Giant Tortoise Exclosures on Aldabra

Tortoise turf is a (by island standards) species-rich micro-plant community that is heavily cropped by herds of grazing giant tortoises. Exactly how tortoise grazing structures this plant community is unknown. To investigate this, three ZARP/URPP-GCB researchers (Rich Baxter, Wilfredo Falcon, and Dennis Hansen) and a Seychelles Islands Foundation ranger spent a month in a ramshackle hut on the far eastern end of Aldabra Atoll. The main objective was to build five 6x6 m exclosures on the tortoise turf. Hauling some 900 kilos of wood and wire mesh up to 3 km inland from the coast was a test of brute strength, while assembling the enclosures was a test of team work. Together with adjacent control plots, the enclosures will be regularly surveyed. It is planned to run the exclusion experiment for 5-10 years, investigating the top-down effect of tortoises on the plant- and invertebrate community and on soil processes.

Photo: From top left going clockwise: tortoise turf, exclosures on the tortoise turf (2x) and field station. Picture Dennis Hansen, 2014.

Veruska Muccione

News