Seasonal differences in the adaptability of herbage species to environmental variations in a long‐term grazing experiment

Abstract

Mixtures of orchardgrass, perennial ryegrass, tall fescue, redtop, Kentucky bluegrass, and white clover were sown in autumn 1973. Two 8‐year grazing experiments were conducted at the National Grassland Research Institute (Nasushiobara, Japan) to determine the effects of grazing intensity and nitrogen levels on pasture ecosystems. These experiments involved two different grazing intensities (1974–1981) and two different nitrogen levels (1982–1989). Large spatiotemporal variations in phytomass due to environmental variations were observed in both experiments. Finlay–Wilkinson analysis was applied to clarify seasonal (monthly) differences in the adaptability of the herbage species, as measured by phytomass, to environmental variations by year and treatments in the two experiments. Seasonality in the adaptability to environments differed greatly among species. In this paper, we examined from livestock farmers’ standpoint whether seasonality in adaptability of herbage species in the grazing pasture could be satisfied. A significantly high adaptability was shown for: orchardgrass from May to July and November; tall fescue in April, June and July, and November; redtop and Kentucky bluegrass in April; and Zoysia japonica in September and October. In contrast, perennial ryegrass and white clover exhibited very low adaptability in any season. Z. japonica and weeds such as Pennisetum alopecuroides, Eragrostis ferruginea and Digitaria adscendens, which had invaded from surrounding areas, showed low adaptability, except in autumn, when they showed moderate adaptability.

Spatiotemporal variation in aboveground biomass in a tropical grass pasture over a 22‐year period

“…It is noted that precipitation had a positive effect on biomass as is the case in much drier regions (mean annual precipitation = 342-580 mm; Ma et al, 2010;O'Connor et al, 2001;Vázquez-de-Aldana et al, 2008;Smart et al, 2007) even at the site of the present study where the growing-season precipitation was as high as 1148-2481 mm. The nonsignificant effect of cumulative stocking density on W, which unexpectedly did not agree with the negative effect of stocking intensity on aboveground biomass (Jones et al, 1995;Yiruhan et al, 2001), can be explained by the fact that the measurements were usually conducted immediately before the rotational stocking periods, that is, when aboveground biomass was recovered from previous stocking. The markedly larger degree of variation in W (33-605 g DM/m 2 ; Figure 4) than that in the number of animals (24-35 cows; see Section 2.1) indicates the occurrence of considerable seasonal and interannual variation in the balance between herbage supply and demand.…”

“…However, limited information is available on the long-term spatiotemporal variation in aboveground biomass in pastures. Although Jones et al (1995) and Yiruhan et al (2001) reported temporal variation in aboveground biomass in sown pastures under cattle grazing over a 21-year period, they did not quantitatively show the effects of climate and management in the form of a model for aboveground biomass. Although Vázquez-de-Aldana et al (2008) conducted 20-year monitoring of aboveground biomass in a native pasture grazed mainly by cattle and developed models to relate aboveground biomass to climatic variables, they focused only on interannual variation without incorporating seasonal variation into the models.…”