A L E X C A V A C A S , B R A N D O N C H A T F I E L D , K E V I N C H E N , A N D S T E V E N M E I G S

http://dnr.wi.gov/topic/Invasives/fact/images/JapaneseBarberryA.jpg

The Effect of Berberis thunbergii on Species Diversity

OUR INSPIRATION

• Bio 130 –Ecology• Learned about how invasive

species affect the environment

• Learned about invasive species at Church Farm• Removed Japanese Barberry,

Winged Wahoo, etc.• Bio 442 – Plant Ecology• Studying effects of invasive

plant species

INTRODUCTION STUDY SPECIES

Berberis thunbergii‘Japanese barberry’

• Dense, woody shrub with spine-bearing branches• 3-6 feet tall• Bright red berries• Seed dispersal facilitated

through defecation of birds and other small animals

• Originally brought from Asia as an ornamental plant• Grew out of control,

became invasive species in Northeast U.S.

http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/Berberis_thunbergii_files/image002.jpg

http://www.nps.gov/plants/alien/map/img/beth1.gif

OUR HYPOTHESESAbiotic

• Light intensity will be lower in areas with B. thunbergii and higher in areas without B. thunbergii

• Light availability will decrease when the cover of B. thunbergii increases

• Soil will be wetter in areas with B. thunbergii

• Soil moisture holding capacity will decrease when the cover of B. thunbergii increases.

Biotic• In the presence of B.

thunbergii, the number of individuals of each resident species will be lower

• The number of individuals of each resident species will decrease as the cover of B. thunbergii increases

• In the presence of B. thunbergii, the number of resident species will be lower.

• The number of resident species will decrease as the cover of B. thunbergii increases.

FIELD STUDY AT CHURCH FARM

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Eastern deciduous temperate forest in Ashford, CT

OUR RESEARCH PLAN• 8 plots with percent cover of B. thunbergii• 8 adjacent plots with no percent cover of B.

thunbergii• Each plot will be 10 square meters• Randomly placed 1 square meter quadrat per plot

DATA COLLECTION• Measure percent cover and number of B. thunbergii and other

plant species in each 10 square meter plot within the understory• Measure percent cover and number of individuals of resident

plant species in each 1 square meter quadrat within the understory

• Measure abiotic factors in each plot (soil moisture, light intensity)

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LIGHT INTENSITY WILL BE LOWER IN AREAS WITH B. THUNGBERII AND HIGHER IN AREAS

WITHOUT B. THUNBERGII  Mean ± SD        Invaded Non-invaded df t p

% Light Reductio

n

72.74 ± 7.27

19.63 ± 7.00

7 13.82 0.000

• Significant difference between average % light reduction and invasion status

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% L

ight

Red

uctio

n (µ

mol

/m²s

)

Non-invadedInvaded

Figure 3 – A comparison of average percent light reductions between invaded and non-invaded plots. Percent light reduction was calculated with light intensity measurements at knee and shoulder height for each plot with and without B. thunbergii. Standard error was used to determine the possible range of light reduction of the plots.

SOIL MOISTURE HOLDING CAPACITY WILL BE GREATER IN AREAS WITH B.

THUNBERGII

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50

75

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225

250

Soil

Moi

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apac

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Invaded Non-invaded

• No significant difference between average SMHC and invasion status

Figure 5 – A comparison of average percent soil moisture holding capacity between invaded and non-invaded plots. Percent SMHC was calculated using the difference between saturated and dried soil for each plot with and without B. thunbergii. Standard error was used to determine the possible range of light reduction of the plots.

  Mean ± SD        Invaded Non-invaded df t p

Soil Moisture 202.16 ± 49.51

184.29 ± 33.47

7 1.160 0.284

IN THE PRESENCE OF B. THUNBERGII, THE NUMBER OF INDIVIDUALS OF EACH RESIDENT SPECIES WILL BE LOWER

0.00

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Spec

ies

Div

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• No significant difference between resident species evenness and invasion status

Invaded Non-invaded

Figure 7 – A comparison of species diversity between invaded and non-invaded plots. Species diversity was calculated using the Shannon-Wiener Index for resident species evenness measurements. Standard error was used to determine the possible range of light reduction of the plots.

  Mean ± SD        Invaded Non-

invadeddf

t p

H’ 0.18 ± 0.19 0.30 ± 0.25 7 0.93 0.384

IN THE PRESENCE OF B. THUNBERGII, THE NUMBER OF RESIDENT SPECIES WILL BE LOWER

012345678910

Spec

ies

Ric

hnes

s • No significant difference between the resident species richness and invasion status

Invaded Non-invaded

Figure 9 – A comparison of resident species richness between invaded and non-invaded plots. Resident species richness is the number of species that are not B. thunbergii in the 10m2 plots. Standard error was used to determine the possible range of light reduction of the plots.

  Mean ± SD        Invaded Non-invaded df t p

Species Richness

7.25 ± 1.75 7.88 ± 2.53 7 0.886 0.405

LIGHT AVAILABILITY WILL DECREASE WHEN THE COVER OF B. THUNBERGII

INCREASES

20 30 40 50 60 70 80 90 1000

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f(x) = 0.199323696061541 x + 60.900693616913R² = 0.297466740309128

% Cover of B. thunbergii

% L

ight

Red

uctio

n (µ

mol

/m²s

)

• Weak, positive correlation between percent cover and average percent light reduction

Figure 4 - A relationship between percent light reduction and percent cover of B. thunbergii in invaded plots. Percent light reduction was calculated with light intensity measurements at knee and shoulder height for each invaded plot. A linear regression was performed to detect a correlation with its corresponding r2.

SOIL MOISTURE HOLDING CAPACITY WILL DECREASE WHEN THE COVER OF B. THUNBERGII

INCREASES

20 40 60 80 1000

50

100

150

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250

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f(x) = − 0.923874408117249 x + 257.018167981962R² = 0.137904862865466

% Cover of

Soil

Moi

stur

e H

oldi

ng

Cap

acity

40 60 80 100

f(x) = − 4.356382 x + 505.13527R² = 0.980721476006513

Berberis thunbergii

Figure 6 – A relationship between percent SMHC and percent cover of B. thunbergii. Percent SMHC was calculated using the difference between saturated and dried soil for each invaded plot. Percent cover is an estimation of invasive plant cover (A) in all invaded plots and (B) in invaded plots with invasive plant cover greater than 40%. A linear regression was performed to detect a correlation with its corresponding r2.

• Weak relationship when percent cover of barberry >25%

• Strong relationship when percent cover of barberry >40%

• Negative correlation between SMHC and percent cover of Japanese Barberry

THE NUMBER OF INDIVIDUALS OF EACH RESIDENT SPECIES WILL DECREASE AS THE COVER OF B. THUNBERGII INCREASES

20 30 40 50 60 70 80 900

0.1

0.2

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0.5

0.6

f(x) = − 0.00521330326944758 x + 0.49141488162345R² = 0.292105725252619

% Cover Berberis thunbergii

Spec

ies

Div

ersi

ty In

dex

• Weak, negative correlation between percent cover barberry and Species Diversity Index

• Species Diversity Index is a Shannon-Wiener calculation using species evenness of invaded quadrats

Figure 8 – A relationship between species diversity and percent cover of B. thunbergii. Species diversity was calculated using the Shannon-Wiener Index for resident species evenness measurements. Percent cover is an estimation of invasive plant cover in invaded plots. A linear regression was performed to detect a correlation with its corresponding r2.

THE NUMBER OF RESIDENT SPECIES WILL DECREASE AS THE COVER OF B. THUNBERGII INCREASES

20 30 40 50 60 70 80 90 100012345678910

f(x) = − 0.0374295377677565 x + 9.47237880496054R² = 0.180619281088592

% Cover Berberis thunbergiiSp

ecie

s R

ichn

ess

• Weak, negative correlation between percent cover barberry and resident species richness (10 sq. meter plots)

Figure 10 – A relationship between resident species richness and percent cover of B. thunbergii. Resident species richness is the number of species that are not B. thunbergii in the 10m2 plots. Percent cover is an estimation of invasive plant cover in invaded plots. A linear regression was performed to detect a correlation with its corresponding r2.

DISCUSSIONRejected or supported?

• Light intensity will be lower in areas with B. thunbergii and higher in areas without B. thunbergii

• Light availability will decrease when the cover of B. thunbergii increases

Justification

• Light intensity decreased in invaded plots because barberry forms dense shrubs

• As barberry cover

increased, light intensity decreased because barberry forms dense shrubs

DISCUSSION

Rejected or supported?• Soil will be wetter in

areas with B. thunbergii

• Soil moisture will increase when the cover of B. thunbergii increases.

Justification

• Perhaps barberry actually does better in dryer soils because there is a weak, negative correlation

DISCUSSION

Rejected or supported?• In the presence of B.

thunbergii, the species diversity will be lower.

• The species diversity will decrease as the cover of B. thunbergii increases.

Justification• Perhaps there was another

factor that we didn’t account for such as nutrient availability, soil pH, or the resident plant species could be good competitors

• An increase in percent cover of Barberry did not significantly decrease the resident plant species population

DISCUSSION

Rejected or supported?• In the presence of B.

thunbergii, the species richness will be lower.

• The species richness will decrease as the cover of B. thunbergii increases.

Justification• Perhaps there was another

factor that we didn’t account for such as nutrient availability, soil pH, or the resident plant species could be good competitors

• An increase in percent cover of Barberry did not significantly decrease the number of resident plant species

STRONG RELATIONSHIPS

• Significant difference between average % light reduction and invasion

status

• Strong relationship when percent cover of barberry >40%

*Soil moisture holding capacity will decrease when the cover of B. thunbergii increases

Light intensity will be lower in areas with B. thunbergii and higher in areas without B. thunbergii

*Need more replicates to support definitively

IN CONCLUSION

Supported HypothesisLight intensity will be lower in areas with B. thunbergii and higher in areas without B. thunbergii• Light intensity decreased in

invaded plots because barberry forms dense shrubs

Future Research• We were limited in time

and study area (Roughly 2 months and only Church Farm)

• More replicates• Could have supported some

of our other hypotheses• Experimental Design• Manipulate the barberry to

find results• Variety in Replicates• Spread out across a larger

area