Abstract
This paper quantifies the relationships among community type, peat layer thickness and habitat age of the mangrove forests in Pohnpei Island, Micronesia and provides a discussion concerning the primary succession and the belowground carbon storage of the main mangrove community types. The ages of the habitat were estimated from a relationship between the thickness of the mangrove peat layer and the formative period, which was decided by calibrated radiocarbon ages. Mangrove communities in the coral reef type habitat were generally arranged in the following order, from seaward to landward: 1) the Rhizophora stylosa or Sonneratia alba community (I or II communities), 2) the typical subunit of the S. alba subcommunity of the Rhizophora apiculata— Bruguiera gymnorrhiza community (III(2)a subunit) and 3) the Xylocarpus granatum subunit of the same subcommunity of the same community (III(2)b subunit). Their habitat ages were estimated to be younger than 460 years, between 360 and 1070 years and between 860 and 2300 years, respectively. Based on these results and other evidences such as photosynthetic characteristics and pollen analysis derived from the previous studies, the primary succession was inferred to have progressed in the order mentioned above. Belowground stored carbon for the main community types in the coral reef type habitat were estimated to be less than 370 t C ha-1 for the I and the II communities, between 290 and 860 t C ha-1 for the III(2)a subunit and between 700 and 1850 t C ha-1 for the III(2)b subunit.
Highlights
The mangrove forests on Pohnpei Island, in the Federated States of Micronesia, have not significantly suffered from human impact
We have studied formative processes of mangrove habitats to predict the effects of anticipated rapid sea-level rise induced by global warming (e.g. Miyagi & Fujimoto, 1989; Kikuchi, 1995) and elucidated forest structure, dynamics, biomass, productivity, and carbon storage abilities of mangrove forests across different habitat types on five permanent plots of 0.1 to 1 ha (e.g. Fujimoto et al, 1995b, 1999b, 2013; Tabuchi, 2006)
Thickness of mangrove peat the III(2)a subunit and the III(2)b subunit were estimated to be younger than 400 years, between 430 and 460 years, younger than 460 years, between 360 and 1070 years and between 860 and 2280 years, respectively (Figure 4). These results suggest that the primary succession of mangrove forest in Pohnpei has progressed in the order mentioned above, along with a relative rise in the ground level as a result of peat accumulation
Summary
The mangrove forests on Pohnpei Island, in the Federated States of Micronesia, have not significantly suffered from human impact. This means that a clear zonation of mangrove communities can be found on the Island. Fujimoto et al, 1995b, 1999b, 2013; Tabuchi, 2006) Through these studies, we have accumulated the phytosociological data necessary to classify community types, as well as the geomorphological data necessary to estimate the peat depth and habitat age. We discussed the successional trends using the data obtained before 1993 to describe the relationship between community types and peat depth in relation to rise in sea-level (Kikuchi et al, 1999)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
