Plant pathogens causing vegetation dieback: a serious threat to the conservation of small mammals in Australia

The soil-borne plant pathogen Phytophthora cinnamomi occurs in most Australian states. It is pathogenic to many Australian species, particularly the Proteaceae, Fabaceae, Dillineaceae and Epacridaceae. In Western Australia, c. 2000 of the 9000 endemic plant species are directly affected by the disease. The epidemic of plant deaths caused by P. cinnamomi is recognised as one of 11 Key Threatening Processes to the Australian Environment, and is now also acknowledged as a potential threat fauna in a range of communities. The implications of landscape modification due to the effects of P. cinnamomi dieback prompted our research, designed to measure the distribution and abundance of small mammals in disease-affected ecosystems. This study was in the Jarrah (Eucalyptus marginata) forests in the Darling Range, Western Australia and measured the distribution and abundance of one small mammal species, the Mardo (Antechinus flavipes) by Elliott trapping in forests with (1) high, (2) mixed and (3) no evidence of Phytophthora dieback. Trap success was highest in sites with no effect of Phytophthora (7.3 animals per 100 trap nights), whereas the lowest trap success was recorded at the high impact sites (0.67 animals per 100 trap night). There was a significant difference in trap success of Mardos in Elliott trapping over 1800 trap nights (x²= 23.19, d.f = 5, p < 0.001). An examination of the distribution of individuals and sexes suggests that Phytophthora-affected sites act as sinks for Mardos, while source areas are healthy, unaffected Jarrah forest.

Predictive distribution models and their application in wildlife conservation

Wildlife managers are often faced with the difficult task of determining the distribution of species, and their preferred habitats, at large spatial scales. This task is even more challenging when the species of concern is in low abundance and/or the terrain is largely inaccessible. Spatially explicit distribution models, derived from multivariate statistical analyses and implemented in a geographic information system (GIS), can be used to predict the distributions of species and their habitats, thus making them a useful conservation tool. We present two such models: one for a dasyurid, the Swamp Antechinus (Antechinus minimus), and the other for a ground-dwelling bird, the Rufous Bristlebird (Dasyornis broadbenti), both of which are rare species occurring in the coastal heathlands of south-western Victoria. Models were generated using generalized linear modelling (GLM) techniques with species presence or absence as the independent variable and a series of landscape variables derived from GIS layers and high-resolution imagery as the predictors. The most parsimonious model, based on the Akaike Information Criterion, for each species then was extrapolated spatially in a GIS. Probability of species presence was used as an index of habitat suitability. Because habitat fragmentation is thought to be one of the major threats to these species, an assessment of the spatial distribution of suitable habitat across the landscape is vital in prescribing management actions to prevent further habitat fragmentation.

Determinants of native avian richness in suburban remnant vegetation : implications for conservation planning

While urban areas are increasingly recognized as having potential value for biodiversity conservation, the relationship between biodiversity and the structure and configuration of the urban landscape is poorly understood. In this study we surveyed birds in 39 remnant patches of native vegetation of various sizes (range 1–107 ha) embedded in the suburban matrix in Melbourne, Australia. The total richness of species within remnants was strongly associated with the size of remnants. Remnant-reliant species displayed a much stronger response to remnant area than matrix-tolerant species indicating the importance of large remnants in maintaining representative bird assemblages. Large remnants are important for other ecological groups of species including migratory species, ground foraging birds and canopy foraging birds. Other landscape (e.g. amount of riparian vegetation) and structural components (e.g. shrub cover) of remnants have a lesser role in determining the richness of individual remnants. This research provides conservation managers and planners with a hierarchical process to reserve design and management in order to conserve the highest richness of native species within urban areas. First of all, conservation efforts should preferentially focus on the retention of larger remnants of native vegetation. Second, where possible, riparian vegetation should be included within reserves or, where it is already present, should be carefully managed to ensure its integrity. Third, efforts should be focused at maintaining appropriate habitat and vegetation structure and complexity.

Countryside elements and the conservation of birds in agricultural environments

Throughout the world, many native species inhabit agricultural landscapes. While natural habitats will form the cornerstone of conservation efforts in production-oriented environments, the success of these efforts will be enhanced by a greater understanding of the potential contribution of the increasingly modified countryside (‘matrix’) elements in these landscapes. Here, we investigate the relative occurrence of birds in some landscape elements (i.e. land-uses, vegetation types) common to agricultural environments around the world. Twenty-seven study mosaics (1 km × 1 km in size), selected to incorporate variation in the cover of native vegetation and the richness of different landscape elements, were sampled in Gippsland, south-eastern Australia. Birds were surveyed in five main types of elements: native vegetation, linear vegetation, plantation, scattered trees and pasture. The greatest number of species was recorded in native vegetation, the most important element for the majority of birds in Australian agricultural landscapes. Nevertheless, most countryside elements had value for many species; particularly structurally complex elements. Ordination analyses (based on presence/absence data for 81 species) showed that the composition of bird communities differed between elements. The number of mosaics in which ‘all species’ and ‘woodland species’ were recorded was positively related to the breadth of elements they used; thus species using a greater number of elements occurred more frequently in the study region. Correlation analyses identified that the richness of woodland species (those of increased conservation concern in Australia) in different elements was influenced by features of the mosaic in which they occurred. Notably, the richness of woodland bird species recorded in scattered trees and pasture increased with local native vegetation cover. Key implications for conservation in Australian agricultural environments include: (1) native vegetation is vital for the persistence of birds in these landscapes, and thus is the primary element on which conservation efforts in agricultural landscapes depend; (2) countryside elements can enhance the conservation value of agricultural landscapes by (a) increasing structural complexity in largely cleared areas and (b) increasing the heterogeneity of the entire landscape; and (3) patches of different elements cannot be managed in isolation from their surroundings, as landscape properties affect the richness of bird assemblages in different elements.

A checklist for ecological management of landscapes for conservation

The management of landscapes for biological conservation and ecologically sustainable natural resource use are crucial global issues. Research for over two decades has resulted in a large literature, yet there is little consensus on the applicability or even the existence of general principles or broad considerations that could guide landscape conservation. We assess six major themes in the ecology and conservation of landscapes. We identify 13 important issues that need to be considered in developing approaches to landscape conservation. They include recognizing the importance of landscape mosaics (including the integration of terrestrial and aquatic areas), recognizing interactions between vegetation cover and vegetation configuration, using an appropriate landscape conceptual model, maintaining the capacity to recover from disturbance and managing landscapes in an adaptive framework. These considerations are influenced by landscape context, species assemblages and management goals and do not translate directly into on-the-ground management guidelines but they should be recognized by researchers and resource managers when developing guidelines for specific cases. Two crucial overarching issues are: (i) a clearly articulated vision for landscape conservation and (ii) quantifiable objectives that offer unambiguous signposts for measuring progress.

Ecosystem conservation in multi-tenure reserve networks : the contribution of land outside of publicly protected areas

Multi-tenure reserve networks have been developed as a mechanism to improve cross tenure management and protection of biodiversity, but also as a means of accounting for biodiversity assets managed for conservation outside of protected areas on public land. We evaluated the contribution of multi-tenure reserve networks to enhancing the comprehensiveness and representativeness of ecosystems in publicly protected areas, using three Australian case studies. All networks contributed to enhancing comprehensiveness and representativeness, but this contribution varied between networks and between components of those networks. Significantly, components on private land and "other public land" in all three networks greatly enhanced the protection of some ecosystems at a subregional scale. The Grassy Box Woodlands Conservation Management Network, in particular made a substantial contribution to conservation, with most components protecting remnants of an endangered and under-represented ecosystem. Multi-reserve conservation networks not only act to protect threatened and under-reserved ecosystems, but they also provide a mechanism to account for this protection. Thus, multi-tenure reserve networks have the potential to provide increased knowledge and understanding to conservation planning decision making processes.

Challenges for native grassland conservation on Victoria's Northern Plains

Discusses some of the challenges faced in attempting to retain and conserve grasslands on Victoria's Northern Plains over the past decade. The development of a strategic vision and directions and opportunities for the future are highlighted.

Reservation of important wetlands - recent experiences in conservation planning and practical implementation in Victoria

The establishment of a comprehensive, adequate and representative (CAR) reserve system is not only an objective of all States and Territories but it is an international commitment, since Australia signed the Convention on Biological Diversity. Various reviews note that Australia lacks a representative freshwater reserve system. However, there has been surprisingly little quantitative analysis on the reservation of freshwater ecosystems from which to identify the gaps or deficiencies in the reserve system.

We compared aspects of reservation in wetlands in northern Victoria before and after a major public land use investigation by the government-appointed Victorian Environmental Assessment Council, which sought specifically to recommend a CAR reserve system. Significant improvements in the reservation status for depleted and under-reserved wetland ecosystems, and improved reserve design have been recommended by the investigation. Increases in the reservation of nationally and internationally significant wetlands were also recommended. These recommendations are now under consideration by the Victorian Government.

Some of the challenges in decision-making during this investigation and their implications on wetland conservation are highlighted. The paper concludes by outlining broader policy dilemmas, decisions and debates that that require addressing in relation to developing a system of Freshwater Protected Areas in Australia.

Towards a set of priorities for bird conservation and research in Australia : the perceptions of ornithologists

Australian delegates at the Australasian Ornithological Conference (2007) were surveyed by questionnaire to determine their perceived research and conservation priorities for Australian birds (n = 134). Respondents were honours or postgraduate students (37.4%), academics (26.2%), wildlife managers (6.5%), land managers (6.5%), environmental consultants (5.6%), independent wildlife researchers (5.6%) or had ‘other’ occupations not relevant to birds or their management (12.1%). Respondents rated their priorities on a predetermined set of issues, and were invited to add additional priorities. ‘Conservation of threatened species’ was considered the highest priority, followed by ‘Conservation of birds and biodiversity in general’, ‘Monitoring’, ‘Management’ and ‘Working with communities’. ‘Animal welfare/rights’ was regarded as comparatively less important. Eight of 11 conservation strategies were regarded as of high importance, these included habitat protection and rehabilitation, threat abatement, research, advocacy and education. This study documents the view of the ornithological community with respect to priority issues facing birds and could potentially feed into government and other policies aimed at conserving and understanding Australia’s birds.

Can sand slugs in rivers deliver conservation benefits? The biodiversity value of tributary junction plug wetlands in the Glenelg River, Australia

Restoration works are carried out to alleviate human impacts and improve habitats within ecosystems. However, human impacts may also create new (anthropogenic) habitat for species to exploit.A dilemma arises when proposed restoration works would remove anthropogenic habitat and the assemblages it supports. Sediment input into the Glenelg River has formed tributary junction plug wetlands at confluences. Sand slug removal is proposed as part of river rehabilitation, but would also drain plug wetlands. We sampled four plug wetland, four river run and three river pool sites to determine whether plug wetlands influence water quality and add to the biodiversity of macroinvertebrates in the Glenelg River.Water quality and macroinvertebrate diversity were similar in plug wetlands, river runs and river pools.Assemblages were distinct among all sites, regardless of type, so there was no characteristic ‘plug-wetland fauna’. Therefore, although removal of plug wetlands would not cause a dramatic loss of invertebrate biodiversity, it would destroy anthropogenic habitat that supports a similar range of species to natural habitats in a river subject to multiple degrading processes. Gains from rehabilitation should be weighed against the value of anthropogenic habitat and the extent of similar habitat lost elsewhere in the ecosystem.

MtDNA diversity of the critically endangered Mekong giant catfish (Pangasianodon gigas Chevey, 1913) and closely related species : implications for conservation

Catfishes of the family Pangasiidae are an important group that contributes significantly to the fisheries of the Mekong River basin. In recent times the populations of several catfish species have declined, thought to be due to overfishing and habitat changes brought about by anthropogenic influences. The Mekong giant catfish Pangasianodon gigas Chevey, 1913 is listed as Critically Endangered on the IUCN Red List. In the present study, we assessed the level of genetic diversity of nine catfish species using sequences of the large subunit of mitochondrial DNA (16S rRNA). Approximately 570 base pairs (bp) were sequenced from 672 individuals of nine species. In all species studied, haplotype diversity and nucleotide diversity ranged from 0.118±0.101 to 0.667±0.141 and from 0.0002±0.0003 to 0.0016±0.0013, respectively. Four haplotypes were detected among 16 samples from natural populations of the critically endangered Mekong giant catfish. The results, in spite of the limited sample size for some species investigated, indicated that the level of genetic variation observed in wild populations of the Mekong giant catfish (haplotype diversity=0.350±0.148, nucleotide diversity=0.0009±0.0008) is commensurate with that of some other related species. This finding indicates that (1) wild populations of the Mekong giant catfish might be more robust than currently thought or (2) present wild populations of this species carry a genetic signature of the historically larger population(s). Findings from this study also have important implications for conservation of the Mekong giant catfish, especially in designing and implementing artificial breeding programme for restocking purposes.