Title Page
Abstract
Contents
Ⅰ. INTRODUCTION 10
Ⅱ. MATERIALS AND METHODS 13
2.1. Field research 13
2.2. Pairwise competition experiment 16
2.3. Statistical Analysis 17
Ⅲ. RESULTS 19
3.1. Field research 19
3.1.1. Competitive effect of the focal invader 19
3.1.2. Trait hierarchy of the focal invader 19
3.1.3. Difference in soil resource between invaded and uninvaded plots 19
3.2. Pairwise competition experiment 24
3.2.1. Competitive effect of the focal invader 24
3.2.2. Competitive effect of the neighboring species 30
3.2.3. Trait hierarchy of the focal invader 33
Ⅳ. DISCUSSION 36
4.1. Competitive effect of the focal invader and neighboring species 36
4.2. Effects of resource level on the competitive outcomes 36
4.3. Possibility of mitigated influence of competition hierarchy by disturbance in real world 37
4.4. Limitations 37
Ⅴ. CONCLUSION 39
References 40
Table. 1. Site descriptions. In addition to the focal invader Lactuca serriola, three predominant co-occurring species in each habitat were selected to measure performance and functional traits and are shown in the table below. 14
Table. 2. Two-way ANOVA results of the effect of L. serriola-invasion, species, and their interaction on neighbors' biomass, four functional traits and RWC in field research. L. serriola data was excluded in the analysis of neighbors' biomass, but included in the analysis of functional traits and RWC to compare competitive ability of... 20
Table. 3. One-way ANOVA results of the effect of L. serriola-invasion on the species diversity and soil resource in field research. p〈0.05 were shown in bold. 21
Table. 4. Two-way ANCOVA results of the effect of competition (Comp.), nutrient level (Nutri.), and their interaction on the species' performance with initial growth as a covariate in pairwise competition experiment.... 25
Table. 5. Two-way ANCOVA results of the effect of competition (including subdivided interspecific competition condition with different neighboring species), nutrient level, and their interaction on the... 26
Table. 6. Three-way ANOVA results of the effect of competition, nutrient level, and their interactions on the functional traits (specific leaf area; SLA, leaf dry matter content; LDMC) and relative water content (RWC)... 35
Figure. 1. All investigated Lactuca serriola habitats (n=9) where trait measurement, plant and soil sampling and seed collection... 13
Figure. 2. Species diversity (mean ± SE) in each community using Shannon's diversity index (a), Simpson's diversity index (b), and species richness (c). Asterisks indicate significant differences between L. serriola-... 21
Figure. 3. Total biomass (a), aboveground biomass (b), and belowground biomass (c) of neighboring species in L. serriola-invaded/uninvaded plots (mean ± SE). Asterisks indicate significant post-hoc differences... 22
Figure. 4. Height (a), specific leaf area (b; SLA), leaf dry matter content (c; LDMC) and relative water content (d) of focal invader L. serriola and neighboring species in invaded and uninvaded plots (mean ± SE). Different... 22
Figure. 5. Soil total nitrogen (a), available phosphorus (b), exchangeable potassium (c), moisture (d; volumetric water content) in the L. serriola-invaded/uninvaded plots (mean ± SE). Asterisks indicate... 23
Figure. 6. Fresh weight of total biomass (a), dry weight of total biomass (b), fresh weight of aboveground biomass (c), dry weight of aboveground biomass (d), fresh weight of belowground biomass (e), and dry weight... 27
Figure. 7. Fresh weight of total biomass (a), dry weight of total biomass (b), fresh weight of aboveground biomass (c), dry weight of aboveground biomass (d), fresh weight of belowground biomass (e), and dry weight... 28
Figure. 8. Fresh weight of total biomass (a), dry weight of total biomass (b), fresh weight of aboveground biomass (c), dry weight of aboveground biomass (d), fresh weight of belowground biomass (e), and dry weight... 29
Figure. 9. Fresh weight of total biomass (a), dry weight of total biomass (b), fresh weight of aboveground biomass (c), dry weight of aboveground biomass (d), fresh weight of belowground biomass (e), and dry weight... 31
Figure. 10. Fresh weight of total biomass (a), dry weight of total biomass (b), fresh weight of aboveground biomass (c), dry weight of aboveground biomass (d), fresh weight of belowground biomass (e), and dry weight... 32
Figure. 11. Mean relative competition intensity (RCI) index of focal invader Lactuca serriola calculated based on the dry weight of total biomass at two different nutrient levels. The graph shows RCIbiomass of L. serriola...[이미지참조] 33
Figure. 12. Specific leaf area (a; SLA), leaf dry matter content (b; LDMC), relative water content (c; RWC), and root-shoot ratio (d) of focal invader Lactuca serriola (LS) and neighboring species, Chenopodium album... 34
Figure. 13. Root-shoot ratio of the focal invader Lactuca serriola (LS) at two different resource levels (mean ± SE). Dry weight of shoot and root was used to calculate root-shoot ratio. Individuals were grown alone... 35