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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.

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Presentation on theme: "The DFC Model: a Regulatory Tool Used in Riparian Forest Management in Washington Steve McConnell Upper Columbia United Tribes Spokane, WA Growth Model."— Presentation transcript:

1 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

2 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

3 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

4 DFC Model Only growth and yield model used as a regulatory tool Derived from ORGANON, SMC version A whole stand model

5 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

6 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!

7 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

8 DFC: Desired Future Condition Characteristics and functions of mature, unmanaged riparian forests –Habitat conditions desirable for salmon recovery

9 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

10 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

11 RMZ’s: a Graphical Depiction Zones – core, inner and outer

12 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)

13 RMZ Widths, by Stream Size

14 Forest Practices Rules Stand Age-140 Basal Area Targets Stand Basal Area for DFC Rules is Calculated from the Area-Adjusted Core+Inner zones

15 DFC: Desired Future Condition Management today that puts stands on a trajectory towards “DFC” Stand growth and Rx details derived from the DFC Model





20 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

21 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

22 Desktop Analysis Results

23 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

24 DFC Model Related Reports Desktop analysis Riparian stand characteristics Sensitivity analysis (Roorbach et al.) FPA field check review Model and manual problems Synthesis

25 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

26 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.

27 Desktop Analysis: Follow-up Exploratory Study Developed a Study Design (was not reviewed by the SRC) Developed specific objectives

28 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

29 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

30 Desktop Analysis Results





35 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 Tot al 1Small80’ 103.0  12.6 055 1Large100’ 102.0  4.0 314 2Small80’ 87.4  7.1 72532 2Large100’ 102.6  5.7 20727 3Small80’ 80.4  1.8 38240

36 Desktop Analysis Results

37 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

38 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

39 Site and Stand Analyses: Site Class

40 Site and Stand Analyses: Major Species

41 Site and Stand Analyses: HA BA by Major Species

42 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

43 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

44 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

45 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

46 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

47 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

48 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.

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