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The past compounded by the present: ecological challenges and decisions for peri-urban and amenity agricultural landscapes.

Fiachra Kearney and Neil MacLeod

CSIRO Sustainable Ecosystems, 360 Carmody Road, St. Lucia, Brisbane Qld 4067.


Ecological sustainability and natural resource management are ubiquitous terms in landscape management across Australia. Extension practice faces a challenge in the application of a meaningful definition to these terms in peri-urban and amenity agricultural landscapes, such as on the eastern seaboard. Numerous smallholdings, multiple land uses and competing landholder attitudes create complex socio-physical mosaics. Increased landscape modification and accelerated ecological simplification results. Development regularly occurs in former agricultural lands with relictual habitat only. Effective conservation efforts require these complex mosaics to be linked to ecologically meaningful spatial and temporal scales. We suggest that sub-catchments, delineated by stream order and managed within defined ecological principles and thresholds, may be one way to stabilise natural resources. However, even with this approach linked to ecosystem metrics, it is likely that biodiversity will continue to decline in response to current and past development practices and the rapidity of land conversion. Biodiversity conservation planning and subsequent extension is unlikely to stem the rate of species loss without ecologically sensitive infrastructure planning and land use restrictions.

Three Key Learnings: (1) Essential ecosystem functional requirements can be swamped by the number of agendas, expectations and pressures stemming from social complexity; (2)conservation in these landscapes must use appropriate management units and be prepared to face problematic ecological triage decisions based on ecological theory and available resources and; (3) innovation in conservation and extension practice that recognises natural systems and their genetic, taxonomic and ecosystem diversity as the primary stakeholders is imperative for true and meaningful ecological sustainability in landscape management.


Amenity landscapes; landscape intensification; conservation planning.


Despite the considerable efforts of land management organisations and agencies, conservation groups and individuals, natural resources and biodiversity remain in a state of decline around Australia. This decline is in parallel with global resource degradation, loss of meta-population viability (Frank and Wissel 1998) and local population or total species extinction (Ceballos and Ehrlich 2002; Gaston 2005). The drivers behind these processes are varied and complex, but often relate to modern human land use and conversion (Friesen, Eagles et al. 1995; Hobbs and Mooney 1998; Sala et al. 2000; Gaston 2005).

Natural resource management (NRM) in Australia is supposed to counter these declines, and is a ubiquitous term, yet it is rarely defined (Lowe et al. 2003). When it is defined (Lowe et al. 2003), it is often ambiguous and imprecise, limited in meaning. On the eastern seaboard of Australia and the south-west corner of Western Australia, peri-urbanisation (human population growth in rural lands) is increasing pressure on the environment as well as the ability of NRM to counter the problems associated with this landscape intensification. Those problems include ecological simplification through development in areas with re-growth or relictual (high degree of fragmentation and loss) vegetation. The sheer number of people moving into rural landscapes and their self-interests requires much clearer NRM philosophies and an acceptance that without incorporating ecological theory and biodiversity thresholds into NRM, landscapes will continue to decline. To realise those targets and philosophies in peri-urban landscapes, the barrier of addressing critical ecological issues within the context of small-scale cadastral boundaries needs to be overcome.

This study is informed by the Agricultural State Level Investment Program AG14 research project, a project currently assessing the ecological effects of peri-urbanisation and potential management approaches to the problems. In addition, regional NRM plans and the overarching NRM objectives of the Department of Environment and Heritage and Landcare Australia were reviewed.

The peri-urban problem

NRM typically attempts to strike a balance between people’s needs, the economy and the environment - the so-called triple bottom line. However, it is often the case that the requirements necessary to maintain functioning ecosystems and genetic, taxonomic and ecosystem diversity come a poor third in line to economic and social development. Because of this, any meaningful biodiversity gains face major hurdles. Biodiversity targets are usually imposed on peri-urban landscapes in their present state, regardless of what has already been lost, and with the knowledge that land use will inevitably continue to intensify. The upshot of this is that even when specific biodiversity statements are used, an enormous disparity emerges between the intent of those statements and the reality of actual conservation. At the Commonwealth level natural resource management agencies recognise this disparity and the difficulties to be faced with reconciling the problem (Lowe et al. 2003; Read and Bessen 2003)). Unfortunately, as the Commonwealth largely drives NRM nation-wide, the disparity is pervasive all the way to extension and on-ground practice. Even where regional bodies actively incorporate national biodiversity outcomes - as specified by the Natural Resource Management Ministerial Council (NRMMC 2002a,b) - they are embedded within an institutional framework that recognises the human population, not the environment, as the prime stakeholder.

This is a problem of particular concern in peri-urban landscapes as peri-urbanisation may well be threatening processes of greater significance and impact than the land uses (mainly agriculture) that it supplants. The trend produces human disturbance dynamics that drastically alter relictual habitat and intensify pressure in landscapes, and in Australian environments this intensification regularly occurs in pre-stressed agricultural lands (Barr 2003; Alig et al. 2004). The full impacts of this landscape conversion are open to debate, but there is undoubtedly increased resource appropriation (Yeoman and Nally 2005), and the intensification of human activity can have important deleterious effects on the biota (Friesen et al. 1995; Miller and Hobbs 2002) often with irreversible consequences . The impact of infrastructure development and associated activity has been shown to negatively impact not only the habitat in which activity occurs (Friesen, Eagles et al. 1995), but also adjacent habitats (Conner et al. 2005; Yeoman and Nally 2005). Other problems associated with population growth include reduction in species diversity within woodland patches adjacent to residential development, independent of patch size (Friesen et al. 1995), homogenisation of habitat and landscapes (McKinney and Lockwood 1999), direct mortality (Rosen and Lowe 1994), local species extinction (Findlay and Bourdages 2000), and genetic differentiation due to fragmentation by roads (Keller et al. 2004). Increased numbers of domestic pets cause additive predation pressure, and less obvious impacts include the adverse effect of night lighting on nocturnal species (Grigione and Mrykalo 2004). Numerous other associated factors play a role in decreasing the viability of ecosystems in amenity landscapes, including edge effects, invasion of exotic and native pest species and an increased incidence of fire.

With an increasing population and large numbers of small properties with various land uses, attempting to incorporate and accommodate everyone’s viewpoint usually swamps the requirements of the natural systems. Properties are often small (2-100 hectares) with few land use restrictions, meaning that even with sound ecological management practices they only contribute limited ecological benefit. In order to achieve viable ecological sustainability it is important that these critical ecological problems are raised in priority, and that NRM looks beyond the local cadastral boundary.

Our argument is not intended to censure NRM efforts and achievements per se, as these are laudable. Rather, it is a criticism of the widespread use of the term ‘biodiversity conservation’ in NRM statements, while in reality practices are limited in their ability to minimise species loss or protect complex ecosystem interactions. Fortunately, notable exceptions do occur (Read and Bessen 2003). It is also a criticism of the failure of NRM practice to view the natural environment as the premier stakeholder in negotiations and decisions. This means the environment - the landscape and its life-sustaining resources - is consistently allocated the weaker negotiating position and is consistently required to compromise its remaining biological diversity and integrity of natural resources. Neither do we suggest that humans in the landscape are oppositional. Rather we argue that the current practices designed to manage the landscapes with humans as a part of the whole are oppositional if NRM aspires to maintain long-term ecological function and biodiversity conservation; both of which are touted in NRM policy.

What should NRM consider in peri-urban landscapes?

In rapidly changing landscapes the basic tenets of NRM require re-evaluation. Does the same tenor endure in peri-urban landscapes; a landscape with more roads and human infrastructure, more people and attitudes, vehicles and activities? If so, once again NRM is being driven by anthropogenic needs rather than ecosystems’ functional requirements, and with more people comes a greater number of expectations. As such, what is considered ‘sustainable’ will differ markedly from a position where NRM is defined by using ecosystem function or biodiversity thresholds; i.e. driven by ecosystem requirements. As an example, it is likely that much of the current development and land management practices in South East Queensland and around the high development Australian seaboard locations will exceed fundamental ecological thresholds for the long-term maintenance of species. By upholding ecosystems and natural resources as the primary beneficiary of NRM, the underlying principle would dictate that development and poorly managed or unrestricted land uses that exceed these thresholds should be challenged.

The effective application of any NRM practice also requires the marrying of meaningful landscape scales to human-centric scales; e.g. realistic logistical and legislative management units to appropriate landscape units, and short human temporal scales to long-term ecological processes. In urbanising landscapes the real biodiversity value of the land should be judged, along with the extent to which human disturbance will negatively alter that value. By incorporating these elements, areas of high biodiversity value may be protected with the limited funds available before they too are heavily compromised. It is important to note that socio-ecological thinking recognises people as part of an ecosystem. The recommendations proposed in this paper inherently incorporate this concept, as they are based on managing landscapes as they presently exist, and do not suggest reverting back to an earlier socio-economic state. They do however suggest a number of shifts are required to stem social exploitation of landscapes. NRM needs to work much more closely with planners, scientists and legislators to manage peri-urban areas.


The scale of ecological function at which fauna, flora and physical processes occur is of paramount importance for attempts to restore or maintain ecosystem health (Ludwig et al. 2000; Briggs 2001; Turner et al. 2001). The scale of the property units in peri-urban landscapes, typically smallholdings, is usually too small to be useful management units. Sub-catchment scales are more likely to be effective for achieving ecologically meaningful landscape management targets. As with most scale units, sub-catchments are still a compromise between ecological function incorporating all tiers of ecosystem hierarchy and the ability to manage them. A catchment is often large enough to encompass relationships between physical processes and biodiversity, is a management unit currently recognised by NRM bodies and can fit relatively easily into a bioregional framework. However, logistical, economic and social constraints in extension can make management of an entire catchment difficult. Therefore, where appropriate, sub-catchments, based on Horton/Strahler stream orders (Horton 1945; Strahler 1957), are recommended.

A sub-catchment, regardless of stream order, does not represent a critical threshold of scale, where an abrupt change in a quality, property or phenomenon is apparent (Greiner 1997; Turner et al. 2001 pp. 29). However, these units represent measures of landscape scale that can be reasonably matched to important landscape ecological processes, such as hydrological flows, erosion and nutrient loss from a system, as well as some degree of biodiversity conservation. They are also useful because delineating a landscape at larger units can make it difficult to manage degradation effectively, whereas many problems at a sub-catchment level, such as weed infestation, poor management practices and inappropriate developments may be addressed with greater relative benefits for the entire catchment. As with all scale units however, catchments and sub-catchments have particular biophysical limitations. Hydrological recharge and discharge areas can be tens to hundreds of kilometres away (Greiner 1997), and animals, particularly vagile species, may utilise parts of a landscape on a seasonal basis or require extensive area in order to sustain a viable population. Therefore, while sub-catchment units are useful for relating landscape scale to management and planning with important ecological consequence, their relationship to biological and ecological hierarchy is still restricted. Nonetheless, as management units they offer far greater opportunities for biodiversity and resource management than small properties, and efforts should be made to move towards some form of overarching regulation for sub-catchments. Extension programs and peri-urban landholders could benefit from incorporating widely available sub-catchment maps or datasets into landscape and property planning.

Ecological considerations

Two of the primary considerations for biodiversity conservation in NRM are the cost and relative importance of managing a given area to minimise or prevent biodiversity loss - defined as: the long-term or permanent qualitative or quantitative reduction in components of biodiversity and their potential to provide goods and services, to be measured at global, regional and national levels (Convention on Biological Diversity 2004). As biodiversity can be measured at multiple scales and is not a discrete entity, this definition is automatically inclusive of local levels, an essential consideration for extension workers. However, the risk of future biodiversity loss may not always be a useful measure when weighed against remaining biodiversity in that landscape. In some locations degradation has already occurred to such an extent that biodiversity is restricted to generalist and invasive species, and future loss may be negligible. Even where resources are relatively stable (figures 1 & 2), biodiversity values may be low (figures 3 & 4) and in these localities it may be more appropriate to direct efforts and funds towards continued resource stabilisation and appropriation restriction, acknowledging biodiversity loss is not the main focus. In this way funds can be directed towards conserving biodiversity at locations where species loss is under greater threat. Resource stabilisation would be aimed at the prevention of soil and nutrients leaking (MacLeod 2004) from the system, with the inference that downstream biodiversity will benefit indirectly. This is a triage approach, and despite being less than ideal, it is driven by limited funding and the current weakness of NRM in catering for ecosystem requirements.

Figure 1. Soil surface condition in 30 sub-catchments in SEQ. Condition is generally good (Source: MacLeod 2004).

Figure 2. Soil erosion was minimal in 30 sub-catchments in SEQ., mainly confined to disturbance points such as tracks and watering points (Source: MacLeod 2004).

Figure 3. Woodland cover was poor overall. Only six sub-catchments had >30% cover, considered the minimum threshold for ecosystem function (Source: MacLeod 2004).

Figure 4. The number of viable woodland patches was low (Source: MacLeod 2004).

The triage approach does not suggest simply ignoring sub-catchments of lower biodiversity value, but rather it is based around the allocation of limited financial resources in addition to the current state and likely future state of the sub-catchment in question.

The process of peri-urbanisation is occurring at a rate that exceeds our ability to understand many landscape attributes in depth. Ecosystem and species ecology such as source and sink populations, predator/prey relationships, lag effects and even population distributions all lack vital data. Although these gaps will limit the efficacy of biodiversity conservation efforts, the theories underlying them mean that for many species they will be negatively affected by fragmentation and intensive land use. This knowledge should inform NRM in peri-urbanising areas.


Varied, and in many cases dissimilar, land uses on numerous smallholdings are draped across the ecologically and socially diverse landscapes of the eastern seaboard and the south-west corner. Recognising and maintaining these land uses while simultaneously attempting to maintain ecological function and biodiversity requires considerations of ecological integrity at an appropriate landscape scale. Sub-catchment management is a compromise that may allow for a degree of meaningful biodiversity conservation in highly sub-divided landscapes with numerous land uses, but only if fundamental ecological theory underpins the conservation planning and the land is acknowledged as the primary stakeholder in its own future. In this regard, the land should be represented more equitably in ‘stakeholder’ considerations by greater use of theoretical and empirical data that reflect functional processes and resource and biodiversity thresholds. NRM does not currently do this satisfactorily. We also suggest that highly judicious decision-making in extension practice be employed at a sub-catchment level to triage sub-catchments into two categories: a) biodiversity maintenance/resource stabilisation and b) resource stabilisation only. There are large data gaps in the ecological knowledge of peri-urbanising landscapes, but land conversion is occurring too rapidly to keep pace. It is highly likely that genetic, taxonomic and ecosystem loss will continue without sound ecologically based management, implemented through land use restrictions and highly sensitive infrastructure development.


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