Andre Zerger

Reversing a tree regeneration crisis in an endangered ecoregion

Global food demand is growing rapidly. Livestock grazing can provide a valuable source of protein, but conventional grazing is often unsustainable. We studied an 800,000-ha section of a threatened ecoregion in southeastern Australia. Conventional management in the region involves continuous livestock grazing with few rest periods and regular fertilizer application. By using remotely sensed data on tree cover and extensive field data on livestock grazing regimes, soil chemistry, tree diameters, and tree regeneration, we show that the region is facing a tree regeneration crisis. Under conventional management, across the region, millions of hectares of land currently supporting tens of millions of trees will be treeless within decades from now. This would have severe negative ramifications for biodiversity and key ecosystem services, including water infiltration and shade provision for livestock. However, we identified an unexpected win–win solution for tree regeneration and commercial grazing. A relatively new practice in the region is fast-rotational grazing, characterized by prolonged rest periods in between short, intensive grazing events. The probability of regeneration under fast-rotational grazing was up to 4-fold higher than under conventional grazing, and it did not differ significantly from the probability of regeneration in ungrazed areas. In addition, trees were more likely to regenerate where soil nutrient levels were low. These findings suggest that the tree regeneration crisis can be reversed by applying low-input, fast-rotational grazing. New policy settings supporting these practices could signal a turning point for the region, from ecological decline to ecological recovery.

Eliciting and integrating expert knowledge for wildlife habitat modelling

Expert knowledge regarding the distribution of sambar deer (Cervis unicolor) in Lake Eildon National Park (LENP), Victoria was used to build a wildlife habitat model to assist with park management. The paper presents two methods for eliciting expert knowledge. These were a quantitative geographical information system (GIS)-based approach using a customised graphical user interface, and a qualitative approach that uses semi-structured interviews. The GIS approach is valuable as it is objective, repeatable and provides a spatial context for knowledge elicitation. Experts were asked to provide estimates of sambar sightings and predicted densities with the assistance of contextual environmental data including terrain, roads, hydrology and rainfall surfaces. The quantitative knowledge elicitation process did not identify any sambar environmental niches in the Park, and the experts disagreed about the location of likely habitat. On the other hand, the qualitative assessment showed very strong expert agreement and a combination of this information and published literature was used to build a habitat map. The results of the analysis indicate that sambar deer occur throughout the entire Park. It is envisaged that the results can be used as baseline information for population modelling and natural resource management in the Park. Elicitation of knowledge is complicated by a number of factors including computer proficiency and study site familiarity. The relatively large cohort used in this study and the inherent inconsistencies that were encountered indicate that wildlife managers should interpret results carefully from habitat models that use only a relatively small cohort of experts.

Tree decline and the future of Australian farmland biodiversity

Farmland biodiversity is greatly enhanced by the presence of trees. However, farmland trees are declining worldwide, including in North America, Central America, and parts of southern Europe. We show that tree decline and its likely consequences are particularly severe in Australias temperate agricultural zone, which is a threatened ecoregion. Using field data on trees, remotely sensed imagery, and a demographic model for trees, we predict that by 2100, the number of trees on an average farm will contract to two-thirds of its present level. Statistical habitat models suggest that this tree decline will negatively affect many currently common animal species, with predicted declines in birds and bats of up to 50% by 2100. Declines were predicted for 24 of 32 bird species modeled and for all of six bat species modeled. Widespread declines in trees, birds, and bats may lead to a reduction in economically important ecosystem services such as shade provision for livestock and pest control. Moreover, many other species for which we have no empirical data also depend on trees, suggesting that fundamental changes in ecosystem functioning are likely. We conclude that Australias temperate agricultural zone has crossed a threshold and no longer functions as a self-sustaining woodland ecosystem. A regime shift is occurring, with a woodland system deteriorating into a treeless pasture system. Management options exist to reverse tree decline, but new policy settings are required to encourage their widespread adoption.

Beyond Modelling: Linking Models with GIS for Flood Risk Management

Spatially explicit hydrodynamic flood models can play animportant role in natural hazard risk reduction. A key element of these models that make them suitable for riskreduction is the ability to provide time-series inundation information about the onset, duration and passingof a hazard event. Such information can be critical for landuse planning, for mapping evacuation egress routes,and for locating suitable emergency shelters to name only a few risk treatments. This research contends that abarrier to effective risk reduction is providing disaster managers with access to model results in a structured andflexible framework that allows consequences of different hazard scenarios to be assessed and mapped. Toaddress these limitations, a framework has been developed that links a commercial relational databasemanagement system with a GIS-based decision support system. The framework utilises industry standard dataexchange protocols and results in efficient time-series hazard data management. A case study based in Cairns,in far-north coastal Australia is presented to illustrate how the system has been developed. Results show that theframework reduces data volumes significantly, while making pre-run modelled inundation results rapidly accessibleto disaster managers. Of note is the ability of the framework to present results in terms of risk to buildings,roads and other spatial features in urban regions, and to provide answers to relatively complex risk questions.

Geo-temporal tracking and analysis of tourist movement

Agent-based simulation is a decision support tool that has recently been used by park managers to better plan the development of tourist infrastructure such as paths, buildings and viewing platforms and to understand the relationships between visitor flows and acceptable levels of crowding. The objective in these studies is to simulate the current and projected movement of individuals in relationship to pedestrian infrastructure or management actions to determine the impact on visitor experience and infrastructure capacity. A number of projects have been undertaken in Australia and the United States using agent-based models. However, research has shown that there is a need for new methods to collect calibration and validation data in order to validate spatial/temporal simulation models. This paper presents the results of experiments designed to track humans at the Twelve Apostles National Park, Victoria, Australia over 3 days in an effort to develop typologies of trip itineraries. The research used running race timing equipment known as the Alge timing system to monitor the movement of people in the park along a constrained network. A series of receivers recorded the precise positions of 900 individuals who were wearing unobtrusive ankle transmitters. This paper examines the technical aspects of tracking humans using race-timing technology and proposes some methods to analyse this data to determine whether typologies of tourist behaviour do indeed exist. The research also comments on the utility of the data to address the requirements of the recreational behaviour simulator, an agent-based modeling framework which has been used extensively for national park management.

Toward landscape-wide conservation outcomes in Australia's temperate grazing region.

Agriculture and livestock grazing threaten biodiversity around the world. In the grazing landscapes of eastern Australia, a common conservation strategy has been to exclude livestock from large patches of trees (typically > 5 ha). This has major local benefits, but is unlikely to stem regional biodiversity loss. Using a case study from the Upper Lachlan catchment in New South Wales, we show that (1) approximately 30% of tree cover occurs as very small patches or scattered trees; (2) large patches have disappeared from 90% of the landscape; and (3) large patches are 3.5 times more likely to be in unproductive upland areas than in lowland areas of high conservation concern. Given the limitations of focusing on large patches of trees to achieve regional conservation outcomes, the next generation of conservation initiatives should consider a new suite of additional measures that could deliver biodiversity benefits across broad areas of the region. Two key measures that must be considered are new incentives fo...

Multi-criteria assessment for linking regional conservation planning and farm-scale actions

Regional-scale ecological restoration priorities such as increasing the extent and quality of native vegetation are generally planned at catchment scales, while on-ground restoration actions are generally implemented at paddock or farm scales. This paper describes the use of spatial multi-criteria assessment methodologies to construct maps of regional conservation priorities and assesses how these maps map influence farm-scale actions in Western Victoria, Australia (e.g. farm-scale revegetation for salinity, wind erosion, stock shelter, etc). The study also incorporates agricultural production in the decision analysis through the use of historical yield mapping data obtained from harvest logs from precision agriculture equipment. Via a stakeholder workshop, farmer land use priorities were elicited with and without access to maps of regional conservation priorities. Results highlight that production imperatives drive farmer-led conservation actions and that regional conservation priorities have only limited impact on actions. The paper also identifies limitations of applying MCA methods across multiple decision-making scales such as the need to generalise priorities where domain knowledge is relatively high, and the challenges associated with MCA criteria definition.

The extent of dryland salinity in remnant woodland and forest within an agricultural landscape

Dryland salinity is considered a significant and increasing threat to sustainable land management and biodiversity across large parts of temperate Australia. However, there is little information on the extent of this threat to terrestrial ecosystems in south-eastern Australia. This paper provides a quantitative assessment of the extent of dryland salinity in remnant native woody vegetation in the agriculture-dominated landscape of the Boorowa Shire located in the South West Slopes bioregion of south-eastern Australia. The amount and type of native woody vegetation in the Boorowa Shire affected by dryland salinity was assessed by analysing the extent of overlap between the following three spatial data layers: (1) woody vegetation mapping derived from high-resolution satellite imagery, (2) existing vegetation community mapping predicted from field data and expert opinion and (3) existing dryland salinity outbreak mapping derived from air photo interpretation and filed verification. There were more than 6000 patches of salt outbreak in woody vegetation in the Boorowa Shire, 383 (6%) of which were 1 ha or larger in area. Almost 2000 ha of woody vegetation were affected by dryland salinity, representing ~3% of the extant native woody vegetation in the Boorowa Shire. The vegetation type with the largest total area affected by dryland salinity was yellow box (Eucalyptus melliodora Cunn. Ex Schauer)–Blakely’s red gum (E. Blakelyi Maiden) woodland. As a proportion of their current extent, vegetation communities lower in the landscape were significantly more affected than those higher up the topographic sequence, with 14% of riparian communities and nearly 6% of yellow box–Blakely’s red gum woodland exhibiting symptoms of dryland salinity. About 1% of white box (E. albens Benth) woodland, and of hill communities which are on mid- and upper slopes, were affected. The pattern of salinity outbreaks in relation to landscape position and vegetation type is significant for biodiversity conservation because the vegetation communities most affected by salinisation are those most heavily cleared and modified post-European settlement. Throughout the South West Slopes of New South Wales, remnants of riparian communities and yellow box–Blakely’s red gum woodland are highly cleared, fragmented and degraded. Dryland salinity represents an additional threat to these vegetation communities and their component species. Salinisation of woodland ecosystems poses significant problems for land managers. The long-term viability of these woodland remnants needs to be considered when allocating limited public funds for woodland conservation, whether on private land or in formal reserves.

A multilayer feedforward neural network for automatic classification of eucalyptus forests in airborne video imagery

Eucalypt tree dieback is a disease that threatens the survival of woodlands in Australian national parks. For mapping and monitoring the spatial distribution of dieback, airborne imaging technologies can be more effective than ground surveys. Amongst the numerous types of airborne sensors, the video camera provides images with very high spatial resolution. In order to detect individual defoliated Eucalyptus trees at Mt Eccles national park (south‐western Victoria), aerial video data was acquired across the study site. Highlighting the health status of sparse and mainly unclustered defoliated eucalypts at Mt Eccles through video images was deemed to be achievable in several steps. This paper introduces a classification method based on a feedforward neural network, whose main goal is to perform a segmentation of the video frames into three classes, namely, bare branches or trunks, healthy canopy and understorey vegetation. The aim of the algorithm is to create a subset of the eucalypt tree group, including defoliated and dead trees, for further analysis. The results suggest that the recognition of trunks and systems of bare branches is feasible using the neural network architecture. This provides a means to pre‐process the video data so as to analyse the health of trees and thus assist park managers with managing dieback.

Thematic Issue Editorial: Science to improve regional environmental investment decisions

Natural resource managers are faced with multi-million dollar decisions about where and when to invest for the best overall environmental outcomes. The challenge is to design policy and target investment in management actions cost-effectively to achieve multiple environmental, social and economic objectives. This means developing innovative tools that can assist managers decide what they can do to improve environmental outcomes, where and when intervention is likely to be most effective. It also requires the testing of these frameworks and decision tools against historic studies of the effectiveness of past policies and investment strategies. Considering both the socio-economic and biophysical aspects in an integrated manner is an essential part of analysing costeffective natural resource management decision-making. Typical methodological approaches can include: