Suchergebnisse

The Ramsar Convention is unquestionably the backbone of modern wetland management theory and practice. In the last four decades, it has mainstreamed wetlands in the environmental discourse and fostered the development of a comprehensive institutional framework for wetland governance. However, many of the wetlands that occur in human-dominated landscapes remain acutely threatened. The problem is most alarming in urban areas, especially in the fast expanding cities of the developing world, where unprecedented wetland destruction is leading to recurring environmental disasters. This triggers the question: are these failures in wetland governance purely induced by factors exogenous to Ramsar-based institutions or are they manifestations of conceptual drawbacks within Ramsar conceptual framework. Here, we investigate the success and failures of the application of the Ramsar framework's policy directives and management guidelines for urban wetlands using two rapidly expanding cities in South Asia as case studies – Colombo (Sri Lanka) and Kolkata (India). We conclude that despite its remarkable achievements over the past four decades, the Ramsar framework has several conceptual drawbacks that weaken its effectiveness in complex urban contexts. An inadequate recognition of the complex dynamics of urban social-ecological systems, an inadequate recognition of the political complexity of the policy processes, and a lack of an environmental justice perspective are the main shortcomings contributing to failures in urban wetlands governance. While we acknowledge that some solutions are contingent upon national and transnational level socio-political processes and reforms, we offer a set of technical and strategic modifications to the Ramsar framework that can significantly improve its effectiveness in urban wetlands governance.

Urban wetland governance is a policy area with global causes and consequences, that hasn't gained the deserved attention in environmental research. Rapid global urbanization of coastal areas has endangered many important wetland systems. These wetlands provide essential ecosystem services and their degradation put large urban communities at significant risk. This paper investigates the characteristics of urban wetland governance systems and related policy development across four globally spread cases: New York, Tokyo, Kolkata and Colombo. The cases were analyzed using selected policy analysis criteria and discussed within the context of global policy trends, urbanization patterns and environmental change. Despite the apparent diversity of the cases we observed many similar characteristics among the existing institutional arrangements and common policy drivers. However the local factors such as property markets, national or state level urban development polices and community wetland use had the decisive sway over policy and institutional development. We conclude that trying to set globally-applicable normative policy directives or universal ecological reference points are bound to fail in urban wetland governance. The strengths and weaknesses of some important institutional features in the four cases are compared in the analysis and the possible ecological consequences are discussed. The analysis also derives some common lessons for urban wetland governance in major urban areas.

Context
Invasive mammalian predators are often associated with fragmented landscapes, and can compound the impacts of habitat loss and fragmentation on native fauna. Knowledge of how invasive predators are influenced by different landscape structures can assist in the mitigation of their impacts.

Aims
The aim of the present study was to investigate the influence of landscape structure and site-scale habitat attributes on the frequency of feral-cat and red-fox detections in fragmented agricultural landscapes.

Methods
Field surveys of the frequency of red-fox and feral-cat visitation at a site scale were stratified for six different habitat types in six study subregions. The habitat types were large remnant patch interior, large remnant patch edge, small remnant patch, roadside verge, regrowth patch and open agricultural land adjacent to a remnant patch. Sites were centred in a 1-km buffer area from which landscape composition and configuration were calculated. We applied a generalised linear model and an information-theoretic approach to determine the effect size and importance and rank of the explanatory variables on red-fox, feral-cat and pooled cat and fox detection rates.

Key results
The most important factors influencing detection rates had a positive effect and included: the dominance of cropping in the landscape (cat, fox, pooled cat and fox); and the density of vegetation at a site scale (fox, pooled cat and fox). The number of native habitat patches was also an important factor in the models of red foxes and pooled invasive predators.

Conclusion
Spatially heterogeneous cropping landscapes incur higher rates of invasive-predator detections than do intact native-woodland and pasture landscapes at the 1-km scale. At a site scale, elevated invasive-predator detections occurred at sites with dense vegetation, characteristic of narrow woodland and the edges of large woodland patches.

Implications
The research findings highlight that vertebrate pest management needs to target highly fragmented agricultural landscapes that are more likely to have elevated levels of invasive-predator activity. Landscape restoration efforts need to consider the redesign of landscapes to make them less suitable for predators and more hospitable for native wildlife.

Little is known about the drivers and governance strategies of appropriation of urban nature in the global south. We compare urban land-grabbing in the city of Colombo, Sri Lanka, with broader understanding of rural land-grabbing in the developing world. We show that the colonial legacy of appropriation and alteration of urban wetlands in Colombo has attained new heights in the neo-liberal period. This cyclical process has caused acute irreversible damage to the wetland ecosystem and a vast majority of the urban poor, with the marginalised continuing to suffer dispossession and environmental hazard. In recognition of the inherent limitations of 'uncontrollable' hybrid ecologies, potent social struggles have emerged to resist the continued appropriation agenda. As this cycle is perpetuated, broader social struggles for democratic urban governance have overtaken the pursuit of narrow political-economic goals and internal policy reform.

The selection of methods for wildlife surveys is a decision that will influence the accuracy and comprehensiveness of survey outcomes. The choice of methods is commonly based on the species of interest, yet is often limited by the project budget. Although several studies have investigated the effectiveness of various survey techniques for detecting terrestrial mammal and reptile species, none have provided a quantitative analysis of the costs associated with different methods. We compare the detection success and cost efficiency of cage traps, Elliott traps, pit-fall traps, hair funnels, direct observation, and scat detection/analysis for detecting the occurrence of terrestrial reptile and small mammal species in urban bushland remnants of Brisbane City, Queensland, Australia. Cage traps and Elliott traps coupled with hair funnels were the most cost-effective methods for detecting the highest number of ground-dwelling mammal species. Pit-fall traps and direct observations were the most cost-effective methods for maximising the number of reptile species identified. All methods made a contribution to overall detection success by detecting at least one species not detected by any other method. This suggests that a combination of at least two complementary methods will provide the most successful and cost-efficient detection of reptile and mammal species in urban forest remnants. Future studies should explicitly test these findings and examine efficient trapping combinations across different habitat types and for other fauna groups.

Context
Global climate change will lead to increased climate variability, including more frequent drought and heatwaves, in many areas of the world. This will affect the distribution and numbers of wildlife populations. In south-west Queensland, anecdotal reports indicated that a low density but significant koala population had been impacted by drought from 2001–2009, in accord with the predicted effects of climate change.

Aims
The study aimed to compare koala distribution and numbers in south-west Queensland in 2009 with pre-drought estimates from 1995–1997.

Methods
Community surveys and faecal pellet surveys were used to assess koala distribution. Population densities were estimated using the Faecal Standing Crop Method. From these densities, koala abundance in 10 habitat units was interpolated across the study region. Bootstrapping was used to estimate standard error. Climate data and land clearing were examined as possible explanations for changes in koala distribution and numbers between the two time periods.

Key results
Although there was only a minor change in distribution, there was an 80% decline in koala numbers across the study region, from a mean population of 59 000 in 1995 to 11 600 in 2009. Most summers between 2002 and 2007 were hotter and drier than average. Vegetation clearance was greatest in the eastern third of the study region, with the majority of clearing being in mixed eucalypt/acacia ecosystems and vegetation on elevated residuals.

Conclusions
Changes in the area of occupancy and numbers of koalas allowed us to conclude that drought significantly reduced koala populations and that they contracted to critical riparian habitats. Land clearing in the eastern part of the region may reduce the ability of koalas to move between habitats.

Implications
The increase in hotter and drier conditions expected with climate change will adversely affect koala populations in south-west Queensland and may be similar in other wildlife species in arid and semiarid regions. The effect of climate change on trailing edge populations may interact with habitat loss and fragmentation to increase extinction risks. Monitoring wildlife population dynamics at the margins of their geographic ranges will help to manage the impacts of climate change.

Context
Habitat thresholds are the critical point(s), below which the probability of occurrence of a species declines. Identifying thresholds assists land managers to decide how much habitat is needed to conserve a species. However, for any given species, a threshold may not exist, or might occur at one scale but not at others, and it may differ across regions. The use of critical habitat thresholds can negatively affect populations if simplified conservation targets for habitat retention are prescribed. This problem is relevant to the koalas where there is evidence of habitat thresholds in mesic regions, but no studies of thresholds in semiarid regions.

Aims
The aim of the present study was to investigate whether a threshold exists between the occupancy of a site by koalas and habitat variables at both the site and at four landscape scales in the semiarid Mulgalands Bioregion of Queensland, Australia.

Methods
We modelled habitat relationships using standard and piece-wise logistic regression, and an information-theoretic approach, to determine whether the best model that explained the occupancy–habitat relationships was linear or had a distinct threshold. The site-scale variable was the percentage of primary eucalypt species. The landscape-scale variables included the amount of primary and secondary habitat, and an interaction between them.

Key findings
There was a threshold relationship between the occurrence of koalas and the percentage of primary trees at the site scale. At the landscape scale, most threshold models failed to converge, and evidence pointed to a linear relationship between habitat amount and koala occupancy.

Conclusions
Conservation actions for koalas in the Mulgalands Bioregion should concentrate on protecting the primary tree resource for koalas, namely, river red gums (E. camaldulensis). However, the maintenance or restoration of primary and secondary habitat to distances of 1000 m from the creek is important because of the linear relationship between koala presence and habitat amount.

Implications
As habitat is lost in the semiarid Mulgalands Bioregion, koala occupancy declines. If known thresholds from mesic regions are used to define a minimum amount of habitat to be retained for koalas, conservation of local koala populations may well fail.

Context
The impacts of climate change on the climate envelopes, and hence, distributions of species, are of ongoing concern for biodiversity worldwide. Knowing where climate refuge habitats will occur in the future is essential to conservation planning. The koala (Phascolarctos cinereus) is recognised by the International Union for Conservation of Nature (IUCN) as a species highly vulnerable to climate change. However, the impact of climate change on its distribution is poorly understood.


Aims
We aimed to predict the likely shifts in the climate envelope of the koala throughout its natural distribution under various climate change scenarios and identify potential future climate refugia.


Methods
To predict possible future koala climate envelopes we developed bioclimatic models using Maxent, based on a substantial database of locality records and several climate change scenarios.


Key results
The predicted current koala climate envelope was concentrated in south-east Queensland, eastern New South Wales and eastern Victoria, which generally showed congruency with their current known distribution. Under realistic projected future climate change, with the climate becoming increasingly drier and warmer, the models showed a significant progressive eastward and southward contraction in the koala's climate envelope limit in Queensland, New South Wales and Victoria. The models also indicated novel potentially suitable climate habitat in Tasmania and south-western Australia.


Conclusions
Under a future hotter and drier climate, current koala distributions, based on their climate envelope, will likely contract eastwards and southwards to many regions where koala populations are declining due to additional threats of high human population densities and ongoing pressures from habitat loss, dog attacks and vehicle collisions. In arid and semi-arid regions such as the Mulgalands of south-western Queensland, climate change is likely to compound the impacts of habitat loss, resulting in significant contractions in the distribution of this species.


Implications
Climate change pressures will likely change priorities for allocating conservation efforts for many species. Conservation planning needs to identify areas that will provide climatically suitable habitat for a species in a changing climate. In the case of the koala, inland habitats are likely to become climatically unsuitable, increasing the need to protect and restore the more mesic habitats, which are under threat from urbanisation. National and regional koala conservation policies need to anticipate these changes and synergistic threats. Therefore, a proactive approach to conservation planning is necessary to protect the koala and other species that depend on eucalypt forests.

Context
Mapping the habitat and distribution of a species is critical for developing effective conservation plans. Koala (Phascolarctos cinereus, Phascolarctidae) distribution is constrained by the nutritional and shelter requirements provided by a relatively small number of key tree species in any given area. Identifying these key species provides a practical foundation for mapping koala habitat and prioritising areas for conservation.

Aims
To determine key tree species for koalas in Noosa Shire (south-eastern Queensland, Australia) as a basis for mapping koala habitat quality.

Methods
We applied a faecal-pellet survey methodology in 1996/97 to assess evidence of use by koalas of 4031 trees from 96 randomly stratified survey sites across different eucalypt-forest and woodland communities. Results were compared with those from a later survey undertaken in 2001/02 involving 5535 trees from 195 sites that were distributed across broadly similar areas with the aim to investigate aspects of koala landscape ecology.

Key results
A total of 66.7% of the 1996/97 survey sites contained koala faecal pellets, recorded under 953 eucalypt trees (14 species) and 1670 non-eucalypt trees (27 species). The proportion of trees at a given survey site that had koala faecal pellets at the base ranged from 2.2% to 94.7% (mean = 31.13 ± 2.59% s.e.). For the 2001/02 dataset, koala pellets were found at 55.4% of sites, from 794 eucalypt and 2240 non-eucalypt trees. The proportion of trees with pellets ranged from 3% to 80% (mean = 21.07 ± 1.77% s.e.). Both the 1996/97 and 2001/02 surveys identified the same three tree species (forest red gum, Eucalyptus tereticornis, swamp mahogany, E. robusta, and tallowwood, E. microcorys) as the highest-ranked for koala use in the study area. Three additional species (red mahogany, E. resinifera, small-fruited grey gum, E. propinqua, and grey ironbark, E. siderophloia) were identified in the 1996/97 surveys as key eucalypt species. Of the non-eucalypts in the 1996/97 dataset, coast cypress pine (Callitris columellaris) and broad-leaved paperbark (Melaleuca quinquenervia) ranked highest for use by koalas, followed by pink bloodwood (Corymbia intermedia) and brush box (Lophostemon confertus). White bottlebrush (Callistemon salignus), hard corkwood (Endiandra sieberi), M. quinquenervia and C. intermedia ranked highest in the 2001/02 dataset. The findings showed significantly greater use of larger eucalypts (i.e. 300-mm to >600-mm diameter at breast height).

Conclusions
The identified key eucalypt species, being the critical limiting resource for koalas, were used to assign koala habitat-quality classes to mapped regional ecosystem types to create a Koala Habitat Atlas (KHA) for Noosa Shire. The combined two highest quality classes based on abundance of the key eucalypt species comprised only 15.7% of the total land area of the Shire.

Implications
The KHA approach provides a practical and repeatable method for developing koala habitat-suitability mapping for national-, regional- and local-scale conservation and recovery planning purposes.