羊草克隆种群的螺旋扩张规律

The spiral elongation rule in clonal population of Leymus chinese

羊草是欧亚大陆草原东部区域的一个优势物种。其优势地位的取得是羊草种群年复一年不断克隆复制过程中进行螺旋扩张的结果,其中,每一个螺旋圆环代表一个生长季,进而每个生长季可再分为不同的种群成长阶段,执行不同的生存发展策略:5月下旬—7月下旬为成熟扩张期,羊草的成熟母株通过水平伸长根茎执行扩张策略;7月下旬—10月下旬为幼苗占领期,通过地下芽输出为地上子株执行占领策略;10月下旬—来年3月下旬为羊草的休眠期;3月下旬—4月下旬为它的生长准备期;4月下旬—5月下旬为生长巩固期,子株发育为成熟的母株,完成了领地的彻底控制,执行的是巩固策略。羊草的游击型分株和密集型分株源自于共同的母株,二者位置相互分开,不但可以避免内部竞争,而且通过根茎之间的连接进行资源共享,从而在对外竞争中始终处于优势地位,这是羊草的克隆区隔避险策略;羊草种群通过产生遗传异质性的种子来避免因外界环境条件巨变所造成的整体灭绝,执行的是一种有性繁殖避险策略。羊草在既定策略基础上也表现出明显的二八规律,即通过80%比例的密集型分株进行旧领地的巩固,以20%比例的游击型分株进行新领地的扩张。总之,羊草通过扩张,占领,巩固,再扩张,再占领,再巩固,这样的年复一年的螺旋扩张,成为了当地的优势物种。其研究结果能为提高羊草生产力和种子产量及恢复受损草原生态系统提供十分重要的科学支持。

Leymus chinensis is dominant species in eastern regions of the Eurasian Steppe. The dominant position was obtained as a result of spiral elongation for Leymus chinensis population through clonal growth year by year. For Leymus chinensis population, a spiral ring meant a growing season; furthermore, a growing season included many growth stages when they respectively experienced different growth strategies. From late May to late July it was spreading stage when mature parent shoots elongated young rhizomes, adopted elongation strategy; from late July to late October occupied stage of daughter shoots when buds come up and became daughter shoots, developed occupation strategy; from late October to next late March dormancy stage; from late March to late April prior stage of growth; from late April to late May growth and consolidation stage when daughter shoots grew and developed into mature parent shoots, firmly occupied the area, pursued consolidation strategy. Moreover, clonal spacing evading risk strategy was adopted in order to not only avoid competition between clumping shoots and spreading shoots through both of which separating in parent shoots, but also fight against outward competitors through source sharing as the interlinking of rhizomes; meanwhile sexual propagation evading risk strategy in order to avoid thorough extinction, when suffering from tremendous changes of environment, through getting seeds of genetic heterogeneity of population ; twenty-eighty rule through 20% spreading 80% clumping shoots for occupation of previous area. Therefore, L. chinensis become a through its spreading, occupation, consolidation, then, spreading again, occupation creates a scientific backing for improving productivity of shoot and seed and also for ecosystems. shoots for occupation of new area and dominant population in the local area again, and consolidation again. This the restoration of degraded grassland