Is Small-Scale Species Richness Limited by Seed Availability or Microsite Availability?

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Ecological Society of America is collaborating with JSTOR to digitize, preserve and extend access to Ecology. Abstract.To evaluate the relative roles of seed availability and competitive interactions in creating within-community patterns of species richness in unproductive grassland, we conducted a sowing experiment in a dry calcareous (alvar) grassland, where both the number of arriving seeds and the number of arriving species were approximately doubled compared to the natural seed rain. Also, in half of the plots, 36% of the vegetation and bryophyte cover was removed to simulate disturbance. Sowing significantly increased species richness and the number of seedlings in plots. Disturbance increased the number of seedlings but had no significant effect on species richness. In the first year, the highest number of seedlings was found in disturbed and sown plots. The dynamics of seedling numbers differed among species. Of the 15 sown species, seedlings of nine species were found in some plots. The number of seedlings of two species were not dependent on treatments, those of three species depended only on sowing, and for four species there was a significant positive interaction between sowing and disturbance. The establishment of sown species was not dependent on initial species richness or number of adult ramets in experimental plots. It was concluded that, though the behavior of individual species may differ, the local deficiency of seeds may be an important force generating small-scale community patterns of calcareous grasslands.

The role of plant species size in invasibility: a field experiment

“…S3b, d). This is particularly important given that propagule pressure has consistently been a strong predictor of invasion success (Everett 2000;Turnbull et al 2000;Zobel et al 2000;Brown and Fridley 2003;Lockwood et al 2005;Von Holle and SimberloV 2005). We hypothesize that communitylevel seed production, which determines the probability that a gap will be captured by a resident species, will play a large role in determining the degree to which a community is susceptible to invasion (Fig.…”

Seed, dispersal, microsite, habitat and recruitment limitation: identification of terms and concepts in studies of limitations

“…The two concepts at each spatial scale are expected to form a gradient of all possible combinations of the two respective types of limitations. Garbary et al (1991); Eriksson (1995); Tilman (1997); Turnbull et al (1999) b Eriksson and Ehrle´n (1992); Eriksson (1994); Louda and Potvin (1995); Ackerman et al (1996); Ehrle´n and Eriksson (1996); Edwards and Crawley (1999b); Juenger and Bergelson (2000); Turnbull et al (2000); Zobel et al (2000); Grieshop and Nowierski (2002); Kelly and Dyer (2002); Maron et al (2002); Miller and Duncan (2003); Szentesi and Jermy (2003); Wilsey and Polley (2003) c Connell and Green (2000); de Steven and Wright (2002) d Crawley and Brown (1995); Crawley and Long (1995); …”

Enhancement of local species richness in tundra by seed dispersal through guts of muskox and barnacle goose

“…Levine and Murrell 2003). Empirical studies manipulating the seed rain, either by seed addition (Turnbull et al 2000;Zobel et al 2000) or by the suppression of local seed production (Kalamees and Zobel 2002), have found an eVect on local diversity through recruitment. In other words, while most studies of seed dispersal address the processes that make seeds move, processes that make seeds stop moving may be as important in creating seed rain patterns and, hence, through recruitment, patterns of plant community composition and richness (Levine and Murrell 2003).…”