Holding on
The plight of the palms on Round Island, off the coast of Mauritius (2 minute preview, 4 minute read)
Writing about extinction and thinking about the tortoises of Mauritius and Rodrigues has reminded me of the time I spent there, 23 years ago. I realised that I have many more photos and stories than the ones I shared last year. Since I’ve been sick with a cold all week and haven’t been very productive, I thought I would go easy on myself and just share some of those with you rather than try to write a longer piece.
In the days before humans and introduced mammals destroyed the plant life and killed all the tortoises and dodos, Mauritius was almost entirely covered with forest. In wetter areas, hardwood trees formed a dense, dark canopy which was highly resistant to the frequent cyclones which lashed the island1. In drier areas, however, the land supported a kind of open forest known as palm savannah. The trees were widely spaced and there were many palms among the hardwoods. The ground was protected by dense and deep-rooted grasses like the native vetiver and zoysia grasses. While tortoises would have grazed on them, after millions of years evolving together, I assume that they didn’t damage the roots, and that this protected the soil underneath.
One of the most important reserves is Round Island, which is twenty kilometres from the northernmost tip of the mainland, and has never had predators such as rats. I’ve written about Round Island before (here’s the link), but I have many more pictures from there and some of them illustrate the disasters which befell the palm savannah. The first two images show some of Round Island’s landscape today. You might be able to see some small palm trees in the distance, but much of the island is bare rock. It wasn’t always. It was covered with grass and palm trees – and a rich, fertile soil which was nourished with the bounty of the sea, via the droppings of thousands and thousands of seabirds. There was even a kind of snake, the burrowing boa, so named because it burrowed into the soil.
What happened to the island? Goats and rabbits. They didn’t just eat the cover of native grasses, they destroyed it. Without the grasses, the soil washed away and now sits at the bottom of the Indian Ocean. Although the goats and rabbits have been eradicated, the damage they caused is irreversible. The burrowing boa was last seen in 1969, and it seems unlikely that it has survived in the tiny amount of remaining soil. We don’t really know how many plants have become extinct either.
However, some clung stubbornly to the rock and have not yet followed the tortoises and dodo to extinction. They may yet recover, although they are still teetering on the brink.