Tropical Darwin NT ecosystems, wildlife and monsoonal storms.

Journal of Southern Hemisphere earth systems science, 2019

This research is the extension of a project studying the impact of 19th century severe weather events in Australia and their relation to similar events during the 20th and 21st century. Two floods with the worst known impacts in the Murray-Darling Basin (MDB) are studied. One of these events which occurred during 1956 is relatively well known and the Bureau of Meteorology archives contain good rainfall data covering the period. Additionally, information on the weather systems causing this rainfall can be obtained. Rainfall, flood and weather system data for this event are presented here and compared with a devastating event during 1870. Although archived Australian rainfall data is negligible during 1870 and there is no record of weather systems affecting Australia during that year, a realistic history of the floods and weather systems in the MDB during 1870 is created. This follows an extensive search through newspaper archives contained in the National Library of Australia's web site. Examples are presented showing how the meteorological data in 19th century newspapers can be used to create weather charts. Six such events in 1870 are demonstrated and three of these had a phenomenal effect on the Murray-Darling system. The 1870 floods followed drought type conditions and it is remarkable that it was worse in many ways than the 1956 event which followed flood conditions in the MDB during the previous year. The events in 1870 caused much loss of life from drowning in the MDB in particular from an east coast low (ECL) in April 1870 and two Victorian weather systems in September and October 1870. In 1956, there were also record-breaking events especially during March when all-time record monthly rainfall were reported in New South Wales. Overall the greatest impact from flooding across the whole MDB was associated with the 1870 flooding. Analyses of heavy rainfall areas in the MDB showed a linear trend increase from 1900 to 2018. Analysing the same data using an 8-year moving average highlighted three peaks around the five highest annual rainfall years. The largest peak occurred around 1950 and 1956, the second largest around 1973 and 1974 and the third around 2010. Each of these 5 years occurred during negative phases of the Interdecadal Pacific Oscillation (IPO) and positive phases of the Southern Oscillation Index (SOI). Studies have shown that the SOI is a climate driver in the MDB along with a persistent blocking high-pressure systems south of Australia along longitude 1408E with a low to its north. Three major blocking events with record rainfall and flooding in the MDB occurred in 1983, 1984 and 1990. This was during the period 1977-1990 when blocking was conducive to heavy rain in the MDB and was coincident with a positive phase of the IPO, thus helping conflict with the IPO-MDB heavy rainfall relationship. Persistent and unexplained middle level westerly winds kept subtropical Queensland clear of tropical cyclones during the negative phases of the IPO from 1999 to 2009 and during the 1960s, influencing low rainfall in the MDB during those periods.

On a mild September day in Adelaide, 1893, Sir Charles Todd presented a timely and optimistic review of meteorological work in Australia. For almost half a century, Todd had been a central player in scientific negotiations which attempted to fix, predict, or alleviate the effects of Australian weather. Still the climates of the Australian colonies defied attempts to categorise according to colonial expectations. Furthermore, seasonal variation proved a problem for centralised management and agricultural practice. By the 1890s, new technologies and a growing network of meteorological observers had built an increasingly detailed climate data set across the continent. But the seasons, the rain and longer term climate trends continued to undermine generalisations about the weather. Todd's paper attempted to position contemporary meteorology in Australia both within the western meteorological canon, and in relation to the politics of contemporary natural knowledge. Reflecting Todd's structure, Under Such Sunny Skies is a story of the prehistory of a discipline (Australian meteorology) and an institution (the Bureau of meteorology) against the backdrop of the discovery and articulation of real and imagined climate and weather rules, as nineteenth century Australian settlers and scientists came to terms with the limits and extremes of climate in a continent of extraordinary variability.

2011

2008

Ecological degradation within areas of remnant forest may be amplified if the effects of fragmentation interact with the effects of other environmental disturbances such as wind storms. We used before-after comparisons to assess the effects of Tropical Cyclone Larry on remnant and continuous rainforest in the Wet Tropics uplands of north-eastern Australia. Vegetation structure was measured three years before the cyclone and six months afterwards, at eight continuous forest sites and eight remnants (6-37 ha), within 20 km of the cyclone's track. The cyclone caused extensive defoliation, felling and breakage of stems and branches (greatest among the trees>100 cm diameter which had around 50 % stem loss), and increased litter and woody debris. Cyclone effects were strongly influenced by a site's spatial position (P = 0.005, 0.001 in multivariate analyses of overall damage). Maximum damage occurred 10-15 km south of the cyclone track, perhaps because of the additive effects...

2010

Snails Land Snail Ordtrachia septentrionalis EN. www.landmanager.org.au/view/index.aspx?id=183153 Snails Land Snail Prototrachia sedula VU. Group English Name Scientific Name NT Status National Status Info* Fish Speartooth Shark Glyphis sp. A VU CR www.landmanager.org.au/view/index.aspx?id=177020 Fish Northern River Shark Glyphis sp. C Group English Name Scientific Name NT Status National Status Info* Mammals Pig-footed Bandicoot Chaeropus ecaudatus EX EX www.landmanager.org.au/view/index.aspx?id=351835 Mammals Desert Bandicoot Perameles eremiana EX * Click on the hotlinks on the right to go to the management-related information of on the North Australian Land Managers web site EX = Extinct Angiopteris_evecta King Fern Angiopteris evecta What it looks like: The King Fern, elsewhere known as the Giant Fern, is a distinctive large ground-dwelling fern with massive green fronds arising from a short or non-existent trunk. Where it lives: While found at scattered locations through rainforested areas of eastern Australia and across the globe, in the Northern Territory, King Ferns are known only from one place-in northeastern Arnhem Land. Like most large ferns, King Ferns are dependent on a moist, shady environment. In the Northern Territory, they grow only around a single perennial spring in a monsoon rainforest patch, in a narrow sandstone gorge. Importance as an indicator: With its restricted distribution and narrow habitat requirements, persistence of King Fern in Arnhem Land will be a good indicator of the health of the monsoon thicket in which it grows. The wet conditions it requires are particularly sensitive to changes in hydrology caused by unseasonably dry weather or water extraction. Drying out of the rainforest may allow incursions by fire. Look after King Fern and other plants of monsoon rainforests by managing fire well. Backburning around rainforest patches early in the year to reduce fuel hazards will protect these sensitive habitats from periodic fire incursions. However, repeated burning may promote the growth of Annual Sorghum, which increases fire hazard. So try not to burn exactly the same place every year. If necessary, burn after the first wet season storms to control Sorghum and reduce fire hazard. Make sure decisions about developments in the catchment consider impacts on groundwater availability.