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Bare Substrate (bare + substrate)
Selected AbstractsBreeding habitat use and the future management of the critically endangered Southern Corroboree FrogECOLOGICAL MANAGEMENT & RESTORATION, Issue 2009David Hunter Summary The Southern Corroboree Frog (Pseudophryne corroboree) is one of Australia's most critically endangered frog species. The species occurs entirely within Kosciuszko National Park, which has a history of cattle grazing (up to the 1970s). A consequence of cattle grazing has been a significant reduction in the extent of montane and sub-alpine peat-bog systems that the species uses as breeding habitat. Furthermore, climate change and associated increased wildfire frequency is expected to further reduce the extent and quality of peat bogs throughout the Australian Alps. In this study, we investigated habitat selection for breeding pools and nest sites within peat-bog systems in order to inform the conservation management of the species and guide other management practices being undertaken in peat bogs where this species occurs. Occupancy of breeding males at bog pools was found to be positively associated with increasing pool area, water depth and mid-day temperature, and negatively associated with extent of bare substrate. The majority of breeding pools identified were ephemeral. Nest sites within vegetation where males call and where females deposit their eggs were located at mid-elevations in a range of vegetation types, with the majority of nests being within moss and sedge dominated by Sphagnum cristatum and Empodisma minor. We also found that male nest sites were not randomly distributed within the edges of pools, but were more often located in areas of loose vegetation. These results highlight the potential sensitivity of the Southern Corroboree Frog to predicted changes in peat-bog systems resulting from climate change such as earlier drying and a possible reduction in the size of bog pools. A monitoring programme focused on key features of the breeding habitat should be undertaken to provide a basis for developing and assessing management actions implemented in peat bogs occupied by this species. [source] Spatial and temporal analysis of vegetation mosaics for conservation: poor fen communities in a Cornish valley mireJOURNAL OF BIOGEOGRAPHY, Issue 9 2003E. J. Southall Abstract Aim Biogeographers increasingly realize the importance of seeing plant communities as spatial mosaics and understanding the spatial and temporal heterogeneity of a site is often a key to successful conservation. The aim of this paper is to examine the approaches to the description and analysis of spatial and temporal variation in sub-communities within patch mosaics of vegetation in order to inform conservation management. The activities of the tin streaming industry in Cornwall over the last century have created a highly varied mosaic of poor fen vegetation on Goss Moor National Nature Reserve (NNR). The wetland mosaics comprise dry hummocks and different sized wet pools. The size and depth of the pools determines the rate and type of vegetation that develops, as does the nature of boundary or edge. The ergodic hypothesis is used to describe the various plant sub-communities and their boundaries to identify pathways of hydroseral succession. A further aim was to test the use of Ellenberg Indicator (EI) values as a tool for the rapid description of spatial and temporal environmental change on wetland sites with a view to their management. Location Goss Moor National Nature Reserve, Cornwall, UK. Methods An extensive survey of the whole wetland complex was undertaken to identify patches of poor fen vegetation containing Potentilla palustris (L.) Scop. and Menyanthes trifoliata L. At each patch, species abundance data were collected as well as associated environmental information such as depth of the organic layer and standing water depth, patch location, patch size and boundary type. The plant sub-communities present were defined using techniques of numerical classification [two-way indicator species analysis (twinspan)] and ordination [detrended correspondence analysis (DCA)] and these were ordered using the ergodic hypothesis in order to characterize the stages of the hydrosere. Floristic and environmental relationships were examined using canonical correspondence analysis (CCA). Further environmental differences between the poor fen sub-community types were characterized by weighted EI values for acidity (R), moisture (F), nitrogen (N) and light (L). Results and conclusions Twelve poor fen sub-community types were described and found to be distributed along a primary environmental gradient of organic matter depth, surface water height and bare substrate. Separation of the poor fen communities by a moisture gradient was considered as spatial evidence for hydroseral succession, which begins with the colonization of open-water pools created by tin excavations. High water levels were associated with the swamp communities, increased organic depth was associated with poor fen, and the type of boundary was shown to affect the resulting community composition. Weighted Community Ellenberg Indicator values for nitrogen, light, reaction and moisture are recommended as an effective tool for indicating differences between plant (sub-)communities. The importance of examining sub-community mosaics in the study of hydroseral development is stressed and the manner in which both sets of information may be used to underpin the conservation management of the site is demonstrated. [source] Novel repair method for technical enamels based on sol,gel and sol-dispersion coatings,MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 2 2008S. Benfer The aim of the work presented here is the development of a novel repair method for technical enamels by using chemical nanotechnology. Good adhesion of coatings requires good wettability of the substrate by the repair solution. This was achieved by different pre-treatments of the steel substrates. Low sintering temperatures of the coatings can be ensured by the use of nanoparticle-based systems. Based on liquid metal alkoxides, a colloidal alumina sol and metal salts homogeneous sols with up to seven enamel compounds were prepared. The sols were brush coated onto plain and partly enamelled steel substrates and sintered in a furnace, by inductive heating or an IR emitter. Thin (single layer,,,1µm) crack-free layers were obtained on nearly all substrates independent of the sintering conditions investigated. The local sintering methods (IR emitter, inductive heating) allow to produce multiple coating systems in short times. Electrochemical impedance spectroscopy (EIS) provides evidence of the protective effect of these layers compared to the bare substrate, but as a result of their chemical composition the layers are not stable in the electrolytic environment for longer times. The thickness of such multiple coatings (20 layers, ,,8 µm) is still small compared to that of a technical enamel. Therefore, sol dispersion systems containing powder particles and sol components are applied on top of the sol,gel layers to increase the thickness of the sintered layers. [source] Dry season habitat use by critically endangered white-shouldered ibis in northern CambodiaANIMAL CONSERVATION, Issue 1 2010H. L. Wright Abstract We present the first scientific study of white-shouldered ibis Pseudibis davisoni habitat preferences in dry dipterocarp forest. Foraging sites included seasonal pools, forest understorey grasslands and fallow rice fields, with terrestrial sites used more following rainfall. Habitat and anthropogenic effects in logistic models of foraging site selection were examined by multimodel inference and model averaging. White-shouldered ibis preferred pools with greater cover of short vegetation (<25 cm) and less of the boundary enclosed, and forest sites with greater cover of bare substrate and lower people encounter rate. At forest sites, livestock density was positively related to bare substrate extent and thus may improve suitability for foraging ibis. At pools, livestock removed tall vegetation between the early and late dry season indicating their importance in opening up foraging habitats after wet season growth. However, by the late dry season, pools with greater livestock density had less short vegetation, the habitat favoured by ibis. Conservation strategies for white-shouldered ibis must consider a range of habitats, not just seasonal wetlands, and should incorporate extensive grazing and associated burning practises of local communities. Further understanding of the effects of these practices on vegetation, prey abundance and prey availability are therefore needed for effective conservation of this species. This will also develop our understanding of potentially beneficial anthropogenic influences in tropical environments. [source] | ||||||||||