Infrastructure expansion challenges sustainable development in Papua New Guinea

The island of New Guinea hosts the third largest expanse of tropical rainforest on the planet. Papua New Guinea—comprising the eastern half of the island—plans to nearly double its national road network (from 8,700 to 15,000 km) over the next three years, to spur economic growth. We assessed these plans using fine-scale biophysical and environmental data. We identified numerous environmental and socioeconomic risks associated with these projects, including the dissection of 54 critical biodiversity habitats and diminished forest connectivity across large expanses of the island. Key habitats of globally endangered species including Goodfellow's tree-kangaroo (Dendrolagus goodfellowi), Matchie's tree kangaroo (D. matschiei), and several birds of paradise would also be bisected by roads and opened up to logging, hunting, and habitat conversion. Many planned roads would traverse rainforests and carbon-rich peatlands, contradicting Papua New Guinea's international commitments to promote low-carbon development and forest conservation for climate-change mitigation. Planned roads would also create new deforestation hotspots via rapid expansion of logging, mining, and oil-palm plantations. Our study suggests that several planned road segments in steep and high-rainfall terrain would be extremely expensive in terms of construction and maintenance costs. This would create unanticipated economic challenges and public debt. The net environmental, social, and economic risks of several planned projects—such as the Epo-Kikori link, Madang-Baiyer link, Wau-Malalaua link, and some other planned projects in the Western and East Sepik Provinces—could easily outstrip their overall benefits. Such projects should be reconsidered under broader environmental, economic, and social grounds, rather than short-term economic considerations

Home range of the Huon tree kangaroo, Dendrolagus matschiei, in cloud forest on the Huon peninsula, Papua New Guinea

Tree kangaroos (Marsupialia: Macropodidae, Dendrolagus) are some of Australasia's least known mammals. Basic questions concerning the population and conservation status of many species remain unanswered. However, there is sufficient anecdotal evidence of population decline and local extinctions to designate tree kangaroos as New Guinea's most endangered mammal group. Tree kangaroo home ranges were sampled at one site in Papua New Guinea (Wasaunon). Radio telemetry analyses were used to estimate home range sizes, which were estimated to be 81.8 ± 28.8 ha for males and 80.8 ± 20.3 ha for female Huon tree kangaroos (Dendrolagus matschiei). Food plants species for Huon tree kangaroos (D. matschiei), were collected at Wasaunon with the aid of landowners, and later identified by botanists in Papua New Guinea and Australia. The collections support Australian data that tree kangaroos are browsers, with the largest proportion of their diet coming from leaves and shoots from a wide variety of plants from at least 18 families for the Huon tree kangaroos, and at least 40 families from a previous study conducted in the same region (Dendawang) approximately 35km southeast of Wasaunon. Landowners from different areas of the region were in agreement that tree kangaroos prefer eating leaves and stems of plants, with fruits and flowers comprising a relatively minor proportion of the animals' diets. Additional information on tree kangaroo biology and conservation status was obtained through the use of informal landowner interviews. Interviews did not produce quantifiable results, but they did give some insights into tree kangaroo food plant species and human utilisation. The responses indicated that over 70 species of food plants were being utilized by the Huon tree kangaroos, D. matschiei, at Wasaunon, and an additional 91 species from Dendawang

Spatial Requirements of Free-Ranging Huon Tree Kangaroos, Dendrolagus matschiei (Macropodidae), in Upper Montane Forest

Tree kangaroos (Macropodidae, Dendrolagus) are some of Australasia's least known mammals. However, there is sufficient evidence of population decline and local extinctions that all New Guinea tree kangaroos are considered threatened. Understanding spatial requirements is important in conservation and management. Expectations from studies of Australian tree kangaroos and other rainforest macropodids suggest that tree kangaroos should have small discrete home ranges with the potential for high population densities, but there are no published estimates of spatial requirements of any New Guinea tree kangaroo species. Home ranges of 15 Huon tree kangaroos, Dendrolagus matschiei, were measured in upper montane forest on the Huon Peninsula, Papua New Guinea. The home range area was an average of 139.6±26.5 ha (100% MCP; n = 15) or 81.8±28.3 ha (90% harmonic mean; n = 15), and did not differ between males and females. Home ranges of D. matschiei were 40–100 times larger than those of Australian tree kangaroos or other rainforest macropods, possibly due to the impact of hunting reducing density, or low productivity of their high altitude habitat. Huon tree kangaroos had cores of activity within their range at 45% (20.9±4.1 ha) and 70% (36.6±7.5 ha) harmonic mean isopleths, with little overlap (4.8±2.9%; n = 15 pairs) between neighbouring females at the 45% isopleth, but, unlike the Australian species, extensive overlap between females (20.8±5.5%; n = 15 pairs) at the complete range (90% harmonic mean). Males overlapped each other and females to a greater extent than did pairs of females. From core areas and overlap, the density of female D. matschiei was one per 19.4 ha. Understanding the cause of this low density is crucial in gaining greater understanding of variations in density of tree kangaroos across the landscape. We consider the potential role of habitat fragmentation, productivity and hunting pressure in limiting tree kangaroo density in New Guinea rainforests

Forest edge disturbance increases rattan abundance in tropical rain forest fragments

Human-induced forest fragmentation poses one of the largest threats to global diversity yet its impact on rattans (climbing palms) has remained virtually unexplored. Rattan is arguably the world’s most valuable non-timber forest product though current levels of harvesting and land-use change place wild populations at risk. To assess rattan response to fragmentation exclusive of harvesting impacts we examined rattan abundance, demography and ecology within the forests of northeastern, Australia. We assessed the community abundance of rattans, and component adult (>3 m) and juvenile (≤3 m) abundance in five intact forests and five fragments (23–58 ha) to determine their response to a range of environmental and ecological parameters. Fragmented forests supported higher abundances of rattans than intact forests. Fragment size and edge degradation significantly increased adult rattan abundance, with more in smaller fragments and near edges. Our findings suggest that rattan increase within fragments is due to canopy disturbance of forest edges resulting in preferential, high-light habitat. However, adult and juvenile rattans may respond inconsistently to fragmentation. In managed forest fragments, a rattan abundance increase may provide economic benefits through sustainable harvesting practices. However, rattan increases in protected area forest fragments could negatively impact conservation outcomes.Peer reviewe

The proportional incremental change in home range area, moving out from the centre of activity in increments of 5% isopleths (means ± standard error; n = 15).

<p>Core areas corresponded to minima on the curve and the 90% isopleth was taken to represent the entire range- excluding the strong effects of outliers that increased the incremental changes at more inclusive isopleths (i.e. 95% and 100%). A) Harmonic mean; minima are at 45% and 70%. B) Kernel; minima are at 50% and 75%.</p

Home ranges of male Huon tree kangaroos, <i>D. matschiei</i>, at Wasaunon, Huon Peninsula, Papua New Guinea.

<p>A) 45% harmonic mean isopleth core areas with minimal overlap between neighbouring males. B) 90% harmonic mean isopleth areas with extensive overlap between neighbouring males. Ranges of individual males are denoted with different line styles.</p

Spatial arrangement of the genders in Huon tree kangaroo home ranges.

<p>These are 45% harmonic mean isopleth core areas, showing that both males and females have relatively exclusive core ranges with respect to their own gender, but that males tend to overlap several females. Female ranges are denoted by broken lines and males by unbroken lines.</p