Do different competitive abilities of three fern species explain their different regional abundances?

Abstract

Question: Do different competitive abilities of three fern species explain their different regional abundances? Location: Estonia, Europe. Methods: The factorial pot experiment, in which single individuals of three fern species were grown in natural soil with 0, 2,4, and 8 neighbouring individuals of Deschampsia flexuosa. Results: The response patterns of different biomass fractions and morphological parameters of fern species were similar to each other. The diploid D. expansa was the most vulnerable to competition, while tetraploid D. carthusiana and D. dilatata were more tolerant. D. carthusiana allocated relatively more to below‐ground parts than the other two species and allocation to roots increased when neighbour density increased. For D. expansa and D. dilatata, allocation to below‐ground parts decreased at high neighbour density, while in D. dilatata also the relative length of the stipe increased. Thus, the response of D. carthusiana corresponds to a ‘persistence type’ and that of D. dilatata to a ‘foraging type’. Conclusions: Lower vulnerability of D. carthusiana to competition, compared to D. expansa, may explain the higher regional and local abundance of the former. The rarity of D. dilatata in Estonia, however, could rather be explained by the impact of climatic factors, since this species is near its northeastern distribution limit in Estonia.

Phenotypic plasticity and biomass allocation pattern in three Dryopteris (Dryopteridaceae) species on an experimental light-availability gradient

“…Ontogenetic shifts towards lesser root growth have been observed in several species (Ledig et al 1970;Hawthorn and Cavers 1982;McConnaughay and Coleman 1999). Also, in the previous study, allocation to below-ground parts decreased with increasing neighbour density in both D. expansa and D. dilatata in conditions where no extreme shade was imposed as a treatment (Rü nk et al 2004). This shows that the usual plastic response to shading--decreased relative allocation into roots--is nevertheless present in the three fern species under observation.…”

“…In a previous study on relative competitive ability of three congeneric fern species with different distribution and abundance patterns in boreo-nemoral Europe--Dryopteris carthusiana, D. expansa and D. dilatata--we found that this trait did not directly explain the relative commonness/relative rarity of the three fern species (Rü nk et al 2004). There was, though, a clear difference in how each species responded to competitive stress.…”

“…Hill and Silander 2001;Hietz 2001;Proctor 2003;Reudink et al 2005;Saldañ a et al 2005) determine the distribution of fern sporophytes or gametophytes (Hill 1971;Li and Ong 1997;Greer and McCarthy 1999). Considerably less attention has been turned on life-history traits (Cousens et al 1988;Peck et al 1990;Guo et al 2003) and biotic interactions (Hamilton and Lloyd, 1991;Chiou and Farrar 1997;Greer and Curry 2004;Rü nk et al 2004). Only a few studies on the comparative ecology of gametophytes and sporophytes of the same species have been conducted (Sato and Sakai 1981;Cousens et al 1988;Suzuki et al 2005).…”

Habitat characteristics and vegetation context of Osmunda regalis L. at the southern edge of its distribution in Europe

“…Coherently with other studies on ferns (Rünk et al 2004), the low abundance of O. regalis near its distribution limits in Europe is linked to climatic factors. The annual availability of water proved to be the main climatic factor limiting at the southern edge of its distribution in Europe.…”

“…However, the ecology of pteridophytes has been investigated much less than that of other vascular plants and few studies have analysed the causes of variation in the local abundance or rarity of particular fern species (Cinquemani Kuehn and Leopold 1993;Kelsall et al 2004;Rünk et al 2004).…”