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The Decline of Old Growth:A Comparison of Unmanagedand Managed Ponderosa Pine

Forests

Service Learning Project,Jacinda Thomas

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Biodiversity

Unmanaged

young trees crowd area

fierce competition

fewer numbers of and smaller shrubs, herbs, andgrasses

lower biodiversity

High biodiversity

strong indicator of health

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Comparison of Biodiversity Between Managed and

Unmanaged Old-Growth Ponderosa Pine Forests

13.50

0.602.03

0.87

8.198.75

0.511.95

0.82

7.54

0

2

4

6

810

12

14

16

Species Richness Pileou's Evenness

Index

Shannon-Wiener

Diversity Index

Simpson Index of

Diversity

Simpson

Reciprocal Index

number

Managed

Unmanaged

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Comparison of Importance Values Between Managed andUnmanaged Old-Growth Stands

(These represent the top 5 of 68 species of plant recorded)

2.8 3.1

8.19.1

6.8

2.9

16.7

2.3

9.5

3.6

0

5

10

15

20

ABICON ARNCOR FRAVIR PINPON POANER

re

lativeimportance

(%)

Managed

Unmanaged

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Density

Crowded stands

Tree density high

Trees compete

Canopy dense

Hinders smaller plants and brush to produce food

Death takes away the nitrogen-rich material

Stand weakens, disease sets in

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Duff Layers

Duff is the decomposing plant material onthe forest floor

Provides nitrogen for vegetation

Holds soil moisture

Blocks the sun

Cools the soil

Blocks raindrop erosion

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Comparison of Relative Cover Under Managed andUnmanaged Ponderosa Pine Forests

41.8

6.1

27.3 25.1

61.1

9.5

21.9

5.7

0

10

20

30

40

50

60

70

Duff/Litter Rel Cover DWD Rel Cover Tree Rel Cover Plant Rel Cover

relativecover(%)

Managed

Unmanaged

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Growth Rings

Indicate amount of yearly growth

Healthier tree

Less rings More growth occurs

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Comparison of soil moisture, tree growth rates and disease

frequency between managed and unmanaged old growth ponderosa

pine stands in Coffeepot Flat on the Fremont Winema NationalForest

17.95

2.18 2.6

9.33

2.77

32.5

0

5

10

15

20

25

30

35

40

soil moisture (%) growth rate (rngs/cm) disease frequency (%)

Managed

Unmanaged

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Basal Area 264, TPA 55, Canopy Cover 44%

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Basal Area 507, TPA 293, Canopy Cover 75%

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Results

Lower tree density

Higher percent soil moisture

Higher biodiversity Faster growth (fewer growth rings/cm)

Lower rates of disease

Less duff

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Conclusion

Old growth forests falling apartFire suppression

high densities

disease and insect damage

Possible solution thin understory (historic fire effects)

Concerns remain, should be considered