Introduction | Issues | Sustainability | Land clearing | Threatened species | Invasive species | Carbon | Hydrology | Disturbance | Adherence to permits | Management | References

Introduction

Perceptions of endless empty land and bountiful water resources generate considerable pressure to increase the agricultural output of Northern Australia. One of the foremost areas of growth promoted is forestry, both in the form of broadscale plantations of timber products and as part of mixed farming enterprises. This raises questions of both the industry's economic and environmental sustainability. Forests have values additional to the provision of timber products and energy, including natural systems that provide ecological services, wildlife habitat, climate moderation, water catchments, food resources and carbon storage. Any decision to expand forestry activities should consider potential impacts on these values. Existing activities need to be managed to minimise such impacts.

Early forestry programs in the Top End were of limited scope. Harvesting of native timber began in the 1860s, but was always a minor industry, with Ironwood, eucalypts and Cypress Pine being the main species taken. Despite pessimistic reports about forestry opportunities in both 1933 and 1955, a Northern Territory forestry program was funded in 1958. Over the next two decades, plantations were established in the Darwin region and on the Cobourg and Gove Peninsulas. Estimates of the size of these plantations vary. One account placed the total at around 3,000 ha, another reported 5,000 ha on the Tiwi Islands alone. The species used were primarily Cypress Pine and Darwin Stringybark. However, poor growth rates resulted in these plots being abandoned, and while many are still standing, they do not appear to be included in current accounts of Top End plantations.

Increased interest in plantation forestry in the late 1990s saw around 6,000 hectares of mainly African Mahogany plantation being established in the Douglas Daly region. Northern Territory Budget Papers of 2009 estimated that a further 40,000 hectares of forestry plantations would be established in the Douglas Daly, but expectations have been considerably dampened in the 2010 papers in the aftermath of the global financial crisis and failed managed investment funds that owned large plantations in the Territory.

The Top End Regional Tropical Hardwood Forestry Project has established at least 26 separate farm forestry trials since 1998, with plots in the Darwin rural area, at Batchelor, in the lower Mary River catchment, in the Douglas Daly region and near Katherine. These trials aimed to identify suitable species for broader use. Research investigating the potential of Bamboo plantations to provide quality timber products is also underway.

Timber harvesting from native forest continues, but its scale is difficult to determine. An 850 ha timber harvesting operation has been established on Gove Peninsula to provide timber for Indigenous housing. Melville Island Bloodwood, Darwin Woollybutt and Darwin Stringybark sourced from native forests cleared to make way for Acacia on the Tiwi Islands are advertised as coming from plantations.

Pressure for plantation forestry in northern Australia is likely to increase, particularly as the world’s available timber resources are in decline and demand continues to rise. An additional driver is the search for fossil fuel replacements, for which such species as Giant Reed and Jatropha have been advocated in the media. While Sandalwood, planted for its perfume, is being planted enthusiastically in the Kimberley where there is ready access to irrigation, a lack of irrigation infrastructure makes it unlikely that forestry in the Northern Territory will embrace this species in the near future.

Forestry operations have a role in mining, in the salvaging of marketable timber, the production of charcoal from wood residue and the rehabilitation of mine sites.

Today, forestry can provide employment opportunities for Indigenous communities in remote areas, where employment opportunities are often limited. Such has been the case on the Tiwi Islands. However, the economic viability of both plantation forestry and biofuel operations in the Top End has yet to be demonstrated. So far, attempts at establishing a biodiesel enterprise in the Darwin area have faltered, the $48 million biodiesel operation going into receivership in 2008, after less than two years of operation. Cypress Pines from the plantation at Howard Springs have been harvested to produce garden mulch. Australia's three largest capital-raising forestry companies (Great Southern Plantations, TimberCorp and Forest Enterprises Australia), all with significant plantations in the Top End, have also gone into receivership.

A Senate Enquiry into forestry and mining operations on the Tiwi Islands raised questions about the viability of the Territory's largest forestry operation. Receivers appointed to oversee the plantation pronounced the operation to be commercially unviable in 2009. Sales of the native timber cleared to make way for the plantation had recorded losses, and the majority of the plantation had to be replanted after destruction by Cyclone Ingrid in 2005. Acacia is expected to attract sub-optimal prices.

Constraints to economically viable forestry in the Top End include small tree stature, sparse stand density, slow growth rates and often low-quality termite-affected wood. However the biggest draw-backs seem to be distance from markets and an inability to benefit from economies of scale.

This profile examines the implications that forestry and biodiesel operations have for wildlife conservation, and provides some management considerations for future operations. For an industry with questionable economic benefit, it is even more imperative that development is not undertaken at the expense of the Top End's high quality environmental values.

Issues

The Top End has high conservation values because its landscapes are relatively intact compared with those of either southern Australia or tropical savannas elsewhere in the world. Maintenance of these values relies on land management practices that are compatible with wildlife conservation. Extensive land clearing, whether for plantation forestry or other purposes, reduces and fragments wildlife habitat. Tree clearance, irrigation of tree crops and replacement of open woodlands with densely-spaced tall trees can all disrupt habitats and species that depend on existing water-tables and stream flow. Some of the preferred timber and biofuel species have weedy tendencies and may invade surrounding native vegetation. Fertiliser and pesticide use in plantations can also have adverse effects on native plants and animals. For these reasons, extensive plantation forestry is considered incompatible with wildlife conservation.

Harvesting of timber, on the other hand, can have minimal environmental impact and be compatible with wildlife conservation where small volumes of timber are harvested for local fencing and building requirements.

Both industry codes of practice and government regulations aim to minimise the impact of forestry activities on the environment. The Northern Territory Code of Practice for Forestry Plantations addresses biodiversity, management of soil, water and weeds and the handling of toxic chemicals. Where a forestry operation is liable to impact on nationally threatened species, the Australian Government imposes conditions on the operation, which also address these issues.

Australia's Sustainable Forest Management Framework was developed in 2008. The following principles from the Framework directly concern wildlife conservation:

• Maintenance of productive capacity of forest ecosystems
• Conservation of biological diversity
• Maintenance of ecosystem health and vitality
• Conservation and maintenance of soil and water resources
• Maintenance of forest contribution to global carbon cycles

Adherence to codes of practice, sustainability frameworks and conditions of operation are important for minimising the impact of forestry operation on environmental values. However, codes of practice are voluntary and conditions attached to forestry operations require the diligent monitoring of compliance.

Sustainability

The first concern when extracting a natural resource from the environment is whether the practice is environmentally sustainable. That is, whether harvesting and replanting practices ensure replacement of the resource at a level equivalent to its removal. Clearance of native forests for the creation of forest plantations destroys natural landscapes and wildlife habitat. The Northern Territory Government is committed to the principle that timber species, along with other wildlife, should be managed through sustainable utilisation.

Aboriginal Traditional Owners sustainably harvested timber products from native forests over several millennia. Modern Indigenous harvesting of Bombax and Kurrajong from native forests for woodcarving in the Maningrida area has been shown to be sustainable. The lack of similar studies for other timber harvesting operations in the Territory makes it difficult to assess their sustainability. It has been argued that the small size of operations makes such studies unlikely. African Mahogany has been identified as the fastest growing timber species, but there is no information on whether this species is capable of providing a sustainable forest industry. Moreover, the short history of plantations in the Territory means that there is no information on the ability of plantations to support second and subsequent rotations.

Land clearing

In most cases in the Northern Territory, vegetation clearing is required to make land available for forestry plantations. This means clearing woodlands that have considerable value for wildlife, water-catchments, culture and carbon storage.

Plantation forestry is a major change in land use that results in a number of environmental impacts, depending on the scale of the operation. These include impacts on the atmosphere (through greenhouse gas emissions), hydrology (through increased susceptibility to erosion, water-table drawdown and changes in run-off water quantity and quality) and ecology (through habitat loss and fragmentation and the risk of weed invasion).

Before commencing major land clearing and land use change, biodiversity values should be carefully considered as part of a comprehensive environmental impact assessment, along with social and economic factors and the long term viability of forestry operations.

Threatened species

A history of forestry operations dating back to 1898, coupled with a desire for economic development on the Tiwi Islands led to the establishment of a commercial plantation of Acacia mangium in 2001. This plantation is governed by a set of Australian Government conditions that include minimising the impact on biodiversity values. The Northern Territory Code of Practice for Forestry Plantations declares that "There will be no net loss of biodiversity values associated with new plantation development". The existence of several threatened species in the Tiwi Islands gives the Australian Government jurisdiction over the forestry operations, and stringent conditions have been applied.

The plantation forests on the Tiwi Islands currently cover an area of 29,000 ha, and there are proposals to expand the area to 100,000ha. The Tiwi Islands were recently listed as a site of conservation significance in the Northern Territory, as they contain internationally significant populations of threatened plants and animals and a number of endemic species.

Key issues relating to plantation forestry operations on the Tiwi Islands include project commencement prior to assembling adequate biodiversity information; conversion of extensive tracts of wildlife habitat into monoculture; and implementation of sufficient buffering of identified sensitive environmental features such as threatened plant populations.

Any major change in land use, such as establishment of large-scale plantations, is likely to cause localised changes in biodiversity. Studies have shown that populations of the Brush-tailed Rabbit-rat on the Tiwi Islands have substantially decreased and it is possible that broad scale habitat change from plantation forestry operations have contributed to this decline. Flow on effects from the change in land use, such as more frequent hot fires aimed at protecting forestry assets, may have reduced the availability of key resources for this species, such as hollow logs, tree hollows, tall, fruit-bearing understorey shrubs and grass food species. Other species that have been affected by habitat changes and the associated effects include Armstrong’s Cycad, Red Goshawk, Tiwi Hooded Robin, Butler’s Dunnart, and Tiwi Masked Owl as well as a number of rainforest plants.

Invasive species

Farm forestry enterprises have been increasing in recent times in the Top End. It is important that such schemes are underpinned by sound, scientific and economic information. Unfortunately some programs have introduced weedy species that have been environmentally devastating and failed to provide the livelihoods promised. Neem is a case in point. Promoted as a source of a cure-all with insecticide and biofuel potential, it is readily spread by birds. It has invaded sandy beds and banks of rivers and creeks across the seasonally dry tropical savannas from the Kimberley to the Queensland Gulf. In the Northern Territory, it has spread along the Victoria River, and invaded native woodlands at Humpy Doo. There is little evidence of anyone making their livelihoods from these trees.

Jatropha is another plant promoted for its biofuel potential, also with little economic assessment, but with real environmental risks. It is a declared weed in both the Northern Territory and Western Australia and it has potential to invade modified areas. Another weedy species considered for biofuel, Giant Reed, is known to invade wetland habitat.

Biofuels may indeed have a legitimate place in the north Australian landscape. The native tree Pongamia grows naturally in near-coastal environments across the north. It is reported to be a highly productive species, producing up to two tonnes of oil per ha. It can be invasive outside its native range, but it’s high fire-sensitivity makes it unlikely to become a pest in the north.

Acacia mangium has a weed risk potential as its seeds are dispersed by birds and its seedlings can establish outside plantation areas. However, it has high feasibility for control. Soil disturbance associated with forestry operations allows the establishment of other weed species, notably Gamba Grass and Perennial Mission Grass.

Carbon

The value of forests for carbon storage has been only recently appreciated. As living systems, forests absorb and emit carbon on a daily basis. Overall, Top End Forests are a carbon sink, storing more carbon in the plants and soil than they release. Carbon is lost to the atmosphere when forests are logged, cleared or burnt. Land clearance in the Daly River catchment is estimated to produce between 140 and 222 tonnes of carbon dioxide per ha. Land clearance in the Northern Territory was responsible for 4.5 % and 7 % of the Territory's carbon emissions in 2005 and 2006, respectively. At present, agriculture, including forestry, is excluded from global carbon accounting based on the Kyoto Protocol, but a "voluntary" market for carbon has grown among corporations wanting to demonstrate their environment credentials. This gives carbon stored in forests an economic value, dramatically altering the economics away from clearing land for forestry. In Queensland, a legislated ban on tree clearing for the next 120 years in specified natural forests has allowed “avoided deforestation” to be included in that state's emission reduction targets. No provision for permanent protection from tree clearance exists in the Northern Territory, making its commitment to a 60% reduction in carbon emissions by 2050 that much more difficult.

In line with the Kyoto Protocol, the Australian Government's Greenhouse Friendly program includes the establishment of forest plantations after 1990 as contributing to carbon storage if land clearance is not required, and the trees remain standing for at least 70 years. The short rotation cycles for Acacia (13 years) and African Mahogany (20 years) preclude plantations using these species from this program.

There is little likelihood that conservation to maintain the integrity of existing forests will afford carbon credits. However, avoided deforestation can be profitable and may shift the economic balance in favour of managing extant native vegetation.

Hydrology

Fast growing tree species preferred for plantation forestry can uptake and consume a much greater volume of ground water when planted in high density than the original or adjacent native vegetation. The hydrological effect of this is a net water draw-down that effectively extends the long dry season period of low or no water availability. This can have negative consequences for surrounding vegetation communities especially for water dependent ecosystems such as rainforests and wetlands. Extended reductions in ground water availability can also impact on wildlife populations that utilise moisture loving plants, for example magpie geese which feed on water chestnut sedges. The maintenance of intact vegetation along major river systems and the provision of adequate riparian buffers along streams will help catchments seasonally recharge their ground water supplies and help maintain water quality.

Disturbance

Native and plantation forestry require the creation and maintenance of a network of access tracks and roads for the transport of commercial quantities of logs and pulp. These also provide the entry for weeds via vehicles and soil disturbance. The most serious weeds are the introduced high biomass pasture grasses that can fuel high intensity fires. Such fires may threaten the desired tree species and forestry operations require ongoing active fire management that needs to consider protection of both forestry resources and nearby fire-sensitive vegetation.

Plantations may be more susceptible to cyclonic damage than the native vegetation they replace. Cyclone Ingrid damaged 4,000 ha of Acacia mangium on the Tiwi Islands in 2005. Fast growing species, such as Acacia mangium are particularly susceptible. Moreover, the break in the canopy may make native vegetation adjacent to plantations more vulnerable to disturbance.

Soil is the fundamental agricultural asset as the nutrients and moisture in the soil are essential for healthy tree growth and loss of soil will reduce forest productivity. Some soil disturbance is inevitable during forestry infrastructural works, harvesting and maintenance activities. Such works need to be undertaken in a manner that keeps soil disturbance and erosion risks to a minimum.

Adherence to permits

Areas most sought after for plantation forestry have soils of high fertility and support tall forests. The tallest trees are found growing along watercourses, where harvesting is prohibited. However breaches in both log size and harvesting from such areas have occurred. Rigorous conditions are being attached to all new forestry operations and these will require adequately resourced compliance monitoring. Indeed, between 2004 and 2006, conditions regarding the required buffers for the protection of rainforests and wetlands on the Tiwi Islands were breached.

Management

One of the key management challenges for the Northern Territory is how to retain its significant biodiversity values amongst increasing pressure for utilisation of natural resources and economic development. This represents a huge challenge involving a diverse range of stakeholders, all with varying interests. Proposals for land use activities should be assessed in the context of sustainable development policy and with the adoption of a precautionary approach where there are key knowledge gaps.

Any new or proposed expansions of existing plantation forestry operations must be carefully considered with the use of rigorous environmental impact assessment procedures. There must also be relevant social, cultural and economic assessments, and a determination of the long term viability of the operations. Proposed plantation forestry operations require an independent environmental impact assessment and a land clearing permit from the Northern Territory Government. If it is on Commonwealth land or is likely to impact on a matter of national environmental significance, then it will also require approval from the Australian Government. Plantation forestry operations should be rejected in areas with significant biodiversity values. If forestry plantation operations are approved, adequate areas of intact land must be set aside for maintenance of habitat and ecosystem functions, including sufficient buffers of native vegetation around sensitive habitats.

Forestry plantation operators have an obligation to ensure communities and stakeholders are fully informed about the impacts, costs, risks and benefits of operations. Monitoring of plantation forestry zones should be part of a strategic and comprehensive regional plan to prevent impacts to biodiversity, particularly in terms of fire, surface and groundwater quality and quantity, quarantine issues, soil erosion and spread of weeds and pest animals. There needs to be provisions to ensure compliance and enforcement of environmental conditions imposed on plantation operators. Conditions approving any forestry operations should include provision of appropriate environmental offsets, to prevent net loss of environmental values in the area. There should also be a requirement for the rehabilitation of affected areas once operations are complete, using best-practice forest rehabilitation techniques.