Reduced intraspecific competition in introduced plant populations suggests a role for self-limitation in invasion success

Ecological diversity depends on mechanisms that promote species coexistence, yet some non-native plants form monospecific stands, suggesting an ability to escape self-limiting processes that constrain native flora. Whereas invasion success is often attributed to enhanced interspecific competition, it may also result from reduced intraspecific competition within introduced populations. Using a controlled greenhouse experiment, I compared competitive outcomes among single native and introduced populations of five plant species (Gleditsia triacanthos, Pinus sylvestris, Paulownia tomentosa, Solidago canadensis, Viola sororia). Individuals were grown in within-range (native × native, introduced × introduced) and across-range (native × introduced) pairings to test whether introduced populations exhibit weaker intraspecific competition. Introduced populations generally showed reduced self-limitation compared with native conspecifics, consistent with relaxed intraspecific density dependence. Be..., Experimental set up Greenhouse competition experiments were conducted from April to August in 2019 (P. sylvestris), 2020 (G. triacanthos, S. canadensis), and 2021 (P. sylvestris, P. tomentosa, V. sororia). Groups of 4–6 introduced- and home-range seeds of the same species were sown 2 cm apart in 10 × 10 cm pots filled with commercial potting soil (Fox Farm ocean forest, Arcata, CA USA). After germination, seedlings were thinned to ensure a 1:1 competition pairing of similar-sized individuals. Each experiment included three competition pairings: (1) Introduced × Introduced (n = 132 individual plants), (2) Home × Home (n = 148) and (3) Introduced × Home (n = 183). This resulted in a total of n = 463 plant replicates, with variation in species-level replication due to differences in recruitment success: G. triacanthos (n = 160), P. sylvestris (n = 115), P. tomentosa (n = 108), S. canadensis (n = 50) and V. sororia (n = 30). The plants were grown under ambient spring/summer light conditions..., , # Reduced intraspecific competition in introduced plant populations suggests a role for self-limitation in invasion success Release.from.self.limitation.csv ## Description of the data and file structure Ident = line identification Date = year of experiment Study2 = experimental species (Gleditsia = Gleditsia triacanthos, Pinus = Pinus sylvestris, ``` Paulownia = Paulownia tomentosa, Solidago = Solidago canadensis, Viola = Viola sororia) ``` Habit = woody or (herb)aceous Total.g = Total plant biomass Origin = origin range (Inv = introduced, Nat = home range) Type = type of competition (Intra = intraecotypic; Inter = interecotypic) , ,生态多样性依赖于促进物种共存的机制，但部分外来植物可形成单优种群（monospecific stands），这暗示它们能够逃脱制约本土植物区系的自我限制过程。尽管入侵成功通常被归因于增强的种间竞争（interspecific competition），但也可能源于引入种群内部种内竞争（intraspecific competition）的减弱。本研究通过受控温室实验（controlled greenhouse experiment），对比了5种植物（皂荚*Gleditsia triacanthos*、欧洲赤松*Pinus sylvestris*、毛泡桐*Paulownia tomentosa*、加拿大一枝黄花*Solidago canadensis*、堇菜*Viola sororia*）的本土种群与引入种群间的竞争结果。实验设置了同分布区（本土×本土、引入×引入）以及跨分布区（本土×引入）的配对种植模式，以检验引入种群是否表现出更弱的种内竞争。与本土同物种种群（conspecifics）相比，引入种群普遍表现出更低的自我限制效应，与种内密度依赖作用松弛的假说相符。…… ## 实验设置 温室竞争实验分别于2019年（欧洲赤松）、2020年（皂荚、加拿大一枝黄花）及2021年（欧洲赤松、毛泡桐、堇菜）的4月至8月开展。将同一物种的4~6粒引入种群与本土种群种子，以2厘米间距点播于填充商品营养土（美国加利福尼亚州阿卡塔市Fox Farm Ocean Forest营养土）的10×10厘米花盆中。出苗后，间苗至保留1:1比例的同规格大小个体以进行竞争配对。每个实验包含三种竞争配对模式：(1) 引入×引入（n = 132株个体），(2) 本土×本土（n = 148株），(3) 引入×本土（n = 183株）。最终共计463株植物重复样本，因物种间萌发成功率差异，各物种的重复数存在波动：皂荚（n = 160）、欧洲赤松（n = 115）、毛泡桐（n = 108）、加拿大一枝黄花（n = 50）、堇菜（n = 30）。植株在春季/夏季自然光照条件下培养…… # 引入植物种群的种内竞争减弱提示自我限制在入侵成功中的作用 "Release.from.self.limitation.csv" ## 数据与文件结构说明 `Ident`：行标识 `Date`：实验年份 `Study2`：实验物种（Gleditsia=皂荚*Gleditsia triacanthos*，Pinus=欧洲赤松*Pinus sylvestris*，Paulownia=毛泡桐*Paulownia tomentosa*，Solidago=加拿大一枝黄花*Solidago canadensis*，Viola=堇菜*Viola sororia*） `Habit`：生长型（木本或草本） `Total.g`：植物总生物量 `Origin`：种群起源（Inv=引入种群，Nat=本土种群） `Type`：竞争类型（Intra=种内生态型竞争；Inter=种间生态型竞争）