Fire & Forest Ecosystem Health Team

What We're Working on Now

As we wait for the forest treatments to be completed, the FFEH team has focused on placing the SNAMP research in a broader management framework and developing novel approaches to measuring forest response.

In a recent Bioscience paper, Dr. Scott Stephens and his colleagues summarized the effectiveness of forest fuel reduction treatments in changing fire behavior in the western United States. In particular they evaluated mechanical thinning and prescribed fire – two essential elements of the SPLAT treatments used in the SNAMP study sites. Stephens and his colleagues concluded that:

… both prescribed fire and its mechanical surrogates are generally successful in meeting short-term fuel-reduction objectives and in changing stand structure and fuel beds such that treated stands are more resistant and resilient to high-intensity wildfire.

Stephens et al. 2012. Bioscience 62:549-560.

They also found at the stand level that these treatments had only minor negative impacts on wildlife (birds and small mammals), understory plant diversity, exotic plant invasions, and bark beetle attack. However the efficacy and impact of the individual treatments across the landscape remain unaddressed and is a central question of the SNAMP study, a question we hope to definitely answer in the next year.

On the forest health side, John Battles has been collaborating with the de Valpine Lab at UC Berkeley () to reliably estimate tree growth from periodic inventory data. The growth response of individual trees is the primary measure of forest health in the SNAMP study. Our rationale is that growth is an excellent indicator of tree vitality and that a necessary (but not sufficient) condition for a healthy forest is healthy trees. Our initial workplan relied on direct sampling of tree growth via increment cores to detect any treatment effect. Our ability to empirically detect change relies on both sample size and time since treatment. We anticipate that it will take 4-5 years to measure changes in growth in any individual tree with a sample size of approximately 100 trees per species (5) per site (2 , N=1,000). Under the new schedule, re-measurement will occur 1-2 years post-treatment. The shortened time since treatment so greatly reduces the power of the direct measure of growth (i.e., increment core) that we have decided not to re-core trees in 2013.

Instead we have been working on a modeling approach that estimates tree growth from periodic diameter measurements. We plan to use our pre and post inventory data to parameterize a state-space model using Bayesian statistics that accounts for the complexities introduced by inventories and the potential driving factors. One of the key drivers to evaluate is the impact of management on growth. While we lose the directness of an empirical test, we gain a huge increase in our sample size. We have measured 12,365 trees in our study sites. The more than 10 x increase in sample size greatly increases our chance of detecting an immediate treatment effect on tree growth.

Melisss Eitzel, a graduate student in de Valpine’s lab, is the lead author of a manuscript in revision that describes our approach. She built a hierarchical Bayesian growth model for white fir from Blodgett Forest data (near Last Chance). Included below is a figure from the appendix that shows the model results for white fir trees of various sizes (Fig.1 ). In most but not all cases, the model estimates the trend in growth remarkably well. Her research proves-the-concept of our revised approach to measuring treatment effects on tree growth in the SNAMP study areas.


Figure 1. A selection of model estimates for white fir trees across a size gradient. Results from Eitzel et al. In revision. Estimating tree growth models from complex forest monitoring data. Ecological Applications. The filled circles represent inventory measurements and the open circles represent model predictions.

The FFEH workplan is available here

Updates

THE PAST

Discussion

Kim_Ingram said at 11:35 a.m., 21 July 2014 ,

The following response to Jerry Bloom's comments re. the American Fire comes from John Battles, SNAMP PI:

"As for ...

Kim_Ingram said at 9:42 a.m., 21 July 2014 ,

The following comments and concerns were sent to me from Jerry Bloom, a participant in our field trip to the ...

Kim_Ingram said at 1:40 p.m., 3 November 2011 ,

Prescribed Burning for Beargrass Enhancement on the Last Chance Project November 3, 2011 "I was forwarded notice about a planned ...