You are not currently logged in.
Access your personal account or get JSTOR access through your library or other institution:
Negative Effects Overpower the Positive of Kelp to Exclude Invertebrates from the Understorey Community
Sean D. Connell
Vol. 137, No. 1 (Sep., 2003), pp. 97-103
Stable URL: http://www.jstor.org/stable/4223734
Page Count: 7
Preview not available
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.
Oecologia © 2003 Springer