Connell Sean D
Southern Seas Ecology Laboratories, School of Earth and Environmental Sciences, The University of Adelaide, 5005 South Australia, Australia.
Oecologia. 2003 Sep;137(1):97-103. doi: 10.1007/s00442-003-1312-6. Epub 2003 Jun 19.
Marine macroalgal forests are one of the most widespread and studied habitats on subtidal coasts, but there remain challenges in understanding why many sessile invertebrates are anomalously absent from understorey communities. In a series of experiments on recruitment of invertebrates, I partitioned the habitat-modifying effects of kelp into their positive and negative effects. Experiments revealed that a reduction of light intensity and removal of sediment by canopies acted to facilitate recruitment, but physical abrasion by the canopy acted as a negative force to overpower these positive effects. Understorey assemblages, therefore, represent biased subsets of taxa from a local pool capable of colonization. On balance, negative effects acted to exclude invertebrates from the understorey community. The asymmetric strength of negative effects not only explains the enigma of exclusion but also indicates that, when it exists, understorey coexistence with canopy plants must reflect a more even match between positive and negative effects.
大型海藻林是潮下带海岸最广泛分布且研究最多的栖息地之一，但在理解为何许多固着无脊椎动物异常地未出现在林下群落方面仍存在挑战。在一系列关于无脊椎动物招募的实验中，我将海带对栖息地的改变作用分为其积极影响和消极影响。实验表明，树冠层降低光照强度和清除沉积物的作用有助于招募，但树冠层的物理磨损起到了负面作用，抵消了这些积极影响。因此，林下组合代表了来自能够定殖的本地类群库的有偏差的子集。总体而言，负面影响使得无脊椎动物被排除在林下群落之外。负面影响的不对称强度不仅解释了排除之谜，还表明，当林下与树冠植物共存时，必须反映出正负影响之间更均衡的匹配。
