三江源区不同建植期人工草地甘肃马先蒿生物量分配

摘要

The succession of degraded ecosystem is a process of interaction between environment and botany in different succession stages.The plants show the feature of morphological plasticity and resource investment pattern is different in the course.In this study, we took the typical weeds of Pedicularis kansuens which growing in different periods of artificial grassland in the source region of three rivers as research object.The heavily degraded alpine meadow was control plot,and we compared P.kansuensis's morphological characteristics,organ biomass and resource investment conditions among the degraded grassland with artificial grasslands which ages were 5 and 10 years.It showed that in different periods P.kansuensis's morphological characteristics such as plant height, stylar height, the number of individual flowers all have significant differences,root length,the number of bifurcate and leaf' difference were not significantly different.Seen from the organ biomass that root biomass,stem and leaf biomass, reproductive organ biomass in this three sample plots had significant differences,but the total biomass difference was not significantly different.Compared with severely degraded grassland,in artificial-grassland of 5 and 10 years, P.kansuensis's total biomass,stem and leaf biomass,reproductive organ biomass and the number of flowers were declined at the beginning of succession and rose latterly,which changing curve like the letter "V'.And the root biomass,plant height increased gradually,but stylar height decreased following with grassland planting time.The proportion of relative resources investment showed significant differences along with grassland age.The proportion of underground and above part relative investment increased with the time prolongation and the breeding investment exhibit decreased year by year.As total biomass for individual size parameter,in the same period, P.kansuensis's absolute biomass has obvious individual size dependence, and individual stem and leaf biomass, root biomass and flower biomass were increased significantly with the increase of the body size.However,in different grasslands, P.kansuensis's each organ biomass individual size dependence responsiveness was different,the stem and leave biomass and root biomass size dependence increased consistently with the length of sample fixed years, but the flower biomass size dependence was trend to decrease,%以三江源区不同建植期人工草地中典型杂草甘肃马先蒿为研究对象,以建植前为对照,比较建植期为5年、10年的垂穗披碱草人工草地中马先蒿形态特征、器官生物量和资源投资状况.结果表明:(1)甘肃马先蒿在不同建植期人工草地中个体形态特征如株高、花柱高、花数目存在显著差异,而根系长、分枝数、叶片数差异不显著;不同阶段各器官生物量发生改变,根系生物量、茎叶生物量、繁殖器官生物量变化差异显著,而总生物量无显著差异.(2)综合建植前与建植后5、10年这3个时期样地中甘肃马先蒿在形态特征与资源投资状况的变化特征发现:总生物量、茎叶生物量、繁殖器官生物量、花数都呈现先下降再上升的"V"字形变化趋势,根系生物量、株高逐渐增大,而花序长度则持续下降;资源相对投资比例也随建植期的不同表现出明显的差异,地上部分和地下部分的相对投资随时间的增加而上升,繁殖投资则表现出逐年降低的趋势.(3)以总生物量为个体大小参数,在同一时期内甘肃马先蒿各器官的绝对生物量具有明显的大小依赖性,随着个体大小的增加,茎叶生物量、根系生物量和花生物量均显著增加.但不同建植期人工草地中各器官生物量的个体大小依赖性响应程度不同,其中茎叶生物量和根系生物量的大小依赖程度随建植年限的增加而增加,而花生物量的个体大小依赖性却随建植期的延长而减弱.