Thread by @RewildingS

(1/11) It turns out #rewilding is all about #tortoises! Here’s another Mauritius tortoise paper for you by Griffiths et al. (2014), where they look at non-native tortoise grazing as a long-term restoration strategy.

(2/11) First, some context. Round Island restoration began in the 1970's by removing introduced herbivores (rabbits and goats). They previously grazed non-natives preventing non-natives out-competing native plants, although also prevented native forest regrowth.

(3/11) When non-native herbivores (rabbits and goats) were removed, non-natives plants out-competed native plants. Restoration efforts has involved manually promoting forest regrowth and manually clearing non-native plants.

(4/11): The authors conducted an 11-month enclosure experiment to see the effects of Aldabra giant tortoise and Madagascan radiate tortoise grazing on plant communities, in comparison to free-roaming tortoises.

(5/11) This was to see whether these non-native herbivores could act as functional surrogates for the extinct Mauritian giant tortoises, as well as being a more cost-effective way for restoration projects.

(6/11) Tortoises reduced vegetation height, plant cover, and plant biomass. This effect was generally greater by Aldabran giant tortoises.

(7/11) This influenced the abundance of adult plants, seedlings, flowers and seeds, and again this was greater in Aldabran tortoise enclosures.

(8/11) In free-roaming tortoises, similar effects were found in grazing plots, and ~90% diet consisted of non-native plants. Therefore, they were pretty effective at controlling the abundance and biomass of non-native plant species.

(9/11) Functional analogues were more cost-effective for non-native plant control in the long-term. Initial costs were 6-times higher but, after six years, human labour costs overtake the cost of using tortoises as functional surrogates.

(10/11) Despite this, the authors do conclude that human intervention is still likely necessary to maintain species diversity and restore rare native plants across the island.

(11/11) The authors remind us that caution is required with functional analogues, however these results continue to show the benefits of functional surrogates across spatial and temporal scales.

Here at @RewildingS, we hope everybody is doing alright out there. Hopefully this snippet of information is somewhat a small distraction from everything else going on. Remember #StayHome.

Some corrections...oops. Paper is 2013, the full link is here: conbio.onlinelibrary.wiley.com/doi/full/10.11…