The human-made cloud forest on Green Mountain, Ascension Island represents an example of how unrelated and unassociated plant species can form a functioning ecosystem without a shared evolutionary history. 19th-century accounts of the island, including that of Charles Darwin on his expedition aboard the Beagle, described the rocky island as destitute and bare. Plants were brought to the island by colonists, but the most important change occurred in 1843 with the terraforming of Green Mountain by botanist Joseph Dalton Hooker, who recommended planting trees on Green Mountain and vegetation on the slopes to encourage deeper soils. Plants were regularly sent from England until, in the 1920s, the mountain was green and verdant, and could be described as a functioning cloud forest. Although some of the species likely were introduced together because of their coevolutionary relationships, the overwhelming mechanism governing relationships is clearly ecological fitting. The system has changed dramatically and even provides ecosystem services such as carbon sequestration, all as a result of ecological fitting. This is important in the light of climate change for two reasons: species ranges may be shifting dramatically, and ecological fitting is an important mechanism for the construction of communities over ecological time, and it shows that human-made systems could be integral in the mitigation of climate change.