Forest Investment Account (FIA) - Forest Science Program
FIA Project Y103008

    Group selection silvicultural systems to maintain caribou habitat in high elevation forests (ESSFwc3) in central BC
Project lead: Walt Klenner (Ministry of Forests and Range)
Author: Newsome, Teresa A.
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
UPDATE 2009-10
The only change to this project is the natural regeneration study. It was scheduled for field measurement in 2008, but after reviewing the 10th year published paper (Steen et al. 2008), it is not necessary to continue the original study on the effects of scarification and hand seeding. However, it is necessary to assess the ability of natural regeneration to restock blocks and whether free-growing has been met in the three openings sizes at each block. This project also provides the opportunity to input into the Silviculture Surveys Procedure Manual (Forest Practice Branch 2008) on how to survey group selection systems, and the selection of inter-tree distances in the ESSFwc3. We propose in 2009 to continue to study the natural regeneration ingress and densities in the three opening sizes using the standard silviculture survey methodology (Forest Practices Branch 2008). Plots (3.99 m radius) will be centred at locations selected for the original study. There is no cost implication to the original work plan as there were funds for analysis and reporting in the original schedule for 2009/2010.

This is a long-term research project that supports current policy (Cariboo-Chilcotin Land-Use Plan (CCLUP) (Prov.B.C. 1995), and CCLUP - Mountain Caribou Strategy (Youds et al. 2000)) and provides an integrated approach to resource management. Mountain caribou are on the provincial ‘threatened’ list and in the CCLUP, they are considered a key management species. Under the federal Species at Risk Act (SARA) mountain caribou are designated as threatened within Southern Mountains National Ecological Area (SMNEA) and recovery planning is underway provincially through the Species at Risk Co-ordination Office (SaRCO). The CCLUP -Mountain Caribou Strategy has ‘modified harvesting options’ for 53,000 ha of critical caribou winter range in the upper elevations of the Engelmann spruce – subalpine fire zone (ESSFwc3). The Quesnel Highland project was developed to test group selection silvicultural systems that retain caribou habitat (forage lichens associated with old-growth forests) while extracting timber, achieving regeneration, conserving biodiversity and understanding the effects of partial cutting on peak streamflow. This project fits well with the management recommendations proposed by Stevenson et al. (2001).

Forest practices are currently the greatest habitat management concern for mountain caribou (Mountain Caribou Technical Advisory Committee 2002). Associated with forest practices are habitat fragmentation, reduction in winter food supply, increased human access and associated disturbance, and alteration of predator-prey relationships. The recovery planning process, through SaRCO, is considering all these factors in an options report for various populations of caribou (Mountain Caribou Science Team 2006). In the Quesnel Highland planning unit three of the five options include ‘modified harvesting’. Because of the ‘threatened’ status of the caribou nationally, convincing data regarding modified harvesting will be needed to ensure that the land continues to contribute to the annual allowable cut (AAC). It is essential to continue monitoring the research trial to either confirm success or learn how to modify the silvicultural systems to achieve success.

Caribou eat arboreal (tree-dwelling) lichens almost exclusively during the winter and logging can have a drastic effect on available lichen biomass (Stevenson 1979, 1990; Rominger 1994). Clearcutting is not compatible with maintaining mountain caribou habitat as it completely removes arboreal lichen. Lichen dispersal, establishment and growth are slow (due to required substrate and microclimate conditions) and it may take over a century before the quantity of lichen within a clearcut is comparable to that found in old-growth stands. Partial cutting through group selection systems may provide sufficient arboreal lichen through space and time. On our research trial, after 10 years, lichen has increased in the residual forest in the partially cut treatments compared to the no-harvest treatments (Waterhouse et al. 2007). This was first evident at the 10-year assessment but periodic measurements are needed to confirm this result over time. Tree fall and recruitment also contribute to the lichen loading in the stand.

The ESSF zone is biologically rich and extensive (13.3 million ha) and is currently dominated by old forests. Outside of caribou habitat, as timber harvesting progresses, via the clearcut silvicultural system, much of the forest will be managed on a 120 year rotation. The consequences to wildlife of shifting from old to younger seral forest could be significant. In contrast to clearcutting, group selection silvicultural systems are a possible way to continuously provide old forest habitat attributes required by many species (Waterhouse et al. 2004; Klenner and Sullivan 2003; Leupin et al. 2004).

To be considered a successful silvicultural system adequate regeneration of conifer species must be achieved. There has been relatively little information on regeneration, either natural or planted, following partial cutting at high elevations over 1500 m in B.C. (Farnden 1994, Lajzerowicz 2000, Jull and Stevenson 2001). Early results (5 years) have been published from across several high elevation partially cutting trials in B.C. (Lajzerowicz et al. 2006). The results of this study, and other provincial trials in the ESSF (Jull and Stevenson 2001, and Vyse 1997), will provide a significant advance in knowledge over the longer term.

Peak snow accumulation and snow melt rate are significant because the ESSF has the highest snow accumulation of all forested zones in B.C. and because snow melt rate largely determines the magnitude of spring floods throughout much of the Interior. Spring floods, in turn, affect on fish habitat and the suitability of riparian areas for human use. Timber harvesting tends to increase accumulation and melt rate but little information is available on how the widespread use of group selection in the ESSF might affect peak flows downstream. Watershed models are normally used to try to predict this but there is little field data to allow critical parameters to be estimated reliably for group selection in the ESSF. Snow-free date is another important variable for silvicultural (growing season) purposes. Other snow research projects on group selection and strip cuts (Golding and Swanson 1978, Kattleman, et al. 1983 and Gottfried 1991) have been in very different geographic areas and have had a very different objective (maximizing inflow to reservoirs). This project is producing empirical models of accumulation, melt rate, and snow-free dates as functions of site characteristics such as canopy density, basal area, and gap patterns (Teti 2003 and 2004). These results compliment research projects on the plateau (SBS, SBPS, and MS BEC zones) where Teti is studying the effects of beetle-related canopy mortality on snow. Partner researchers are currently modifying watershed models to allow stand-level snow data to be used to help predict the effects of forest changes on streamflow. The results from our ESSF sites will be useful when those models are applied to watersheds with higher elevation headwaters.

The research project has three phases of development: pilot trial, replicated trial and adaptive management trial. This proposal covers activities associated with the pilot and replicated phases. The pilot trial (one 30 ha block) was partially cut using group selection silvicultural systems in 1991. Three group selection treatments, a no-harvest and a clearcut treatment were included in the design. The replicated research trial (4 blocks x 4 treatments) was harvested in 1992/93. The results from the pilot and replicated trials led to the development of the Mt. Tom adaptive management trial, north of Wells, B.C. and the Isaiah Creek trial on Quesnel Lake in the ICH zone (low elevation habitat).
Related projects:  FSP_Y081008FSP_Y092008,  EP1104.02


EP1104.02 Final technical report (0.2Mb)

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Updated August 16, 2010 

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