does allelopathy explain the scarcity of spruce and fir trees in the beech gaps of great smoky...
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Does Allelopathy Explain the Scarcity of Spruce and Fir Trees in the Beech Gaps of Great Smoky Mountains National Park?
Monica PoteatDr. David Vandermast
Elon University
Beech Gaps
• Great Smoky Mtns.
• High elevations
• Deciduous– American beech (Fagus
grandifolia)
• Evergreen – Red spruce (Picea rubens)
– Fraser fir (Abies fraseri)
Other Theories
• Height difference (Whitaker 1956)
• Inadequate seed rain (Pavlovic 1981)
• Lack of shade tolerance (Harlow et al. 1991)
• Beech soil pH/chemistry (Russell 1953; Fuller 1977)
Allelopathy
• The production of biomolecules by one plant species which can inhibit the germination and/or growth of other plant species (Rizvi et al. 1992)
Hypothesis
Beech allelopathy inhibits the germination and mass accumulation of
red spruce and Fraser fir seeds
Experimental Set-Up
Species Used:• Lettuce (Lactuca sativa) • Red spruce• Fraser fir
Soil Treatments:• Top Soil• Beech forest soil
Watering Treatments:• Deionized Water• Leachate
– 1:5 ratio of beech forest leaves and deionized water
Treatment Set-Up
Top Soil/ dH20
Beech soil/ dH20 Top soil/Leachate
Beech soil/ Leachate
RESULTS: LETTUCE
Top Soil/ dH20
Beech soil/ Leachate
Days
0 2 4 6 8 10 12 14 16 18 20 22 24
Ave
rag
e G
erm
ina
tio
n (
%)
0
20
40
60
80
Top soil- dH2O
Beech soil- dH2O
Top soil- LeachateBeech soil- Leachate
AAB
ABB
Average Germination of Lettuce
M
ass
(g
)
0.0000
0.0005
0.0010
0.0015
0.0020
0.0025
Top soil- dH2O
Beech soil-dH2O
Top soil- Leachate
Beech soil- Leachate
A
B
A
B
Treatment
Average ABM of Lettuce
RESULTS:RED SPRUCE
Top soil- dH2O
Beech soil- Leachate
Days
0 5 10 15 20 25 30
Ave
rag
e G
erm
ina
tio
n (
%)
0
20
40
60
80
Top soil- dH2O
Beech soil- dH2O
Top soil- LeachateBeech soil- Leachate
A
AB
BAB
Average Germination of Red Spruce
Mas
s (g
)
0.0000
0.0005
0.0010
0.0015
0.0020
Top soil- dH2O
Beech soil- dH2O
Top soil- Leachate
Beech soil- Leachate
Treatment
A
B
AAB
Average ABM of Red Spruce
RESULTS:FRASER FIR
Top soil- dH2O
Beech soil- Leachate
Days
0 5 10 15 20 25 30 35 40
Ave
rag
e G
erm
ina
tio
n (
%)
0
5
10
15
20
25
30
35
Top soil- dH2OBeech soil- dH2OTop soil- LeachateBeech soil- Leachate
A
B
ABAB
Average Germination of Fraser Fir
Mas
s (g
)
0.000
0.001
0.002
0.003
0.004
0.005
0.006
Top soil- dH2O
Beech soil- dH2O
Top soil- Leachate
Beech soil-Leachate
Treatment
A
B
AB
C
Average ABM of Fraser Fir
Important Findings
• Leachate germinations all lower than deionized water (even if not statistically significant)
• Leachate and/or beech soil treatments significantly reduce germination and/or mass– Different species respond differently to allelogens
• Sickly seedlings
What our findings mean in relation to...
• Other allelopathic studies– American beech leaf leachate
has been shown to lower leaf area and biomass of the seedlings of sugar maple (Hane et al. 2003)
• Competitive Exclusion
• Beech Bark Disease
• Beech are a foundation species within gaps– Define community– Create stable conditions
Why is this important?
http://fisc.er.usgs.gov/c1258_Dodd/circ1258_8a.jpg
Conclusion
Allelopathy is an important mechanism through which beech forests competitively exclude the
red spruce and Fraser fir.
Acknowledgments
• Dr. Vandermast• Elon University SURE program• Elon College Fellows Program• Great Smoky Mountains National Park (permits)
– Keith Langdon, Supervisor of Science Projects– Dr. Michael Jenkins, Ecologist
• Judy Poteat