Successional convergence in experimentally disturbed intertidal communities

Area of Science:

• Ecology
• Community Ecology
• Ecological Succession

Background:

• Understanding variation in community assembly is crucial in ecology.
• Beta-diversity analysis helps infer the roles of deterministic and stochastic processes in shaping ecological communities.
• The timing of disturbances can significantly impact community assembly trajectories.

Purpose of the Study:

• To investigate the effects of disturbance timing on community assembly.
• To compare community assembly processes across three distinct regions with varying environmental conditions.
• To assess the relative importance of deterministic versus stochastic processes in rocky intertidal ecosystems.

Main Methods:

• Experimental clearing of rocky intertidal quadrats at three different times of the year across Portugal, Azores, and Canaries.
• Monitoring community assembly for one year post-disturbance.
• Analysis of alpha, gamma, and beta-diversity using Jaccard, Bray-Curtis, and an adapted Raup-Crick metric.

Main Results:

• Alpha and gamma diversity remained constant across regions and throughout succession.
• Beta-diversity was highest in early succession and decreased over time, indicating increasing similarity.
• Community structure, when accounting for species richness, initially resembled random assembly but became more structured than expected by chance over time.

Conclusions:

• Disturbance timing influences early community assembly, but deterministic processes increasingly structure communities over time.
• Priority effects appear weak across the studied regions, suggesting they do not strongly dictate long-term community structure.
• Ecological community assembly is shaped by deterministic factors, even with initial stochasticity, across diverse environmental settings.