COS 17-9
Distribution of Eucalytus deglupta in volcanically disturbed landscape in Papua New Guinea
The Lake Hargy Caldera (LHC) of Papua New Guinea is one of several major calderas on the island of New Britan. The island breached the ocean surface in the late Miocene (8-10 million years ago) as the result of volcanic uplift, and the Quaternary volcanoes found there define the Bismark volcanic arc that formed in response to northward subduction of the small Solomon plate beneath the Bismark plate.The latest caldera-forming eruption of Hargy volcano took place about 11,000 years ago. The result of both historic and recent volcanic activity has produced four distinctive areas within the 10 x 12 km caldera. Eucalyptus deglupta is a canopy emergent tropical species whose natural range includes the Bismark Archipelago. Naturally occurring E. deglupta is a fast growing, shade intolerant species that rapidly colonizes disturbed areas of primary rainforest. Explorations within the LHC in 2009-2011 have begun to document the spatial distribution and population structure of E. deglupta within the closed broadleaf lowland rainforest within the caldera. Four separate stands were located and diameter at breast height (DBH) of 25 to 50 trees were measured within three stands to begin to describe the structure and distribution of E. deglupta stands.
Results/Conclusions
Tree stands along the drainage river had mean DBHs of 180cm (+50) cm. and ranged 80cm to 350cm. In contrast, trees along the lake edge had DBHs of approximately 80 cm (+80) but a range of 10 cm to 300 cm). Frequency distributions of DBHs show distinct differences among stands o0f E. deglupta within the caldera. Differences among stands in mean DBH and distribution suggest different stand genesis events and subsequent successional patterns. Such patterns can then be used to infer possible scenarios for stand establishment.