Forest Health and TSR: how do pests “move the needle”?

1. Stefan Zeglen, Forest Pathologist, West Coast Region Jim Brown, Senior Analyst, Forest Analysis and Inventory Branch Forest Health and TSR: how do pests “move the needle”? CSC Winter Workshop, Nanaimo, BC February 27, 2014

2. Scale matters CSC Winter Workshop, Nanaimo, BC February 27, 2014

3. The Mythology of Pests • Myth 1: Pests don’t matter on the Coast like they do in the Interior. • Myth 2: Even if pests are present they never do enough damage to worry about. • Myth 3: Pest losses are already accounted for in growth & yield models. CSC Winter Workshop, Nanaimo, BC February 27, 2014

4. Accounting for pest impacts • Most basic: • Unsalvaged loss estimates or non-recoverable loss estimates (NRL) • More refined: • Operational Adjustment Factors (OAF) for model estimates • Catastrophic loss estimates: • One-off calculations for large scale events CSC Winter Workshop, Nanaimo, BC February 27, 2014

5. Unsalvaged loss estimates • Required component of TSR data packages. • Usually include losses to wind, wildfire, landslides, insects and diseases. • Data used comes from wildfire records, aerial overview surveys (AOS) and other reports. • Usually provided as a m³/year adjustment. • Tempered by district knowledge of salvage rates for various events. • Updated each TSR cycle. CSC Winter Workshop, Nanaimo, BC February 27, 2014

6. Operational Adjustment Factors • Used to adjust model output (e.g., TASS/TIPSY) of stand volume projections. • Restricted to a set of insects or diseases in a defined area • (e.g., root disease in the CDFmm and CWHxm1) • Data is usually sourced from fixed plots (e.g., G&Y PSP, research trials) measured over time. • Updated as new information becomes available. CSC Winter Workshop, Nanaimo, BC February 27, 2014

7. Catastrophic loss estimates • Rarely necessary. • Attempts to predict impact on a large scale from biological spread and mortality factors. • Most recent example is the Provincial Level Projection of the Current Mountain Pine Beetle Outbreak (M Eng and A Walton). • Intended to drive decision-making and mitigation response over a large area. CSC Winter Workshop, Nanaimo, BC February 27, 2014

8. Factoring Forest Health into Timber Supply Forecasts Some Considerations • What are the forest health factors influencing the forest • What stand types / tree species / ages are affected • What are the ST/ LT influences of these factors: • timber yield (recoverable volume) • timber grades and species mix • stand development, growth and future yields • Are losses constant over time (endemic) or periodic (epidemic) • To what extent is it possible to salvage damaged timber (considering access, economics, shelf life) CSC Winter Workshop, Nanaimo, BC

9. Unsalvaged loss estimates • Often applied as a constant reduction in the periodic supply, though estimates could vary over time or by forest type if information supports doing so. • Estimates are based on observed losses, taking into account salvage and recovery, ideally over the previous 10 years or more. • Recognized uncertainty that historic losses = future losses (given changing economics, management practices and climate) CSC Winter Workshop, Nanaimo, BC February 27, 2014

10. Unsalvaged loss estimates Example, Fraser TSA, 2013 TSR CSC Winter Workshop, Nanaimo, BC February 27, 2014

11. Operational Adjustment Factors In Timber Supply Analysis • Natural stands are modelled using VDYP7, often with the assumption that endemic losses are reflected in the net volume estimates. • Managed stands are modelled using TASS/TIPSY. Since TASS models fully stocked stands free of significant health factors, OAFs are necessary. • A standard OAF1 of 15% was developed from research trials to account for stands gaps and losses that act over the life of the stand. • Locally defined OAFs are needed to account for accute outbreaks or other endemic factors not accounted in the standard OAF1 • Ideally local defined OAFs are based on stand monitoring data (e.g. a YSM/CMI) including field derived volume estimates. CSC Winter Workshop, Nanaimo, BC February 27, 2014

12. Operational Adjustment Factors • A YSM project in the Morice TSA targeted stands between 15 and 50 years old • Initial results suggested that TIPSY volumes are overestimated and inventory heights are underestimated. • The project also provided information to assess the incremental forest health impact of pine stem rusts • There are a number of approaches that could be used to adjust MSYT for forest health factors using YSM results CSC Winter Workshop, Nanaimo, BC

13. Operational Adjustment Factors • A worst-case scenario assumes affected trees will die at rotation and applies an incremental OAF1 to account for losses. This is similar to how we typically adjust for root disease on the coast OAF1 (10%) for stem rusts CSC Winter Workshop, Nanaimo, BC

14. Operational Adjustment Factors • Alternatively, TASS can be used to simulate the change in stand dynamics from a (e.g. western gull rust) Early rust event adapted from J. Goudie & I Cameron 2014 CSC Winter Workshop, Nanaimo, BC

15. Operational Adjustment Factors • TASS allow for a more complex simulation of stand response to early mortality and growth losses. adapted from J. Goudie & I Cameron 2014 CSC Winter Workshop, Nanaimo, BC

16. Operational Adjustment Factors • YSM provides a means of collecting data on the effects of forest health factors and developing assumptions to account for them in T.S.A. • When using OAFs one must understand how the factor alters the dynamics and conditions of a stand and how well the model effectively simulates those dynamics. • TASS modelling and/or custom OAFs may be the most appropriate means of adjusting for both tree mortality and live-stem volume losses. CSC Winter Workshop, Nanaimo, BC