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Hurricane disturbance accelerates invasion by alien tree Pittosporum undulatum in Jamaican montane rain forests

Biodiversity Conservation, BRB

Available Online

Bellingham, Peter J.

Excurra, E.

Healey, John R.

Tanner, Edmund V. J.

Questions: Do past disturbance, soil nutrients, or species diversity predict the invasion success of the alien tree Pittosporum undulatum in an island montane rain forest? What are the consequences of its invasion for forest composition and species diversity? Location: Blue Mountains, Jamaica. Methods: Censuses of trees ? 3 cm DBH in permanent plots in four sites within ca. 7 ha; 19742004 (intensive sites) and in 16 plots within 250 ha; 19902004 (extensive plots). Results: Pittosporum was unrecorded in the intensive sites before a severe hurricane in 1988: by 2004 all four sites were invaded. Pittosporum had invaded 25% of the extensive plots in 1990 and 69% in 2004, where its basal area increased from 0.5 ± 0.4 (SEM) m2.ha?1 in 1990 to 2.8 ± 1.3 m2.ha?1 in 2004. It had zero stem mortality and diameter growth rate exceeded that of native species fourfold. Pittosporum's basal area in the extensive plots in 2004 was positively related to the stand basal area damaged in the 1988 hurricane and negatively related to soil N concentrations. Pittosporum invasion was unrelated to stand-level tree species diversity in the extensive plots but as its basal area increased over time the basal area of native species and stand-level diversity declined. Conclusions: There are no obvious functional attributes of Pittosporum unrepresented in the native tree flora although it has high photosynthetic efficiency compared with native trees. More widespread invasion of these forests by Pittosporum seems inevitable since hurricanes, which accelerated the invasion, affect these forests frequently.

Hurricane Activity and Large-scale Pattern of Spread of an Invasive Plant Species

Biodiversity Conservation, BRB

Available Online

Bhattarai, Ganesh P.

Cronin, James T.

Disturbances are a primary facilitator of the growth and spread of invasive species. However, the effects of large-scale disturbances, such as hurricanes and tropical storms, on the broad geographic patterns of invasive species growth and spread have not been investigated. We used historical aerial imagery to determine the growth rate of invasive Phragmites australis patches in wetlands along the Atlantic and Gulf Coasts of the United States. These were relatively undisturbed wetlands where P. australis had room for unrestricted growth. Over the past several decades, invasive P. australis stands expanded in size by 635% per year. Based on tropical storm and hurricane activity over that same time period, we found that the frequency of hurricane-force winds explained 81% of the variation in P. australis growth over this broad geographic range. The expansion of P. australis stands was strongly and positively correlated with hurricane frequency. In light of the many climatic models that predict an increase in the frequency and intensity of hurricanes over the next century, these results suggest a strong link between climate change and species invasion and a challenging future ahead for the management of invasive species.

Quarantine (Biosecurity) Legislation

Available Online

Government of Samoa

Quarantine (Biosecurity) Act 2005

On Prevention and Control of an Uncertain Biological Invasion

Available Online

Olson, Lars J.

Roy, Santanu

This paper examines how optimal prevention and control policies depend on the economic and biological characteristics of a randomly introduced biological invasion where the objective is to minimise the expected social costs from prevention, control, and invasion damages. The results characterise how optimal prevention and control policies vary with the initial invasion size, the invasion growth rate, and the probability distribution of introductions. The paper also examines the conditions under which the optimal policy relies solely on either prevention or control, the conditions under which it is optimal to completely prevent new introductions, and the conditions under which eradication of established invasions is optimal.

Invasive species : unwelcome pests in the Pacific

Biodiversity Conservation, BRB

Available Online

Secretariat of the Pacific Regional Environment Programme (SPREP)

Invasive species are plants or animals living where they dont belong and causing harm. Also known as introduced, alien or pest species, they are species that have been brought into a new environment and whose introduction can : Threaten many native and endemic species with extinction by eating them or competing for food, light, water or shelter Damage ecosystems so that they are less able to provide essential services such as clean water, erosion protection, insect control etc Harm humans and animals from bites, stings or disease Reduce the tourism attractiveness of an area Impact on the species that Pacific Islanders rely on for their livelihoods

Restoration of Nu'utele & Nu'ulua islands, Aleipata island group, Samoa: report of expedition to trial the capture and holding of friendly ground doves (Gallicolumba stairi)

Available Online

Butler, David J.

The restoration of the Islands of Nuutele and Nuulua is a priority of the Government of Samoa and the communities of Aleipata District. Planning is well advanced on a key element of this, the eradication of Pacific Rats (Rattus exulans) by aerial spreading of toxic baits in mid-2006. The Friendly Ground Dove has been identified as a non-target species that may be at risk of taking the baits and one for which the Nuutele and Nuulua populations are significant. Several approaches for safeguarding these have been discussed and this expedition was designed to test the feasibility of the preferred approach, namely the capture and holding of birds in a safe situation on Nuutele during the aerial operation and their release once the baits are non-toxic.

Restoration of Nu'utele & Nu'ulua islands, Samoa.: 1.0 Eradication of Pacific rat (Rattus exulans) : draft project plan

Available Online

Butler David J.

The islands of Nu'utele and Nu'ulua have been identified as highly significant sites for conservation in Samoa. They hold large populations of species currently found nowhere else in the country' including threatened land-birds, seabirds and nesting turtles. They also are the only offshore islands large enough and far enough offshore to be considered as refuges for several of the nation's species threatened on the larger islands by introduced mammalian pests. Such refuges have assumed greater importance as recent severe cyclones (Ofa - 1990, Val - 1991 & Heta - 2004) have reduced bird and bat numbers.

Restoration of Nu'utele & Nu'ulua, Aleipata islands, Samoa protection of friendly ground dove during proposed rat eradication / D.J. Butler

Available Online

Butler, D.J.

For one of the species potentially at some risk of poisoning under the proposed rat eradication regime, the Friendly Ground Dove, Nuutele and Nuulua hold populations that are nationally significant. The complete loss of these populations would threaten the survival of the taxon in Samoa. Some authors consider the Samoan doves to be a separate race (Gallicolumba s. stairi) from those in Fiji and Tonga (Watling, 2001). Outside Samoa, the race is only found on the small island of Ofu, American Samoa where it is threatened. So the loss of Nuutele and Nu'ulua birds could threaten the race with extinction.

Invasive alien species : a new synthesis / edited by Harold A. Mooney ... [et al.]

Mooney Harold A ... [et al.].

Conservation of kakerori (Pomarea dimidiata) in the Cook Islands in 2003/04

Available Online

Robertson Hugh A

Saul, Edward K

In 1989, the kakerori (Pomarea dimidiata) was one of the 10 rarest bird species in the world, with a declining population of just 29 birds. During each breeding season since then, rats have been poisoned within the 155 ha of forested hill country they occupy in the Takitumu Conservation Area in southeastern Rarotonga. As a result, the kakerori population has rebounded, with a minimum of 292 birds found on Rarotonga in August 2003. In 2001/02, the emphasis of management shifted from the .recovery. of kakerori to a programme aimed at .sustaining. the population at 250.300 individuals. The major changes were an experimental reduction in rat poisoning effort to a level where recruitment of kakerori balances annual mortality, and a series of transfers to establish an insurance population on the island of Atiu. In 2003/04, all bait stations were filled fortnightly, rather than the previous mix of weekly and fortnightly refills. This reduced labour costs by 30% to 32 person days, and used a total of 39 kg of Talon® (active ingredient brodifacoum), which was only 13% of the maximum annual poison use over the same area during the .recovery. phase of the programme. Breeding success was high (0.91 fledglings/ breeding territory), even in the unpoisoned areas, and a record total of 80 fledglings was detected. The fortnightly poisoning regime offers promise as an effective, cheaper and less toxin-intensive method than that used previously, and so we recommend maintaining this regime in 2004/05, so that the longerterm effects can be assessed. A third and final batch of 10 young kakerori was transferred to Atiu Island in August 2003. This .insurance. population is becoming well established; the five breeding pairs monitored in 2003/04 each raised two fledglings, and a minimum of 15 birds was found in May.June 2004 in the small part of the island that was searched.

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