Local provenance in rehabilitation of degraded landscapes: a case study from the Hawkesbury–Nepean catchment, Australia

Throughout Australia thousands of volunteers are engaged in Landcare projects that should help rehabilitate degraded landscapes. Many of these projects involve tree planting, but their seed is not necessarily of local provenance. Based on a survey of 85 Landcare groups working in the Hawkesbury–Nepean catchment, data were collected about Landcare groups' knowledge of their seed source, understanding of local provenance and the ecosystem in which they were planting trees and the source of funding for their projects. The findings from the study indicate that about one in five (21%) of the groups surveyed that introduced plant material were not aware of local provenance issues. Indirect indications were that a large number of Landcare groups state-wide may be doing more harm than good to the landscape while trying to rehabilitate it. The data also showed that one in seven (13%) of the groups funded by the Australian Government through the Natural Heritage Trust (NHT) had limited awareness of local provenance issues. With millions of dollars being spent on 'works on the ground', it would be prudent to allocate some funds to document and monitor current Landcare activities, so that the environmental outcomes can be quantified and more effective Landcare policies can be developed in the future.     

Pre‐ and post‐impoundment nitrogen in the lower Missouri River

Large water‐sample sets collected from 1899 through 1902, 1907, and in the early 1950s allow comparisons of pre‐impoundment and post‐impoundment (1969 through 2008) nitrogen concentrations in the lower Missouri River. Although urban wastes were not large enough to detectably increase annual loads of total nitrogen at the beginning of the 20^th century, carcass waste, stock‐yard manure, and untreated human wastes measurably increased ammonia and organic‐nitrogen concentrations during low flows. Average total‐nitrogen concentrations in both periods were about 2.5 mg/l, but much of the particulate‐organic nitrogen, which was the dominant form of nitrogen around 1900, has been replaced by nitrate. This change in speciation was caused by the nearly 80% decrease in suspended‐sediment concentrations that occurred after impoundment, modern agriculture, drainage of riparian wetlands, and sewage treatment. Nevertheless, bioavailable nitrogen has not been low enough to limit primary production in the Missouri River since the beginning of the 20^th century. Nitrate concentrations have increased more rapidly from 2000 through 2008 (5 to 12% per year), thus increasing bioavailable nitrogen delivered to the Mississippi River and affecting Gulf Coast hypoxia. The increase in nitrate concentrations with distance downstream is much greater during the post‐impoundment period. If strategies to decrease total‐nitrogen loads focus on particulate N, substantial decreases will be difficult because particulate nitrogen is now only 23% of total nitrogen in the Missouri River. A strategy aimed at decreasing particulates also could further exacerbate land loss along the Gulf of Mexico, which has been sediment starved since Missouri River impoundment. In contrast, strategies or benchmarks aimed at decreasing nitrate loads could substantially decrease nitrogen loadings because nitrates now constitute over half of the Missouri's nitrogen input to the Mississippi. Ongoing restoration and creation of wetlands along the Missouri River could be part of such a nitrate‐reduction strategy. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.     

Plagioclase preferred orientation, Foreshore Group metasediments, Bluff, New Zealand

Recrystallised plagioclase in volcanic metasediments of the Foreshore Group (hornblende-hornfels facies) has a strong preferred orientation with crystal a-axes [100] lying parallel to bedding and with a maximum parallel to a lineation (= maximum principal strain axis or axis of greatest elongation); composition varies widely from bed to bed from oligoclase to anorthite. The preferred orientation is interpreted to result from the mechanical rotation of elongate plagioclase ejecta in the original unconsolidated tuff during strain caused by intrusion of the adjacent Bluff igneous complex. Evidence for such an orienting mechanism is found in the preferred orientation of large unrecrystallised plagioclase ejecta. Matrix plagioclase is generally recrystallised to form granoblastic mosaics; this texture represents a mimetic recrystallisation which reduced grainboundary energy in the fine-grained matrix during the thermal event immediately succeeding deformation.     

Shark interactions in pelagic longline fisheries

Substantial ecological, economic and social problems result from shark interactions in pelagic longline fisheries. Improved understanding of industry attitudes and practices towards shark interactions assists with managing these problems. Information on fisher knowledge and new strategies for shark avoidance may benefit sharks and fishers. A study of 12 pelagic longline fisheries from eight countries shows that incentives to avoid sharks vary along a continuum, based on whether sharks represent an economic disadvantage or advantage. Shark avoidance practices are limited, including avoiding certain areas, moving when shark interaction rates are high, using fish instead of squid for bait and deeper setting. Some conventionally employed fishing gear and methods used to target non-shark species contribute to shark avoidance. Shark repellents hold promise; more research and development is needed. Development of specifically designed equipment to discard sharks could improve shark post release survival prospects, reduce gear loss and improve crew safety. With expanding exploitation of sharks for fins and meat, improved data collection, monitoring and precautionary shark management measures are needed to ensure that shark fishing mortality levels are sustainable.     

Time-Distance Seismology and the Solar Transition Region

Time-Distance ‘travel time’ perturbations (as inferred from wave phase) are calculated relative to the quiet-Sun as a function of wave orientation and field inclination in a uniform inclined magnetic field. Modelling indicates that the chromosphere-corona Transition Region (TR) profoundly alters travel times at inclinations from the vertical θ for which the ramp-reduced acoustic cutoff frequency ω _c cosθ is similar to the wave frequency ω. At smaller inclinations phase shifts are much smaller as the waves are largely reflected before reaching the TR. At larger inclinations, the shifts resume their quiet-Sun values, although with some resonant oscillatory behaviour. Changing the height of the TR in the model atmosphere has some effect, but the thickness and temperature jump do not change the results substantially. There is a strong correspondence between travel-time shifts and the Alfvén flux that emerges at the top of the modelled region as a result of fast/Alfvén mode conversion. We confirm that the TR transmission coefficient for Alfvén waves generated by mode conversion in the chromosphere is far larger (typically 30 % or more) than for Alfvén waves injected from the photosphere.     

Interannual variability in glacier contribution to runoff from a high‐elevation Andean catchment: understanding the role of debris cover in glacier hydrology

We present a field‐data rich modelling analysis to reconstruct the climatic forcing, glacier response, and runoff generation from a high‐elevation catchment in central Chile over the period 2000–2015 to provide insights into the differing contributions of debris‐covered and debris‐free glaciers under current and future changing climatic conditions. Model simulations with the physically based glacio‐hydrological model TOPKAPI‐ETH reveal a period of neutral or slightly positive mass balance between 2000 and 2010, followed by a transition to increasingly large annual mass losses, associated with a recent mega drought. Mass losses commence earlier, and are more severe, for a heavily debris‐covered glacier, most likely due to its strong dependence on snow avalanche accumulation, which has declined in recent years. Catchment runoff shows a marked decreasing trend over the study period, but with high interannual variability directly linked to winter snow accumulation, and high contribution from ice melt in dry periods and drought conditions. The study demonstrates the importance of incorporating local‐scale processes such as snow avalanche accumulation and spatially variable debris thickness, in understanding the responses of different glacier types to climate change. We highlight the increased dependency of runoff from high Andean catchments on the diminishing resource of glacier ice during dry years.     

The value of multiple earthquake missions: the EEFIT L’Aquila Earthquake experience

In November 2012 EEFIT launched its first ever return mission to an earthquake affected site. The L’Aquila Earthquake site was chosen as this is a recent European event of interest to the UK and European earthquake engineering community. The main aims of this return mission were to document the earthquake recovery process and this paper presents an overview of the post-disaster emergency phase and transition to reconstruction in the Aquila area after the earthquake. It takes an earthquake engineering perspective, highlighting areas mainly of interest to the fields of structural/seismic engineering and reconstruction management. Within the paper, reference is made to published literature, but also to data collected in the field during the return mission that would not otherwise have been available. The paper presents some specific observations and lessons learned from the L’Aquila return mission. However, in light of current international efforts in conducting return missions, the paper ends with some reflections on the value that return missions can provide to the field of earthquake engineering in general, based on the EEFIT L’Aquila experience.     

Daily time budgets and activity patterns of sandgrouse (Pteroclididae) in contrasting arid habitats in Spain and Israel

Time budgets and activity patterns of sandgrouse were studied in semi-arid agricultural land in Spain (Black-bellied and Pin-tailed Sandgrouse) and in more desertic conditions in Israel (Black-bellied and Spotted Sandgrouse). During c. 75% of daylight hours, all four species were either foraging or inactive. The birds in Israel spent more time foraging than those in Spain, despite having lower thermoregulatory costs, reflecting a likely difference in the productivity of the sites. Partitioning of foraging habitat was evident at both sites and, contrary to expectation, it was the larger Black-bellied Sandgrouse which spent the most time foraging. In Israel, Spotted Sandgrouse became inactive at high temperatures whereas the Black-bellied continued to forage, utilizing the shade available in its dwarf shrub foraging habitat. The range of Black-bellied Sandgrouse may be limited by its thermoregulatory ability in hot conditions and its need to forage for long periods.     

A study of the chemistry of pore fluids and authigenic carbonates in methane seep environments: Kodiak Trench, Hydrate Ridge, Monterey Bay, and Eel River Basin

Analyses of the chemical and isotopic composition of carbonates rocks recovered from methane seepage areas of the Kodiak Trench, Hydrate Ridge, Monterey Bay Clam Flats, and the Eel River Basin, coupled with the studies of the chemistry of the pore fluids, have shown that these carbonates have grown within the sediment column. Geochemical profiles of pore fluids show that, in deep water seeps (Kodiak Trench—4450 m; Monterey Bay—1000 m; Hydrate Ridge—650 m), δ¹³C (DIC) values are low (isotopically light), whereas in the Eel River area ( 350–500 m), δ¹³C (DIC) values are much higher (isotopically heavier). In all cases, the δ¹³C values indicate that processes of methane oxidation, associated with sulfate reduction, are dominant in the shallow sediments. Data on the isotopic composition of authigenic carbonates found at sites in Kodiak Trench, Eel River Basin South, and Eel River Basin North indicate a variable composition and origin in different geochemical environments. Some of the authigenic carbonates from the study sites show a trend in their δ¹³C values similar to those of the pore fluids obtained in their vicinity, suggesting formation at relatively shallow depths, but others indicate formation at greater sediment depths. The latter usually consist of high magnesium calcite or dolomite, which, from their high values of δ¹³C (up to 23‰;) and δ¹⁸O (up to 7.5‰), suggest formation in the deeper horizons of the sediments, in the zone of methanogenesis. These observations are in agreement with observations by other workers at Hydrate Ridge, in Monterey Bay, and in the Eel River Basin.