Biodiversity conservation research: Australia's priorities

Australian and New Zealand Environment and Conservation Council and Biological Diversity Advisory Committee
Commonwealth of Australia, 2001
ISBN 0 6425 4742 4

D. What is changing and why?

Living organisms, including humans, have evolved in response to the combined effects of interactions within ecosystems and other biophysical processes. Some have become specialised in niche environments in richly complex ecosystems, which tend to buffer individual species from change. Others are adaptable generalists. The impact of human activities is, however, bringing environmental change at a speed beyond the adaptive ability of most species and ecosystems.

Action is needed urgently to conserve ecosystems before they are damaged, to restore ecosystems to the extent that may be possible and to prevent further damage. The work needs to be based on the best scientific information available and undertaken strategically to ensure resources are used to the greatest possible effect.

We need to know what the threats are, what effects they have and how those effects can be prevented or ameliorated.

Threats

Humans, a single species among billions of species, are the greatest threat to biodiversity. In our daily activities, we give little regard to the long term flow-on effects that might impact on biodiversity. The combination of rising per capita consumption and an increasing population has put enormous pressure on the world's resources. In company with our relatively few domesticated plant and animal species, we are competing with all other species for land and water. We need to meet society's demands with the least possible impact on ecosystems.

All of our activities threaten biodiversity in some way – more so when managed poorly. Intense land-uses such as urban expansion, agriculture and plantation forests displace rich native ecosystems with species-poor ecosystems. Cattle and sheep graze on native pastures across huge areas of Australia discouraging some plants, encouraging others and creating changes in population size and species balance throughout the food web. Mining and oil exploration activities can be locally devastating, requiring complete reconstruction of the landscape that is affected and, where managed poorly, can contaminate catchments downstream. Even tourists and local residents enjoying simple recreational pleasure in areas with unique biodiversity and beautiful landscapes disturb the wildlife and trample the vegetation – the very attributes they appreciate.

Land clearing and marine trawling

The single most threatening activity is wholesale land clearing and, in marine environments, the combination of fishing and the establishment of new benthic trawl grounds 31. These can cause such severe loss that the remaining habitat is fragmented and, for many species, effectively becomes a series of isolated island-like ecosystems.

In continuous land ecosystems and ones joined adequately by vegetated corridors, there is a gradual exchange of diverse genetic material throughout populations when animals interbreed, pollen is carried and seed is dispersed. This maintains each population's ability to adapt to environmental changes. In habitat fragments, the breeding populations of species of all kinds – from mammals to insects and trees to ferns – may be too small and the genetic diversity that is left diminishes over time. Species become more vulnerable and are more likely to become locally extinct. A downward spiral is created with continuing loss of species and loss of their moderating influence on the biophysical habitat. The ecosystem appears attractive but it has become depauperate.

Research is needed to determine the size of habitat that is required to maintain genetic diversity in an acceptable proportion of the species in different ecosystems. We need to know how important vegetation or benthic fauna fragments are, how wide vegetation corridors must be, and what they must contain to effectively link habitat patches. For instance, occasional mature paddock trees which provide nesting sites may be critical for the survival of some birds, while other animals may require a corridor providing continuous vegetation cover to link habitat patches. We need to know to what extent farm forestry, with and without planted native understorey, can provide habitat or link habitat patches for some species. Similar research is needed in marine areas to understand the amount of trawling that can occur within an ecologically sustainable harvesting regime.

Land clearing is causing other problems. Without vegetation cover the soil is exposed to erosion, leading to loss of topsoil and excessive sediment and nutrient load in waterways through to the coast. As a consequence of clearing trees, dryland salinity is threatening 15 million hectares of arable land and causing an unprecedented loss of agricultural production and rising costs. The Murray-Darling Basin Salinity Audit has considerably advanced our understanding of the problem in that region. The Draft Basin Salinity Management Strategy, released in September 2000, identified strategies and set targets for reversing the progress of dryland salinity. Land clearing also means a loss of carbon sequestration and is thought, therefore, to be contributing to global warming, sea level rise and changing global climatic patterns. All of these factors are damaging our native ecosystems on land, along rivers, in wetlands and estuaries and in the marine environment.

Introduced weeds, ferals, pests and diseases

The effects of introduced species vary from case to case, but they all compete with native species, inexorably changing the ecosystem balance. Invasive weeds compete with native plants for sunlight, water and nutrients. Introduced aquatic plants can block waterways. Feral predators such as foxes and cats can decimate populations of native mammals, birds and reptiles. Feral herbivores 32 such as rabbits and goats graze a wide range of native plants and compete with native species. Some have a diverse diet, for example, wild pigs graze on pasture and also prey on small native mammals and insects. Many ferals, such as rabbits, pigs, water buffalo and goats, also cause extensive habitat damage by digging burrows, digging for food, fouling waterways with their manure, breaking up the ground with their hooves and overgrazing so that the land is exposed to erosion. Feral honey bees can disrupt native pollinators. On Christmas Island, the introduced crazy ant attacks the red crabs, reducing the foraging by crabs on seedlings, and this is changing the rainforest ecosystems. The sea has not escaped invasions. For example, in coastal waters off Tasmania large numbers of the Northern Pacific sea star are preying on native marine life and the Japanese kelp, Undaria pinnatifida, is growing over and replacing native seaweeds.

The cost to Australia each year of feral animals, invasive weeds and introduced pests and diseases is not known – it includes loss of agricultural and pastoral land productivity, the cost of eradication programs and the loss of ecosystem services (see Section C: How Does Our Biodiversity Function?). The cost of weeds to Australian agricultural industries has been estimated at over $3 billion per year 33 and there is an additional loss from their impact on Australia's urban and recreational areas, natural ecosystems and tourism.

The possibility of new introductions of invasive species is an ever present threat and quarantine controls need to be maintained to prevent this. Nearly all of our most notorious feral animals and many of our agricultural and environmental weeds were introduced deliberately 34 35 36. In the case of plants, the characteristics that make a successful crop or pasture species, such as rapid growth, persistence, high seed production, a strong competitive ability and tolerance of the Australian climate, can make a successful weed.

There is a further threat from species that are already present in Australia but are not yet widespread. Introduced species can be sleepers, that is, they occur often for decades in small populations, but later adapt sufficiently to the Australian environment or benefit from disturbance so that their population explodes and they become invasive.

Even native species can become a problem if introduced to other parts of Australia. The Cootamundra wattle and sweet pittosporum, for example, are invasive outside their natural range. The root rot fungus Phytophthora, which is particularly devastating in the ecosystems in Western Australia, may have been introduced there from eastern Australia around 1900.

Targeted research is needed on species which have the potential to become significant invasive species, pests or diseases in Australia. Where the species has not yet reached Australia, the likely means of introduction 37 need to be identified so that quarantine officers can be vigilant. Development of an emergency eradication plan may also be expedient where the risk of introduction and potential subsequent damage are high, such as for guava rust, a South American fungus which can infect eucalypts and their relatives.

For species that already occur in Australia, an eradication program may be warranted before the species becomes too numerous. Research into invasive species would support the efforts of Australian Quarantine and Inspection Service staff who carry out weed risk assessments as part of our border controls and Environment Australia staff who identify species at risk of becoming environmental weeds, ferals and pests in Australia 38.

Management options for the eradication and control of invasive species need to be assessed for effectiveness and priority for limited funds. Preventing introductions and eradicating high-risk species that could become invasive can be cost-effective compared to trying to control established invasive species. Short and long term effects also need to be taken into account. For example, fencing to exclude cattle and sheep from river frontages has proven effective in allowing ecosystems to regenerate. The types of fences required to exclude ferals such as rabbits and foxes could, however, also restrict the movement of many native species and limit the size of interbreeding populations. It is not clear how this would affect the survival of these species in the long term, as the fences could create genetic islands, lead to gradual loss of genetic diversity in fenced-in populations and eventually make the native species more vulnerable.

Genetically modified organisms

Genetically modified organisms (GMOs ) need to be assessed on a case by case basis 39 as some have the potential to be invasive or to transfer genes to native species. Novel genetic material can be replicated and appear in new combinations with other biological characteristics down through the generations. Once a modified organism has escaped, survived and successfully reproduced, its genetic material may be difficult, if not impossible, to eradicate.

A case in point is the genetic modification of eucalypts to contain a Bt gene which will reduce attack by certain kinds of insects. The purpose of this exercise would be to increase commercial timber productivity – constant defoliation by insects can decrease annual wood production by about 20 per cent, because the trees devote their energy to replacing damaged leaves rather than to growing.

However, the Bt gene could be passed to eucalypts in the environment. In eucalypt woodlands, insects are the dominant herbivores – that is, they eat the bulk of the plant material in the ecosystem. They are in turn a major food source for birds, lizards, mammals and predatory insects. The emergence of insect resistant eucalypts would affect the populations and the distribution of native species throughout the food chain, changing the species balance in the woodland ecosystem 40.

Altered fire regimes

Humans have altered fire regimes across Australia. Although much of our biodiversity has evolved to survive or thrive on fire, a change from the usual local fire pattern can cause a decline or even local extinction of species. This can happen when the fires become too frequent, too infrequent, occur in an unusual season or the intensity alters. Many tree species take ten years or more to reach maturity and set seed so that, for example, regular fires five years apart will kill emerging young plants before maturity and eventually exhaust the capacity of mature trees to regrow, eliminating these species from the area. In contrast, a single fire in the wet season in monsoonal Australia can catch native Sorghum grass at a time when most viable seed has germinated and before it has produced new seed, resulting in an immediate severe local decline. Where there is local extinction, recovery might occur with the species gradually spreading in from neighbouring areas. If the habitat has become fragmented, this may not be possible.

Fertilisers, herbicides, pesticides and pollution

Other threats to biodiversity from human activities include pollutants from heavy industry, traffic in urban areas, domestic sewage and waste water, fertilisers, herbicides and pesticides used in agriculture. These kinds of pollution find their way into our rivers, estuaries and the marine environment.

Excessive use of fertiliser rich in phosphorous and nitrogen has several effects. Where fertilisers are washed into waterways, the extra nutrients encourage growth of aquatic plants and native species of cyanobacteria. With excessive growth, these can compete with fish and invertebrates for oxygen, sometimes suffocating the aquatic animals. When the growth of cyanobacteria coincides with a dry season or lower rainfall than usual, toxic algal blooms may also develop. On land, applications of phosphate fertiliser stimulate nitrogen fixation by plants, which makes the soil more acidic. Many plant species and soil micro-organisms are not tolerant of acid soils. The acidity also changes the soil biochemistry, sometimes releasing soil minerals in toxic concentrations.

Conservation status of biodiversity

Ongoing work is required to establish the conservation status of Australia's biodiversity. This work is most critical where species and ecological communities are or could be threatened and measures may need to be taken to protect and restore habitat critical to their survival 41.

As discussed previously, an ecosystem that has been reduced in size or complexity may become vulnerable to local impacts, creating a downward spiral with continuing loss of genetic diversity within species, local extinctions and loss of the moderating influence of these species on the biophysical habitat. In seeking to conserve species and ecological communities, we need to know the minimum threshold condition and extent below which further loss will lead inevitably to continuing decline.

Modelling and management decisions

Predictive modelling tools have many applications. Models could assist in predicting the impacts from threats such as land clearing and marine trawling and be used to identify management strategies and techniques. Models would help in identifying the minimum threshold condition and extent of species, ecological communities and ecosystems below which further loss will lead inevitably to continuing decline unless conservation interventions are successful. Predictive modelling is discussed in more detail in Section E: What are the Management Options? (see priority 12).

Priority research

8. Identifying threats to biodiversity conservation

Identify and investigate threatening processes in native ecosystems including those in terrestrial, fresh water, estuarine and marine environments.

Highest priority research

In local areas and on a regional basis, determine and investigate the factors that present the most significant threat to ecosystems and remnant habitat.

  • Consider the level of threat posed to native ecosystems by, for instance, fire regimes, urban sprawl, water resource allocation, dryland salinity, weeds and ferals, agriculture, grazing, mining, the commercial and non-commercial use of native flora and fauna and changed climate patterns.

For example, investigate habitat fragmentation caused by land clearing, benthic trawling, and land and marine industry activities.

  • Determine the effects of habitat fragmentation and off-site impacts of activities such as agriculture on ecosystem processes, genetic diversity, the survival of species including selected invertebrates and micro-organisms, ecosystem health and biophysical processes.
  • Take into account the cumulative effects of impacts.
  • Determine the threshold conditions below which:
    • decline in the ecological community is inevitable; and
    • biodiversity losses are unacceptable.
  • Develop and assess management strategies and techniques (see priority 13).

Research of national importance

  • Determine the effects of threats on ecosystem processes and health, biophysical processes, genetic diversity and the survival of species. Take into account the cumulative effects over time and as a result of different threats.
  • Where possible, identify early warning signs of threats.
  • Determine the threshold level of threat below which:
    • decline in the ecological community is inevitable; and
    • biodiversity losses are unacceptable.

Application

To provide the basis for:

  • assessing the conservation status of species and ecological communities;
  • assessing risks to biodiversity conservation from proposed human activities;
  • identifying opportunities for intervention to prevent threats or reduce the impact;
  • developing and assessing the effectiveness of methods and techniques used to reduce impacts and restore habitats and ecosystems;
  • management planning, setting conservation priorities and adaptive management – at a local and regional level; and
  • developing ecologically sustainable production practices.

Comments

Understanding threats to biodiversity conservation is critical to taking effective management action (10-15) and requires a good knowledge of Australia's biodiversity (1-7).

Related research

Prerequisite:

(1)-(6) identify and monitor changes in ecosystems, ecological communities, species, ecosystem function, processes and services

Follow up:

(9) determine the conservation status of species and ecological communities
(10) identify a system of conservation reserves
(11) assess risks from proposed activities
(12) develop predictive models
(13) develop and evaluate conservation management strategies and practices
(14) develop ecologically sustainable industry practices
(15) develop educational materials

Relevant policy commitments and legislation

National Strategy for the Conservation of Australia's Biological Diversity: Objectives 1.1, 1.2.1(b), 3.1-3.6 and 4.1.4(f)

Convention on Biological Diversity: Articles 7(c), 8(g) and 8(h)

Commonwealth Environment Protection and Biodiversity Conservation Act 1999: Sections 171, 274, 282, 301A

Priority research

9. Determining the conservation status of biodiversity

Determine the conservation status of native species and ecological communities.

Highest priority research

Determine the conservation status of native species and of ecological communities which are or may be:

  • threatened 42;
  • of commercial value; and
  • included in a representative system of conservation reserves.

Identify habitat that is critical to the survival of listed threatened species and ecological communities.

Research of national importance

  • Research genetic diversity within critically threatened species, documenting the occurrence of distinctive populations.
  • Determine the threshold condition and extent below which the further loss of habitat and loss within species and ecological communities causes:
    • inevitable further decline in the ecological community; and
    • unacceptable biodiversity losses in the short and long term.
  • Determine the extent of loss that can occur from all causes without jeopardising ecosystem sustainability.

Application

To provide the basis for:

  • making protective management decisions;
  • determining the capacity of restored habitat to off-set habitat loss;
  • identifying a system of conservation reserves; and
  • developing ecologically sustainable production.

Related research

Prerequisite:

(1)-(6) identify and monitor changes in ecosystems, ecosystem processes, ecological communities and species
(8) identify threats to biodiversity conservation

Follow up:

(10) identify a system of conservation reserves
(12) develop predictive models
(13) develop and evaluate conservation management strategies and practices
(14) develop ecologically sustainable industry practices
(15) develop educational materials

Relevant policy commitments and legislation

National Strategy for the Conservation of Australia's Biological Diversity: Objectives 1.1.1 and 4.1.4(e)

Convention on Biological Diversity: Article 7(a)

Commonwealth Environment Protection and Biodiversity Conservation Act 1999: Sections 171-174, 178-194; critical habitat 207A

Footnotes:

31. Trawling that reaches the ocean floor removes bottom dwelling fauna such as sponges which provide habitat for fish, crustacea and other mobile species. Repeated trawling can prevent recovery.

32. Feral herbivores include: rabbits, hares, goats, water buffalo, deer, horses (brumbies), camels, donkeys.

33. Reference: Combellack JH, 1989.

34. Ferals were introduced for food (goats, cattle), for sport (rabbits, foxes and deer), to control pests (cane toads), as work animals (dogs, horses, donkeys and camels) and as domestic companions (cats and dogs). Invasive weeds were introduced for food (blackberries), softwood timber, hedge plants (prickly pear and gorse), agricultural crops, pasture grasses and as ornamental plants.

35.About 66% of weeds introduced from 1971 to 1995 were brought in as ornamental plants (Groves RH 1998). Of the more than 220 exotic plants which have been proclaimed noxious weeds in Australia, 46% were introduced intentionally and 31% as ornamental plants (Parsons and Cuthbertson 1992).

36.A 1993 survey evaluating four decades of pasture introductions in northern Australia found that of 474 introduced pasture grasses and legumes, only 4% came to be recommended as useful but 15% became listed as weeds of crops and/or conservation (Lonsdale 1994). Less than 1% were useful without also becoming weeds.

37. Many invasive species travel to Australia as contaminants in ship ballast water, on ship hulls, as weed seeds contaminating grain imports and as diseases of imported animals and plants.

38. An alert list has been developed for environmental weeds. Work has been undertaken to identify mammals, reptiles, birds and fresh water fish that pose an environmental risk.

39. The Gene Technology Act 2000 (Commonwealth) provides for case-by-case assessment of proposed releases of genetically modified organisms. The regulatory requirements set out in the Gene Technology Regulations are expected to come into effect in 2001.

40. Environmental problems could arise in several ways. The emergence of Bt gene resistant insects would change native ecosystems and also threaten the commercial success of the Bt tree. A management strategy would need to be implemented to ensure that target insects did not develop resistance to the gene.

41. EPBC Act Section 207A.

42. See Appendix 3 - Definitions.