Forest Investment Account (FIA) - Forest Science Program
FIA Project M075024

    Mountain Pine Beetle Impacts on Young Age Class Pine Leading Stands in the SBS Biogeoclimatice Zone
Project lead: Hawkins, Chris
Author: Hawkins, Chris D.B.
Imprint: [BC] :, 2007
Subject: Forest Investment Account (FIA), Dendroctonus Ponderosae, British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
As of fall 2004, about 7 million hectares have been infested by MPB in BC (1). The Chief Forester has predicted significant timber supply fall down in the mid-term (2). This prediction assumes about 40 percent attack in age class 4 and little or no attack by MPB in stands of age class 3 and younger. We have been assessing (sampling) the impact of MPB in young to mature (age classes 1 to 8) pine leading stands in the: southwest portion of Prince George Forest District [SBS dw2 and dw3]; the southern part of the Vanderhoof District [SBS mc], and the southeast portion of the Lakes TSA (SBS dk). This work is supported by MPB projects Y061021, M065002, and CFS MPBI 8.23. We will have sampled in excess of 200 stands (more than 1000 plots) by the end of the current field season (January 2006). Initial findings show attack rates in older stands are at or near the predicted 80 percent level (3). From our observations, age class 4 stands have attack rates similar to the older mature stands. We have also observed minor mortality and attack in age class 1 stands. However, preliminary findings from age class 2 and 3 indicate mortality rates up to 50 percent with some stands exceeding 80 percent attack rates in 2005. This is contrary to the published literature (4,5) and timber supply assumptions (6,7). Clearly the attack of younger age class stands will further exacerbate the mid-term timber supply referred to by the Chief Forester (2,8). In addition to MPB mortality and attack, we have sampled: regeneration [species <1.4 m tall], advanced regeneration [species =1.4 m in height and <7.5 cm at dbh], shrub, herb and moss cover, tree hierarchy (dominant, co-dominant, etc), and crown closure. Characterizing stand dynamics and landscape patterns temporally and spatially across the affected area will identify the key variables (assumptions) needed to perform up-to-date timber supply analyses in the central BC interior. Furthermore, the data will allow us to describe i) residual stand structure after MPB attack, ii) regeneration in MPB affected stands in a range of SBS sub-zones, and iii) MPB attack levels in young (age class 1 to 4) stands. Our preliminary findings indicate that regeneration and advanced regeneration differ by sub-zone and site series. As a result, when the mature layer is killed by the beetle, some stands may be satisfactorily stocked and others will not be stocked. This is particularly important for the younger age class stands that are the ones most likely not to be logged. Given the limited resources available for post MPB restoration, knowing which stands in each sub-zone that will likely have adequate regeneration provides a ranking of the need for intervention in a stand. This will allow for allocation of fiscal resources in the most efficient fashion. The regeneration component also has a significant impact on future timber supply. As a result of the high levels of MPB activity observed in young pine stands, we will re-sample age classes 2 to 4 (older age class 1 in areas with extreme attack) stands sampled in 2005 (SBS dw, mc, and dk) in order to understand some temporal effects of MPB dynamics within these stands. There is a paucity of information on MPB dynamics in young age class pine leading stands. Collection of this data will also allow better parameterization of timber supply analysis in the Prince George and Lakes TSA. We also propose to sample young pine leading stands in the Bowron and Willow River drainages (SBS mk, wk and possibly vk). This will further facilitate our understanding of MPB dynamics in young stands in the sub-boreal, improve timber supply analysis, assist restoration activities, and detail stand development projections in the Prince George TSA. The extent at which the MPB is attacking younger stands (age class 1 to 4) with smaller trees is a crucial component for: timber supply considerations, planning for restoration activities on unlogged stands, and determining and planning for social impacts on affected communities (Pers. Com. J. Snetsinger, BC Chief Forester, December 2004). Without the young stand data, plans to deal with these issues will not be complete and will potentially fail.
Contact: Hawkins, Chris, (250) 960-5614,


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Updated August 16, 2010 

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