Spatiotemporal dynamics of the clone of white clover in a grazed sward

研究了白三叶草单克隆在放牧草地上的时空动态。首先，开发了测定和描述白三叶草无性系生长的新技术。利用该技术，在多年生黑麦草-白三叶草草地上对目标无性系进行了2年的克隆生长监测。结果表明：(1)夏至深秋间无性系分布广泛，冬至初夏间无性系大小减小；这种萧条是由于融霜循环造成的。(2)无性系破碎化发生在冬季至早春。有根和分支的模块可能是分离的地点。(3)观察到压碎现象。(4)找出分支策略。(5)评价了牛的落叶程度和形态。未被吃掉的健康叶片数量很少。它们位于匍匐茎顶端附近。(6)在密集放牧的草地上，对白三叶草无性系的落叶胁迫都很严重。(7)落叶胁迫使其受到严重损害，并促进其大小变化，导致高死亡率。

Spatiotemporal dynamics of a single clone of white clover was examined in a grazed sward. Firstly, new techniques were developrd to measure and describe the clonal growth of white clover. Using the techiques, clonal growth of the target clone was monitored for two years in a perennial ryegrass-white clover sward. Following results were obtained : (1) The clone spreaded widely in summer to late-autumn but decreased its size in winter to early-summer. This depression was due to the thawing-frosting cycle. (2) Fragmentation of the clone occurred in winter to early-spring. Modules with roots and branches were likely to be sites for the separation. (3) Crush phenomenon was observed. (4) Branching strategy was found out. (5) The extent and pattern of defoliation by cattle were assessed. Number of healthy leaves which were not eaten was small. They placed near around the apex of stolons. (6) In an intensively grazed sward, defoliation stress to white clover clones was uniformly severe.(7) Defoliation stress gives them heavy damage and promotes the changes in size, resulting in high mortality risk.