日本那须地区人工草地牧草生物量随时间变化的解析--I 地上生物量

为了揭示草地生态系统的现存生物量随时间的变化规律与气候条件和人为干扰(放牧压,施肥量等)之间的关系,从1974年开始至1994年,每年的4月至11月,在位于日本中部那须地区的国立草地研究所内的人造围栏放牧草场进行了放牧试验.结果表明,在1974至1994年的21年间,在不同放牧处理(放牧压分别为轻度和重度/施肥分少量和大量)的条件下,地上现存生物量的季节变化非常明显,其变化范围为:150～380 g DW m-2.用4次方多项式检验表明牧草成长模式呈双峰曲线,每一年中不同放牧条件下地上现存生物量的最大值都出现在6月份左右,第二个峰值出现在9,10月份.复合回归分析的结果得出了体现现存生物量和气温,放牧压(或施肥量)之间的定量关系的多项回归方程式.协方差分析结果表明放牧压力,施肥量以及季节和年度的变化,以及他们之间的相互作用对现存生物量有着显著影响 (P<0.05) 或极显著影响(P<0.01).本研究表明在现存放牧强度下不会对地上生物量造成毁灭性的影响,而是在其承受范围之内.

Analysis of Temporal Changes in Herbage Biomass of a Sown Grassland in Nixinasuno,Japan I Aboveground Biomass

In order to understand the temporal changes of biomass in grassland ecosystem, and to clarify the relation between these changes and climatic factors and artificial disturbance, a grazing trail was carried out during a 21-year period from 1974 to 1994 at a sown grassland of the National Grassland Research Institute, located in Nishinasuno, the central area of Japan. The data sets of biomass for each month (from April to November) in the 21-year period were analyzed. It showed aboveground biomass ranged from 150 to 380 g DW m-2 from 1974 with large seasonal variation under the different grazing treatments,high or low grazing intensity/ high or low nitrogen application. A fourth-order polynomial in the ANOVA indicated that the seasonal changes in aboveground biomass tended to show a growth pattern with two peaks, which appeared in early summer and autumn for each of the treatment in all years. The result of a multiple regression analysis clarified the relation between aboveground biomass and meteorological conditions, and the result of an analysis of variance (ANOVA) showed aboveground biomass had significant differences (P<0.05) even more significant (P<0.01) with the effects of grazing intensity, nitrogen application,and the seasonal and annual factors.After 21 years grazing, aboveground biomass had no tendency to decrease by either high or low grazing intensity.