How is Regeneration of Plants after Mowing Affected by Shoot Size in Two Species-Rich Meadows with Different Water Supply?

Abstract

Mowing a meadow is an example of an equalizing process that reduces differences among species by removing aboveground biomass approximately 5 cm above ground. This regular disturbance that affects all plants prevents competitive exclusion of small species and thus allows coexistence of numerous species differing in shoot size. In this paper we search for the mechanism behind this by comparing the shoot biomass of 41 common species in dry and wet species-rich meadows in mown and recently abandoned plots in June (before mowing) and in October. We asked the following questions: i) Do the plants differ in proportion of biomass lost by mowing? ii) Are the mown plants able to compensate for biomass lost by mowing? iii) Is the compensatory ability of mown plants related to their size? iv) Is the compensatory ability of plants related to severity of disturbance (removed biomass)? v) Does water availability in meadows affect these features? Our results revealed that the earlier explanation of equalization of meadow plants after mowing due to the proportionally larger biomass loss in larger plants than small plants does not represent the entire mechanism. Even when larger plants in the wet meadow lost more biomass, the proportion of lost biomass was not dependent on plant size, and compensation ability (growth of mown in comparison with unmown plants) was not related to the lost biomass in this meadow type. On the contrary, the observed pattern could be explained by different compensation abilities of small versus tall plants. In addition, according to our expectations, the compensation for lost biomass in the wet meadow was higher than in the dry one.

Changes in biomass allocation in species rich meadow after abandonment: Ecological strategy or allometry?

“…Each block contained nine permanent plots (three rows of three) in which either the fallow treatment (i.e. abandonment) was applied from 2005, or mowing was continued (for further details on experimental set up, see Klimešová et al, 2010). Out of all species only those species occurring in all of the selected plots in a given meadow in June 2006 were selected for data collection, resulting in 22 and 19 target species occurring on the dry and wet meadows respectively (Table 1).…”

“…After mowing, the ability to compensate for the lost biomass is a key factor in determining the biomass allocation late in the season and is affected by plant size and shoot architecture (Klimešová et al, 2010). On the contrary, for fallow plots, the competition for light is a crucial factor.…”

“…The mown meadow was more "leafy" in October while the abandoned meadow was less "leafy" and this effect could be attributed to the shoot architecture of meadow plants (Klimešová et al, 2008(Klimešová et al, , 2010; (ii) in the wet meadow, the effect of abandonment, under which plants steadily increased investments into supportive structures, was most pronounced. This indicates a strong effect of species composition and/or environmental factors on the respective meadows.…”

“…An advantage of meadow communities is that they represent the most species rich communities on a small scale recorded by researchers (Wilson et al, 2012) and therefore allow for examining biomass allocation of a large number of species growing in one community under the same conditions. Although all species in the meadow community are herbaceous and small, there is still some variability in stature (Klimešová et al, 2010), at least in species rich stands.…”

“…Abandonment above all other effects is associated with increasing competitive milieu and consequent successional changes resulting in decreasing species richness and changes in species composition towards woody species (Falińska, 1999;Kahmen and Poschlod, 2004;Doležal et al, 2011). In the dense vegetation cover of a meadow, competition for light plays an important role and the coexistence of species differing in size is enabled by the equalizing effect of regular mowing which allows the persistence of small plants regarded as weaker competitors (Zobel, 1992;Klimeš and Klimešová, 2001;Klimešová et al, 2010). A first response of resident species to altered competitive milieu, before any species-exclusion happens, is an increase in size and a change in biomass allocation to different organs, resulting in an increased allocation to stems, petioles, i.e.…”