Period: 7 May - 5 June 2003. Country: Indonesia
(1) Elevation Dynamics and Species Coexistence Caused by Heterogeneity in Cycles of Organic Matter in Tropical Peat Swamp Forests
SHIMAMURA Tetsuya  (Division of Southeast Asian Area Studies)
Key Words: Tropical Peat Swamp Forest, Species Coexistence, Biomass, Forest Production and Decomposition, Nutrient Concentration

An uprooted root plate of large buttress

A large buttress tree of Swintonia glauca
(2) In tropical peat swamp forests, the peat surface is characterized by considerable topographic heterogeneity at various scales, ranging from tens of centimeters to several meters. The large buttressed trees have large amounts of roots supporting the aboveground organs. The root architecture raises the peat surface around the buttresses, forming mounds. Some species have numerous pneumatophores that enable root respiration during flooding. Such species are found in non-mounds, while juveniles of other species are found on mounds. This study evaluates the relationship between plant distribution and dynamics of microtopography in a tropical peat swamp forest.

(3) I conducted research in a tropical peat swamp forest in Kermutan Wildlife Sanctuary, Riau Province, East Sumatra, Indonesia in May 2003. The result of spatial point pattern analysis indicated that different types of habitats regulate the regeneration process according to flood-tolerance of trees, and contribute to species coexistence. For example, around the large buttresses there were fewer juveniles of flood-tolerant species and vice versa.
          I studied matter production and nutrient cycles (ingrowth cores, litter traps and decomposition experiments) on different habitats. It was revealed that habitats are maintained by different regimes of decomposition and production, and changes in the balance between production and decomposition lead to changes of microtopography. For example, disturbances of buttressed trees cause the disappearance of mounds because of degraded production, and the establishment of large buttressed trees results in the creation of mounds because of increasing production. The dynamics of microtopography explain the species coexistence on a spatio-temporal scale. The creation and disappearance of mounds provide regeneration niches for flooding-intolerant and -tolerant species, respectively.

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