Endemic flora
Seven endemic vascular plant species remain on Ascension out of an original ten that have been scientifically described since humans first discovered the island in 1501. In addition, at least sixteen of Ascension’s eighty native mosses, liverworts and hornworts are endemic
Ascension’s endemic plants adapted to colonise a young volcanic landscape, isolated from most competitors, pests and herbivores. Dramatic changes to the island since human arrival, including the introduction of goats, rats, mice and over 400 plant species, have reduced and fragmented the ranges of many endemics.
With the few remaining sub-populations isolated and limited in genetic diversity, they are increasingly prone to extinction and potentially more vulnerable to climate change. Moreover, rain is scarce on Ascension. Already pushed to remote, dry fringes of the arid lowlands, an increased drought risk could present a major risk to the Ascension spurge, Euphorbia origanoides. Meanwhile, endemic plants that grow on Green Mountain, the island’s highest peak, rely on fog near the summit for moisture. If climate change raises the cloud level and leaves the mountain immersed in fog less often, fog-dependent ferns, grasses and bryophytes are likely to suffer from more frequent and prolonged droughts.
The first element of the project will be to better understand the issues faced by the island’s endemic flora:
Researchers at the University of East Anglia are working to produce specific, local predictions of how Ascension’s climate will change.
Scientists from the French National Institute for Agricultural Research will also be studying how the Ascension spurge performs under different drought stress scenarios, while Ascension’s Conservation and Fisheries Directorate will monitor soil moisture levels across the spurge’s range to determine how conditions vary spatially.
On Green Mountain, we will monitor how vegetation structure affects moisture capture from incoming mist.
Armed with this information, the CRACAB team will then be better able to manage endemic flora to improve its resilience to climate change. We plan to investigate the following management options:
We aim to translocate Ascension spurge to areas of the island which will be most suitable for survival under the future climate, taking into account how hydrological factors meet the species’ needs. Initially the colonies will be managed, by building passive irrigation systems, until they are well established and have developed a self-sustaining seedbank.
For our mountain plants, there has always been a need to control invasive species. However, we will aim to build-back better communities which are more resistant to reinvasion and have enhanced capacity for mist-interception. We will create nets on the mountain to harvest fog water and channel it into storage tanks, using passive irrigation systems to help the communities establish. We will also trial artificial mist interception techniques directly, allowing water to be dripped onto sensitive bryophyte banks, sustaining them through lengthening dry spells.

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NEWS & UPDATES
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