Designing ecosystems in degraded tropical coastal dunes
Coastal dunes are prone to degradation and subsequent destruction by natural and human-induced disturbances. Worldwide, human disturbances have had a great impact on coastal dunes, resulting in loss of important ecosystem services (coastal protection). In the Port of Veracruz, Mexico, harbour expansion completely destroyed the dune area. A 2-km-long 10- to 20-m-high artificial and unstable dune, parallel to the coastline, was left. To revegetate this dune, we used 3 artificially created plant communities in which the dominant species had contrasting growth forms: Opuntia stricta (Cactaceae), Panicum maximum (tall grass), and Paspalum spp. (short grass). We monitored the vegetation and species turnover during 5 y. Plant cover reached almost 100% after only 1 y. Sand stabilization occurred at a faster rate on those locations covered by both grass types, but diversity of growth habits was highest at the Opuntia treatments. From 29 to 37% of the original dune species returned. The rehabilitated community was dominated by generalist herbs and vines (80%). Remnant patches with native vegetation played an important role in species turnover and promoted colonization by thicket and tropical dry forest species. The created ecosystems provided the required ecosystem service (prevention of shifting sand) and were self sustaining (at least over the 5-y period this study lasted), but with low diversity. When human disturbance is devastating, revegetation or even created ecosystems may be the only solution. However, restoration with native species should be promoted whenever possible.