Download The Effect of Barberis thunbergii on Species Diversity

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The Effect of Berberis thunbergii
on Species Diversity
ALEX CAVACAS, BRANDON CHATFIELD, KEVIN
CHEN, AND STEVEN MEIGS
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
http://www.columbia.edu/itc/cerc/danoffburg/invasion_bio/inv_spp_summ/Berberis_thunbergii_
files/image002.jpg
INTRODUCTION
STUDY SPECIES
• Originally brought from
Asia as an ornamental
Berberis thunbergii
plant
‘Japanese barberry’
• Grew out of control,
• Dense, woody shrub
became invasive species
with spine-bearing
in Northeast U.S.
branches
• 3-6 feet tall
• Bright red berries
• Seed dispersal
facilitated through
defecation of birds and
other small animals
http://www.nps.gov/plants/alien/map/img/
beth1.gif
OUR HYPOTHESES
Abiotic
• 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
1
7
2
8
5
6
3
4
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
http://www.testersandtools.com/im
ages/QVTIMG20080917091740650.jp
http://www.biconet.com/testing/GIFs/
ep2.jpg
• 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)
LIGHT INTENSITY WILL BE LOWER IN AREAS
WITH B. THUNGBERII AND HIGHER IN AREAS
WITHOUT B. THUNBERGII
% Light
Reduction
72.74 ± 7.27
19.63 ± 7.00
df
7
t
p
13.82 0.000
100
90
% Light Reduction
(µmol/m²s)
• Significant
difference between
average % light
reduction and
invasion status
Mean ± SD
Invaded
Non-invaded
80
70
60
50
40
30
20
10
0
Invaded
Non-invaded
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
Soil Moisture
Mean ± SD
Invaded
Non-invaded df
202.16 ± 49.51 184.29 ± 33.47 7
t
1.160
p
0.284
Soil Moisture Holding Capacity
250
225
• No significant
difference between
average SMHC and
invasion status
200
175
150
125
100
75
50
25
0
Invaded
Non-invaded
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.
IN THE PRESENCE OF B. THUNBERGII, THE
NUMBER OF INDIVIDUALS OF EACH
RESIDENT SPECIES WILL BE LOWER
H’
t
p
0.93 0.384
0.45
Species Diversity Index
• No significant
difference
between resident
species evenness
and invasion
status
Mean ± SD
Invaded
Nond
invaded
f
0.18 ± 0.19
0.30 ± 0.25 7
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
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.
IN THE PRESENCE OF B. THUNBERGII,
THE NUMBER OF RESIDENT SPECIES
WILL BE LOWER
Mean ± SD
Invaded
Non-invaded
Species Richness
Species Richness
7.25 ± 1.75
10
9
8
7
6
5
4
3
2
1
0
df
7.88 ± 2.53
7
t
0.886
p
0.405
• 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.
LIGHT AVAILABILITY WILL DECREASE
WHEN THE COVER OF B. THUNBERGII
INCREASES
% Light Reduction (µmol/m²s)
• Weak, positive
correlation between
percent cover and
average percent light
reduction
100
y = 0.19x + 60.90
r² = 0.2975
90
80
70
60
50
40
30
20
10
0
0
10 20 30 40 50 60 70 80 90 100
% Cover of B. thunbergii
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
• Negative correlation between SMHC and percent cover of
Japanese Barberry
•
Weak
relationship
when
percent
cover of
barberry
>25%
Soil Moisture Holding
Capacity
350
300
•
250
200
150
100
y = -0.924x + 257.02
r² = 0.138
50
Strong
relationship
when
percent
cover of
barberry
>40%
y = -4.356x + 505.14
r² = 0.981
0
0
20
40
60
80
100
0
% Cover of
20
40
60
80
100
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.
THE NUMBER OF INDIVIDUALS OF EACH
RESIDENT SPECIES WILL DECREASE AS THE
COVER OF B. THUNBERGII INCREASES
• 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
Species Diversity Index
0.6
0.5
y = -0.0052x + 0.4914
r² = 0.2921
0.4
0.3
0.2
0.1
0
0
10
20
30
40
50
60
70
80
90
% Cover Berberis thunbergii
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.
• Weak, negative correlation
between percent cover
barberry and resident
species richness (10 sq. meter
plots)
Species Richness
THE NUMBER OF RESIDENT SPECIES
WILL DECREASE AS THE COVER OF B.
THUNBERGII INCREASES
10
9
8
7
6
5
4
3
2
1
0
y = -0.0374x + 9.472
r² = 0.181
0
10 20 30 40 50 60 70 80 90 100
% Cover Berberis thunbergii
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.
DISCUSSION
Rejected or supported?
Justification
• Light 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
• Light availability will
decrease when the
cover of B. thunbergii
increases
• As barberry cover
increased, light intensity
decreased because
barberry forms dense
shrubs
DISCUSSION
Rejected or supported?
Justification
• Soil will be wetter in
areas with B. thunbergii
• Soil moisture will
increase when the
cover of B. thunbergii
increases.
• 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?
Justification
• In the presence of B.
thunbergii, the species
richness will be lower.
• 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
• The species richness will
decrease as the cover
of B. thunbergii
increases.
• An increase in percent
cover of Barberry did not
significantly decrease the
number of resident plant
species
STRONG RELATIONSHIPS
Light intensity will be lower in
areas with B. thunbergii and
higher in areas without B.
thunbergii
• Significant difference between •
average % light reduction and
invasion status
*Soil moisture holding
capacity will decrease
when the cover of B.
thunbergii increases
Strong relationship when percent
cover of barberry >40%
*Need more replicates to
support definitively
IN CONCLUSION
Supported Hypothesis
Light 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