Vegetation 1 – Coastal Vegetation

When De Trobriand discovered Denis in 1773 he found it luxuriantly vegetated with a 50/50 patchwork of forested and grassland areas. The soil in the interior he described as rich and dark and though he found no standing water he recorded that he felt a shallow well would readily find it. Within 70 years of this discovery however, the vegetation on Denis had been changed almost beyond recognition, being described as agricultural land, the likely crops being maize and cotton. Further changes in land use followed through the years leading ultimately to the patchwork of secondary habitats that we find today.

The coastal vegetation on Denis plays a vital role in the island’s ecosystem. The hardy plants that grow there serve to:

• bind the sand against the eroding action of the sea,
• protect the interior vegetation from the worst rigours of sea winds and salt spray,
• provide a habitat for various animal species including nesting grounds for marine turtles.

The coastal vegetation on Denis is dominated by three indigenous species: Scaevola/Veloutye (Scaevola sericea), Bay Cedar/Bwa D’amand (Suriana maritima) and Beach Gardenia/Bwa Kassan (Guettarda speciosa).

Scaevola is the most common and familiar beach shrub throughout the central archipelago and it forms dominant stands along the majority of the northwest and north coasts of Denis. Scaevola is unmistakeable with its characteristic large glossy, bright green leaves, 5-petalled white flowers (with all petals restricted to the lower half of the flower) and round white fruits. Scaevola provides a sheltered habitat for nesting turtles and the tawny hermit crab. Whist the blue pigeons on Denis also show a taste for its berries.

Bay Cedar can be found intermittently along the west and southern coasts and forms quite thick stands on certain areas of the East coast where perhaps it is too exposed to the southeast monsoon for Scaevola to form dominant stands.

Beach Gardenia typically grows as a tree on Denis and can be found scattered along the west and northern coasts of the island whereas on the east coast it forms extensive dominant stands a feature which is to the best of my knowledge peculiar to Denis and suggests a concurrence of factors that particularly favour its growth and propagation.

The coastal vegetation at the southern point of the island exhibits an interesting community of species. Here Scaevola grows along with Bay Cedar, Tournefortia argentea and mature specimens of Pisonia grandis. This transitions, as one moves inland, through beach gardenia, into mixed stands of Cordia subcordata, Thespesia populnea and Pisonia. This combination and succession of species speaks to stability in the habitat and enquiries have revealed that the area has not been disturbed within living memory. This coupled with descriptions of the island from the 1880s onwards as having a band of coastal vegetation surrounding the interior production landscapes suggests that this area may be as close to a relict of the original coastal vegetation as remains on Denis and is therefore of particular research and conservation interest.