A comparison of plant communities on the basis of their clonal growth patterns

Abstract

This study was performed to analyse how a vegetative propagation pattern of plants affects the coexistence of species and subsequent species richness of the community. We compared community average clonal growth in the herbal communities of forests, wooded meadows, and open meadows in Laelatu, Estonia. The parameters used for the calculation of the community averages and measured for each species were ramet life span, rhizome branching, and clonal mobility. We also examined the intrinsic (i.e. independent of the environment) relationship between community clonal growth and plant species density. We found strong correlations between the environmental factors (productivity, light availability, and mowing regime) and community averages of clonal growth parameters, while species density was (negatively) correlated only with community average of rhizome increment. The community average of ramet life span decreased with the increasing biomass of the herb layer. No evidence was found to support the hypothesis that species-rich communities may consist of species with more contrasting mobility compared with species-poor communities. Independent of the effect of the environmental factors, species density was positively correlated with ramet density. There was intrinsic positive relationship between species density and community average of ramet life span at open meadow sites and intrinsic negative relationship between species density and community average of rhizome increment at wooded meadow sites. We conclude that in forest communities the capability of clonal plants to forage for light is favoured, while in unmown meadows a competitively strong phalanx growth form is advantageous. We established that ramet turnover increases and vegetative mobility decreases with increasing species diversity, although these two relationships depend strongly on the type of the studied community.

Understory plant diversity is related to higher variability of vegetative mobility of coexisting species

“…Studies of weighed community-wide VM have not yet demonstrated clear diVerences among communities (Sammul et al 2003(Sammul et al , 2004. We show that CM was signiWcantly higher in understorey plant communities of old forests.…”

“…Moora (&) · M. Öpik · K. Zobel · M. Zobel Institute of Ecology and Earth Sciences, University of Tartu, Lai 40, 51005 Tartu, Estonia e-mail: mari.moora@ut.ee in natural vegetation. Studies in calcareous grassland (Sammul et al 2003(Sammul et al , 2004 have shown that horizontal vegetative mobility (VM) of co-occurring plant species is highly variable. However, we do not know whether VM diVers between communities or patches within communities, or if species diVer in how plastic their VM is under natural conditions.…”

“…Information on the actual clonal mobility of species in a plant community is extremely rare. We know of only one study where this has been quantiWed (Sammul et al 2003(Sammul et al , 2004, and in this grassland system regeneration from seeds may still be quite considerable (Kalamees and Zobel 2002). Although molecular methods can be used to evaluate the contributions from seed dispersal and vegetative growth (Robledo-Arnuncio and Garcia 2007), such analysis are time consuming, expensive and have never been performed on the community level.…”

“…We randomly sampled up to ten ramet of each species in each of six stands (fewer when insuYcient individuals were available), from a homogeneous area of 20 £ 20 m. The belowground clonal fragments of 1,622 plant individuals were excavated from 48 herbaceous plant species (Supplementary Table S1). Possible approaches to measure lateral spread by means of vegetative organs in the Weld have been discussed by several authors (Klimes and Klimesova 1999;Tamm et al 2001;Sammul et al 2004). We measured the lateral spread per year (=VM) following the methods described by Klimes and Klimesova (2005).…”

“…We also calculated the community-wide weighted clonal mobility (CM) for all 4 £ 4 m plots as the weighted average of annual rhizome increment following Sammul et al (2004): CM = a i VM i , where a i is the relative cover of species i in a 4 £ 4 m plot. Large values of CM indicate that vegetatively mobile species and/or individuals have a relatively large share of the total cover (or biomass) of the community.…”