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May
8
2008
Loss of seed dispersers has far-reaching ecosystem impacts
Rewilding is a controversial topic: when important native species have gone, is it OK to bring in exotic alternatives to perform an essential ecosystem role? This week in PLoS ONE Stanford University researcher Dennis Hansen and colleagues report on their experiments to help save the critically endangered tree Syzygium mamillatum, which grows only on the famously dodo-devoid oceanic island of Mauritius. Plants often depend on large herbivores to disperse their seeds: Hansen’s experiments addressed the Janzen-Connell effect, whereby seedling survivorship increases dramatically with dispersal distance by virtue of escaping the specialist herbivores that plague its poor mother. Using Aldabra tortoises Aldabrachelys gigantea as willing stand-ins for the two extinct Mauritanian giant tortoise species Cylindraspis triserrata and C. inepta, Hansen’s team recorded seedling survival in relation to distance from a mature tree and whether it had passed through the gut of one of those lucky tortoises. Despite relatively few gut-passed seeds surviving the ordeal, and coupled with a lower germination rate, the fact that they are likely to be deposited many meters from their parent tree could mean an overall benefit to tortoise seed predation. So, should tortoises be brought in to help save S. mamillatum? After all, they’re not exactly the most difficult animals to keep track of… Source: Hansen DM, Kaiser CN & Müller CB (2008) Seed dispersal and establishment of endangered plants on oceanic islands: the Janzen-Connell model, and the use of ecological analogues. PloS ONE DOI: 10.1371/journal.pone.0002111
Image © Dennis Hansen
Filed Under Endangered species, Habitat, Invasive species, Monitoring, Restoration, Socio-political issues, Tools and technology |
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The Nutcracker’s Eats – and More Recent PLoS ONE News Coverage…
During the last week of April and the first week of May, PLoS ONE published over 100 papers, with another 57 following today. With such a great range of papers, covering topics from some very noisy bats and the eating habits of Paranthropus boisei, to …