Forest Investment Account (FIA) - Forest Science Program
FIA Project S094200

    Quantitative synthesis of abundance, fall rates and decay rates of snags and down wood in BC’s forests
Project lead: Bunnell, Fred (University of British Columbia)
Contributing Authors: Huggard, David J.; Kremsater, Laurie L.; Houde, Isabelle
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
No deviations have been made to the original project. The focus has been on the IDF, ESSF, CWH and SBS zones, and includes most groups of tree species of the province. The second (and final) year focuses on extension.
This project provides a synthesis of information needed to assess the adequacy of stand structures retained across landscapes. Forest managers are faced with comparing existing and projected stand structures with needs of particular species, levels of structures under natural disturbance regimes, or other targets. We lack useable summaries of the most basic information to meet these requirements: the levels of stand structures presently on the landscape and the levels expected under different management regimes.
We propose two main areas of synthesis: 1) analyzing information on chronosequence of snags and down wood in the forest types of BC, including under different management and natural disturbance scenarios; and 2) analyzing mortality, fall and decay rates. These rates are needed by existing models to project snags and down wood under different scenarios. Our emphasis in both areas is a rigorous quantitative analysis of available data (rather than another qualitative review).
Synthesis of existing information is a priority. There are many scattered pieces of information – published papers, reports in various agencies, data files – but that information is poorly used because it has not been gathered together and combined to provide quantitative knowledge. Given that abundant information exists and is not used well, it is more efficient to synthesize existing information than to embark on new studies of snags and down wood across landscapes.
The project adds to our basic understanding of two of the most critical stand structures in forest ecology and is a priority to several existing programs. Forest and Range Evaluation Program (FREP)’s wildlife tree patch effectiveness monitoring is currently struggling to gain information on levels of stand attributes across landscapes. Forest companies are faced with evaluating and deciding among harvesting systems. They are asked by certifiers and others: What levels of stand attributes will result under different management scenarios? What will be left over time? What is in their unmanaged land? State of forest summaries also use such information – what is out there now? Similarly, managers concerned about habitat for species at risk, or species of management concern, often need to know levels of limiting attributes (often snags). In the current salvage of stands killed by mountain pine beetles (and also for salvage after fire), questions arise as to how many snags will be left, what will down wood levels be now and in the future, how do these compare to natural levels or to species needs? The basic information on amounts, decay and fall rates is the necessary first step in decisions as to what silvicultural system to use, including levels and types of retention, partial cut systems (e.g., for maintaining lichen habitat in caribou areas), or salvage strategies. The information supports stand-level structural monitoring, including improving growth and yield models for habitat elements.
This project will also show where lack of information creates most uncertainty. Identified gaps can help direct future research, monitoring and stand-level modeling.
The proposed work complements previous projects that have collated and narratively summarized deadwood information (Bunnell et al 2002a,b, Huggard 2003) by taking the next step of combining that information into quantitative synthetic knowledge. These synthesis results will provide a sounder – and much more conveniently compact – basis for using the many sources of deadwood information. The work also complements existing literature reviews of species’ snag and CWD requirements (e.g., Bunnell et al. 2002a,b). The synthesis of rate information will help support stand modeling, including for pine beetle salvage and emerging issues. The work also complements efforts at monitoring the effectiveness of stand-level practices by providing best estimates of baseline conditions, and effects of alternative practices.


Executive summary (24Kb)
Brochure: Fall and decay rates of snags - a synthesis (0.6Mb)
Brochure: Decay rates of down wood - a synthesis (0.7Mb)

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Updated August 16, 2010 

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