Abstract:

Successful plant invaders usually exhibit three strategies: Jack-of-all-trades (more robust in stressful sites), Master-of-some (more responsive in favorable sites) and Jack-and-master (both robustness and responsiveness). To revisit these strategies, we examined how soil inorganic nitrogen (N) compositions and levels influence the success of native and invasive plant congeners in the context of plant communities.

We conducted an experiment involving three fixed factors: species origin, N composition and N level. Here, we selected 21 plant species (eight pairs of invasive and native congeners and five non-congeneric natives) to assemble plant communities, which were subject to nine N environments consisting of three N compositions (3:1, 2:2 and 1:3 NO₃−/NH₄+) and three N levels (low, medium and high N). We determined the following metrics: total biomass, relative biomass (a proxy of species success), mortality rate and mortality time.

Across nine N environments, native and invasive congeners exhibited similar total biomass, relative biomass and mortality time, but invaders had a marginally lower mortality rate than natives. Similar success between native and invasive congeners was linked to their similar growth and tolerance. N compositions influenced mortality time and N levels affected the total biomass and relative biomass. Importantly, species origin, N composition and N level interactively affected the total biomass, relative biomass and mortality time. These findings suggest that native and invasive plant congeners may be similarly successful across different N environments, and that inorganic N compositions and levels both contribute to plant invasion success.

Key words: congeneric comparison, environmental tolerance, invasion strategy, nitrogen availability, plant growth