Excursion to Green Mountain on Ascension Island
August 2015
The excursion on Green Mountain, on the island of Ascension, starts along the narrow road that leads to the top. At the entrance of the national park, a curious road sign warns about the presence of land crabs.
Photos of land crabs. The land crab of Ascension Island (scientifically known as Johngarthia lagostoma and also referred as terrestrial crab), is an incredible crustacean native to Ascension Island (but not endemic, as it is also found among other South Atlantic islands) characterized by a quite unique life cycle.
Although the juvenile and adult forms of land crab are terrestrial, the larvae are marine, because they can feed exclusively on plankton. Therefore, in order to ensure easy access to the sea, the adult terrestrial crabs mature for reproduction, are forced once a year to leave their nests uphill (essentially a deep hole dug into the ground) and go down to the beach.
Such migration generally occurs during a full moon night in the wet season (typically between March and May) to prevent desiccation. When proper conditions meet, the land crabs run through several kilometers, with gradients of hundreds of meters, from the mountains to the beaches, crossing quite difficult kinds of terrain, including solidified lava fields, before coming back after releasing the larvae. Once the the larvae are mature, they will reach the highlands where their relatives live.
The only road climbing to Green Mountain. It is very steep, but we managed to go up with our 2WD regular sedan car (we got the engine stopping in a couple of occasions). For better safety, and if you plan to go up often, a 4WD car may be a better choice.
While climbing the Green Mountain, there will be beautiful views over Ascension island.
After crossing about 600 meters of elevation line, a dense forest of eucalyptus appear.
Near the summit of Green Mountain there is a small church, a few cottages and a series of buildings dating back to past centuries, when the mountain was home to gardens and shelters for livestock: the top of Green Mountain was chosen for this purpose, because of the much wetter local micro-climate and for the highest fertility of the soil, if compared to the rest of the island. The products obtained from here were intended to meet the demand of the islanders, without have to import everything from overseas.
When the summit of Green Mountain, also known locally as "The Peak", was colonized in the attempt of producing vegetables and fruits locally, many non-native species were introduced.
Without any control, thanks to the particularly humid climate and fertile soil, the species artificially introduced started to reproduce abundantly, finally imposing a huge competition over the weaker local species, who were not able to manage such invasion. Unfortunately, this has determined the extinction of many endemic species, not present in other parts of the world, and now lost forever.
Flowers growing on the top of Green Mountain on Ascension Island.
The Sporobolus caespitosus is a rather rare endemic plant of Ascension, and is considered endangered because among all the world, it only populates the drier side of Green Mountain on Ascension Island. The few endemic plants of Ascension Island are yet threatened by competition from plants and animals introduced by man.
On the summit of Green Mountain there are a number of ghost buildings that were in use until the top of the mountain was first used by the army to guard the sea around the island, and then by the farmers to produce vegetables and take care of livestock.
Some buildings on the Green Mountain, first used as barracks for the army, then as shelters for animals.
A narrow valley near the top of Green Mountain has been partly paved with concrete, in order to convey rainwater toward a tank and then toward an aqueduct used to serve the community at the foot of the mountain. The system was in use until the '60s, then it was decommissioned and abandoned.
The nature is trying to slowly take over the spaces stolen by men: mosses and lichens are the first colonize the surfaces.
On Green Mountain, as well as on the rest of the island of Ascension, it is not unusual to see sheep and rabbits. In particular, the rabbits were reproduced in large numbers, entering into competition with the delicate local species (such as land crabs) therefore endangering an entire ecosystem that does not exists in any other parts of the world.
A common monarch butterfly.
On top of Green Mountain there are a number of paths enough to keep visitors busy for hours. They will offer beautiful views on the island and will let to discover rare endemic vegetation.
The summit of Green Mountain on Ascension Island, almost permanently swept by the winds that blow from the east, without any shelter.
Other plants that can be found on Green Mountain.
The trails of Green Mountain, through tunnels dug into the lava by the army during the nineteenth century. In the bottom-right photo, an obelisk marks the path called Elliot's Pass, built in 1840.
Far away from the summit, along the eastern side of Green Mountain, the landscape becomes more barren and the vegetation is limited to low bushes.
On the left, prickly pears try to make their way through the most recent lava, while the picture on the right, shows gray and orange lichens starting to colonize the rocks.
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