and there is a high incidence of dead trees in the canopy. It was not possible to observe surface fuels due to snow conditions. The addition of Forest Health Factors, the black points and polygons in Figure 4, strengthens the case for placing these areas on the prioritization list. It is interesting to note that this area is designated as both an OGMA and UWR, which appears to be contradictory to sound biodiversity management considering its current condition. Current stand structure is significantly departed from historic structure and is jeopardizing the resilience of historic “old forest” structures. Land-use designations such as OGMA and UWR did not enter our prioritization model as planning elements for reasons that became apparent in this Darke Lake example. “Protection” of the inherent values in landscape-level designations such as OGMA and UWR should not be seen to be in conflict with active restoration provided that the “values” being protected are fully defined. These “values” tend to be specific structures such as snags, downed wood, densities of old trees by species, understory plant communities, etc. These are all elements of biodiversity and ecosystem resilience that can be addressed at the operational level (5.3.1 Setting Appropriate Objectives).

Figure 5. Hillslope on the west side of Darke Lake.

The modeling combination of HNFR, FRCC, and FHF would suggest that the west side of Darke Lake should be a good candidate for restoration. Ecologically, this makes a great deal of sense. However, when we consider operational-level complexity (difficulty of burning), this area ranks as very high difficulty. Given the high difficulty associated with treating this area both from a technical and cost perspective these areas ranked lower within this project’s overall treatment priorization scheme. Essentially, those areas with the worst FRCC and FHF issues are also the most difficult and costly to treat. As a result, in this analysis they have a lower priority for treatment, which is the inverse of what would result if the prioritization ranking only considered HNRC, FRCC, and FHF.

Several factors make the west side of Darke Lake a very complex restoration project. First and foremost is its proximity to private land and dwellings. Two large parcels of private land are identified in Figure 4. The wildland-urban interface can be viewed two-ways in this analysis: as a significant socio-economic factor to consider, and as an impetus to treat. Any large-scale project utilizing prescribed fire becomes more expensive the closer it is to high values at risk. This type of burn area requires more resources on holding actions and mop-up when compared with burns further from the interface. Additionally, more effort is required to conduct public consultation and education, and smoke management becomes a more significant concern that can limit the burn window and may put more restrictions on the prescription.

The second contributor to complexity on the west side of Darke Lake is tree density and potential surface fuel load. This landscape would require extensive fuel modification, including the commercial removal of timber, before prescribed fire could be applied. Using prescribed fire alone is not advised because of issues identified in 5.3.1 Setting Appropriate Objectives. Identifying areas based on cost of treatment, which has been addressed in this analysis, can be further parsed to include areas requiring commercial thinning prior to wildland fire use. Where tree removal is considered appropriate under the MOE’s new tree removal regulations, these areas could provide a stream of revenue that could be used to fund restoration-burning activities.

The east side of Darke Lake, Photo points B (Figure 6) and C (Figure 7), is modeled as FRCC 1, meaning it is least departed from historic conditions. From a landscape perspective (Figure 6) the forest is more open than the opposite side of the valley. At the stand-level (Figure 7) the rate of forest ingrowth becomes apparent.

Figure 6. Landscape view of the east side of Darke Lake.

 

Figure 7. Stand-level view of forest structure on the east side of Darke Lake.


This area, as a candidate for restoration, has definite advantages over the west side forests. Project complexity is reduced by the forest structure and fuelbed characteristics. A light spring burn, or even a fall burn, is possible here whereas on the west side of the valley only a fall burn would be feasible (due to aspect and fuelbed moisture). It would still be advisable to do some fuel modification prior to prescribed burning on a site such as this to gain a higher precision in meeting burn objectives (5.3.1 Setting Appropriate Objectives). Project cost in this situation would be greatly reduced compared with those across the valley but would still be high due to proximity to the WUI.

5.2                             Analysis and Mapping Summaries

5.2.1                       Distribution of Historic Natural Fire Regimes within the study area

Within the total study area of 2,966,765 ha, there were 850,000 ha (29%) assigned to a Historic Natural Fire Regime II (Table 5). A significant portion of the total study area (621,404 ha – 21%) was within other fire regime classes or was not classified due to problematic data (where forest cover data is missing), or alpine and alpine tundra (Figure 8). Table 5 provides an area summary of the HNFR classes. HNFR classes I, II, and IV accounted for 80% of the classified HNFR area and were primarily associated with the lower elevation valley bottom forests that occur within the study area. Vegetation within these areas are typically dominated by Douglas-fir and Ponderosa pine forests. These fire regimes represent the areas most heavily impacted by resource extraction and human development. The three fire regimes HNFR I, II, and IV were similar in their distribution; HNFR I, II, and IV accounting for 27%, 29%, and 24% of the study area respectively.

Table 5. Area summary of ownership and historic natural fire regimes within and outside of timber harvesting land base for the study area.

 

HNFR

 

I

II

IV

Other

Inside THLB

ha (%)

ha (%)

ha (%)

ha (%)

Federal Ownership

0

0

0

0

Provincial Ownership

343,025 (22)

622,194 (39)

455,791 (29)

172,416 (11)

Private Ownership

0

0

0

0

No Data

0

0

0

0

 

 

 

 

 

Outside THLB

 

 

 

 

Federal Ownership

27,306 (2)

7,423 (1)

1,442 (0)

28,001 (2)

Provincial Ownership

210,036 (15)

202,496 (15)

213,424 (16)

336,208 (25)

Private Ownership

211,878 (16)

26,011 (2)

14,850 (1)

84,364 (6)

No Data

55 (0)

32 (0)

106 (0)

157 (0)

 

 

 

 

 

Ownership Totals

 

 

 

 

Federal Ownership

27,306 (1)

7,423 (0)

1,442 (0)

28,001 (1)

Provincial Ownership

553,061 (19)

824,690 (28)

669,215 (23)

508,623 (17)

Private Ownership

211,878 (7)

26,011 (1)

14,850 (1)

84,364 (3)

No Data

55 (0)

32 (0)

106 (0)

157 (0)


Figure 8. Historic natural fire regime within the study area.

5.2.2                       Distribution of Condition Class Within the Study Area

As discussed early in the report condition class provides a good measure of ecosystems that require some form of restoration to improve biodiversity and forest health. For all ownership categories 45% of the study area was departed (Condition Class 2 and 3) from its historical condition in terms of fuel loading, vegetation composition, and structure (

 

Condition Class

 

1

2

3

Other

 

ha (%)

ha (%)

ha (%)

ha (%)

Inside THLB

 

 

 

 

Federal Ownership

0

0

0

0

Provincial Ownership

606,142 (38)

359,321 (23)

619,182 (39)

8,781 (1)

Private Ownership

0

0

0

0

No Data

0

0

0

0

 

 

 

 

 

Outside THLB

 

 

 

 

Federal Ownership

40,624 (3)

3,275 (0)

8,371 (1)

11,902 (1)

Provincial Ownership

352,033 (26)

115,229 (8)

184,328 (14)

310,573 (23)

Private Ownership

141,625 (10)

14,180 (1)

62,169 (5)

119,128 (9)

No Data

55 (0)

21 (0)

27 (0)

247 (0)

 

 

 

 

 

Ownership Totals

 

 

 

 

Federal Ownership

40,624 (1)

3,275 (0)

8,371 (0)

11,902 (0)

Provincial Ownership

958,175 (32)

474,550 (16)

803,510 (27)

319,354 (11)

Private Ownership

141,625 (5)

14,180 (0)

62,169 (2)

119,128 (4)

No Data

55 (0)

21 (0)

27 (0)

247 (0)

 

 

 

 

 

 

 

 

 

 

 

Table 6. Area summary of ownership and condition class within and outside of the timber harvesting land base for the study area.

 

 and Figure 9). The total area for all ownership categories in Condition Class 3 was larger (874,077 ha – 29%) when compared with Condition Class 2 (492,026 ha – 16%). Outside of the THLB, where the MOE has greater responsibilities the provincially owned area within condition class 2 and 3 was 115,229 ha (8%) and 184,328 ha (14%) respectively. The provincially managed area was significantly greater within the THLB where condition class 2 and 3 accounted for 359,321 ha (23%) and 619,182 ha (39%) of the total THLB.

 

Condition Class

 

1

2

3

Other

 

ha (%)

ha (%)

ha (%)

ha (%)

Inside THLB

 

 

 

 

Federal Ownership

0

0

0

0

Provincial Ownership

606,142 (38)

359,321 (23)

619,182 (39)

8,781 (1)

Private Ownership

0

0

0

0

No Data

0

0

0

0

 

 

 

 

 

Outside THLB

 

 

 

 

Federal Ownership

40,624 (3)

3,275 (0)

8,371 (1)

11,902 (1)

Provincial Ownership

352,033 (26)

115,229 (8)

184,328 (14)

310,573 (23)

Private Ownership

141,625 (10)

14,180 (1)

62,169 (5)

119,128 (9)

No Data

55 (0)

21 (0)

27 (0)

247 (0)

 

 

 

 

 

Ownership Totals

 

 

 

 

Federal Ownership

40,624 (1)

3,275 (0)

8,371 (0)

11,902 (0)

Provincial Ownership

958,175 (32)

474,550 (16)

803,510 (27)

319,354 (11)

Private Ownership

141,625 (5)