Influence of species richness and environmental context on early survival of replanted mangroves at Gazi bay, Kenya
Kirui, B. Y. K.; Huxham, M.; Kairo, J.; Skov, M. (2008). Influence of species richness and environmental context on early survival of replanted mangroves at Gazi bay, Kenya. Hydrobiologia 603: 171-181. dx.doi.org/10.1007/s10750-007-9270-3
In: Hydrobiologia. Springer: The Hague. ISSN 0018-8158; e-ISSN 1573-5117, more
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| Author keywords |
Mangrove reforestation, survival, salinity, species richness and ecosystem function, environmental context, Kenya |
| Authors | | Top |
- Kirui, B. Y. K.
- Huxham, M.
- Kairo, J., more
- Skov, M.
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| Abstract |
Mangrove reforestation projects often suffer from low sapling survival, especially after transplanting saplings from nurseries to reforestation areas. This may be due to the sediment conditions at the target site, the planting strategy or failure to re-establish ecosystem processes. We examined experimentally the influence of environmental context, species richness and identity, sapling height and position on sapling survival and environmental variables linked to ecosystem functioning at deforested sites in Gazi Bay, Kenya. At site 1, a high shore location, 32 plots (36 m2) were planted with 8 treatments: all possible combinations of Avicennia marina, Bruguiera gymnorrhiza, andCeriops tagal and an unplanted control (total: 3390 saplings; 4 plots/treatment). At site 2, a low shore location, the influence of sapling height, sapling position and sediment depth were tested by planting with 697 Sonneratia alba in a single monospecific plot (341 m2). After ~2 years, there were significant differences in survival among the three species at site 1 with Bruguiera gymnorrhiza recording the lowest survival rate (29%). Survival was correlated with salinity (a strong effect) and height above chart datum (a weaker effect) at site 1. Sapling position did not significantly affect survival at either site. There was thus no evidence that early survival of transplanted saplings is influenced by the species mix in which they are grown, or by their position in the plot. Rather the tolerance of individual species to salinity was the key to their survival at the high tidal site. Species mix also had no significant effects on environmental variables in the plots. The former presence of a species at a site does not guarantee it will succeed there again if environmental degradation has exceeded species’ tolerance. |
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