Contrasting influences of inundation and land use on the rate of floodplain restoration

This study examined the assisted natural restoration of native vegetation in an Australian floodplain wetland where flows were reinstated and the river was reconnected to the floodplain, following cessation of agricultural cultivation. Extant vegetation was surveyed three times during an inundation event at plots with different land‐use histories. Restoration rate was more influenced by past land use than long‐term inundation frequency and success decreased with antecedent land‐use intensity. Prolonged land‐use history (>3 years cultivation) restricted restoration success. Sites with longer cultivation histories tended to have fewer aquatic species, more terrestrial species and exotic species. For example, amphibious responders with floating leaves were found only in reference plots and less frequently in farmed treatment plots. In this scenario, increased persistence of exotics and dryland species suggested alternative trajectories. Fields with a short land‐use history (1–3 years of clearing and cultivation) resembled undisturbed floodplain communities, consistent with a ‘field of dreams’ hypothesis. Although river–floodplain reconnections can restore wetlands, legacy effects of past land use may limit the pace and outcomes of restoration.Australian Postgraduate AwardAustralian Research Council. Grant Number: DE120102221ARC Centre of Excellence for Environmental Decisions Australian Research Council Linkage Project. Grant Number: LP088416

Trading water to improve environmental flow outcomes

As consumptive extractions and water scarcity pressures brought about by climate change increase in many world river basins, so do the risks to water-dependent ecological assets. In response, public or not for profit environmental water holders (EWHs) have been established in many areas and bestowed with endowments of water and mandates to manage water for ecological outcomes. Water scarcity has also increasingly spawned water trade arrangements in many river basins, and in many instances, EWHs are now operating in water markets. A number of EWHs, especially in Australia, begin with an endowment of permanent water entitlements purchased from irrigators. Such water entitlements typically have relatively constant interannual supply profiles that often do not match ecological water demand involving flood pulses and periods of drying. This article develops a hydrologic-economic simulation model of the Murrumbidgee catchment within the Murray-Darling Basin to assess the scope of possibilities to improve environmental outcomes through EWH trading on an annual water lease market. We find that there are some modest opportunities for EWHs to improve environmental outcomes through water trade. The best opportunities occur in periods of drought and for ecological outcomes that benefit from moderately large floods. We also assess the extent to which EWH trading in annual water leases may create pecuniary externalities via bidding up or down the water lease prices faced by irrigators. Environmental water trading is found to have relatively small impacts on water market price outcomes. Overall our results suggest that the benefits of developing EWH trading may well justify the costs. © 2013. American Geophysical Union. All Rights Reserved.Jeffery D. Connor, Brad Franklin, Adam Loch, Mac Kirby, Sarah Ann Wheele

A simplified incubation method using chip-trays as incubation vessels to identify sulphidic materials in acid sulphate soils

Acid sulphate soils (ASS) can pose a significant hazard to natural ecosystems and developed areas situated within ASS landscapes. Management techniques used to minimize these hazards rely on methods that can classify ASS materials. These methods have traditionally required complex and time-consuming techniques. A new simplified incubation method, modified from existing ones, was therefore developed to classify ASS materials in a timely manner. The simplified incubation method was found to be a viable alternative where samples cannot be incubated to a stable pH because of logistical or time constraints, but where there is still a need to classify slowly acidifying sulphidic materials. The use of chip-trays as incubation vessels was also examined. Chip-trays offer many advantages in terms of transport, storage and analysis of soil samples compared with soil-slabs. This study establishes an acceptable level of precision (x ± 0.1 pH units with 95% confidence) for pH measurements in the incubation method and confirms that an acceptable level of precision is obtainable when using chiptrays in the pH incubation method.N. Creeper, R. Fitzpatrick, P. Shan