Página 1 dos resultados de 8 itens digitais encontrados em 0.004 segundos

Towards a hierarchical framework for modelling the spatial distribution of animals

Mackey, Brendan; Lindenmayer, David
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.94%
Aim: A hierarchical framework is presented for modelling the spatial distribution of terrestrial vertebrate animals. Location: The location of the study is the montane ash forests of the Central Highlands of Victoria, south-eastern Australia. Methods: The

Population genetic analysis reveals a long-term decline of a threatened endemic Australian marsupial

Hansen, Birgita D.; Harley, Daniel K.P.; Lindenmayer, David; Taylor, Andrea Carolyn
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.94%
Since European colonization, Leadbeater's possum (Gymnobelideus leadbeateri) has declined across its range to the point where it is now only patchily distributed within the montane ash forests of the Central Highlands of Victoria. The loss of large hollow

Preventing the extinction of a globally endangered species - Leadbeater's Possum (Gymnobelideus leadbeateri)

Lindenmayer, David; Blair, David; McBurney, Lachlan; Banks, Samuel
Fonte: OMICS Publishing Group Publicador: OMICS Publishing Group
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.94%

Factors at multiple scales affecting distribution patterns and their implications for animal conservation - Leadbeaters Possum as a case study.

Lindenmayer, David
Fonte: Kluwer Academic Publishers Publicador: Kluwer Academic Publishers
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.66%
Detailed field and modelling studies have been completed at different spatial scales for the endangered arboreal marsupial, Leadbeater's Possum (Gymnobelideus leadbeateri); a species virtually confined to the ash-type eucalypt forests in the Central Highlands of Victoria, south-eastern Australia. These forests are also subject to considerable pressure to produce timber and paper products. The studies of Leadbeater's Possum highlighted the factors influencing the distribution and abundance of the species ranging from broad distribution patterns, the occupancy of habitat patches at the landscape scale, and the use of individual den sites and the quality of trees that provide food within particular stands. These scales correspond to the entire known range of the species, sub-populations within a metapopulation occupying an ensemble of patches at the landscape scale, and colonies occupying den trees in individual stands. Information on the factors influencing the distribution of Leadbeater's Possum at one spatial scale were found to be important for informing processes at another. For example, an understanding of the species' habitat requirements informed the spatial distribution of habitat patches at the landscape level which, in turn...

A survey design for monitoring the abundance if arboreal marsupials in the Central Highlands of Victoria

Lindenmayer, David; Cunningham, Ross; MacGregor, Chris; Incoll, R; Michael, Damian
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.66%
We describe a non-standard sample design for monitoring the abundance of arboreal marsupials in the montane ash forests of the Central Highlands of Victoria, south-eastern Australia. The survey design is based on overlapping and rotating sampling from a given population of sites - in this case 160 sites, each measuring 1 ha in size. Estimates of population sizes are obtained using a model-based statistical analysis. Results so far reveal considerable year-to-year variability in populations of Leadbeater's Possum (Gymnobelideus leadbeateri), the Mountain Brushtail Possum (Trichosurus cunninghamii), and the Greater Glider (Petauroides volans). There appears to be an initial decline in the numbers of Leadbeater's Possum, an increase in the Mountain Brushtail Possum and no change in the Greater Glider and the total number of arboreal marsupials. It will be possible report more substantive findings about long-term trends after several more years of the program. Relationships between current and past counts for Leadbeater's Possum and Mountain Brushtail Possum were very weak. This result appeared to be due to low levels of site fidelity for these two species.

Comment: Economics of a nest-box program of an endangered species, a reappraisal

Lindenmayer, David; MacGregor, Chris; Gibbs, Adrian J
Fonte: NRC Research Press Publicador: NRC Research Press
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.66%
Spring et al. (D.A. Spring, M. Bevers, J.O.S. Kennedy, and D. Harley. 2001. Can. J. For. Res. 31: 1992-2003) recently published a paper on the economics of a nest-box program for the endangered arboreal marsupial, Leadbeater's possum (Gymnobelideus leadbeateri) in southeastern Australian forests. While their paper is a useful one, there are some important limitations of nest-box programs that need to be highlighted. In the case of Leadbeater's possum, we have undertaken extensive nest-box studies in Victoria mountain ash (Eucalyptus regnans F. Muell.) forests, where the vast majority of populations of the species now occur. Although large numbers of nest boxes have been deployed, very few have actually been occupied, which is a major problem since the effectiveness of any nest-box program will depend on patterns of use by the target species. Given very low levels of nest-box occupancy, harvesting regimes such as those that lead to on-site tree retention are needed to better conserve hollow-dependent species like Leadbeater's possum. Moreover, the need for nest boxes in the first place indicates that logging practices are presently not ecologically sustainable, and modified forestry practices need to be adopted.

The use of nest boxes by arboreal marsupials in the forests of the Central Highlands of Victoria

Lindenmayer, David; MacGregor, Chris; Cunningham, Ross; Incoll, R; Crane, Mason; Rawlins, A; Michael, Damian
Fonte: CSIRO Publishing Publicador: CSIRO Publishing
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.66%
The results are reported of a nest-box study conducted in two locations in the mountain ash (Eucalyptus regnans) forests of the Central Highlands of Victoria (south-eastern Australia) to compare usage of different nest-box designs located at different heights in trees. A total of 96 nest boxes was established using a rigorous experimental design - two regions (Powelltown and Toolangi State Forests), two forest age classes (20-year post-logging regrowth and 60-year fire- and salvage-logging regrowth), two nest-box designs (large boxes with large entrance holes and small boxes with small entrance holes), and two heights at which nest boxes were attached to trees (3 m and 8 m above the ground). The study entailed setting out four nest boxes at each of 24 sites to meet the design criteria. Evidence of occupancy by vertebrates was recorded in a total of 19 of 96 boxes on 11 of 24 sites site during regular inspections over more than three years. Thirteen boxes were used by Leadbeater's possum (Gymnobelideus leadbeateri), six by the mountain brushtail possum (Trichosurus cunninghami) and seven by the common ringtail possum (Pseudocheirus peregrinus). The common ringtail possum and mountain brushtail possum were seen only in high-large boxes but Leadbeater's possum used all but the low-large boxes. There was evidence of spatial dependence in usage patterns...

Modeling count data of rare species: some statistical issues

Cunningham, Ross; Lindenmayer, David
Fonte: Ecological Society of America Publicador: Ecological Society of America
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
47.66%
Most species abundance data show that a small number of species contribute the vast majority of individuals to a community. Thus, most taxa in a community are uncommon or rare. Yet such species will frequently be of ecological, conservation, or management interest. Data for uncommon or rare species will be presence/absence data or counts of abundance that contain a greater number of zero observations than would be predicted using standard, unimodal statistical distributions. Such data are generally referred to as zero-inflated data and require specialized methods for statistical analysis. Statistical approaches to modeling zero-inflated data include nonstandard mixture models; two-part, conditional models; and birth process models. In this paper, we briefly summarize two of these methods and illustrate the two-part, conditional approach to the problem of modeling count data with extra zeros. An advantage of this approach includes separate fits and separate interpretations of both components of count data; that is to say, the presence/absence component and the abundance component (given presence) can be analyzed separately. This can be valuable not only for simplicity, but also such a two-step method may assist ecological understanding in cases where the basis for species presence might be separated from the underlying reasons affecting the population size of that species at those sites where it is present. We present two case studies of the application of the two-part conditional model for modeling count data with extra zeros. One deals with modeling relationships between counts of the rare and endangered arboreal marsupial...