Bird declines over 22 years in forest remnants in southeastern Australia: Evidence of faunal relaxation?

MacHunter, Josephine; Wright, Wendy; Loyn, Richard; Rayment, Philip Robert

doi:10.1139/x06-159

Cited by 34 publications

(26 citation statements)

References 33 publications

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“…If the neutral model is a good approximation for the mechanisms causing hyperbolic relaxation, then we expect that T 50 ≃ t 50 . For two of the cited studies (37,38), it was necessary to make some extra assumptions to compare their results with neutral predictions, because these studies did not estimate relaxation times, although the data do allow such a calculation. More information about the methods can be found in SI Text, where we derive an equivalence for their system.…”

Section: Methodsmentioning

confidence: 99%

Neutral theory as a predictor of avifaunal extinctions after habitat loss

Halley

Iwasa

2011

Proc. Natl. Acad. Sci. U.S.A.

111

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The worldwide loss of natural habitats leads not only to the loss of habitat-endemic species but also to further and protracted extinctions in the reduced areas that remain. How rapid is this process? We use the neutral theory of biodiversity to answer this question, and we compare the results taken with observed rates of avifaunal extinctions. In the neutral model, we derive an exact solution for the rate of species loss in a closed community. The simple, closedform solution exhibits hyperbolic decay of species richness with time, which implies a potentially rapid initial decline followed by much slower rates long term. Our empirical estimates of extinction times are based on published studies for avifaunal extinctions either on oceanic islands or in forest fragments, which span a total of six orders of magnitude in area. These estimates show that the time to extinction strongly depends on the area. The neutral-theory predictions agree well with observed rates over three orders of magnitude of area (between 100 and 100,000 ha) both for islands and forest fragments. Regarding the species abundance distribution, extinction times based on a broken-stick model led to better agreement with observation than if a log-series model was used. The predictions break down for very small or very large areas. Thus, neutrality may be an affordable assumption for some applications in ecology and conservation, particularly for areas of intermediate size.extinction debt | faunal relaxation | biodiversity loss | extinction rates T he primary driver of extinction in terrestrial environments today is habitat loss (1, 2). In particular, the loss of large portions of tropical rainforest through land conversion was estimated to lead to rates of species extinction hundreds of times higher than the background rate (3). However, the ensuing extinctions will not be realized immediately, because most of the species found in the destroyed habitat are also found in the remaining area. Instead, extinctions occur in the course of the following decades, centuries, or even millennia after the initial habitat contraction. This process has been called faunal relaxation (4). Another term used is extinction debt, which refers to the degree to which the species richness exceeds the speciescarrying capacity of the diminished area (5, 6). A good understanding of this phenomenon is required to explain why the extinctions forecasts are not immediately observed.Empirically, extinction is difficult to observe, because we must establish the absence of an organism simultaneously everywhere before we can be sure that it is extinct. As a result, organisms thought extinct frequently pop up again in subsequent surveys (7). Despite this, a large body of empirical work related to extinction debt has been assembled (review by Kuussaari et al.) (6), including various workarounds using natural experiments (4, 8, 9), microcosms (10), and historical data (11,12). An important and still unresolved part of the picture is to find the dynamic model of extinction in the comm...

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Section: Methodsmentioning

confidence: 99%

Neutral theory as a predictor of avifaunal extinctions after habitat loss

Halley

Iwasa

2011

Proc. Natl. Acad. Sci. U.S.A.

111

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“…Positions of vegetation characteristics and species traits relative to the origin indicate relative contributions to the RLQ axes (plots b and c) recorded species that nest and/or forage arboreally. These species may not persist in a landscape with fewer trees or may face increased inter-specific competition for nest and food resources, possibly leading to local population declines or local extinction (Tilman et al 1994;MacHunter et al 2006;Huste and Boulinier 2007). For example, the loss of patches of hollow-bearing trees may negatively affect hollow-nesting parrots, such as the nationally threatened superb parrot, Polytelis swainsonii (EPBC Act 1999).…”

Section: Relationships Between Species Traits and Vegetation Charactementioning

confidence: 99%

Linking bird species traits to vegetation characteristics in a future urban development zone: implications for urban planning

et al. 2012

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Identifying the relationships between species traits and patch-scale vegetation characteristics in areas designated for urban development can improve our understanding of how animal communities may change with urbanization. We explored the implications of this premise to the urban planning process in a mixed-use landscape in Canberra (Australia), prior to its development into new suburbs. We used RLQ analysis to relate bird foraging, nesting and body size traits to patch-scale vegetation characteristics. Relationships between species traits and vegetation characteristics within the development zone suggest that species that forage and nest on the ground and in the understory strata, and smaller-bodied species will be most negatively affected by urbanization. Identifying the relationships between species traits and vegetation characteristics may be used by urban planners to (i) identify potentially critical habitat and species at risk from development, (ii) inform the choice of impact mitigation measures, and/or (iii) distinguish between high and low mitigation Urban Ecosyst measures. Analyses conducted early in the planning process can then be used to allocate proposed land uses in an ecologically sensitive way, and to plan appropriate mitigation measures.

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“…This is perhaps the most parsimonious explanation. Wide year-to-year background variations in bird assemblage composition have been demonstrated in several Australian studies (Maron et al, 2005;Wardell-Johnson and Williams, 2000), as have changes on decadal scales (MacHunter et al, 2006). Many otherwise comparable non-Australian studies do not allow for the possibility of interannual variability, either because the studies are too short-term (two years: Preston and Harestad, 2007;one year: St-Laurent et al, 2008); or because they did not employ controls (e.g.…”

Section: Interannual Variability or Long-term Change Induced By Factorsmentioning

confidence: 99%

Early responses of birds to clearfelling and its alternatives in lowland wet eucalypt forest in Tasmania, Australia

Lefort

Grove

2009

Forest Ecology and Management

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Bird declines over 22 years in forest remnants in southeastern Australia: Evidence of faunal relaxation?

Cited by 34 publications

References 33 publications

Neutral theory as a predictor of avifaunal extinctions after habitat loss

Neutral theory as a predictor of avifaunal extinctions after habitat loss

Linking bird species traits to vegetation characteristics in a future urban development zone: implications for urban planning

Early responses of birds to clearfelling and its alternatives in lowland wet eucalypt forest in Tasmania, Australia

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