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Restoration of Mangrove Plantations & Colonisation by Native Species
From Dr. Norm Duke of Mangrove Watch, Australia:
I caution against using exotic species in rehab projects.
Exotic species everywhere have the advantage of escaping predators and diseases when they first arrive in a new location. So, they flourish there, and they appear to be better competitors – even if they are not! Should we wait to find out? I suggest not! I don’t think we can afford to make things more complicated – more degraded. Ecosystems, more than ever before, need maximal resilience to survive anticipated changes.
There are aspects of an infestation that may never be eradicated – assuming people could kill all the introduced S.apetala plants and seeds, for example. If one tsakes on this heavy task, they will know how difficult it is to remove a species in expansion phase.
There are a number of reasons for caution, like upsets to natural ecosystem trophic linkages, but one less discussed change is the possible inclusion of foreign genetic material into native populations – even of different species! I suspect, this happens in mangroves when allopatric congenerics are grown together. And, a hybrid results. For a number of years now, I have been on the trail of mangrove hybrids – and my list is growing (see my recent Blumea papers for new Rhizophora and Bruguiera hybrids in the IWP. Some, of course, are quite old (created by continental drift) – but there is no reason we will not be getting more as further ‘sibling’ species are introduced and grown together. I am quite sure there are hybrids between S.apetala and other Sonneratia species – based on my observations of this genus in the region.
So, even if you were to eradicate all S.apetala that were recently introduced in southern China, the genes of that species will be forever added to the local species. The question is whether this is acceptable – will it change the way the native species behaves? Who knows?! Is it worth the risk?
Exotic species everywhere have the advantage of escaping predators and diseases when they first arrive in a new location. So, they flourish there, and they appear to be better competitors – even if they are not! Should we wait to find out? I suggest not! I don’t think we can afford to make things more complicated – more degraded. Ecosystems, more than ever before, need maximal resilience to survive anticipated changes.
There are aspects of an infestation that may never be eradicated – assuming people could kill all the introduced S.apetala plants and seeds, for example. If one tsakes on this heavy task, they will know how difficult it is to remove a species in expansion phase.
There are a number of reasons for caution, like upsets to natural ecosystem trophic linkages, but one less discussed change is the possible inclusion of foreign genetic material into native populations – even of different species! I suspect, this happens in mangroves when allopatric congenerics are grown together. And, a hybrid results. For a number of years now, I have been on the trail of mangrove hybrids – and my list is growing (see my recent Blumea papers for new Rhizophora and Bruguiera hybrids in the IWP. Some, of course, are quite old (created by continental drift) – but there is no reason we will not be getting more as further ‘sibling’ species are introduced and grown together. I am quite sure there are hybrids between S.apetala and other Sonneratia species – based on my observations of this genus in the region.
So, even if you were to eradicate all S.apetala that were recently introduced in southern China, the genes of that species will be forever added to the local species. The question is whether this is acceptable – will it change the way the native species behaves? Who knows?! Is it worth the risk?
