Allometry, biomass, and productivity of mangrove forests: A review

Study Number:

50

Author:

A. Komiyama, J. E. Ong, S. Poungparn

Abstract:

We review 72 published articles to elucidate characteristics of biomass allocation and productivity of mangrove forests and also introduce recent progress on the study of mangrove allometry to solve the site- and species-specific problems. This includes the testing of a common allometric equation, which may be applicable to mangroves worldwide. The biomass of mangrove forests varies with age, dominant species, and locality. In primary mangrove forests, the above ground biomass tends to be relatively low near the sea and increases inland. On a global scale, mangrove forests in the tropics have much higher above-ground biomass than those in temperate areas. Mangroves often accumulate large amounts of biomass in their roots, and the above-ground biomass to below-ground biomass ratio of mangrove forests is significantly low compared to that of upland forests (ANCOVA, P < 0.01). Several studies have reported on the growth increment of biomass and litter production in mangrove forests. We introduce some recent studies using the so-called ‘‘summation method’’ and investigate the trends in net primary production (NPP). For crown heights below 10 m, the above-ground NPP of mangrove forests is significantly higher (ANOVA, P < 0.01) than in those of tropical upland forests. The above-ground litter production is generally high in mangrove forests. Moreover, in many mangrove forests, the rate of soil respiration is low, possibly because of anaerobic soil conditions. These trends in biomass allocation, NPP, and soil respiration will result in high net ecosystem production, making mangrove forests highly efficient carbon sinks in the tropics.

Main Results and Conclusions:

• What is allometry? “In many organisms, the growth rate of one part of the organism is proportional to that of another. This is the basic theory of allometric relationships, and therefore, the trunk diameter of a tree is, for example, highly correlated with trunk weight”(129).
• Healthy mangroves support high above and below ground biomass (131).
  • “The highest above-ground biomass, 460 t ha-1, was found in a forest dominated by R. apiculata in Malaysia (Putz and Chan, 1986 )” (131).
  • “The lowest aboveground biomass reported was 7.9 t ha-1 for a Rhizophora mangle forest in Florida, USA (Lugo and Snedaker, 1974)”(131).
  • “…in low latitudes, primary or mature mangrove forests generally have high above-ground biomass. The above-ground biomass is always low in temperate areas and may be related to different climatic conditions, such as temperature, solar radiation, precipitation, and frequency of storms”(131).

• Mangroves provide important habitat to other micro and macro organisms (134-135). 
• Productivity trends in mangroves is reported: “…the above-ground NPP”-net primary productivity-“of mangrove forests tends to be high compared to tropical upland forests, at least in the range of H < 10 m. The high NPP of mangrove forests may be partly due to their high litter production rates”(135).
• Low soil respiration seen in mangrove forests suggests that mangroves are good at sequestering carbon dioxide (135).
• In terms of net ecosystem productivity (NEP), the review of two studies, Komiyama (2006) and Pregitzer and Euskirchen (2004), showed that NEP increases with age of a mangrove stand. An increased NEP in mangrove ecosystems may attribute to better carbon sequestering (136).
• To summarize, mangroves are good for carbon sequestering because they have large biomass, a generally high net primary productivity, and low soil respirations.

Works Cited:

Komiyama, A., 2006. What is required for scientists towards the mangrove management? In: Kyoto Symposium on Mangrove Management. pp. 1–17.

Lugo, A.E., Snedaker, S.C., 1974. The ecology of mangroves. Ann. Rev. Ecol. Syst. 5, 39–64.

Pregitzer, K.S., Euskirchen, E.S., 2004. Carbon cycling and storage in world forests: biome patterns related to forest age. Glob. Change Biol. 10, 2052– 2077.

Putz, F., Chan, H.T., 1986. Tree growth, dynamics, and productivity in a mature mangrove forest in Malaysia. Forest Ecol. Manage. 17, 211–230.