Wood to water : short-term effects of the re-introduction of wood to streams in agricultural environments

Rehabilitation of streams on agricultural properties has become a priority for landholders and managers in recent years in Australia. Fencing and re-vegetation of riparian zones are first priorities to improve riparian habitat values and biodiversity, however changes to in-stream habitat complexity are unlikely to result in the short term. Little evidence exists to guide subsequent rehabilitation actions to address this issue. Artificially re-introducing wood to such streams may be a useful strategy to increase habitat complexity more rapidly, thereby improving in-stream biodiversity values. To test this hypothesis, as a part of the larger Productive Grazing, Healthy Rivers project, small pieces of wood were introduced to eight sites on beef and dairy properties across southern Victoria, monitoring aquatic macroinvertebrates, water quality, hydrology and habitat quality. Comparing macroinvertebrate communities before and after treatment, and between experimental and control sites, changes in community composition and colonisation are explored.

Rehabilitating agricultural streams in Australia with wood : a review

Worldwide, the ecological condition of streams and rivers has been impaired by agricultural practices such as broadscale modification of catchments, high nutrient and sediment inputs, loss of riparian vegetation, and altered hydrology. Typical responses include channel incision, excessive sedimentation, declining water quality, and loss of in-stream habitat complexity and biodiversity. We review these impacts, focusing on the potential benefits and limitations of wood reintroduction as a transitional rehabilitation technique in these agricultural landscapes using Australian examples. In streams, wood plays key roles in shaping velocity and sedimentation profiles, forming pools, and strengthening banks. In the simplified channels typical of many agricultural streams, wood provides habitat for fauna, substrate for biofilms, and refuge from predators and flow extremes, and enhances in-stream diversity of fish and macroinvertebrates.

Most previous restoration studies involving wood reintroduction have been in forested landscapes, but some results might be extrapolated to agricultural streams. In these studies, wood enhanced diversity of fish and macroinvertebrates, increased storage of organic material and sediment, and improved bed and bank stability. Failure to meet restoration objectives appeared most likely where channel incision was severe and in highly degraded environments. Methods for wood reintroduction have logistical advantages over many other restoration techniques, being relatively low cost and low maintenance. Wood reintroduction is a viable transitional restoration technique for agricultural landscapes likely to rapidly improve stream condition if sources of colonists are viable and water quality is suitable.

Does adding wood to agricultural streams enhance biodiversity? An experimental approach

Riparian clearing and the removal of wood from channels have affected many streams in agricultural landscapes. As a result, these streams often have depauperate in-stream wood loads, and therefore decreased habitat complexity and lower levels of in-stream biodiversity. The introduction of wood was investigated as a possible rehabilitation technique for agricultural streams. Wood was re-introduced to eight streams in two separate high-rainfall, intensively grazed regions of Victoria, Australia and the effect on aquatic macroinvertebrate communities was measured. The addition of wood increased overall family richness and the richness of most functional feeding groups occupying edge and benthic habitats within the stream. Wood addition led to less overlap between benthic and edge macroinvertebrate communities, suggesting increased habitat heterogeneity within the stream ecosystem. Of all sampled habitats, wood supported the greatest density of families and was colonised by all functional feeding groups. Wood habitats also had the highest overall richness and supported the most taxa that were sensitive to disturbance. These findings suggest that re-introducing wood to agricultural streams is an appropriate rehabilitation technique where those streams are affected by reduced habitat complexity. Additional work is needed to confirm these findings over larger spatial and temporal scales.

Large versus small wood in streams : the effect of wood dimension on macroinvertebrate communities

Conventionally, most research and restoration involving in-stream wood focuses on large wood (>0.1 m diameter), excluding any smaller pieces. However, this may neglect a major component of in-stream habitat, as small wood can constitute the majority of pieces, particularly in small streams. The ecological benefit of large wood is well established, but corresponding benefits associated with small wood (0.05-0.1 m diameter) have not been demonstrated. To test the effect of wood dimension on macroinvertebrate community composition, we compared the fauna occupying large wood habitats with that occupying small wood at eight streams in south-eastern Australia. The relationships between wood dimensions and its macroinvertebrate fauna were complex. Community composition did not vary with wood dimension, and no significant correlations were found between other macroinvertebrate attributes (including family richness and evenness) and wood dimension, including diameter. However, analysis of covariance suggested that large wood supported a greater diversity and abundance of macroinvertebrates, indicating that the method of analysis could influence the result. Adjustment for differences in sample dimension using rarefaction determined that these findings were likely to be a result of the surface area and volumes sampled varying with the dimension of the wood. Per unit surface area, and per unit volume, small wood supported a similar number of families to large wood. Thus we conclude that, relative to the available surface area, small and large wood can be equivalent in their contribution to the available habitat in a stream. Therefore, the potential value of small wood as a habitat resource warrants its explicit consideration for inclusion in ecological and rehabilitation studies.

Deep sea diver

Work exploring the way the figure is effected by time and desires

Migration exhibitions and the question of identity: reflections on the history of the representation of migration in Australian museums, 1986-2011

Museums and Migration explores the ways in which museum spaces - local, regional, national - have engaged with the history of migration, including internal migration, emigration and immigration.

Exhibitions as sub-brands: an exploratory study

The purpose of this paper is to explore the adoption of major exhibitions, often called blockbusters, as a sub-branding strategy for art museums. Focusing the experience around one location but drawing on a wide data set for comparative purposes, the authors examine the blockbuster phenomenon as exhibition packages sourced from international institutions, based on an artist or collection of quality and significance. The authors answer the questions: what drives an art museum to adopt an exhibition sub-brand strategy that sees exhibitions become blockbusters? What are the characteristics of the blockbuster sub-brand?

First report of a phytogeographically mixed (transitional) Middle-Late Permian fossil wood assemblage from the Hami area, northwest China, and implications for Permian phytogeographical, paleogeographical and paleoclimatic evolution in central Asia

A diverse and well-preserved fossil wood assemblage is described, for the first time, from the Middle Permian Taerlang Formation and the Upper Permian Quanzijie Formation in the vicinity of the Tianshan Town, Hami City of northwestern China. On the basis of wood microstructure, the fossil woods are classified into three genera and five species, including one new genus: Prototianshanoxylon gen. nov. and two new species: Prototianshanoxylon erdaogouense sp. nov., Prototianshanoxylon hamiense sp. nov. The new genus is characterized by window-like cross-field pitting and mixed tracheid radial wall pitting that suggest a transitional type between araucarioid-type and protopinoid-type pittings.Phytogeographically, the fossil wood assemblage is characterized by an admixture of elements of both temperate Angaran (represented by wood specimens with moderately to well defined growth rings in their secondary xylem) and tropical-subtropical north subregion of the Cathaysian floras (with wood specimens lacking well-defined growth rings). Such a phytogeographically mixed fossil wood assemblage is interpreted to represent a transitional and complex climate condition between a cool temperate and tropical to subtropical zones, showing both seasonal variation and unstable climate conditions. Previously, similarly mixed floras have already been found to exist widely in northern China ranging in age from Early to Late Permian, but the mechanisms thought to be responsible for their formation were varied and remain controversial. In this study, the formation of these mixed Permian floras of North China is linked to the closure of the Tianshan-Hingan seaway coupled with the collision and amalgamation of Siberia with North China and the Tarim block, in a manner much like closing a pair of scissors with the closure of the seaway proceeding gradually and progressively from west to the east.

Cement-Wood composites: effects of wood species, particle treatments and mix proportion

The aim of this research was to investigate the effects of wood species, particle treatments and mix proportion on the physical (density) and mechanical (compressive strength and dynamicmodulus of elasticity) properties of cement-wood composites. Different mix proportions were investigated, based on the cement: wood ratio of 0.3:0.7, in volume, with Pinus elliottii and Eucalyptus grandis sawdust percentages of 0-100, 25-75, 50-50, 75-25 or 100-0. Sawdust particles were pre-treated with either lime or cement coating to improve cement and wood compatibility. Results show that wood species, particle treatments and mix proportions may influence the physical and mechanical properties of cement-wood composites. In general, results confirm that Eucalyptus sawdust and cement are naturally compatible and do not require any previous particle treatment to avoid compatibility problems.