刈割加遮荫对互花米草生长和存活的影响

该研究比较了在5月份实施刈割加不同程度遮荫处理后,互花米草地上部分和地下根茎6个月内的生长与死亡状况。结果表明:(1)单纯刈割处理在前2个月显著降低互花米草株高和生物量等生长指标(P0.05),随后地上部分生长和开花特征逐渐恢复并接近对照水平;而地下根茎存活率一直呈下降趋势;(2)刈割后加不同程度遮荫处理均可以有效抑制互花米草的生长并导致植株死亡,抑制效果显著高于单纯刈割的处理(P0.05),且遮荫程度越高抑制作用越明显。(3)刈割后加1层遮荫、2层遮荫和3层遮荫处理的平均透光率分别为15.27%、2.29%和0.31%,分别于11月份、7月份和7月份时导致互花米草地上部分全部死亡,至11月份时地下根茎存活率分别为3.68%、2.09%和1.70%,接近全部死亡。综合考虑治理费用、治理所需时间和治理效果,刈割后加1层遮荫是经济、有效的控制互花米草的方法。

Combined effects of mowing and shading on growth and survival of Spartina alterniflora

Spartina alterniflora, native to the Atlantic and Gulf coasts of North America, has invaded many estuaries and coasts of the world. Due to its well-developed rhizomes, seedlings usually emerged even the above-ground parts were cleared. So ensuring the death of rhizome is critical to control the weed. We examined the growth and survival rate of both above-ground parts and rhizome of S. alterniflora under only mowing and mowing+shading treatments in Guangxi Zhuang Autonomous Region, China. The results were as follows:(1)Plant height and biomass were significantly reduced at early stage after just mowing in May(P<0.05), while all above-ground growth characters increased during the following six months and were closed to the control group in November(P>0.05). However, rhizome survival rate showed contrary trend to the growth characters of above-ground parts.(2)Comparing to control and only mowing groups, the mowing+shading treatment restrained plant growth and resulted in death obviously. And the restraining effect was positively correlated with shading degree.(3)The light transmittances of mowing+single layer shading net, mowing+double layers shading net and mowing+triple layers shading net were 15.27%, 2.29% and 0.31% respectively, and rhizome survival rate were 3.68%, 2.09% and 1.70% in November respectively. Above-ground parts were all dead at November in mowing+single layer shading treatment, while they were all dead at July in mowing+double layers shading treatment and mowing+triple layers shading treatment. Considering the cost, lasting time and efficiency, we suggest that sowing plus single-layer shading treatment could be an effective method of controlling S. alterniflora in Guangxi Zhuang Autonomous Region.