模拟物理空间资源对麻疯树幼苗生长的影响

密度效应为常见的生态学术语,但对其本质缺乏认识。物理空间也是一种资源（M cConnaughay＆Bazzaz,1991）,为密度效应的认识提供了线索。本文利用密度与容器大小模拟物理空间资源对麻疯树幼苗形态与资源配置的影响,来阐明物理空间资源影响现象与机制。在密度栽植时,立地异质性无法抗拒无意中得到了空间限制的资源依赖性结果,增加了解释的复杂性与价值性。结果表明：1）大容器个体苗高、直径、头年生高度、当年生高度、叶片数量,叶生物量、根系生物量、头年生生物量、当年生茎生物量、总体生物量都明显大于小容器;2）大容器根系资源配置明显小于小容器,大容器当年生叶与茎生物量配置较高,而头年生茎生物量相对配置较低,表明空间不足限制了根系发育从而限制了地上部分生长能力;3）试验后测定容器土壤肥力,发现小容器肥力利用充足,元素浓度明显低于大容器;4）高密度组个体形态与生物量参数较大,中密度次之,低密度最低,这一意外结果与微地形造成的水分差异有关;5）高密度在资源充足,加剧了空间限制,使得当年生茎与根系生物量相对配置增加,而低密度因微地形可能水分缺乏明显,根系生物量配置增加。物理空间也是一种资源,这种资源与生态学中生态空间含义不同,单纯是一种资源因子。

The Influence of Physical Space on the Seedling Growth of Jatropha curcas by Simulating Experiments

The density effect was the common terms in ecology,but less attention was paid to its essential.Physical space also was a kind of resources（McConnaughay Bazzaz,1991）,and provided a clue for deeply knowing the density effect.This paper dealt with the influences of simulating physical space by density and container on seedling morphology and resource allocation of Jatropha curcas and demonstrated the phenomenon and mechanism of influences of physical space resource.While planting of designing density,it was no way to eliminate the site heterogeinity of experiment-used nursery land（mainly influencing micro-hydrological effects）,and unconsciously got the experimental result of resource dependency of space limitation,which added the complexion of analysis.The results indicated：1） all the seedling height,diameter,branch length of last year,branch length of this year,leaf amounts,leaf biomass,root biomass,biomass of last year,branch biomass of this year,total biomass in the bigger container was higher than those in the smaller container;2） The root allocation in the bigger container was lower than that in the smaller container,this-year leaf and branch biomass allocation in the bigger container was relatively higher,but the last-year branch biomass allocation was lower,which implied that space limitation limited the morphology and aboveground growth by limiting the root growth;3） The soil fertlization after experiments was measured and found that utility of elements in the smaller container was enough and had a lower element content than that in the bigger container;4） The experiment indicated that individual morphology and biomass allocation in the higher density group were relatively higher,the lowest in the low density group and medium in the medium density.This result was related to moisture difference brought about by micro topograpgy;5）The higher density added the space limitation while resource was enough,which rendered the increases of this-year branch and root biomass relative allocation,but moisture probably was in shortage in low density experiments and the root biomass allocation increased.The physical space also was a kind of resource,this resource had different meanings and only was a resource factor,as compared with ecological space in ecology.