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Dive into the research topics where Philip Gibbons is active.

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Featured researches published by Philip Gibbons.


Conservation Biology | 2008

The Future of Scattered Trees in Agricultural Landscapes

Philip Gibbons; David B. Lindenmayer; Joern Fischer; Adrian D. Manning; A. Weinberg; Julian Seddon; Paul Ryan; G. Barrett

Mature trees scattered throughout agricultural landscapes are critical habitat for some biota and provide a range of ecosystem services. These trees are declining in intensively managed agricultural landscapes globally. We developed a simulation model to predict the rates at which these trees are declining, identified the key variables that can be manipulated to mitigate this decline, and compared alternative management proposals. We used the initial numbers of trees in the stand, the predicted ages of these trees, their rate of growth, the number of recruits established, the frequency of recruitment, and the rate of tree mortality to simulate the dynamics of scattered trees in agricultural landscapes. We applied this simulation model to case studies from Spain, United States, Australia, and Costa Rica. We predicted that mature trees would be lost from these landscapes in 90-180 years under current management. Existing management recommendations for these landscapes--which focus on increasing recruitment--would not reverse this trend. The loss of scattered mature trees was most sensitive to tree mortality, stand age, number of recruits, and frequency of recruitment. We predicted that perpetuating mature trees in agricultural landscapes at or above existing densities requires a strategy that keeps mortality among established trees below around 0.5% per year, recruits new trees at a rate that is higher than the number of existing trees, and recruits new trees at a frequency in years equivalent to around 15% of the maximum life expectancy of trees. Numbers of mature trees in landscapes represented by the case studies will decline before they increase, even if strategies of this type are implemented immediately. This decline will be greater if a management response is delayed.


PLOS ONE | 2012

Land management practices associated with house loss in wildfires

Philip Gibbons; Linda van Bommel; A. Malcolm Gill; Geoffrey J. Cary; Don A. Driscoll; Ross A. Bradstock; Emma Knight; Max A. Moritz; Scott L. Stephens; David B. Lindenmayer

Losses to life and property from unplanned fires (wildfires) are forecast to increase because of population growth in peri-urban areas and climate change. In response, there have been moves to increase fuel reduction—clearing, prescribed burning, biomass removal and grazing—to afford greater protection to peri-urban communities in fire-prone regions. But how effective are these measures? Severe wildfires in southern Australia in 2009 presented a rare opportunity to address this question empirically. We predicted that modifying several fuels could theoretically reduce house loss by 76%–97%, which would translate to considerably fewer wildfire-related deaths. However, maximum levels of fuel reduction are unlikely to be feasible at every house for logistical and environmental reasons. Significant fuel variables in a logistic regression model we selected to predict house loss were (in order of decreasing effect): (1) the cover of trees and shrubs within 40 m of houses, (2) whether trees and shrubs within 40 m of houses was predominantly remnant or planted, (3) the upwind distance from houses to groups of trees or shrubs, (4) the upwind distance from houses to public forested land (irrespective of whether it was managed for nature conservation or logging), (5) the upwind distance from houses to prescribed burning within 5 years, and (6) the number of buildings or structures within 40 m of houses. All fuel treatments were more effective if undertaken closer to houses. For example, 15% fewer houses were destroyed if prescribed burning occurred at the observed minimum distance from houses (0.5 km) rather than the observed mean distance from houses (8.5 km). Our results imply that a shift in emphasis away from broad-scale fuel-reduction to intensive fuel treatments close to property will more effectively mitigate impacts from wildfires on peri-urban communities.


Biological Conservation | 2002

Hollow selection by vertebrate fauna in forests of southeastern Australia and implications for forest management

Philip Gibbons; David B. Lindenmayer; Simon C. Barry; M.T. Tanton

Abstract We examined the types of hollows, and types of hollow-bearing trees, occupied by vertebrate fauna in temperate eucalypt forests in southeastern Australia. Hollow-bearing trees are selected for retention in wood production forests to mitigate the effects of logging on hole-nesting fauna. A total of 471 hollows was examined in 228 trees felled as part of routine logging operations. Fauna had occupied 43% of all hollows (⩾2cm minimum entrance width; ⩾5cm depth). Hollows with small (2–5cm), medium (6–10cm) and large (>10cm) minimum entrance widths had occupancy rates of 29, 44 and 62%, respectively. The internal dimensions of hollows, especially hollow depth, were the best predictors of hollow occupancy, even when variables measured at the tree and site levels were considered. Fauna occupied 57% of all hollow-bearing trees. In a Poisson regression model, the number of hollows in trees that contained evidence of occupancy was positively associated with: (1) the total number of hollows visible in the tree; (2) the proportion of the trees crown that contained dead branches; and (3) tree diameter. The number of different vertebrate species that occupied trees was positively associated with the same explanatory variables except tree diameter. Thus, our results suggest that trees with multiple hollows and dead branches in the crown should be preferentially selected for occupancy by hollow-using fauna. Our results suggest that trees with the largest diameter are not the most suitable for retention. Possibly because they contain proportionally fewer hollows with small entrances, which are favoured by some vertebrate species.


Forest Ecology and Management | 1996

Issues associated with the retention of hollow-bearing trees within eucalypt forests managed for wood production

Philip Gibbons; David B. Lindenmayer

The conservation of hollow-dependent fauna is a major forest management problem in natural eucalypt forests managed for wood production. Eucalypt forests support a diverse fauna that utilise hollows in trees. Hollow-bearing trees are a component of forest structure often lost or substantially modified as a result of timber harvesting operations, especially those that are intensive (like clearfelling) and take place on a short rotation (< 120 years) One approach adopted to conserve populations of hollow-dependent fauna in eucalypt forests has been to retain suitable trees in logged areas. This paper reviews a wide range of issues associated with the retention of such trees ranging from: (1) the characteristics of trees which should be selected for retention; (2) the number and spatial arrangement of retained stems; (3) the need for recruitment of new hollow-bearing trees to ensure there is a perpetual supply of such resources; and (4) how best to protect those trees that are retained. We also consider factors such as the inter-relationships between tree retention strategies and silvicultural requirements, and on-site tree retention strategies and forest management at the landscape-scale. A major conclusion from our study is that the array of issues associated with the retention of trees with hollows in eucalypt forests is considerably more complex than reflected by current management practice. Indeed, it appears that most existing prescriptions for the retention of trees with hollows in logged sites may not ensure a perpetual supply of a range of types of hollow trees or provide the necessary habitat conditions to support viable populations of some species of hollow-dependent fauna. This is because current prescriptions typically do not take account of factors such as: the prolonged periods until hollows first begin to develop in Eucalyptus trees; mortality and collapse amongst retained stems; and the need to supply trees with suitable characteristics and in a suitable configuration to meet the requirements of the full range of vertebrate taxa that utilise this resource. Taking these factors into account, we conclude that only modified partial cutting systems would adequately provide for the needs of all cavity-using species across logged sites in eucalypt forests. A major problem confounding attempts to develop more informed prescriptions for the retention of trees in logged areas is a lack of data on key topics such as stem longevity and hollow ontogeny, mortality of retained trees on logged sites and cavity use by animals. There is scope for some of these data to be readily gathered in routine timber assessment and inventory, stand regeneration surveys and fauna and vegetation surveys. We recommend that forest and wildlife management agencies review their field survey methods and include some new measures among the range of data collected. There is also considerable merit in instigating new tree and forest modelling projects to simulate long-term stand conditions in wood production eucalypt forests. Such studies would guide forest and wildlife managers in the development of tree retention strategies needed to create and maintain stand characteristics suitable to support populations of hollow-dependent wildlife over not one, but many rotations. Given the uncertainty associated with the effects of these operations on hollow-dependent fauna, and continued timber harvesting operations in these forests, we recommend a strategy which maintains a variety of approaches to management. Such a strategy is akin to ‘risk spreading’ and would involve implementing a range of tree retention strategies within cutting areas as well as the adoption of a number of strategies at the landscape level (e.g. wildlife corridors).


Forest Ecology and Management | 2000

Cavity sizes and types in Australian eucalypts from wet and dry forest types–a simple of rule of thumb for estimating size and number of cavities

David B. Lindenmayer; Ross B. Cunningham; M Pope; Philip Gibbons; Christine Donnelly

Abstract We describe the relationships between the number, size and type of cavities in six species of eucalypt trees from southern New South Wales (south-eastern Australia) and tree diameter, tree height, tree species and other measures. The eucalypt species studied were:-Narrow-leaved Peppermint ( Eucalyptus radiata ), Mountain Swamp Gum ( Eucalyptus camphora ), Mountain Gum ( Eucalyptus dalrympleana ), Red Stringybark ( Eucalyptus macrorhyncha ), Ribbon Gum ( Eucalyptus viminalis ), and, Broad-leaved Peppermint ( Eucalyptus dives ). E. radiata and E. macrorhyncha supported almost twice the proportion of branch-end hollows than cavities assigned to other categories. Cavities in the main trunk were the predominant hollow class in E. viminalis and E. dalrympleana . Large diameter trees were characterised by more branch-end hollows, whereas main trunk cavities were typically the most prevalent cavity type in smaller diameter stems. We identified a simple, general rule that highlights the relationships between cavities and readily measured tree attributes. Our data show that, in general, both the number of cavities and cavity size were directly proportional to tree diameter, but inversely proportional to the square root of tree height. This proportionality changed between different tree species. E. dives and E. viminalis supported, on average, larger cavities than other species, whereas the cavities in E. macrorhyncha were smaller than the other taxa sampled. This simple general relationship may make it possible to make rapid crude estimates of cavity abundance across large areas of forest by measuring simple tree attributes such as tree diameter and tree height.


PLOS ONE | 2012

Interacting Factors Driving a Major Loss of Large Trees with Cavities in a Forest Ecosystem

David B. Lindenmayer; Wade Blanchard; Lachlan McBurney; David Blair; Sam C. Banks; Gene E. Likens; Jerry F. Franklin; William F. Laurance; John Stein; Philip Gibbons

Large trees with cavities provide critical ecological functions in forests worldwide, including vital nesting and denning resources for many species. However, many ecosystems are experiencing increasingly rapid loss of large trees or a failure to recruit new large trees or both. We quantify this problem in a globally iconic ecosystem in southeastern Australia – forests dominated by the worlds tallest angiosperms, Mountain Ash (Eucalyptus regnans). Tree, stand and landscape-level factors influencing the death and collapse of large living cavity trees and the decay and collapse of dead trees with cavities are documented using a suite of long-term datasets gathered between 1983 and 2011. The historical rate of tree mortality on unburned sites between 1997 and 2011 was >14% with a mortality spike in the driest period (2006–2009). Following a major wildfire in 2009, 79% of large living trees with cavities died and 57–100% of large dead trees were destroyed on burned sites. Repeated measurements between 1997 and 2011 revealed no recruitment of any new large trees with cavities on any of our unburned or burned sites. Transition probability matrices of large trees with cavities through increasingly decayed condition states projects a severe shortage of large trees with cavities by 2039 that will continue until at least 2067. This large cavity tree crisis in Mountain Ash forests is a product of: (1) the prolonged time required (>120 years) for initiation of cavities; and (2) repeated past wildfires and widespread logging operations. These latter factors have resulted in all landscapes being dominated by stands ≤72 years and just 1.16% of forest being unburned and unlogged. We discuss how the features that make Mountain Ash forests vulnerable to a decline in large tree abundance are shared with many forest types worldwide.


PLOS ONE | 2014

An Empirical Assessment and Comparison of Species-Based and Habitat-Based Surrogates: A Case Study of Forest Vertebrates and Large Old Trees

David B. Lindenmayer; Philip S. Barton; Peter W. Lane; Martin J. Westgate; Lachlan McBurney; David Blair; Philip Gibbons; Gene E. Likens

A holy grail of conservation is to find simple but reliable measures of environmental change to guide management. For example, particular species or particular habitat attributes are often used as proxies for the abundance or diversity of a subset of other taxa. However, the efficacy of such kinds of species-based surrogates and habitat-based surrogates is rarely assessed, nor are different kinds of surrogates compared in terms of their relative effectiveness. We use 30-year datasets on arboreal marsupials and vegetation structure to quantify the effectiveness of: (1) the abundance of a particular species of arboreal marsupial as a species-based surrogate for other arboreal marsupial taxa, (2) hollow-bearing tree abundance as a habitat-based surrogate for arboreal marsupial abundance, and (3) a combination of species- and habitat-based surrogates. We also quantify the robustness of species-based and habitat-based surrogates over time. We then use the same approach to model overall species richness of arboreal marsupials. We show that a species-based surrogate can appear to be a valid surrogate until a habitat-based surrogate is co-examined, after which the effectiveness of the former is lost. The addition of a species-based surrogate to a habitat-based surrogate made little difference in explaining arboreal marsupial abundance, but altered the co-occurrence relationship between species. Hence, there was limited value in simultaneously using a combination of kinds of surrogates. The habitat-based surrogate also generally performed significantly better and was easier and less costly to gather than the species-based surrogate. We found that over 30 years of study, the relationships which underpinned the habitat-based surrogate generally remained positive but variable over time. Our work highlights why it is important to compare the effectiveness of different broad classes of surrogates and identify situations when either species- or habitat-based surrogates are likely to be superior.


PLOS ONE | 2012

Not All Kinds of Revegetation Are Created Equal: Revegetation Type Influences Bird Assemblages in Threatened Australian Woodland Ecosystems

David B. Lindenmayer; Amanda R. Northrop-Mackie; Rebecca Montague-Drake; Mason Crane; Damian Michael; Sachiko Okada; Philip Gibbons

The value for biodiversity of large intact areas of native vegetation is well established. The biodiversity value of regrowth vegetation is also increasingly recognised worldwide. However, there can be different kinds of revegetation that have different origins. Are there differences in the richness and composition of biotic communities in different kinds of revegetation? The answer remains unknown or poorly known in many ecosystems. We examined the conservation value of different kinds of revegetation through a comparative study of birds in 193 sites surveyed over ten years in four growth types located in semi-cleared agricultural areas of south-eastern Australia. These growth types were resprout regrowth, seedling regrowth, plantings, and old growth. Our investigation produced several key findings: (1) Marked differences in the bird assemblages of plantings, resprout regrowth, seedling regrowth, and old growth. (2) Differences in the number of species detected significantly more often in the different growth types; 29 species for plantings, 25 for seedling regrowth, 20 for resprout regrowth, and 15 for old growth. (3) Many bird species of conservation concern were significantly more often recorded in resprout regrowth, seedling regrowth or plantings but no species of conservation concern were recorded most often in old growth. We suggest that differences in bird occurrence among different growth types are likely to be strongly associated with growth-type differences in stand structural complexity. Our findings suggest a range of vegetation growth types are likely to be required in a given farmland area to support the diverse array of bird species that have the potential to occur in Australian temperate woodland ecosystems. Our results also highlight the inherent conservation value of regrowth woodland and suggest that current policies which allow it to be cleared or thinned need to be carefully re-examined.


Ecological Monographs | 2011

Cross‐sectional vs. longitudinal research: a case study of trees with hollows and marsupials in Australian forests

David B. Lindenmayer; Jeffrey Wood; Lachlan McBurney; Damian Michael; Mason Crane; Chris MacGregor; Rebecca Montague-Drake; Philip Gibbons; Samuel Banks

How different are insights based on cross-sectional studies from those of longitudinal investigations? We addressed this question using a detailed case study encompassing a rare suite of inter-connected cross-sectional and longitudinal investigations that have spanned the past two decades and included work on: (1) the decay and collapse of large-cavity forest trees (termed “trees with hollows”), (2) populations of a suite of species of arboreal marsupials that are reliant on trees with hollows as nesting and denning sites, and (3) relationships between the abundance, type, and condition of trees with hollows and the presence, abundance, and species richness of these animals. Our case study was from the montane ash eucalypt forests of the Central Highlands of Victoria, southeastern Australia. Our longitudinal studies led to new insights that either would not have been possible from a cross-sectional study, or which were unexpected because they did not conform, or only partially conformed, to postulated res...


Climatic Change | 2012

Priorities in policy and management when existing biodiversity stressors interact with climate-change

Don A. Driscoll; Adam Felton; Philip Gibbons; Annika M. Felton; Nicola T. Munro; David B. Lindenmayer

There are three key drivers of the biodiversity crisis: (1) the well known existing threats to biodiversity such as habitat loss, invasive pest species and resource exploitation; (2) direct effects of climate-change, such as on coastal and high elevation communities and coral reefs; and (3) the interaction between existing threats and climate-change. The third driver is set to accelerate the biodiversity crisis beyond the impacts of the first and second drivers in isolation. In this review we assess these interactions, and suggest the policy and management responses that are needed to minimise their impacts. Renewed management and policy action that address known threats to biodiversity could substantially diminish the impacts of future climate-change. An appropriate response to climate-change will include a reduction of land clearing, increased habitat restoration using indigenous species, a reduction in the number of exotic species transported between continents or between major regions of endemism, and a reduction in the unsustainable use of natural resources. Achieving these measures requires substantial reform of international, national and regional policy, and the development of new or more effective alliances between scientists, government agencies, non-government organisations and land managers. Furthermore, new management practices and policy are needed that consider shifts in the geographic range of species, and that are responsive to new information acquired from improved research and monitoring programs. The interactions of climate-change with existing threats to biodiversity have the potential to drive many species to extinction, but there is much that can be done now to reduce this risk.

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David B. Lindenmayer

Australian National University

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Adrian D. Manning

Australian National University

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Julian Seddon

Commonwealth Scientific and Industrial Research Organisation

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Karen Ikin

Australian National University

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Andre Zerger

Commonwealth Scientific and Industrial Research Organisation

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Chris McElhinny

Australian National University

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Darren S. Le Roux

Australian National University

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Mason Crane

Australian National University

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