The black box sapling that didn’t get the email!

For the drought-tolerant, salt-tolerant species black box (Eucalyptus largiflorens), normally found at higher elevations and outer edges of Murray-Darling floodplains, the accepted wisdom is that young trees need to be 20-30 years old in order to produce seed. This time-span is rather daunting for ecosystem managers trying to support recruitment in black box communities to increase their rate of replacement. So my amazing find this week is good news, even if it blasts accepted theory out of the water! On the Calperum floodplain next to Ral Ral Creek anabranch, a dense sea of river red gum saplings carpets the creek banks under majestic old river red gums. In the middle of thousands of red gum saplings 2-3 m high, a single black box sapling was flowering gloriously and proudly, defying all the understood rules that it was much, much too young for such productivity!! Now I have to check for other black box saplings that didn’t get the email about when they are supposed to flower!!

Posted in black box, caring for our planet, eucalypts, Murray-Darling Basin, native vegetation, phenological cycles, recruitment, regeneration, sustainable natural resources management, waterways | Tagged , , , , ,

a thriving River Murray wetland

Happiness is a wetland drying down after a flood and providing habitat and food for more than 3000 waterbirds! Spotlit in the late afternoon light, stilts, avocets, ducks, spoonbills and herons quietly forage for their favourite foods. The numbers are easier to count when they occasionally take to the sky for a fly-past. This wetland received environmental water in summer and winter of 2016, and then was filled naturally by the flood peak in December 2016, and still persists as a shallow lagoon in March 2017. Environmental watering prior to the flood has boosted productivity and the wetland  is providing a rich food source as indicated by the large number of waterbirds present.


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New life on Murray floodplains

Six weeks on from the recent flood in the South Australian Murray Valley, floodplains and wetlands are in the best condition seen since the floods of 1990-93. The dominant response is vibrant, vigorous growth of groundcovers, shrubs and trees.

A series of events have contributed to the current good condition of floodplain vegetation communities. The 2010-12 floods relieved the extreme stress of the Millenium drought, when millions of mature river red gums and black box trees were stressed, dying or dead.

The 2016 flood came in the nick of time, to prevent the decline of germinated seedlings and recovering canopies following the 2010-12 floods.

Rainfall played a part too, with good summer rains in 2012, 2014 and 2015, and extraordinary rains in September 2016 that were four times the average volume. With so much available moisture, all plants are concentrating on new growth, with fresh luminous green leaves showing strong recovery on eucalypts. Vigorous vertical lignum stems are bending under their own weight in the process of creating dense tangled lignum thickets.

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After the Flood . . .

The health of the River Murray valley in South Australia is showing dramatic improvement following a very useful seasonal flood in spring-summer 2016. The flow event peaked at 94,865 ML/d at the South Australian border on 30 November 2016 and had continuous flows >40,000 ML/d for 75 days, meaning that water overflowed onto the floodplain during from mid-October to late December in South Australia. There was a long slow rise in flows, but a very rapid recession.

The wetting of the floodplain kick-started life cycles in plants, animals, birds, fish and frogs. The first signs were deafening frog calls at night and thousands of dragonflies by day. Feeding waterbirds at floodplain pools indicated the presence of macroinvertebrates and small fish to provide their food.

Nardoo waterplants wakened from dormancy in the dry clay and floated in pools like giant four-leafed clover, persisting after the water dried in lush damp pockets. As the flood receded, it left a green carpet of seedlings and a jungle of green growth in lignum bushes. Seedlings and saplings of river red gum and black box which germinated after the 2010-12 floods put on a burst of new growth, adding to the multiple shades of green across the floodplain.

Stressed mature black box trees generated clumps of healthy new leaves and burst into flower. This flood was in the nick of time, to assist recovery of stressed trees, to top up soil moisture and to sustain the growth triggered by the previous floods, continuing recovery from severe vegetation damage in the Millenium drought. The River Murray ecosystem has been given a very welcome boost!

Posted in black box, caring for our planet, ecosystem services, environmental flows, eucalypts, floods, Murray-Darling Basin, native vegetation, recruitment, regeneration, river red gums, sustainable natural resources management, wetlands | Tagged , , , , , , , , ,

Diary of a Red Gum May-December 2016

The red gum in our street started 2016 with a high volume of healthy buds, but these were steadily lost in windy storms through the year. After the tree dropped its eighth branch in 12 months, in May the Council sent in the tree trimmers, who administered a serious hair cut through the middle canopy and over-hanging branches. Nearly one-third of the canopy disappeared, with its bud crop.

Challenges continued with multiple storms through winter and spring combining heavy rains and wind, with piles of debris post-storm representing significant losses of immature buds and fruit. A serious hail storm in November with hail the size of golf balls did not cause as much damage as the previous year, when hail the size of marbles stripped large amounts of foliage from the red gum.

But by late November, the tree was recovered and full of life, covered in luxuriant dense flower clusters and reverberating with the steady hum of bees. The dawn chorus was in full voice, as shrieking rainbow lorikeets drank nectar from the flowers. The ground was covered with a carpet of cream stamens and crunchy flower caps.

After a tumultuous year with continuous losses, plenty of buds survived for a profuse flowering event, with the flowers now transitioning into immature fruit which will develop seed for summer 2017.

The heavy flowering in November also provided evidence in support of the hypothesis that red gums have alternate heavy and light annual flowering volumes. This tree previously flowered profusely in November 2014, but only lightly in November 2015. The new prediction is thus for light flowering in November 2017.

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Good Christmas news for Murray-Darling Basin Plan

At the Nature Foundation SA (NFSA) Christmas drinks, SA Water Minister Ian Hunter reported excellent progress on implementation of the Murray-Darling Basin Plan, now on the C0AG agenda, with the Prime Minister taking responsibility. The upstream states are on notice to speed up their work on proposals needed to deliver promised environmental water. With all key national and state liberal politicians pledging support for returning the full 3200 GL, it looks like a good New Year for the Murray-Darling Basin!

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River Murray floodplains are flooding!

The current flood is a major gift from Nature to the South Australian River Murray valley, boosting continued recovery from massive damage in the Millennium drought and bringing boom times back to ecosystems. The rich toffee-coloured water is clear water coming from multiple Murray catchments, full of tannins from dissolved leaves, with no water flowing in from Darling catchments which would bring high loads of suspended clay and reduce water clarity.


The River Murray spills over its banks into floodplain wetlands in the Woolpunda reach

This extensive flood has spread onto upstream floodplains in the Murrumbidgee, Lachlan and Macquarie catchments which had not been flooded for 20 years, and picked up unprecedented amounts of carbon. This has meant that the first flows down the rivers and into South Australia were totally depleted of oxygen due to the natural process of decomposition of huge volumes of leaves, nutrients and plant debris on floodplains. There were numerous reports of fish kills, sadly including hundreds of adult Murray cod which were trapped between two flows of de-oxygenated water in the anabranch creeks around Lake Victoria.

As the flood progresses downstream, oxygen is returning as the water flows over weirs and spreads out onto Riverland floodplains. The food chains are kicking off, with thousands of dragonflies, insects and microscopic water species, including tiny fish. Waterbirds are starting to feed in floodplain pools, with pelican fishing groups already in action.

Unfortunately, recent news reports about the flood have focussed on the early flows of low oxygen ‘black water’ and the impacts of flooding on shack areas. However, most shacks are designed to allow floods to flow underneath raised structures, and the rewards for shack-owners will come as the water levels fall and increased numbers of fish and yabbies emerge just around the Christmas holidays.

This flood is a major bonus for river health, piggy-backing on the benefits of the 2010-2012 floods and providing the ‘boom’ in the river’s boom and bust ecosystem. The peak level is slightly above the peak of the February 2011 flood, and will boost continued growth of millions of red gum and black box seedlings generated back then. The clear Murray water allows light to penetrate up 10 times further into the water column than in Darling water, boosting photosynthesis. Watch for an explosion of life in coming weeks, as fish, frogs, yabbies, tortoises and plants respond to ideal conditions. This is the time to visit the River Murray and see it burst into life!


lush new growth on river red gums is lime green, highlighting the dramatic environmental response to the life-giving flows

Posted in caring for our planet, ecosystem services, environmental flows, eucalypts, floods, Murray-Darling Basin, native vegetation, regeneration, river red gums, waterways | Tagged , , , , ,