Variation in different measures of diversity during primary succession on a tropical coastal dune

Background: The understanding of the processes that govern community assembly during ecological succession helps determine the ecological attributes in restoration and monitoring programmes.

Aims: The aim of this long-term study of primary succession was to analyse changes in species richness, diversity, taxonomic distinctness and functional types to understand community assembly processes.

Methods: For 25 years, species turnover was monitored in 150 permanent plots in a dune system on the coast of the Gulf of Mexico.

Results: Earliest successional states had low species diversity and richness, a high unevenness in the taxonomic tree structure, and a lower number of functional groups, with psammophytes being dominant. Richness and diversity increased in a humped-back shape with intermediate states reaching the highest values. Succession generated taxonomic trees that became less uneven and more diverse, and the diversity of functional groups increased.

Conclusions: The processes underlying community assembly are complex during succession: sand movement acts as an environmental filter affecting the dominant functional groups, and species interactions probably change from facilitation to competition. The understanding of the combined processes affecting the different measures of diversity over time can improve the effectiveness of restoration and conservation practice in dune systems.