Evaluating the adaptability of herbage species to environmental variation through a long‐term grazing experiment

Abstract

AbstractMixtures of orchard grass, perennial ryegrass, tall fescue, redtop, Kentucky bluegrass and white clover were sown in the autumn of 1973. Two 8‐year grazing experiments were carried out at the National Grassland Research Institute (Nasushiobara, Tochigi, Japan) to determine the effects of grazing intensity and nitrogen levels on the pasture ecosystem: two different grazing intensities (1974–1981) and two different nitrogen levels (1982–1989). Large temporal and spatial variations in phytomass were observed in both experiments. To clarify the adaptability of the phytomass of the herbage species to environmental variations in year, season and treatments, we re‐examined the data obtained in these two experiments using a Finlay‐Wilkinson analysis. Orchard grass and tall fescue achieved significantly higher phytomass in a more fertile environment in that they showed a high adaptability to environmental variation. Redtop and Kentucky bluegrass showed an increase in phytomass proportional to environmental improvement. The phytomass performances of perennial ryegrass and white clover were almost independent of environmental variation in that their adaptability was low. Finally, Zoysia japonica and weeds such as Pennisetum alopecuroides and Digitaria adscendens, which were invaders from the surrounding areas to the experimental site, were not observed in the pasture during the first 8‐year period; during the second 8‐year period, they showed moderate adaptability.