Discrete steps of successional pathways differ in kelp forest and urchin barren communities

Abstract

The role of organisms in community assembly and functioning is a crucial question of community ecology. We address this issue in a particular marine coastal ecosystem at SE Pacific: although kelp forests and urchin barrens are conspicuous benthic systems in rocky habitats, only a few studies have been focused on studying their successional patterns (especially following disturbances). In this work, we present successional pathways from micro-periphyton to macro-organisms observed during a 14-month period in kelp forests and urchin barrens in the Antofagasta Peninsula, Chile. The community composition and structure showed habitat-specific successional pathways with different dominant organisms in these two communities. Likewise, during their successional trajectories, both communities showed different number of discrete temporal stages. Kelp forests displayed a longer successional pathway of 7 discrete stages, while the barren bed succession pathway was composed only of 4 stages. We argue that this difference would be due to self-organising processes. This finding may have relevant implications for conservation and monitoring, since the intensive harvest of kelp species will not only increase the dominance of urchin barrens, but it would also facilitate its own, self-determined, more efficient (with few steps) successional pattern and the consequent persistence.