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