Moora Mari, Zobel Martin
Department of Botany and Ecology, Tartu University, 40 Lai St., EE2400, Tartu, Estonia.
Oecologia. 1996 Oct;108(1):79-84. doi: 10.1007/BF00333217.
We were interested in the role of arbuscular mycorrhiza (AM) in the competition between plants of different sizes. A pot experiment of factorial design was established, in which AM root colonization and competition were used as treatments. Five-week-old Prunella vulgaris seedlings were chosen as target plants (i.e. plants whose response to competition was studied) and the following (13 replicates of each) were used as neighbours: (1) a large, 10-week-old P. vulgaris, (2) two P. vulgaris seedlings, and (3) a large, 10-week-old Fragaria vesca. In the experiment where small neighbours were grown together with small target plants, competition did not reduce target plant weight significantly, compared to the other two treatments. The competitive effects of large neighbours were significant, regardless of species (both older neighbours reduced the weights of target plants similarly), but there was a clear difference between intra- and interspecific competition when plants were mycorrhizal. In intraspecific competition with a large neighbour, the target plant shoot weight was reduced 24% when inoculated with AM. Thus, AM amplified rather than balanced intraspecific competition. In interspecific competition with old F. vesca, the shoot weights of target plants were 22% greater when inoculated with AM than when non-mycorrhizal. The results showed that, for given soil condition, AM might increase species diversity by increasing competitive intraspecific suppression and decreasing the interspecific suppression of small plants by larger neighbours.
我们对丛枝菌根（AM）在不同大小植物间竞争中的作用感兴趣。开展了一项析因设计的盆栽试验，其中将AM根系定殖和竞争作为处理因素。选用5周龄的夏枯草幼苗作为目标植物（即研究其对竞争反应的植物），并将以下植物（每种13个重复）用作邻体植物：（1）一株10周龄的大型夏枯草，（2）两株夏枯草幼苗，（3）一株10周龄的大型野草莓。在小邻体植物与小目标植物共同生长的试验中，与其他两种处理相比，竞争并未显著降低目标植物的重量。大型邻体植物的竞争效应显著，无论其物种如何（两种较老的邻体植物对目标植物重量的降低作用相似），但当植物形成菌根时，种内竞争和种间竞争存在明显差异。在与大型邻体植物的种内竞争中，接种AM时目标植物地上部重量降低了24%。因此，AM增强而非平衡了种内竞争。在与老的野草莓的种间竞争中，接种AM的目标植物地上部重量比未形成菌根时重22%。结果表明，在给定的土壤条件下，AM可能通过增强竞争性种内抑制和减少大型邻体植物对小型植物的种间抑制来增加物种多样性。
