Occurrence and output of all types of belowground buds of Leymus chinensis and the dynamics of formation and maintenance of aboveground shoots

Seasonal variations of densities of all types of buds,parent and daughter shoots of Leymus chinensis were investigated.The origin of current year parent shoots was 80% from shoot buds and daughter axillary shoots,15% from apical rhizome buds and daughter apical rhizome shoots,and 5% from axillary rhizome buds and daughter axillary rhizome shoots,from total buds and shoots formed during previous years.When parent shoots were growing,apical rhizome buds began to generate and spread horizontally to occupy niches during 20 May,one month earlier than axillary shoot buds and axillary rhizome buds.By 20 June,the horizontal apical rhizome buds started growing into vertical apical rhizome buds and finally into daughter rhizome shoots.Similarly,by 20 June,shoot buds and axillary rhizome buds occurred and finally developed into daughter shoots.Parent shoots of L.chinensis produced both a lower proportion of spreading shoots(i.e.apical rhizome buds and shoots,or axillary rhizome buds and shoots) and a higher proportion of clumping shoot(i.e.shoot buds and axillary shoots),resulting in a combined growth form.This enables L.chinensis to maintain an asexual propagation mechanism through continuous growth of buds,daughter shoots and parent shoots between and within years.Higher precipitation can promote the density of all types of buds,leading to an increase in density of daughter and parent shoots.