刈割对羊草叶面积指数的影响

对经过17年不同刈割处理的内蒙古羊草草原羊草种群的叶面积指数进行了比较研究,结果表明:连年刈割使羊草叶面积指数迅速下降,轮休则能减弱下降趋势;隔几年刈割一次会促进羊草种群的生长,增加其叶面积指数;结实期和结实后期刈割,叶面积指数下降最大,开花期刈割次之,果后营养期刈割下降最小;羊草叶面积指数的变化主要由刈割后种群密度的变化引起,平均单叶面积对其影响较小;分株叶片数的变化对叶面积指数无显著影响;羊草叶面积指数的变化与羊草营养枝高度、干重、密度和种群相对生物量之间呈显著相关关系,与生殖枝高度和群落总生物量相关不显著.

Effect of Mowing to the Leaf Area Index of the Leymus chinensis Population

A comparison and analysis of the leaf area index(LAI)of Leymus chinensis of the Inner Mongolia L.chinensis population, which had undergone different mowing treatment for 17 years, reveals that the leaf area index of the L. chinensis population rapidly decreased under successive years of mowing, and the negative effect could be weakened by rotative mowings. Mowing every several years could promote the growth of L. chinensis population and increase its leaf area index, while mowing during the seed setting and post seed-setting stages would seriously decrease the leaf area index. Less serious negative effect to LAI occurs when mowing during the L.chinensis flowering stage. The least negative effect to the LAI of the grass happens when mowing after the seed has matured. The variation of L.chinensis LAI results mostly from the difference of the grass's offshoots density, also from the variation of the average leaf area, whereas the mean leaf number per offshoot affects very slightly the LAI. The LAI of L.chinensis. population is significantly correlated to the height of the vegetative tillers of each plant, the weight of dry matter, the density of the offshoots, and relative biomass, but not to the height of the reproductive tillers and the total community biomass.