Comparison of FVS projection of oak decline on the Mark Twain

National Forest to actual growth and mortality as measured over

three FIA inventory cycles

Don Vandendriesche, Data GuruForest Management Service Center

Fort Collins, Colorado

Linda Haugen, Plant Pathologist Northeastern Area State and Private Forestry

St. Paul, Minnesota

• Ozark Mountains of MO

• Central Hardwoods

• Human Disturbance History

• Lots of Oak

• Oak Decline

• What’s the future of these stands?

Where and Why???

Oak Decline has had a significant effect on stand

conditions in MO

FVS of FIA data for OD on MTNF Methods: • Data source • calibration • regeneration • strata • mortality groupings• Oak Decline Event Monitor (ODEM)

Results: • Static use of FVS to compare actual measured

values from 3 cycles.• FVS modeling– choosing “best” model• Into the future– take 1 stratum 100 years out

THE DATA• 157 Common stands on the MTNF re-

measured in FIA cycles 3 (1976-1977), 4 (1986-1987), and 5 (1999-2003), with the identical center pin. After filtering to exclude disturbed plots, non-oak types, small diameter and other anomalous plots, there were about 100 stands available for analysis.

• Data from 911 FIA plots (all oak type) from cycles 3, 4, and 5 on the MTNF were pooled for adjusting max tree and stand growth in FVS.

The Data

Cycles 3 and 4 Cycle 5

Calibration of FVS• 557 plots from cycles 3 and 4 used for FVS self-calibration of

growth model (ReadCorD).

• Defect values to apply in calculation of merchantable volume were based on values which the MTNF used in 2005 Forest Plan Revision. Cycle 4 FIA data was used to determine the allocation of this defect across size classes.

• Species and size distribution from 911 FIA plots from cycles 3, 4, and 5 were used to indicate the max size that different tree species were allowed to grow, and mortality related to stand density index/ basal area maximums and species distribution. These were built into addfiles (CapSize and Adj_OD).

• 911 plots used for regeneration imputation… see following slide.

Wednesday AM:

“Some Assembly Required”

Imputation of Regeneration• Potential tree species for regeneration were divided

into 9 possible shade tolerance and max height attainment groups.

(for instance: high shade tolerance, mid height attainment group; low shade tolerance, high height attainment group; etc.)

• 911 FIA plots from cycles 3, 4, and 5 were used to determine the typical distribution of advance regeneration (of each of the 9 potential shade tolerance/height attainment groups) under different canopy density and ecological strata.

• An “addfile” was created to determine ecological strata and size/density class of each plot and impute the appropriate amount of advance regeneration as saplings from the appropriate shade tolerance/height attainment groups.

Categories for regeneration imputation

Shade tolerance/ht maximum example

Intolerant / Midstory Sassafras

Intolerant / Overstory, Noncomm. Bitternut hickory

Intolerant / Overstory, Pine Shortleaf pine

Intolerant / Overstory, Comm. Scarlet Oak

Intermediate Overstory American elm

Intermediate / Overstory, Comm. Black oak

Tolerant / Understory Dogwood

Tolerant / Midstory Red Maple

Tolerant / Overstory Green ash

Imputation of Regeneration• Potential tree species for regeneration were divided

into 9 possible shade tolerance and max height attainment groups.

(for instance: high shade tolerance, mid height attainment group; low shade tolerance, high height attainment group; etc.)

• 911 FIA plots from cycles 3, 4, and 5 were used to determine the typical distribution of advance regeneration (of each of the 9 potential shade tolerance/height attainment groups) under different canopy density and ecological strata.

• An “addfile” was created to determine ecological strata and size/density class of each plot and impute the appropriate amount of advance regeneration as saplings from the appropriate shade tolerance/height attainment groups.

Thursday afternoon:

Regeneration Imputation

Grouping the sites/plots into StrataThe 100 sites were assigned to strata:• High site quality was defined as a site index of

greater than 70. Low was 70 or below. (Since Black oak was not always the site index tree

species measured, site index for each site was adjusted to be a Black Oak site index Averaged over the 3 cycles.)

• Aspect: Southerly = 113-292 degrees; Northerly = 0-112 and 293-360 degrees.

Grouping the sites/plots into Strata

Good Site = Northerly aspect, SI > 70

Moderate Site = Northerly aspect, SI <=70

OR Southerly aspect, SI >70

Poor Site = Southerly aspect, SI <=70

Breaking the sites/plots

into mortality groupings

Manion and Griffin. 2001 Forest Science 47(4):542-549

Mathematical “Law of de Liocourt”

Stable ecosystem: mortality per diameter class is constant.

Breaking the sites/plots into mortality groupings

• FIA Cycle 3 tree distribution and mortality data was used to calculate the relative mortality percent per year in each size class necessary to maintain current stand structure. For oak on the MTNF, this baseline relative mortality value was very close to 2% mortality per year across all size classes.

• Sites/plots were assigned to a high or low mortality group, by strata, based upon the mortality recorded between cycles 3 and 4. Sites with > 2% relative mortality were assigned to the high mortality group.

The Oak Decline Event MonitorThe ODEM is a .kcp (addfile) that

calculates the risk and probability of an oak decline event, then applies mortality.

Target species types: Red Oaks, White Oaks, Hickories

Probability of an oak decline event depends on factors including:

• Proportion of basal area in the target species groups

• Site quality, Stand age.

Red Oak Mortality > White Oak mortality > Hickory mortality

It’s enough to make you want to crawl into your shell and hide.

Results: “Static” Use of FVS

Good Sites Moderate Sites Poor Sites

1 site high mortality,

14 sites low mortality

15 site high mortality,

34 sites low mortality

10 sites high mortality,

26 sites low mortality

Species Distribution – Poor Sites

Moderate Site (North Aspect, SI <70)

Low Mortality

Plo

t 20

065

Poor Site (South Aspect, SI<70)

Low Mortality

Plo

t 20

154

Moderate Site(North Aspect, SI<70)

High Mortality

Plo

t 29

010

“Post-Decline”

Basal Area in cycle 5: Measured vs. Predicted via various modelsSite grouping #

sites

Cycle 3 measured

Cycle 5 measured

Cycle 5

“out of box”

Cycle 5 “Out of box” + ODEM*

Cycle 5 calibrated

Cycle 5 calibrated + ODEM*

Poor Site,

High Mort10 66.0 80.5 110.8

(+ 30.3)96.6

(+ 16.1)90.0

(+ 9.5)77.2

(-3.3)Moderate Site, High Mort

15 78.5 68.4 94.0

(+ 25.6)70.9

(+ 2.5)56.8

(-11.6)55.9

(-12.5)

Poor Site,

Low mort26 60.3 85.3 104.0

(+ 18.7)91.9

(+ 6.6)86.4

(+1.1)74.4

(-10.9 )Mod Site, Low mort

34 59.1 78.1 99.3

(+ 21.2)89.6

(+ 11.5)86.1

(+8.0)71.8

(-6.3)Good Site,

Low mort14 64.6 95.2 108.7

(+ 13.5)99.9

(+ 4.7)92.2

(-3.0)86.8

(-8.4)

* Oak Decline Event Monitor (ODEM) has a random component, so values vary from run to run.

Which version of model is best???• On High mortality plots, Calibration plus ODEM gave best prediction of volume / BA

• On Low mortality plots, Calibration alone gave best prediction of Volume / BA.

• Never use FVS “Out of the Box”.

• If you can’t Calibrate, the ODEM actually was a good “surrogate”.

But what about species distribution? Does one version of the model do better than another??

Projections from cycle 3 to cycle 5– with and without calibration; BASAL AREA

This series represents 10 sites

Poor Site, High mortality

Projections from cycle 3 to cycle 5– with and without calibration; BASAL AREA

This series represents 26 sites

Poor Site, Low mortality

Results: Using the Model to Project 100 years into the future

Poor Site, High Mortality –

• Projected with Calibrated Model

• (Vs “Out of the Box”!!!)

Poor Site, Low Mortality –

• Projected with Calibrated Model

• Projected with Calibrated Model plus ODEM

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