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Ecosystem Profile: Polynesia-Micronesia

Synopsis of Threats and Constraints
The major threats to Pacific biodiversity are human induced and include invasive species, habitat alteration and loss, destructive harvest techniques and over-exploitation of natural resources. An analysis of data on the globally threatened species in the hotspot indicates that habitat loss and invasive species are the two most serious threats (IUCN Red List 2003). The impact of extreme natural events such as cyclones, drought, and fire may also be significant at times. The future impact of climate change and sea level rise is uncertain at this stage but could be significant, especially on the low lying islands and atolls which could disappear completely (SPREP 1992, Allison and Eldredge 1999).

While many of the threats to native Pacific biodiversity are similar to those in other tropical regions of the world, Pacific island biotas are particularly vulnerable because the biota evolved in the absence of mammalian predators, grazing herbivores and many of the diseases that evolved on larger land masses (Allison and Eldredge 1999). Furthermore, the small size and isolated nature of Pacific islands results in increased vulnerability to disturbances that may be relatively minor on a larger land mass (SPREP 1992).

Threats to Pacific biodiversity are on the increase. Population growth in most countries in the hotspot is in the range of 1-3 percent per annum (SPC 2003a) and there is increasing commercialization, monetization and globalization of Pacific economies. Coupled with these changes in socioeconomic systems has been an erosion of traditional knowledge and traditional systems of resource management.

The outcome of the combination of extreme fragility and increasing threat is that the biological diversity in the Polynesia-Micronesia Hotspot is one of the most highly threatened in the world. Today, only 10,024 square kilometres, or 21 percent of the region’s original vegetation, remain in more or less pristine condition throughout the hotspot (Allison and Eldredge 1999). Rates of deforestation range between 0 and 4 percent per annum in some countries (FAO 2003).

There are a number of constraints to mounting an effective response to environmental threats in most countries in the hotspot. Except in the larger, more developed states and territories, the major constraints include a paucity of technical infrastructure and expertise, a lack of current information on the state of natural resources and biodiversity, a poor understanding of environmental issues amongst the general population, and poor integration of environmental issues in national development planning.

Main Threats

Invasive species
Invasive species (both native and non-native) are arguably the major threat to Pacific biota and native ecosystems. Approximately three quarters of the 476 globally threatened species in the hotspot are threatened by invasive species (IUCN 2003). Invasive species were highlighted as a major threat at all three subregional workshops held during profile preparation. This makes the Pacific islands quite unique in their conservation situation compared with other tropical regions (Olson and Farley 2003). The major challenge is not only to control populations of existing invasive species, but also to prevent new introductions.

Ever since humans first colonized islands of the hotspot up to 3,000 years ago, introduced plants and animals have had a significant impact on native biota. The early Polynesians and Micronesian colonists deliberately introduced a number of plants and animals for food, medicines, building materials, and ornamentation. Some of these deliberate introductions, and other species that were introduced accidentally, became pests. Examples include pigs, dogs, and Pacific rats (Rattus exulans). However, following European colonization from the mid 19th Century onward, hundreds more species were introduced, many accidentally. Now, in many countries in the hotspot, there are as many or more introduced plant species and higher vertebrates as native species and the region is now full of examples of alien species that have become serious pests.

It is not known exactly how many invasive species there are on islands in the hotspot, but it certainly runs into the hundreds. The Pacific Island Ecosystems at Risk database (PIER 2004) lists 297 plant species that are invasive in the hotspot region, with another 125 potentially invasive plant species present in the Pacific (Space pers.comm. 2004). Approximately 82 land snails have been introduced to Pacific islands, many of which are invasive (Cowie 2001). The number of invasive species in other taxonomic groups is not known. The most serious invasive species vary from country to country in the hotspot but there are a few species that appear to be a problem on almost every island. Rats, especially the Pacific rat, and introduced arthropods such as ants, are particularly widespread (ISSG 2003). Other serious invasive species are not widespread but could cause devastation if allowed to spread further. In addition to the PIER database, another source of information on the distribution of invasive species in the hotspot is the Global Invasive Species Database (ISSG 2003). This database was provided to the ecosystem profile team to help inform CEPF strategy development. ISSG has commited to distribute the database on CD-ROM in the Pacific region to help increase public awareness about invasive species and to facilitate effective prevention and management activities.

The classic example of the impact of an introduced predator, is the brown tree snake (Boiga irregularis). In the past 40 to 50 years, this predator from the Papua region has caused the extinction of nine of 11 native species of forest birds and the apparent extinction of three skink species and two species of gecko on Guam (Sherley and Lowe 2000). The snake has now spread to Saipan and there are serious fears that if the snake were to spread throughout the Pacific it would cause similar devastation (Allison and Eldredge 1999).

Fourteen alien vertebrates are considered "significant invasive species" in the South Pacific and Hawaii (Atkinson and Atkinson 2000). The most widespread are pigs, goats, cattle, cats, dogs, mice, and the three species of rat (ibid). The Pacific (Rattus exulans) and ship (or black) rats (R. rattus) are particularly serious pests and consume a wide range of prey including fruits, seeds, insects, snails, lizards and birds, including eggs and nestlings (Sherley and Lowe 2000). Pigs, goats, and cattle cause habitat disturbance by eating tree seedlings and thereby slowing forest regeneration and reducing native plant diversity (ibid). Both dogs and cats prey on seabirds and landbirds particularly surface nesting species, while cats also prey on skinks and geckos (Atkinson and Atkinson 2000). Mongooses are major predators on snakes, insects, frogs and on birds, especially ground dwelling species such as rails. Luckily they are only found on Hawaii and Fiji. Introduced birds, such as the Indian mynah bird, are a problem on some islands where they compete with native birds for food and nest sites and may introduce diseases.

Arthropods are the most numerous invasive species on islands and ants probably pose the greatest arthropod threat to conservation in the Pacific (Nishida and Evenhuis 2000). The potentially most damaging ant invaders include the bigheaded ant Pheidole megacephala, the long legged or crazy ant Anoplolepis longipes, the Argentine ant Lineopthema humile, little fire ant Wasmannia auropunctuta, and others (ibid). Characteristics of ants that make them so destructive include the formation of large, non-competitive multi-queen colonies, the ability to hitchhike readily, highly aggressive behaviour and the limited number of effective control options. Lowland native vertebrates and invertebrates such as crabs, snails and aquatic and semi-aquatic invertebrates have all been decimated by introduced ants by predation, direct competition and by creating favourable conditions for other invasive biota (ibid).

Introduced land snails have decimated native snail species on many islands in the hotspot. The high islands appear to have the highest snail diversity, and are therefore at greatest risk from introduced snail species. The carnivorous rosy wolf snail, Euglandina rosea was introduced to control another introduction, the giant African snail (Achatina fulica), but has unfortunately decimated native land snails, especially in Hawaii, French Polynesia, Guam and American Samoa. On Guam, the flatworm Platydemus manokwari was also introduced to control the Giant African snail and has also impacted native species. Neither of the two introduced biological control agents appear to be effective control of A. fulica populations. Other examples of introduced invasive molluscs include species from the terrestrial Subilinidae, Helicidae, and Helicarionadae families, and freshwater species such as apple snails and Lymnaeid snails (Cowie 2000).

Hundreds of plants have been introduced to islands in the hotspot and more than 30 invasive alien plant species are considered to have become serious threats to native habitats of Pacific islands (Meyer 2000). The impacts of invasive plants on native flora and vegetation include decreased dominance of native species, decreased overall species richness, fewer vertical tiers of plants, and a lower range of biodiversity overall (ibid).

Many of the invasives are heliotropic and are more successful than native species in forest clearings from where they may spread into the forest. The spread of invasive plants has been hastened by habitat degradation on islands from cyclone damage or agricultural and logging activity. Some of the most aggressive weedy invaders include the following (ibid):

  • trees and shrubs: African tulip tree (Spathodea campanulata), lead tree (Leucaena leucocephala), guava species (Psidium cattleianum and P. guajava), velvet tree (Miconia calvescens), red bead tree (Adenanthera pavonina), Koster's curse (Clidemia hirta), Lantana camara, Clerodendrum spp. and giant sensitive plant (Mimosa invisa);
  • the climbing vines Merremia peltata, Mikania micrantha and Passiflora spp.;
  • the grasses Panicum spp., Paspalum and Pennisetum spp.; and
  • the creeping herb Wedelia trilobata and the aquatic plant Eichornia crassipes

Other potentially destructive alien invaders include introduced fishes, amphibians and crustaceans which can impact on native biodiversity by altering habitats, competing for food and living space, introducing pathogens, hybridisation with native species and socioeconomic and environmental impacts (Eldredge 2000). It is important to note the impact of pathogens and diseases on native flora and fauna. A good example is avian malaria that decimated bird populations in Hawaii after it was inadvertently introduced in exotic birds along with the mosquito vector that spreads it.

Habitat alteration and loss
Habitat alteration and loss are another major threat to native species and ecosystems and affect three quarters of threatened species in the hotspot (IUCN Red list 2003). Habitat alteration and loss relate mostly to the conversion of native ecosystems to non-native ecosystems for economic activities such as agriculture and logging and to a lesser extent due to infrastructural development such as roads and settlements. Habitat degradation contributes to the direct impoverishment of biodiversity as well as a number of subsidiary problems including facilitating the influx of invasive weeds and browsing animals, soil erosion, reduced water quality, and the sedimentation of lagoon areas. Such impacts can seriously affect the livelihoods of the rural majority.

In most countries in the hotspot it is the coastal and lowland ecosystems that have been the most severely degraded because they are the closest to fast growing population centers that tend to be in the coastal zone. Intact altitudinal belts of forest on the larger volcanic islands are also being lost and this is impacting on species such as pigeons, doves and fruit bats that move seasonally or less predictably between lowland and montane forests in response to fruiting and flowering patterns.

Fragmentation of natural ecosystems from logging roads and agricultural plantations is a serious threat to many island species which originally had small ranges to begin with, such as plants, land snails and many invertebrates. Furthermore, research in Fiji shows that invasive predators such as rats, cats and mongooses travel into remote forests along roads but that their impact diminishes greatly more than 6km from the nearest road (Olson pers.comm. 2003). Thus the larger, more remote intact blocks of forest may act as island refugia and are particularly important for the conservation of many native species.

Up to date and accurate annual rates of deforestation are lacking for most countries in the hotspot but range from close to zero in Kiribati, Palau, and Tonga to over 2 percent per annum in Samoa and over 4 percent in FSM (FAO 2003). Most of the deforestation is related to agricultural activities such as swidden agriculture and commercial cash cropping of kava, taro, copra, and cocoa. Commercial logging is an issue on some of the larger volcanic islands such as Savaii in Samoa and some of the Fijian islands, but the rate of reforestation is inadequate in relation to the total area being logged and subsequently deforested. Furthermore, the limited reforestation that has occurred has tended to use exotic species that lack fruits eaten by native birds and bats, have limited ecological value, and in some cases are invasive.

Over-exploitation of natural resources and destructive harvest techniques
Overharvesting and the use of destructive harvesting techniques can have major impacts on native biodiversity and ecosystems. The over harvest of natural resources often goes hand in hand with the use of destructive harvesting techniques. Examples include the use of bulldozers to clear land and dredge sand or dynamite and poisons to catch fish.

Hunting is a threat to some species on some islands such as coconut crabs (Birgus latro), fruit bats (mostly Pteropus spp.), pigeons (mostly Ducula and Ptilinopus spp.) and other large birds that are traditional food sources in many parts of the hotspot. Fruit bats in Samoa and Palau have been particularly susceptible to over-exploitation because of the export trade to Guam, where they are a highly desired culinary delicacy. Legal trade in fruit bats was terminated following a 1989 ban by CITES, except in Palau, which has now become the major supplier of fruit bats (Allison and Eldredge 1999).

The overharvest of frugiverous and nectarivorous animal species such as pigeons and fruit bats can be a serious ecological problem because both are important pollinators and/or dispersers of seeds in native ecosystems and are thus critically important to the health of the forest (Whistler 2002). In Samoa for example it is estimated that up to 30 percent of primary rain forest trees may depend on flying foxes for pollination and/or carrying their seeds through the forest (Faasao Savaii 1998). Forest regeneration is likely to be compromised if the populations of such species are reduced too low.

The illegal trade in terrestrial wildlife species does not appear to be a major issue in the hotspot. However, there is some activity targeting species such as Kadavu shining parrot, crested iguanas and giant longhorn beetles in Fiji. Wildlife trade can increase very rapidly if species are targeted and professional operators become involved so vigilance is necessary. An issue of concern is that most countries in the hotspot are not signatories to CITES.

Some plant species are also in serious decline due to harvesting at an unsustainable level. An example is Intsia bijuga a highly valued timber tree in many countries of the hotspot. This formerly widespread tree is threatened because the wood is highly valued for carving, such as kava bowls in Samoa and Fiji. In Samoa the tree (called ifilele) has been extirpated from many places and even in forest conservation areas may be being harvested at an unsustainable rate (Martel and Atherton 1997).

Natural phenomena
The impact of natural phenomena, such as cyclones, floods, drought and fire, on native biodiversity should not be ignored, despite the fact that, in most cases, little can be done about them. Such events are a major contributing factor to the accidental extirpation of isolated populations of many species throughout the hotspot. Cyclones in particular have had a devastating impact on faunal populations and the health of habitats and ecosystems throughout the Pacific. In Samoa for example, cyclones Ofa (1990) and Val (1991) defoliated up to 90 percent of all trees and may have contributed to a drastic population decline of some species such as the insectivorous sheath-tailed bat (Emballonura semicaudata) (Goldin 2002).

The impacts of cyclones on native wildlife such as birds include the following (Faasao Savaii 1998):

  • Mortality due to the cyclone itself;
  • Starvation as a result of the non -existence of fruits for long periods after the cyclone;
  • Predation of grounded wildlife by pigs, dogs, and cats;
  • Hunting by humans; and
  • Failure to breed because of the destruction of broods and stress.

Fire has shaped ecosystems in many countries of the hotspot, especially where it has been traditionally used to clear land such as in parts of Fiji and Micronesia. When forests are burned, especially in dry zones, a savanna dominated by grasslands emerges (Allison and Eldredge 1999). This ecosystem is ecologically depauperate compared with what preceded it. During the dry season, and especially during droughts, these areas are often set on fire again, an action that perpetuates the savanna and demonstrates how the effect of natural phenomena can be magnified by human actions.

Droughts and floods and are a localized and ephemeral problem often related to the El Niño Southern Oscillation phenomenon. While native forests are somewhat immune to flood damage, rainfall runs off much more rapidly from degraded forest, often resulting in soil erosion and flooding downstream with impacts on coastal zones and lagoon ecosystems. Droughts are not generally of long enough duration to be a serious problem to biodiversity in themselves, but may impact on biodiversity by creating the conditions necessary for fires.

Since the impacts of natural phenomena are part of the natural pattern in the Pacific, native species are adapted to such events and will normally recover. However, there are reasons for concern because of the reduction on the available refugia for recovery, that non-native animal and plant species may increase after such events and finally because of the potential increase in such events as a result of anticipated global climate change.

Global climate change and sea-level rise
Global warming and sea level rise may become the most serious environmental threats in the hotspot in future. The Intergovernmental Panel on Climate Change (IPCC) note that the average global surface temperature has risen by about 0.6 C in the 20th Century but the Pacific is likely to warm at a slightly lower rate (Salinger et al 2001). While the exact amount and rate of sea level rise that this will cause remains uncertain, the IPCC estimates a global sea-level rise of between 1.2mm/year and 8.6mm/yr over the period 1990 to 2100, with mid-range estimate of 4.5mm/yr or a total rise of 0.49m by 2100 (IPCC 1996).

It is not known exactly how much the Pacific will deviate from the global forecasts, however, the impacts of even modest increases on atolls which rarely exceed 5m above mean sea level could be catastrophic to both human and non-human biota. Impacts become even more severe when consideration of other effects such as possible increases in intensity and/or frequency of extreme weather events such as floods, drought, and cyclones associated with ENSO are taken into account. According to the IPCC, the natural systems most vulnerable to climate change include marine systems such as coral reefs, atolls and mangroves (Salinger et al 2001). This would include turtle nesting beaches and low lying seabird nesting areas (TNC 2003).

As already highlighted, there are a number of serious constraints to effectively dealing with environmental problems in the hotspot. Foremost is the natural fragility and vulnerability of island ecosystems and biota to outside perturbations. Constraints that have an anthropogenic origin are similar to those in other tropical regions, and include: population growth, the deterioration of traditional systems and increased commercialization of economies, the lack of good public awareness and appreciation by decision makers of environmental issues, a lack of knowledge of the current status of biodiversity, a lack of capacity especially in terms of the paucity of trained staff and resources to deal with environmental problems and the poor integration of environment and development in decisionmaking.

Most of the constraints are highly inter-related. For example, a lack of up-to-date knowledge of the status and threats to biodiversity can lead to a lack of awareness and appreciation by decisionmakers of the environmental costs of development. This lack of appreciation itself can lead to a low emphasis being given to, and subsequent under-resourcing of, environment units and a lack of incorporation and integration of environmental issues in decision making. Similarly, poor environmental awareness is linked to a lack of resources available for dealing with environmental problems, which itself is exacerbated by high population growth.

Population growth
Many environmental management problems can be traced to high rates of population growth and high and increasing population densities. As mentioned earlier, the natural rate of population increase remains high in most hotspot political units, but has been artificially lowered in recent decades due to emigration. As noted, even with current high rates of emigration from many Micronesian and Polynesian countries, the projected population doubling time ranges from 30 to 58 years (SPC 2003a). If the safety valve of emigration were to be turned off, impacts on environment would increase significantly.

Deterioration of traditional systems
In customary land and sea tenure arrangements, a large degree of control is traditionally maintained over use and exploitation of natural resources (ADB 2003). Deterioration of such systems and knowledge about them is occurring as a result of westernisation, industrialisation, urbanisation and accompanying alienation of the youth from their traditions (SPREP 1992). Although traditional systems were not always applied with a conservation ethic in mind, these controls were nevertheless practical management tools that developed over many generations to ensure the continued supply of particular food stocks or medicines (ibid). The decline in the use and knowledge of these systems goes hand-in-hand with a general erosion of the traditional authority of chiefs over people and resources and a move toward more individualistic and capitalistic socioeconomic activity.

As aspirations for western-style livelihoods and demands for material products increase, the traditional subsistence economies of Pacific countries are being supplemented or even replaced by cash economies and cash-earning opportunities. This change in socioeconomic systems has contributed to a number of the proximate threats to biodiversity, including the over-harvest of resources, habitat degradation, and development pressures, along with increased waste production and environmental pollution.

Poor environmental awareness
Poor environmental awareness has long been recognized as a major constraint to adequately dealing with environmental problems at a regional and national level throughout the Pacific. Since Pacific islanders have the most to gain, and to lose, by their behaviour in relationship to the environment, it is clear that raising awareness of the impacts of those behaviours and improving the knowledge base for sound environmental management must become priority actions. The use of “social marketing” tools, where increased awareness is translated into understanding, and finally to behavioral change, offer particular promise.

The following limiting factors to the development of environmental awareness have been identified by SPREP (SPREP 2003c):

  • A lack of trained and experienced personnel dedicated to the task of environmental education and awareness (EEA);
  • Inadequate national budget allocations. National budgets need to ensure adequate allocation of funds to the area of environmental education and awareness; and
  • Lack of mainstreamed activities in environmental education and awareness and a perception that education/awareness is the responsibility of a select few. Private sector, government ministries other than environment and the civil society need to work together in a coordinated fashion to ensure effective action in EEA.

A regional Action Strategy for Environmental Education and Training in the Pacific Region 1998 – 2003, (SPREP 1998) has been endorsed by SPREP members and establishes a regional framework for implementation of environmental education and training. While significant progress has been made in implementing the strategy, much work is still required to develop and implement strategies at the national level (SPREP 2003c).

Poor knowledge of Pacific biodiversity
As already noted, a serious constraint to the development of effective environmental management strategies is the poor knowledge of much of the hotspot’s biodiversity and the lack of consolidation of the biodiversity information that does exist. Good environmental decision making requires a sound information baseline that is systematically upgraded, monitored, and disseminated. This will improve the capacity to plan and evaluate environmental interventions and trends.

The current population and threat status of Endangered species is particularly lacking, even for fairly well known species. Furthermore, there are many candidate threatened species for the Red List that urgently require assessment of population and conservation status. Even the biodiversity and management effectiveness of protected areas, which have been better studied than most areas, is poorly known. The taxonomic data deficiency is particularly pronounced with fish, plants and invertebrates, while the geographic data deficiency is most serious with the more isolated islands especially in the less developed countries of the hotspot. Another issue is the loss of traditional knowledge which, as a result of social change and modernization, is not being passed on to the younger generation. This knowledge must be recorded soon before it is lost forever.

The Action Strategy for Nature Conservation highlights a number of actions that are required to improve the knowledge and understanding of the state of the Pacific’s natural environment and biodiversity. Such actions include the development of standardized indicators and monitoring methods for ecosystems and natural resources, compiling regular state of the environment reports, documenting and disseminating lessons learned from conservation initiatives and traditional knowledge, and identifying research needs to address knowledge gaps in key areas of biodiversity conservation (SPREP 2003a). Another important task is to integrate and consolidate widely scattered data held in museum collections, in the scientific literature and elsewhere, into a standard format for dissemination throughout the Pacific.

Lack of capacity to deal with environmental problems
The lack of human, technical, and financial resources assigned to environmental management is a fundamental constraint to effectively dealing with environmental problems in most hotspot states and territories. Despite the recent strengthening of environment units, a major constraint remains the shortage of staff to perform the wide and expanding range of environmental management functions. As noted, capacity building such as human resource development, improving communications and information, policy, planning, and institutional strengthening remain key regional priorities.

The under-staffing and under-resourcing of environment units is a function not only of the weak economies of many hotspot countries but also the greater emphasis given to economic growth and the perception that environmental management can be dealt with in the latter stages of economic development (ADB 2003). Lack of resources to deal with environmental problems is compounded by the great distance, isolation and dispersed nature of most hotspot states.

The importance of increasing the financial resources assigned to dealing with environmental problems is reflected in the Action Strategy. Recommended actions include raising government funding for conservation, incorporating national conservation funding plans in all NBSAPs or equivalent strategies, development of regional long-term financial mechanisms and directing a portion of natural resource rents to conservation initiatives, amongst others.

Poor integration of environment and development in decisionmaking
It is generally acknowledged that there has historically been poor coordination and integration of environmental issues in decisionmaking in the Pacific as a whole. The lack of integration has been demonstrated in the scant attention to the environment given in national development plans and sectoral plans and policies. This has resulted in conflicts in the roles of different line departments and development that has occurred with scant attention to environmental costs.

It is now acknowledged that little progress will be made if biodiversity conservation continues to be viewed an environmental issue (ADB 2003). Biodiversity conservation efforts must be seen within their correct context as sustaining Pacific livelihoods and economies as well as maintaining essential ecosystem function. As noted, the increased awareness of the linkages between socioeconomic development and ecological integrity has prompted the new emphasis on "mainstreaming" conservation into decision making adopted as the strategic focus of the current Action Strategy for nature conservation (SPREP 2003a).

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