刈割处理对贝加尔针茅草原植物生长与繁殖状况的影响 Ⅱ.第二年重复处理的效果

EFFECTS OF CUTTING TREATMENTS ON PLANT GROWTH AND REPRODUCTIVE STATUS IN Stipa baicalensis STEPPE II.SOME RESULTS AFTER REPEATED TREATMENTS IN THE SECOND YEAR

在上年处理的基础上 ,于 1999年进行重复处理 ,观察贝加尔针茅草原草群、羊草和贝加尔针茅高度、单位面积羊草植株数量及平均每丛贝加尔针茅植株数量变化的累加效应 ,结果表明 ,连续两年重复处理之后 ,累加效应显著。草群高度在春季刈割后可以恢复到CK水平 ,7月 1日以后刈割 ,则明显下降。贝加尔针茅高度的时间动态模式与草群相似 ,对不同留茬的反应更敏感。其植株数受处理时间和留茬高度互作的影响 ,且上年处理的后效具有长时间的作用 ,基本上是低留茬、中、晚期处理 ,植株数减少。羊草的再生高度也与草群高度动态相似 ,前期处理与CK接近 ,以后处理对高度的抑制作用逐渐加大 ,留茬越低越显著。其株数随着处理时间而有不同变化 ,基本规律是早期处理低留茬促进植株数增加 ,中期处理高留茬促进植株数增加 ,而晚期处理再生极少。

The cutting treatments were repeated in 1999 on the base of last year's design and treatments to observe the accumulated effects on the heights of community, Stipa baicalensis, Leymus chinensis and plant numbers of Leymus chinensis in unit area and Stipa baicalensis per bunch. The results showed that the accumulated effects were quite significant when the steppe was repeatedly treated during two growing seasons. The height of community treated in spring could recover to the level of CK. But it obviously decreased when treated on or after July 1. The time dynamic pattern of height of Stipa baicalensis was similar to the community's, but it was more sensitive to the stubble levels. The plant number of per bunch of Stipa baicalensis was influenced by the interaction of treating period and stubble height. The residual effect of last year's treatment could keep for a quite long time. The basic trend was that the plant number decreased when treated in summer or fall, with lower stubble. The regeneration height of Leymus chinensis could recover to the level of CK when treated in spring. But it was checked when treated during the following period. The lower the stubble was, the shorter the regeneration plants grew. The plant number in unit area increased when treated in spring with low level of stubble, or in summer with high level of stubble. But when treated in fall, the regeneration would stop.