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S. G. Haberle


arboreal pollen

swamp Myrtaceae


charcoal density

Kelela Swamp



Nurenk Swamp







12 10 8 6 4 2 0 age (103 years BP)

12 10 8 6 4 2 0

age (103 years BP)

8 4 0

12 10 8 6 4 2 0 age (103 years BP)

1 0.5 0

12 10 8 6 4 2 0 age (103 years BP)

Norikori Swamp

Figure 2. Summary of major changes in pollen records from five highland valleys during the Late Glacial transition and through the Holocene. The four graphs show arboreal taxa, swamp Myrtaceae (dominantly Syzygium), Casuarina pollen percentages (of total pollen sum excluding aquatics) and charcoal density (500 years interpolated sample interval, note different y-axis scales).

by mixed Castanopsis/Lithocarpus forest in the valley. Accession of clays and silts to the site was followed by evidence for widespread forest disturbance, burning and Myrtaceae–Pandanus swamp forest clearance by around 7000 yr BP. After this, forest clearance and burning continued with only minor reversals through to 3000 yr BP, when extensive grassland areas were established. There is a marked rise in Casuarina pollen around 1100 yr BP, suggesting that deliberate planting of this tree may have become important at this time.

(b) Ifitaman Valley The township of Telefomin lies in the Ifitaman Valley at an altitude of around 1500 m. In contrast to the Baliem Valley, Nothofagus-rich forest remains a relatively important forest element throughout the 20 000-year pollen record, despite the relatively low elevation (Hope 1983). Around 12 000 yr BP, regional warming produced a shift in forest composition to a more mixed Nothofagus forest, with only a slight rise in Castanopsis/ Lithocarpus. The Telefomin pollen record shows a major disturbance event between 11 500 and 8500 yr BP, which is possibly discontinuous (inferred from Hope 1983; figure 3), and is interpreted as anthro- pogenic burning and local forest clearance followed by abandonment and reestablishment of primary forest. Another period of disturbance occurs only after 4500 yr BP, when grassland expands rapidly to its present extent, and forest and Myrtaceae swamp forest are cleared from the site. Casuarina appears to be grown in the valley only after 1000 yr BP, in line with the evidence from the Tari Basin and the Baliem Valley. However, unlike these two regions, the extensive grasslands around Telefomin today are rarely used for agricultural purposes and are infrequently burnt.

dominance at different times. The Early Holocene is marked by the development of swamp forest vegetation and a peak in the pollen diversity. This is maintained until around 3000 yr BP when there are indications of swamp forest disturbance, a decline in the pollen diversity and the key indicator taxa, followed by swamp forest clearance commencing around 1700 yr BP.

(d) Jimi Valley Nurenk Swamp (Gillieson et al. 1989) lies at an altitude of 1900 m in the Jimi Valley and shows that a Myrtaceae swamp forest existed around the site prior to 3500 yr BP. Possible watertable changes, tephra-fall events and human activity may have disturbed the site and resulted in the loss of swamp forest cover. Forest disturbance continues until 300–400 yr BP when increased burning and a rise in Casuarina pollen indicated a strong human influence on the site.

(e) Kainantu Valley Norikori Swamp (Haberle 1996) lies at an altitude of 1750 m in the Kainantu Valley and shows that a Myrtaceae–Pandanus swamp forest existed on the site for an undetermined time before 5000 yr BP. Disturb- ance of forest and clearance is already evident by the time Holocene sedimentation begins around 5000 yr BP. Features purported to be fossil agricultural structures in the nearby Arona Valley are dated to around 4500 yr BP and are associated with pollen assemblages representing deforested conditions (Golson & Gardner 1990; Haberle 1996). Forest clearance and burning continue gradually until 1500 yr BP when rapid vegetation change towards an extensive grassland landscape, similar to the present, occurs. Casuarina begins to increase around 600 yr BP.

(c) The Tari Basin Haeapugua lies at an altitude of 1650 m in the Tari Basin and is the only published continuous pollen record from the highlands of New Guinea that spans at least 30 000 yr BP to the present (Haberle 1998b). The record shows that the montane tree Nothofagus is important through- out the record, though other trees, including Castanopsis/ Lithocarpus, Myrtaceae, Dacrydium and Pandanus, attain

4. PALYNOLOGICAL RICHNESS AS AN INDICATOR OF BIODIVERSITY LOSS IN SWAMP FORESTS DURING THE HOLOCENE Palynological richness and the presence of key indicator taxa are used to develop an understanding of biodiversity change through time in the Tari Basin, the one site in the highland valleys that has a continuous record over at least 30 000 years (Haberle 1998b). The pollen diagram (figure 3) and a summary

Phil. Trans. R. Soc. B (2007)

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