Effects of low and high nutrients on the competitive hierarchy of 26 shoreline plants

Abstract

Summary 1We tested the hypothesis that competitive hierarchies are invariant with respect to changing nutrient supply. 2 The competitive performance of 26 shoreline plant species was determined experimentally as the relative ability to suppress the growth of a common indicator (phytometer) species, Penthorum sedoides. Each species was grown with the phytometer under each of two nutrient treatments created with di erent concentrations of a modi®ed Hoagland's solution (n 5 replicates per species/treatment), for two growing seasons. 3 Although shifts in ranking of relative competitive performance were apparent between nutrient levels, competitive performance under high and low nutrient conditions was signi®cantly correlated in both year 1 (r 0.65) and year 2 (r 0.76), when all species were considered. 4 At the broad community scale, the outcome of competitive interactions thus appears to be relatively predictable and independent of the environment, and therefore provides a useful tool for exploring and understanding community pattern. These results cannot address questions related to the outcome of competitive interactions between similar species or the e ects of ®ne-scale pattern.

Competition between Lythrum salicaria and a rare species: combining evidence from experiments and long-term monitoring

“…The experimental design was additive, with one Sidalcea individual as target plant, grown together with or without competitors, following the design of Keddy et al (2000). We compared the competitive effect of Lythrum on Sidalcea with that of two perennial, native competitor species: Salix lasiandra Beth., Pacific willow (henceforth Salix), a shrub that grows up to 150 cm in the marsh, and Oenanthe sarmentosa Presl, Pacific water parsley (henceforth Oenanthe), a low-growing, leafy forb.…”

Biomass allocation to anchoring structures in the aquatic macrophytes from the subcontinental and Atlantic climates in Europe

“…Barko and Smart 1986;Duarte and Kalf 1990;Szmeja 1994a;Keddy et al 2001;Heegaard et al 2001;Szmeja and Boci¹g 2004), and much less frequently on comparative analyses of such relations in the macroscale, for example in geographically distant populations from the same climate or from different climatic zones (Phillips et al 1983;Jacobsen and Terneusb 2001;Santamaría and García 2004). Comparative studies of aquatic macrophytes in the macroscale could become a source of information on the effect of climate in general or its secondary effect on life strategies and evolution of this plant group.…”

Plant Functional Types: Are We Getting Any Closer to the Holy Grail?

“…Attempts to predict interspecific competition from plant traits have had mixed success (Keddy et al 1998, Wardle et al 1998, in particular because species competitive rankings are sensitive to nutrient availability (Keddy et al 2000), disturbance (Suding & Goldberg 2001), and to mycorrhizal associations (van der , Wardle et al 1998. A reasonable consensus has been reached regarding tolerance of competition by neighbours (competitive response) where plant height and seed mass are positively associated with greater tolerance (Goldberg 1991).…”