Forest Investment Account (FIA) - Forest Science Program
FIA Project Y092133

    Silvicultural systems to maintain northern caribou habitat in lodgepole pine forests in central BC
Project lead: Waterhouse, Michaela (Ministry of Forests and Range)
Contributing Authors: Waterhouse, Michaela J.; Armleder, Harold M.; Chapman, Bill K.; Wei, Adam
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
UPDATE: Based on the 2007 data collection, it is necessary to add another tree fall assessment in 2008. The mountain pine beetle mortality has initiated a very active period of treefall that should be measured annually. This will not change other planned activities for 2008-09.

This is a long-term research trial that supports policy (Cariboo-Chilcotin Land-Use Plan (CCLUP (Province of B.C. 1995)) and Species at Risk Act (SARA)), and provides an integrated approach to caribou habitat management. Under SARA, northern caribou are designated as ‘threatened’ within Southern Mountains National Ecological Area (SMNEA) and under the CCLUP, they are considered a key management species (Youds et al. 2002). The goal of this project is to develop and test silvicultural systems that maintain caribou habitat, including terrestrial and arboreal forage lichens, while extracting timber, achieving regeneration, maintaining long-term site productivity and conserving biodiversity. Research is required to continue to provide a sound scientific basis for the ‘modified harvesting options’ under the CCLUP and for the SARA mandated recovery planning process. Over 181,000 ha of caribou habitat is designated for ‘modified harvesting’ (Youds et al. 2002) but due to the ‘threatened’ status of the species nationally, convincing data showing success will be needed to ensure the land continues to contribute to the AAC.

Lichens are widely recognized as the major winter forage of woodland caribou throughout their range (Edwards et al. 1960; Scotter 1967; Ahti and Hepburn 1967). Research in the Itcha-Ilgachuz area in west central British Columbia has shown that terrestrial and arboreal lichens are important forage for caribou during winter (Cichowski 1989). There are negative effects of conventional clearcut logging on terrestrial lichen in lodgepole pine stands (Miège et al. 2001; Woodard 1995; Goward and Miège 1999), though harvesting on a winter snowpack can reduce losses (Coxson and Marsh 2001). There are estimates of recovery and descriptions of long term succession patterns based on retrospective studies in central B.C.(Coxson and Marsh 2001, and Brulisauer 1996); however, these patterns have resulted from fire not forest harvesting. Initial work on the pilot block of our trial indicates that partial cutting retains arboreal and terrestrial lichen and partial shading of terrestrial lichens in openings reduces sudden exposure to solar radiation that causes rapid drying and heating (Miège et al. 2001).

Further investigation with the replicated trial quantifies terrestrial lichen response to group selection and irregular group shelterwoods over time. After 8 years, analysis indicates that lichen recovery is underway in the partial cutting treatments and three adjacent clearcuts, although the amount in the clearcuts lags substantially behind the partial cuts. However, the research trial has now become more complex and important because mountain pine beetle (MPB) has killed 50% or more of the mature trees since 2004 (last assessment). The implications to the lichen community and subsequently, to northern caribou and other species are unknown. To the north of our study, in MPB killed stands, Williston and Cichowski (2006) attribute the decline of lichen partially to increased kinnikinnick and possible landscape level increases in water table. Increased litter fall and gradually increased light could cause lichens to decline. In our study, in addition to lichen and moss species variables such as canopy closure (light), vegetation (layers and species), ground disturbance and moisture, and woody debris (litter fall, slash) will continue to be measured. We are uniquely set up to measure the impact of MPB on northern caribou habitat.

This trial provides an excellent opportunity to measure the response of birds, and tree regeneration to the changing forest structure induced first by partial cutting and now by MPB. In the first 5 years post-harvest, bird species associated with old pine forest were not adversely affected by the partial cutting (Waterhouse and Armleder 2007). The amount of advanced regeneration (pre-harvest) and ingress over 7 years post-harvest in the gaps was substantial in the trial blocks within the SBPSxc but much lower in the MSxv biogeoclimatic subzone (Steen et al. 2007). Although large areas of damaged forest will be salvaged by clearcutting, other areas will be left (e.g. parks, caribou habitat, less economic stands) (Burton 2006). The consequences of leaving these stands, from a regeneration, productivity and biodiversity perspective, need to be assessed through empirical studies (Burton 2006; Chan-McLeod; Griesbauer and Green 2006; Martin et al. 2006). Knowledge generated from this long-term research trial (natural and planted regeneration, growth and yield, tree fall, microclimate and bird survey plots) can be used to inform planning and management actions.

A sub-project examines the relationship between the amount of woody debris and site productivity. Woody debris or organic matter has been identified as critical factor affecting site productivity in the second and subsequent rotations in many types of world forests (Sheng and Xue 1992; Squire 1993; Kimmins 1999; Wei et al. 1997). Such a relationship can help formulate site indices or indicators. These indicators can be used in ecosystem productivity models for forecasting growth and yield particularly in forests of the second or subsequent rotations (Wei et al. 2000). This research project has manipulated the levels of woody debris loading related to harvesting (none, loads associated with stem-only and whole tree harvesting, double stem-only harvesting). Changes in site quality associated with inputs of woody debris could directly affect site productivity. Also, this research will help prescribe soil conservation guidelines in terms of how much woody debris should be retained after harvesting operations to prevent yield decline.

This project was developed in 3 phases: a pilot block, a replicated experimental trial, and an adaptive management trial (Waterhouse 1998). The 40 ha pilot block, harvested in late winter of 1994/95, consisting of three treatments: group selection, and clearcutting with scattered group retention and large island retention. Based on the pilot block, the replicated trial (5 blocks, > 60 ha each) was winter logged in 1995/96 using the following silvicultural system treatments: group selection based on 33% area removal every 80 years (openings = 15 m diameter), irregular group shelterwoods (openings = 30 m diameter) based on 50% area removal every 70 years (stem-only, whole tree harvesting). The study includes no-harvest and clearcut treatments. Plots were installed pre-harvest and data collected for the last ten years for lichen, regeneration, birds, and vegetation. Growth and yield plots and long-term site productivity plots were installed post-harvest. The adaptive management trial (logged 1997 – 2000) was developed to refine operational harvesting techniques (funded by the FIA land base program).

Related projects:  FSP_Y081133FSP_Y103133


Executive summary (37Kb)

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Updated August 16, 2010 

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