刈割对典型草原地带羊草(Leymus chinensis)的影响

Effect of Mowing on Leymus chinensis in Typical Steppe Region

经过１１年不同时期刈割和不同轮割研究结果表明：在羊草的抽穗期（６月２３日）、开花期（７月８日）、结实期（８月２日）、结实后期（８月１６日）和果后营养期（９月１２日）刈割，对羊草在群落地上生物量中所占的比例、羊草生物量、密度、高度均产生不同程度的影响，总的趋势是波动式地下降．随着刈割时间的后移，羊草生物量的分层结构呈现叶量上移，而茎量下移，对割草有利；它的Ｎ、Ｐ含量逐渐下降，在生长旺盛期Ｋ的含量增加，至后期下降．一年割两次（６月２３日和９月１２日）、一年割一次、割二年休一年、割一年休一年和对照（均为８月１６日）５个处理，羊草在群落生物量中所占的比例、羊草生物量、密度、高度均随刈割次数的增多而有不同程度下降，并有一定的相关关系．羊草生物量的分层结构，随刈割次数的增多而层次减少．羊草Ｎ、Ｐ的含量有随刈割次数增多而增加的趋势，Ｋ的含量有一定的波动．

Studying results of 11 years under the different mowing period and the different rotation mowing showed:mowing at heading (June 23),flowering (July 8),seed setting (Aug.2),after seed setting (Aug.16) and seed post maturity (Sept.12) of Leymus chinensis had influence of different on biomass proportion of the species in the community,biomass,density and height;generally speaking,value of these features of L.chinensis decreased with fluetuation.Along the postponenment of mowing time,foliage quantity mowed upward.It′s content of N,P elements decreased gradually,and content of K element increased in growing period,then decreased later.For mowing twice a year (June 23 & Sept.12),mowing once a year,mowing for two years and stopped following year,mowing a year and stopped next year and contrast (all Aug.16) treatments,biomass proportion off L.chinensis in the community,biomass,density and height of L.chinensis had a trend of decrement with increase of mowing times,it was a significant linear correlation.Layer structure of biomass of L.chinensis also decreased with increment of mowing times.Proportion of N,P elements had a trend of increase with increment of mowing times,while proportion of K element fluctuated at some extend.