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The DFC Model: a Regulatory Tool Used in Riparian Forest Management in Washington. Steve McConnell Upper Columbia United Tribes Spokane, WA Growth Model Users Group Meeting January 11, 2007. Acknowledgements. NWIFC, CMER, UCUT John Heimburg Dave Schuett-Hames, Ash Roorbach
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The DFC Model: a Regulatory Tool Used in Riparian Forest Management in Washington • Steve McConnell • Upper Columbia United Tribes • Spokane, WA • Growth Model Users Group Meeting • January 11, 2007
Acknowledgements • NWIFC, CMER, UCUT • John Heimburg • Dave Schuett-Hames, Ash Roorbach • Chris Mendoza, Pete Heide • Doug Martin, Nancy Sturhan • Darin Cramer, Dawn Hitchens and Bonnie Thompson
Presentation Outline • DFC Model Attributes and Role in Management • Desired Future Condition (DFC) management concept • Key attributes of DFC Rules • DFC Model role in management • Model origins and characteristics • Overview of CMER DFC related studies
DFC Model • Only growth and yield model used as a regulatory tool • Derived from ORGANON, SMC version • A whole stand model
DFC Model • Utilizes landowner collected data • Simple enough for lay-persons to use • Limited number of outputs – only those that pertain directly to what landowners need to know to implement rules
DFC Model Role • Project stand basal area growth from current age to stand age 140 • Determines if stands will meet DFC Target • Provides prescriptive details based on site and stand characteristics • Takes a very complicated set of rules and makes them comprehensible!
Characteristics of DFC Rules for Riparian Forests • Fish-bearing streams on private forest lands in western Washington • Core, Inner and Outer Zones • Zone widths vary by site class (I-V) and stream size (LE or GT 10’) • The DFC target is a stand-age-140 basal area target, for each site class
DFC: Desired Future Condition • Characteristics and functions of mature, unmanaged riparian forests • Habitat conditions desirable for salmon recovery
DFC: Desired Future Condition • Goal-oriented management system • “…The stand conditions of a mature riparian forest, agreed to be 140 years of age …a reference point on a pathway and not an endpoint for stands.” • Gauged against a stand basal area target
Management Along Westside, Type F Streams Varies By: • Site productivity: site class I-V • Stream-size: LE 10’ vs. GT 10’ • Harvest method: • no-cut • thin from below • leave trees closest to the stream
RMZ’s: a Graphical Depiction • Zones – core, inner and outer
RMZs: Location, Activities Allowed and Size • Core Zone: closest to stream, no cutting, always 50’ wide • Inner Zone: some cutting, variable width (10 to 100 feet) • Outer Zone: furthest from stream, more cutting, variable width (22 to 67 feet)
Forest Practices Rules Stand Age-140 Basal Area Targets Stand Basal Area for DFC Rules is Calculated from the Area-Adjusted Core+Inner zones
DFC: Desired Future Condition • Management today that puts stands on a trajectory towards “DFC” • Stand growth and Rx details derived from the DFC Model
DFC Model Problems • Three errors in DFC Model calculations were identified, none of them making significant differences to the desktop analysis but possibly affecting implementation
DFC Model Problems • 1) Stand age 140 BAPA is inflated for stands younger than 35 years, • 2) An incorrect value is used in for small stream site class 1, 2, and 3 per acre calculations • 3) For Option 1, the DFC Model gives different inner zone leave tree numbers on the graphical interface than are counted in the inner zone stand table
Sensitivity Analysis (Roorbach) • Scrunches variability for most input variables, minimizing the difference in stand age 140 Basal Area • Major Species, DF or WH, makes an important difference in DFC Model outputs– the largest DFC Model related difference found
DFC Model Related Reports • Desktop analysis • Riparian stand characteristics • Sensitivity analysis (Roorbach et al.) • FPA field check review • Model and manual problems • Synthesis
Desktop Analysis: Exploratory Origins Initial analyses were: • unstructured; outcomes were evaluated without specific objectives. • from a small sample of FPAs from the Olympic Peninsula, • from FPAs that were approved just after new rules were developed
Desktop Analysis: Exploratory Results • Noticed that projected ba-140 almost always exceeded rule ba target • Determined that the required 57 ltpa was a constraint to inner zone timber harvest • Later, determined that the option 2 minimum floor width also constrained timber harvest more than the rule ba target.
Desktop Analysis: Follow-up Exploratory Study • Developed a Study Design (was not reviewed by the SRC) • Developed specific objectives
Desktop Analysis Follow-up: Study Design • Selected 150 FPAs from 2003 and 2004, 75 from each year • Used first DFC worksheet from each FPA • Developed criteria for rejecting FPAs that lacked data or did not meet criteria
Desktop Analysis Follow-up: Objectives • Quantify DFC model-projected BA-140 for each of three riparian prescriptions: 1) no-cut, 2) thin-from-below, and 3) leave trees closest to the stream • Determine the effect of rule components (required leave trees – option 1, and required floor widths, option 2) on DFC Model BA-140 projections
Site Class Steam Size Floor Width Average floor width plus and minus one standard deviation Number of Stands Constrained by Floor Width Number of Stands Constrained by Basal Area Target Total 1 Small 80’ 103.0 12.6 0 5 5 1 Large 100’ 102.0 4.0 3 1 4 2 Small 80’ 87.4 7.1 7 25 32 2 Large 100’ 102.6 5.7 20 7 27 3 Small 80’ 80.4 1.8 38 2 40 Desktop Analysis Results
Desktop Analysis: Conclusions • DFC model projected core+inner zone BA-140 exceed rule targets, because • The 57 iz ltpa (opt-1) almost always (95.3% of worksheets reviewed) required leaving more trees than the rule target alone • The minimum floor widths (opt-2) usually (63% of worksheets reviewed) required leaving more trees than the rule target alone
Riparian Stand Characteristics • Applicable only to subset of riparian stands that meet DFC requirements and selected by landowner for harvest • Provide an overview of characteristics of stands submitted by landowners for management under current rules • A few highlights only
Site and Stand Analyses:Conclusions (Cont.) • Most stands (88.7) were on Site Class 2 and Site Class 3 • There was an almost even split in # of FPAs evaluated,by Species (74 DF and 76 WH) • In core zones, on average, basal area and trees per acre were higher, and percent conifer lower
Site and Stand Analyses:Conclusions (Cont.) • Stands with WH as major species had higher tpa, ba, and RD, but lower qmd than stands with Douglas-fir as major species
DFC Field Check Study • Most stand inventory and site attribute data collected were similar between landowner and CMER Staff • Stream size • Major species • Stand age • Stand inventory
DFC Field Check Study • Biggest differences to buffer strip configuration are a result of stream size call, CMZ delineation and landowner decision on outer zone trees
DFC Field Check Study • There were methodological findings, for example: • 1) there is no method prescribed for determining RMZ length and this can lead to a lot of variability, • 2) the Board Manual and other materials provided to landowners are confusing, difficult to follow and have errors within
Synthesis • The basal area target is a less important constraint to inner zone timber harvest than is the leave tree requirement or minimum floor width • Landowners use Option 2 (leave trees closest to the stream) preferentially
Synthesis • There may be differences in harvest age Douglas-fir and western hemlock stands in terms of basal area, tpa, relative density, qmd and conifer percent. Possibly there should be different management prescriptions for these.
