Long-term Study of Grazing Effects on Green Herbage Mass in Grassland Dominated by Zoysia japonica Steud

Abstract

To clarify the effects of grazing on green herbage mass in Zoysia-dominated grassland, seasonal changes of green herbage mass over 15 years were related to variation in grazing practices. Several factors influencing green herbage mass during grazing periods were analyzed using a linear mixed-effects model. The results of this long-term study showed that the effect of grazing on green herbage mass varied with grazing procedures annually and with grazing history. The linear mixed-effects model determined quantitatively the effect of each factor on green herbage mass. With less than 1200 kg BW ha^-1 of grazing pressure, green herbage mass decreased with increasing grazing pressure; it was negatively affected by plant diversity and season and positively affected by green herbage mass at the start of the grazing period. With more than 1200 kg BW ha^-1 of grazing pressure, green herbage mass remained low regardless of grazing pressure; it was negatively affected by season and positively affected by green herbage mass at the start of the grazing period.