Distribution of tillers of plant species in old permanent grassland with different types of use.

Abstract

A survey of 1647 old permanent grasslands was carried out using 25-sq. cm. samples [see Herb. Abstr. 29, p. 1] and the frequency of dominance of each species in the samples (DF), the frequency of occurrence of each species (PF), and the dominance tendency (Dt=DF/PF X 100) was calculated for each field. Tussock-forming species showed a non-uniform distribution of tillers within the sward and the value of Dt for these species was higher than that for uniformly distributed species. Of the 29 species studied, Deschampsia caespitosa, Festuca arundinacea, Lolium perenne, Dactylis glomerata, Holcus lanatus and F uncus effusus showed high average values for Dt, while rhizomatous species such as Poa pratensis and Agropyron repens [Elymus repens], stoloniferous species such as Trifolium repens, Poa trivialis and Ranunculus repens, and species spreading by means of seed, such as R. acris, Bromus mollis and Rumex acetosa, had low average Dt values. From values of Dt calculated for fields used for hay, hay-pasture (aftermath grazed), alternate pastures (mown for hay in some years only) and pure pastures, it was shown that D. caespitosa, L. perenne, D. glomerata and J. effusus were more regularly distributed in hay-fields than in pastures. In alternate pastures, J. effusus had a low Dt value, F. arundinacea a high Dt. Species having a preference for hayfields showed higher Dt values than elsewhere, owing to their growth not being restricted by grazing. Typical pasture species which spread by means of runners, such as P. pratensis, Agrostis stolonifera and T. repens, were more homogeneously distributed in hayfields; their increased Dt values in pastures was due to their concentration in the spaces between tussocks of other species.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)