The Amery Ice Shelf Ocean Research (AMISOR) project aims to examine and quantify processes involved in the interaction between the ice shelf, the interior grounded ice and the oceanic water masses that circulate beneath it. Two boreholes were melted through the shelf, within 100 km of the calving front, to access the ocean cavity. One (AM02) was at a site where it was believed that basal melt was occurring, and the other (AM01) was in a region with accreted marine ice. At both sites the summertime ocean structure revealed meltwater-modified boundary layers up to 100 m thick immediately beneath the shelf. Salinity and temperature data in the upper cavity at AM02 showed a strong seasonal cycle as a result of a combination of ice-shelf basal melt, and the intrusion of ocean water masses modified by sea-ice processes in Prydz Bay. At AM01, a 200m thick layer of marine ice underlay the meteoric ice, and showed an increase in salinity and decrease in stable-isotope fractionation with depth. The lowest 100m of marine ice was highly permeable, with a rectangular banded textural facies. Other preliminary results from this study are also reported.

Australian forest ecosystems cover almost 16% of Australia’s landmass. As the seventh‐largest forested area worldwide, these forest ecosystems have largely evolved in the face of a changing climate and fire regime, drought and human land use practice. Australian tree ferns contribute to both the unique biodiversity of these forests and current forest product markets. We review the Australian tree fern literature including: the importance of tree ferns for other components of biodiversity; their response to disturbance such as fire and silviculture; and the management of tree ferns as a product for the horticultural market. Most studies focused on tree fern response to wildfire and clearfell burn and sow logging following management and horticultural industry changes. Survival and recruitment of tree ferns after a single fire/logging disturbance event found short‐lived negative impacts. Studies of tree ferns over time include research on growth, with non‐linear growth models found to best describe tree fern age; Cyathea australis grows 2.2 ‐ 4.0 times faster than Dicksonia antarctica on average. Tree ferns perform a keystone function through habitat for epiphytes at the local scale, but it is unknown if this has an impact on biodiversity at the landscape scale. Our review found few studies on survival and recruitment following drought; multiple disturbance events such as repeated logging; and silvicultural techniques other than clearfell burn and sow. No studies had investigated the response of tree ferns to changing climate, invasive species, changes in fire frequency or effect of megafire. We conclude with recommendations for key areas of research including, future impacts due to changing climate, synecology, influence on forests, the impact of silvicultural techniques and the influence of megafires on survival.

Ice-sheet basal ice is warmer than that above because of the heat from the Earth’s interior. The stresses acting on the basal ice are greatest. In addition, the basal ice often contains debris consisting of silt and small stones picked up from the rock over which the ice flows. Because the base is the warmest part of an ice sheet and the stress there is greatest, flow rates in the basal ice are large and often contribute most of the ice movement. It is therefore important, for accurate modelling of the ice sheets, to know whether the debris within the basal ice enhances or retards the flow of the ice. In this paper, we describe laboratory deformation tests in uniaxial compression and in simple shear, on sand-laden ice. We find no significant dependence of flow rate on sand content (up to 15% volume) in the stress range 0.13–0.5 MPa and temperature range –0.02 to –18.0°C. Further work needs to include laboratory tests on debris-laden ice extracted from the polar ice sheets. This work is underway.

No abstract