Category Archives: Climate change

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September 28, 2019

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anthropocene, Climate change, estuaries, Fire, grief, kayaking, landscape photography, national parks, Photography

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Hoarding and hope

Bar Point jetty

Heading straight into the grey emptiness where Bar Island ought to be, out on the river last weekend, I felt grateful that the cloud enfolding me wasn’t bushfire smoke.

Into the emptiness

We live in difficult times.  Rainforests on fire, burning not just in the Amazon but up and down the Australian east coast.  We knew this was coming, we’ve known for a long time.  But it’s hard to believe it’s happening so soon.  Too soon, too close, too damn sad. Unbearable to think about for more than a few moments.

A few eucalypts flowering after a dry winter

So I headed back to beautiful Marramarra Creek, to salve that ache. What precisely is that feeling?  Not quite solastalgia – the pain of losing a beloved landscape.  Not here, not yet – at least not for me, though I guess the traditional owners of this part of the river feel just that.  For me it’s a different kind of climate grief. The sadness of knowing the time is coming when this beautiful place will be changed, razed.

Big Bay on a still morning

I find myself returning again and again to the same places, taking very similar pictures of the very same riverscapes.

Yet another oysterfarm
And another

There’s a comfort in doing something over and over again, repetition with infinite small variations.  A lower tide, raising the oysterbeds.  A jellyfish bloom.  A flush of eucalyptus flowers across the hillside or a flock of honeyeaters swirling their way up river.  The surprising sight of a juvenile sea eagle, quietly sitting in the dappled light of the mangroves

Juvenile white bellied sea eagle
Up Marramarra Creek
And another oysterfarm

If my instagram feed is a little repetitive, I can console myself that by staying on my home patch at least I’m not spewing out carbon and clocking up the air miles.

Mystery objects in the blue

Of course there’s another reason to return – “fog bathing”.  Perhaps I could try to get some kind of wellness movement going. Surely time spent lingering on a misty river is just as healing as walks through the most pristine Japanese forest.

Oysterfarm abstract

And then there’s remembering.  Going back to the same scenes, taking photos over and over, to capture a time and place as you see it in front of you right now.  The same compulsion to hoard pictures as parents have, knowing their toddler will soon be grown and gone.

Bruce and boat
Up Marramarra Creek
Skies over the Hawkesbury

Of course , the memories you’re harbouring aren’t always good.  Two years ago, for instance, the much anticipated multi-family jaunt to the water-access only campsite at Twin Beaches.  Fine still mornings and fireside yarns.  But also engine failure, unexpected high winds, a swamped coracle and endless bickering over alcohol.  Not to mention screaming, blood and an emergency visit to Hornsby Hospital, to have oystershell fragments with their scary bacterial payload scraped from the ten year old’s feet.  What can I say but when heading out on the Hawkesbury check the weather, pack light and wear shoes!

On the way to Twin Beaches
Mangrove saplings of Big Bay
Mirror creek
Sunset skies at Twin Beaches
An overloaded coracle
Pelicans in Marramarra Creek

Marramarra Creek has other memories I can only guess at.  Every time I pass Friendly Island, I ponder on that name and the violence it hints at but hides.

Friendly Island in Marramarra Creek

But memories, even bad ones, can also guide you. As I put Bar Island behind me I found the fog stretching out in all directions.  This line of oysterpoles retreating into white, I knew, would take me where I wanted to go.

Oysterpoles showing the way
Fishermen in front of an invisible Bar Island
On the way to Friendly Bay
On the beach in Bar Island
Cormorants staring out at nothingness
The jetty on Bar Island

If we’re lucky, maybe our stash of memories of beautiful places will tell us how to go forward, and maybe even show us a way back.

One of the pair of whistling kites on Peat’s Island

Other paddles in Marramarra Creek and thereabouts

The silver river

Of gods and map readers

The river that knew

Two sad islands, three whistling kites

Broken bay at low ebb

A scene from the Sydney climate strike on Sept 20

 

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August 24, 2019

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Climate change, estuaries, kayaking, national parks, Native birds, natural history, superb lyrebirds, Uncategorized

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The singing and the sea

Bute with shiny landscape tidiedWhen you put your boat in at Cowan Creek, you know you’re paddling in the sea.  Yes, there are rocky slopes on every side, and eucalypts and banksias lean over the shoreline.  The rows of hot pink bells of epacris longifolia dangle amazingly close to the waves.

Epicris longifolia
Smith Creek reflections
White cheeked honeyeater and banksia

But look over the side of your boat, especially in this big dry, and your gaze falls metres deep into into the crystal clear green water.  It might be called a “creek” but there’s no murky river water here.  Further downstream, where Cowan Creek meets the Hawkesbury proper at Broken Bay, the Pacific meets the horizon and you really know you are in the ocean.

Fishing boat and west head little boy

Fishermen off Flint and Steel Point

Looking out to sea
Lion Island
Fog near America Bay
Speedboat off Juno Point
Cormorant with fish

Cormorant off Juno Point having a snack

But far above the official mouth of the river – the limit of “flat water sailing” drawn between Juno Head and Flint and Steel Bay – the water is briny.  The tide rolls up the Hawkesbury as far as the Grose River Valley, 138 kilometres from the sea, taking a wedge of salty water upstream.  If Broken Bay, where these pictures were taken, is essentially a marine environment, Cowan Creek is not too much different.

Pixellated yachts

Yachts off Cottage Point

Because of course, the Hawkesbury is a drowned river valley.   The river channel that once wound its way twenty five kilometres to the east, across the continent shelf, has long ago disappeared two hundred metres or more beneath the ocean.  The late Quaternary Marine Transgression that drowned the Hawkesbury started 18,000 years ago and went on for 10,000 years, with the water level peaking just a metre or two above current sea levels.

Paul Boon, in his fascinating history of the Hawkesbury, reports that during that time, sea level rose at perhaps 8-10 metres every millennium, at some times as 40 metres in a thousand years (Boon, 2017, Chapter 3). It‘s hard to imagine what that must have been like for the first people here, the Guringai and Dharug people, moving again and again ahead of the rising tide, away from the coastal flat lands to the hills of the Hornsby plateau.

Side illuminated trees for crop

On the way to Stingray Bay

Even more mindboggling to think, as Boon quietly points out, that over the last few decades sea level has been creeping up by around three millimetres a year. If the CSIRO scientists are right, and I for one don’t doubt they are, sea levels are changing as worryingly fast, if not as fast as the speediest rises in the Flandrian Transgression. On the bright side if I live long enough, there’ll be far more of the upper reaches of Cowan Creek to explore, in an admittedly sweaty and decrepit manner, in my kayak

Pink cloud and cowan creek

Sunrise sky near Cotton Tree Bay

Last weekend’s paddle reminded me of what a special place the Hawkesbury is, a drowned river valley where, after rain, waterfalls tumble off the sandstone straight into the sea.  I was coming back from a jaunt to Smith’s Creek when, heading into a bay to avoid a plague of water skiiers, I heard a lyrebird going for broke.

According to Birdlife Australia, superb lyrebirds are inhabitants of moist forests. I’m sure the one I heard scratching around in the undergrowth by the shore, would soon be heading back to the gullies and the treetops.  But in its distant melange of calls – of satin bowerbirds, kookaburras, currawongs, red wattlebirds and other things I just can’t recognise – was a sound I’d never heard a lyrebird make before.  I’m sure I heard an impression of that paradigmatic bird of the beach – the silver gull.

And that’s the soundtrack of the Hawkesbury estuary, right there,

 

What are your bird call spotting skills like, dear reader?  Can you recognise any other shore birds in this estuarine lyrebird’s song?  If you can spot any extra calls, please let me know!

The green water of Cowan Creek
A superb lyrebird I prepared earlier

Other stories from Cowan Creek and thereabouts

A glimpse of a peregrine falcon hunting: death and good fortune in Cowan Creek

Old hands: how Smith’s Creek was nearly Canberra

Stingray Bay – lost and found

The Hawkesbury in winter: the shortest days and how to use them

Broken Bay at low ebb: the troubled history of Hawkesbury oysters

Around the point 2

A winter morning in Cowan Creek

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January 26, 2018

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Backyard birds, Biodiversity, Brush turkeys, Climate change, Death, national parks, nesting, predation, raptors, Seasons

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Wildlife reboot: birds 2.0

Another January, and another trip to Ganguddy, on the western site of Wollemi National Park.  Same marvellous geology, same refreshing dam water, same hot weather.

Clamorous reed warbler with nesting material
Male musk duck – a resident here
Moorhen family
The campsite at night
White faced heron hunting
One of many dragonflies

But some things were different this year.  After the stupendously dry winter, the eucalypt forest was parched, the undergrowth sparse and the leptospermum flowers of last year’s visit few and far between.  We found a patch of sphagnum moss perched in a bowl of sandstone boulders so dry it crunched underfoot.

One very hot white throated tree creeper
Eastern water dragon
Twerking wombat

A “green” satin bowerbird panting in the heat

We spotted plenty of lizards, and the diggers were out in force – lyrebirds wandering through the camp as they tried to scratching their way down to moisture and a wombat turning up to twerk on a picnic bench.  But up in “kingfisher alley”, just before the Cudgegong River disappears into the reed beds, there were fewer blue and green flashes by the water.

Around the camp site, the bowerbirds and treecreepers panted in the heat.  Apart from the ubiquitous reed warblers, there seemed fewer birds altogether.  No sign of the friarbird teenagers of last year, and even the baby swamp hens seemed thin on the ground.

You have to wonder what it takes to change ecosystems irrevocably.  How many dry winters before the old inhabitants decide living and breeding here is just too tricky?  And who would move in to fill their place?

Back at Berowra after the trip, there are changes in the garden too… surprising ones.

We knew we’d be losing the sparrowhawks soon enough, but the family has dispersed in an unexpected order.  The adults disappeared off the scene weeks ago, and by the time we made it home with our ridiculously overloaded vehicle and small and ancient fleet of boats, the siblings had parted too.  There’s just one young’un now.  He seems lonely.

Juvenile collared sparrowhawk with prey
Calling for the missing sibling

There’s a constant plaintive calling from the trees out back, that seems to intensify when he has prey on hand.  I’m not quite sure if he’s warning his imaginary sibling off or calling him to come and share a meal.

And that’s not the only shift in the soundscape around here.  The sparrowhawks have cut a swathe through the bird population on the premises.  Baby brushturkey numbers have fallen from previous plague proportions, noisy miners are few and far between and the “house” birds of yesteryear – red and little wattlebirds – are now just occasional visitors.

Red wattlebird
Little wattlebird

But as the numbers of resident raptors has dropped, a new set of critters have settled in.  Lewin’s honeyeaters which we’ve only seen once or twice in the backyard over the last seven years, have made our backyard their new home.  And we also appear to have acquired some brown thornbills, a raptor snack food if ever there was one.  And the local eastern spinebills, another tasty morsel for a sparrowhawk, are spending more time around here too.

The only explanation I have for the change of personnel is that the hawks have bumped the notoriously territorial wattlebirds, leaving the field open for new arrivals.

Eastern spinebill
Brown thornbill
Lewin’s honeyeater

I’m pretty happy to have a new set of birds in the garden.  My dream scenario, I have to admit, would be to order up some songbirds that are a bit easier on the eye.  My birdwatching brother puts Lewin’s in a honeyeater “bin taxon” of pretty similar and drab looking birds it’s hardly worth distinguishing between.  Cruel, perhaps, but fairly accurate.

So, why not some new holland honeyeaters, for instance – gorgeous looking locals.  Or (still, my beating heart!) what about some pardelotes?  Just one or two?

Spotted pardelote
New holland honeyeater

On the other hand, it’s possible that all the vibrantly coloured small birds in the neighbourhood have been made into multicoloured meals over the past three months by our family of raptors.  After all, there’s got to be some evolutionary reason for all those SBBs*.

*note: this is a throwaway remark absolutely unsupported by any science.

 

Previous posts about Ganguddy

A bit about Ganguddy’s history and geology – and a little Tim Low on the side

Snakes versus whining teenagers – last year at Ganguddy

 

More on our sparrowhawk summer

Death and sibling rivalry

The new generation of sparrowhawks emerges from the nest…

Baby brush turkeys versus nestling sparrowhawks… the battle of the backyard baby birds

The collared sparrowhawks return to our backyard… or are they brown goshawks?

A first glimpse of the sparrowhawks… and a beautiful white goshawk visits the washing line

 

Further reading

Stephen Garnett, Donald Franklin, Glenn Ehmke, Jeremy VanDerWal, Lauren Hodgson, Chris Pavey, April Reside, Justin Welbergen, Stuart Butchart, Genevieve Perkins and Stephen Williams (2013) Climate change adaptation strategies for Australian birds: Final Report, National Climate Change Adaptation Research Facility

Office of Environment and Heritage, Premier’s Department (2011) New South Wales Climate Impact Profile Technical Report: Potential impacts of climate change on biodiversity

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January 12, 2017

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Animal senses, Climate change, Native animals, Uncategorized, Weather

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Too hot to handle?

floppy-claw-small

Although echidnas are pretty common, I’ve rarely seen seen them in Berowra.  So when I saw this one flopped out in the neighbours’ front yard on my sweaty walk home from work yesterday – ambient temperature in the mid 20s even at 7pm – I was worried.  Were echidnas, like fruit bats and stingless bees, troubled by temperature extremes?  Had this one been driven from its usual secluded haunts by this horrid heat wave?  Should I be on the blower to WIRES?

A cursory google did not inspire confidence.  Wikipedia notes that echidnas don’t sweat (in fact, they don’t pant, lick, or even wee on themselves and flap their wings to cool off either) and suggests that they “cannot deal with heat well“.  WIRES agrees that echidnas “cannot tolerate temperatures above 30 degrees“.

Notwithstanding, this seemed to be a very sprightly monotreme.  Most of the echidnas I’ve met have more or less fixed this position:

This beastie, however, was very busy, ignoring me and rummaging around in the flowerbeds.  Could it really be in trouble?  I decided, for the moment, that human intervention wasn’t necessary and then went home to check whether I’d just made a stupid decision.  Should I trust Wikipedia or my instincts?

I hit pay dirt when I found “Thermoregulation by Monotremes” by Queensland’s “Mr Hot Echidna”, Peter Brice.  As a researcher who has devoted time to  inserting “calibrated temperature sensitive radio-transmitters … coated with a smooth layer of inert wax… into the abdominal cavities of echidnas” (Brice et al 2002), he’s your go-to guy on this topic.

Niche subject as it might seem, the way echidnas and platypuses manage their body temperature has played an interesting role in propping up a hierarchical, human-centred view of evolution.  You’ve heard the story before, I’m sure. From this viewpoint, animals whose bodies are set up differently to us fancy-pants “classic mammals” are viewed as “primitive”.  Early twentieth century researchers decided that, for instance, that playpus had “an inadequate regulating mechanism” when after only 17 minutes at 35 degree temperatures, their research subject  “turned onto its back and fainted” (Brice, 2009, 260).  A poignant tale and the sort of thing that led one early twentieth century researcher to conclude that monotremes were “‘the lowest in the scale of warm-blooded animals’” (Brice, 2009, 256)

Don’t get me wrong, echidnas are very weird animals.  And that’s leaving aside the egg laying mammal business and the once-venomous spurs in their backwards facing hind legs.

Echidna back claws

Echidnas are cool. 31 degrees counts as a “normal” body temperature for them, though only females incubating eggs really keep their temperatures steady for long.  They seem to occupy a half-way house between warm blooded and “cold blooded” animals.  Echidnas don’t entirely rely on their surrounding environment to warm themselves as reptiles – ectotherms – do.  But unlike us humans – homeothermic endotherms – with our tedious need for a stable and predictable body temperature – echidnas can run hot or cold.

Just when you thought we were all “thermed”-out, you find that echidnas are also constitutional eurytherms – they can handle wide range of temperatures – and facultative endotherms – they warm their bodies up, in part, by doing stuff.

Echidnas also hibernate – well, some of them do, if they’ve eaten enough by the time the cold weather rolls in. But their hibernation, or its timing at least is, according to Brice (2009, 257) “distinctly odd”.  They often kip out during the late summer and then wake up to mate at coldest part of the year.  And they can deal with fluctuating temperatures in a way I can only envy – for instance, after a chilly night, they can dig their way out of shelter with their blood temperature of only twenty degrees.  With no bedsocks.

Waddling echidna
Echidna eyes

And they can also deal with a day spent in a hollow log at 40 degrees C without expiring from the heat, though no one knows exactly how.

We shouldn’t seeing echidnas and their wildly fluctuating temperatures as primitive, I reckon. Instead we should admire the way these critters harbour resources with their furry but weirdly chilly bodies, helping them live above the snowline in the Alps, in the desert and even on the sizzling streets of deepest surburbia.

echidna-great-face-for-crop-2-small

Echidna, close up and personal

References

Brice, Peter H. (2009) “Thermoregulation in monotremes: riddles in a mosaic” Australian Journal of Zoology, 2009, 57, 255–263

Brice, Peter H., Gordon C. Grigg, Lyn A. Beard, Janette A. Donovan (2002) “Heat tolerance of short-beaked echidnas (Tachyglossus aculeatus) in the field” Journal of Thermal Biology 27(6), 449-57

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March 25, 2016

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Backyard chickens, chicks, Climate change, Death, egg laying, raising chickens, Seasons

Happy Easter from Morgan the syncretic leghorn

We have pommie chooks!  Or from somewhere north of the equator, anyway.  I’m not sure how they managed to make the perilous transcontinental journey before their cute fluffy butts made it to our place at a week old, but somehow they must have dodged border control.

4 fluffy butts horizontal crop

How do I know our feathered friends come from the far north?

Well, here in Sydney, we’re past the equinox and the nights are drawing in.  We may have had a February that smashed heat records, 1.3 degrees C above the longterm averages.   But it’s hours of daylight that tells chickens when to get laying (thanks to that sort-of-third eye) and the days are getting shorter.  Even as the world goes to hell in a handbasket, it is, nonetheless, autumn.

And yet my chooks have decided to start laying.  Just in time for spring with its baby bunnies, and peeping chicks, and Easter eggs, and its celebration of rebirth and renewal.  In the northern hemisphere, that is.

Cleo the Barred Rock
Tigress the Barnevelder
Abby the grown up Barnevelder
Cyan the Australorp

I love Easter.  Most religious festivals are a delicious mish-mash of stuff from the Big Book and whatever else people were into at the time.  But with Easter the syncretism is really out there, bouncing around with its ears pricked up, laying  coloured eggs in the spring greenery.  After witnessing the pre-Good Friday panic by shoppers terrified by the prospect of a day without ready access to a new packet of Cocopops, the nice young guy at the checkout reckoned  we might add a zombie apocalypse to the usual combo of vernal equinox, Passover, and frenzied confectionary consumption.  As he pointed out delicately, Jesus did after all, come back from the dead.

Baby Morgan last October
Morgan with adoptive mother Treasure, five months ago

In the midst of this cultural mash-up, it seems appropriate that it’s Morgan the flighty leghorn, named after a Welsh enchantress in an Arthurian legend, who has marked the occasion of the (deeply seasonally inappropriate) Christian festival of rebirth with the gift of her first lovely white eggs.

A muddled pagan blessing to egg eaters, one and all.

Morgan and Treasure these days
Morgan and Treasure chowing down
Morgan checking it all out

 

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August 29, 2015

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anthropocene, Climate change, estuaries, kayaking, national parks, natural history, predation, waterways

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Broken Bay at low ebb

Oyster leases exposed at low tide

Last weekend I decided to explore the lower reaches of Mooney Mooney Creek from its meeting point with the Hawkesbury, riding on a rising tide. After my spooky solo paddles in Mangrove Creek, I had a hankering for the open horizon and a bit of human life around me. From my put-in at Deerubbin Reserve beside the freeway, and all the way round Spectacle Island, a nature reserve in the mouth of the creek, the constant hum of the traffic and the echoing rumble of trains crossing Brooklyn Bridge remind you that “civilisation” isn’t far away.

Freeway bridge at first light
Crepuscuar rays over Spectacle Island
Brooklyn Bridge in dawn light
The shore of Spectacle Island
Under the freeway bridge
White-faced heron and crabby breakfast

Low tide at Mooney Mooney Creek means mud and oyster leases.  The lingering blue haze from last week’s hazard reduction burns descended on the poles and frames, forlorn in the shallows, blurring them into beautiful abstracts.

The story of oyster farming in the Hawkesbury in recent times is a sad one, full of strange historical ironies.

People have been harvesting shellfish from the shores of the river for a very very long time and Sydney rock oyster has been farmed in Broken Bay since the 1880s.  In those days oysters were dredged from the estuary floor and after the meat was eaten, the shells, along with those from ancient middens, were burnt to make lime for mortar.

Rocky shores of Brisbane Water National Park
Oysters on the beach in Brisbane Water National Park
Oysters upstream in Mooney Mooney Creek

But in 2004, after a hundred years of farming oysters here, Qx disease hit the Hawkesbury.

The “Q” in the name stands for Queensland.  The Sunshine State produces a 10th of the oyster harvest it did in the nineteenth century, thanks to Qx and to the oyster-infesting mudworm (introduced from New Zealand in the 1880s along with imports of oyster spat). The “x” was a scientific shorthand for “what the hell is this anyway?  We really don’t know”.   Since then, researchers have figured out that Qx is caused by Marteilia sydneyi, a single-celled organism that during the summer infects oysters, causing them not just to slowly starve to death, but also to reabsorb their own gonads (nasty!).  The parasite then releases spores that cycle their way through a polychaete worm, Nephtys australiensis, in the winter, before reinfecting the oysters the following season.

M. sydneyi isn’t always the kiss of death.  The parasite is found in estuaries all along the coast of NSW and Queensland, even in “low risk” areas where Sydney rock oysters are still being commercially grown. Environmental stress, it seems, triggers outbreaks of Qx and surprisingly few wild Sydney rock oysters, the ones I saw lining the rocky shores of Mooney Mooney Creek, die from Qx. Which is good, if mysterious, news.

So, facing of losses of over 90% of the harvest, what could save the oyster industry in the Hawkesbury?

It was noxious pest to the rescue.

The Pacific oyster, farmed in Japan for centuries, was smuggled into Port Stephens in the eighties and spread quickly through the intertidal zones of New South Wales.  It’s a fecund and fast growing bivalve, planktonic eggs and larvae travelling far and wide, crowding, outgrowing, and sometimes settling on and smothering native rock oysters. A “selfish shellfish”, in the words of one inspired Tasmanian subeditor.

The very qualities that have made the Pacific oyster such a hateful invader came to the rescue of the Hawkesbury farmers in 2005.  A process for producing sterile “triploid” Pacific oysters had been developed in North America in the 1980s, with the aim of pumping out meatier shellfish fast. When fertility mean spawning 40 million eggs in a season (not to mention changing sex several times over a lifetime) avoiding reproduction saves a lot of energy.

Local farmers restocked with these “triploid” Pacific oysters.  As well as being immune to Qx, they were ready to harvest in less than two years compared to the three and a half years it takes rock oysters to reach the table.  The new “tamed” Pacific oysters took the Hawkesbury by storm.

And then in 2013 disease struck again. Millions of oysters were wiped out overnight by a virus that affected Pacific oysters and Pacific oysters alone.

Like the oyster itself, the scientifically spawned sterile “triploids”, and indeed the settlers that farm them, “oyster herpes” or POMS (Pacific Oyster Mortality Syndrome), first seen in France in the late noughties, had circled the globe to Broken Bay.

Only three oyster farming businesses are still going in the Hawkesbury these days, hanging on for scant supplies of Qx resistant rock oyster spat, first found amongst the survivors of the Georges’ River outbreak in the mid 1990s.

Right now, the derelict oyster farms are mostly places for posses of pied cormorants to hang out.

Pied cormorant
Pied cormorants on an oyster lease
Looking up past Snake Island to the middle reaches of Mooney Mooney Creek
Knackered looking Eastern Curlew
Snake Island
Rock garden in Brisbane Water National Park
Pelican
Rock warbler

But there’s still plenty of life to be found at Mooney Mooney at low water: globe trotters like the eastern curlew, exhausted after a long flight south, and locals like the rock warbler that only lives on Sydney sandstone, compensating for its drab colours and homebody ways with a goth-style nest of grass and spider webs it hangs in the darkness of caves and crevices. And I clocked a new heron record – twenty at least, catching crabs in the mud of low tide.

White faced heron in front of Brooklyn Bridge

References

Michael C Dove, John A Nell, Stephen Mcorrie and Wayne A O’Connor “Assessment of Qx and Winter Mortality Disease Resistance of Mass Selected Sydney Rock Oysters” Journal of Shellfish Research 32(3) 681-87 doi: http://dx.doi.org/10.2983/035.032.0309

Wayne A O’Connor and Michael C Dove “The changing face of Oyster Culture in New South Wales, Australia” Journal of Shellfish Research, Vol. 28, No. 4, 803–811, 2009.

J.A. Nell “The history of oyster farming in Australia” Marine Fisheries Review 63(3), 14-25

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June 12, 2015

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Climate change, Garden trees, Gardening, natural history, Plants and what I know about them, Seasons

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Autumn in terminal decline?

Red wattlebird in our Japanese maple

In amongst the nasty consequences of global warming – sea-level-rise-ocean-acidification-violent-storms-heat-waves-large-scale-extinctions (if you say it quickly and rock back and forth at the same time it doesn’t seem quite so bad) – a decline in the intensity of autumn leaf colour really doesn’t draw the eye.  Bar a few unusual plants like the red-fruited kurrajong and the Antarctic beech, most deciduous plants around here aren’t even natives.  So who cares, eh?

But as I huddle in my chilly house on its shady south-facing hillside, waiting for the leaves on the neighbour’s looming liquidambar to fall, the impact of climate change on deciduous trees seems like a tremendously pressing question.

I’m not the only one gripped by this crucial topic.  The latest  Trends in Ecology and Evolution has roundly denounced the scandalous neglect of autumn. Spring gets its own live feed on BBC TV, but even scientists get depressed by extended discussions of leaf senescence, it seems.   Garnering less than half as many articles as its greener sibling, autumn, according to the indignant authors, is a “neglected season in climate change research”.

Well, neglected no longer!  Not here in the backyards of Berowra.  Right here, right now we bring you…. in the prophetic words of Gallinat and her outraged colleagues… “the future of autumn research”.

Rainbow lorikeets in the bare liquidambar
Liquidambar leaf pattern
Red liquidamba leaves

As we march boldly into fall’s future, I’m cling to the hope that photoperiod (that’s the day-length to you and me) will rescue me from climate change, sending that winter-sun-blocking foliage promptly into the compost bin regardless of how roasting hot it is. And it’s not a vain hope – the amount of light a deciduous plant receives does seem to help many decide whether it’s time to shed their leaves or not.

In the case of liquidambar, long days or lots of light delay dormancy, as you can see from these nifty pictures of a specimen down the street, well illuminated day and night so as to minimise deaths on a local pedestrian crossing, clinging to its leaves long after its neighbours have shrugged their own.

Illuminated liquidambar leaves
The leafy and the leafless
Liquidambar experiencing artificial lighting “long days”

Depressingly, it does seem that sweetgums need cooler weather to finally ditch their leaves, even in the short days of midwinter.   Photoperiod matters most near the poles – but for trees at the lower latitudes (like Sydney, curse it) temperature is the clincher.

This raises interesting questions about the future of the veggie garden. Around the winter solstice it lurks in the shade of our dawn redwood, a living fossil that grew across the temperate Arctic when dinosaurs stomped the earth, and was dramatically rediscovered in the 1940s in a single isolated valley in China.  Will its gorgeous copper needles still fall in time to give my broadbeans a decent run-up to spring when we’re wearing shorts all winter?

Fall leaves of dawn redwood

In the words of a Facebook status update, “it’s complicated”.  Could this be why climate scientists, like nervous singles, are staying well clear?

For instance, warmer springs lead to earlier bud burst, which can sometimes mean earlier leaf-fall.  And deciduous trees in general tend to lose their leaves more readily in dry weather.  “On average”, according to Estiarte and Peñuelas (2015) “climatic warming will delay and drought will advance leaf senescence”.  Work that one out.

And that’s not even throwing nutrient availability into the mix.  For instance, what if trees start going ballistic with all that carbon dioxide in the atmosphere?  This vision of a greenhouse planet jungle awash with joyful plants growing at breakneck speed sounds like something out of a climate denialist fantasy, doesn’t it?  “More open cut mines, pretty please!” beg the earth’s desperate forests “my future is coal!”

Sadly for the wind-farm haters, it mostly doesn’t work like that.  Carbon dioxide can give trees a flying start but eventually the nitrogen supply conks out, or drought and too much CO2 do the leaves in.  Even with the help of globe-trotting survivors like sweet gums and dawn redwoods, coal (and copious quantities of greenhouse gases) won’t make the world greener.  Let’s just hope, even gardening in our bikinis, we can still find gold.

Little wattlebird doing something mysterious with a maple leaf
Sulphur crested enjoying liquidambar seeds
Mooned by a red wattlebird

References

  1. Estiarte, M and Peñuelas, J (2015) “Alteration of the phenology of leaf senescence and fall in winter deciduous species by climate change: effects on nutrient proficiency” from Global Change Biology 21(2) 1005-17
  2. Flexas, J, Loreto, F and Medrano, H. (2012) Terrestrial photosynthesis in a changing environment: a molecular, physiological and ecological approach, Cambridge, Cambridge University Press
  3. Gallinat, AS, Primack, RB, Wagner, DL (2015) “Autumn, the neglected season in climate change research” from Trends in ecology and evolution 30(3)
  4. Warren JM, Jensen AM, Medlyn BE, Norby RJ, Tissue DT, (2015) ‘Carbon dioxide stimulation of photosynthesis in Liquidambar styraciflua is not sustained during a 12-year field experiment’, AOB Plants, vol.7, Article no.plu074
  5. Warren, JM, Norby, RJ, Wullschleger SD (2011) ‘Elevated CO2 enhances leaf senescence during extreme drought in a temperate forest”.  Tree Physiology 31, 117-30
  6. Worrall, J (1993) “Temperature effects on bud-burst and leaf-fall in subalpine larch” Journal of Sustainable Forestry 1(2)
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May 9, 2015

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Backyard birds, Climate change, national parks, Native animals, natural history

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Low tide at Gunyah Beach

“The sea or not the sea?”

That was the question churning through my brain, as I set out for my first solo kayak on the Hawkesbury proper.  Let’s be kind and say I’m not a risk taker (there’s a reason I’m fond of chickens).  And my canoe is properly vintage, made out of wafer-thin plywood back in the early 70s, and now held together by a rich tapestry of epoxy based products and amateurishly applied fibreglass.  Don’t get me wrong – it was the best $100 I ever spent on ebay but our Egg is no ocean-going liner.

Slightly rotten Egg, the day i bought it for $100
Egg being cooked
A rich melange of epoxy products
Replacing the rotten carlin

But setting off on a sunny Saturday morning with a light off-shore wind and a slack tide, I thought my decrepit boat and I might just be able to brave a three kilometre paddle along the widest reaches of the Hawkesbury Estuary, from Brooklyn’s Parsley Bay to Gunyah Beach in Kuring-gai Chase national park.

In Parsley Bay
Map of my jaunt, preserved from harm in a handy ziploc bag

About midway across the 700 metres at the mouth of Porto Bay, I realised the weird rise and fall of the boat was swell, a new and disturbing experience for me as a canoeist.  Well, it was either swell or the kayak was being regularly nudged sideways by bull sharks.  Either way, I was not happy.   It didn’t help that the choppy water was full of floating branches, torn down by  last week’s big winds.  If the sharks didn’t get me, I’d be turned into a giant vegetarian shishkebab by a surfing pine tree.  I was in the ocean, and it was scary.

Storm detritus on Gunyah Beach

Of course, the Hawkesbury “River” is, kinda, the sea – a flooded river valley that has its tidal limit a hundred kilometres or thereabouts from its mouth.  Whenever I think about this, I imagine how strange it must have been for the people living on the plains that once stretched out from the current coastline under what is now the surface of the sea, as the ocean crept slowly up, over ten thousand years, claiming the valleys carved out by the river, pushing people before it into the hills.  Now that’s really going into the unknown.

Waterfall from a hanging valley

In the end, of course, I made my little paddle with no problems at all, apart from an annoying lack of photographic evidence that there was ever anything to fear.  Gunyah Beach (boat access only) even had its own lounge suite on which an unnerved canoeist might rest and recover.  I’m pretty sure the contractual obligation white-faced heron had just stood up after a cup of tea and a chocolate digestive as I arrived.

Ah, a comfy sofa.
Everyone’s been on the beach
Contractual obligation white-faced heron
Striated heron http://birdlife.org.au/bird-profile/striated-heron
Low tide in the creek
White cheeked honeyeaters – everywhere!

Stumbling through the mud around the beach-side lagoon, I found myself in a maelstrom of silvereyes and white cheeked honeyeaters.  I’ve come to realise binaural hearing is a real asset for bird watching.  With one dodgy cochlea I spent half my time whipping my head wildly from one side to the other to work out where the chirping was coming from.  In the end taking random pictures of the bushes seemed the best way to avoid permanent neck injury. I was disproportionately pleased with the few photos that worked out. There’s something particularly delightful about the most minor victories over timidity and incompetence, even if you can’t convincingly frame pootling around in boats in your estuarine backyard as some kind of heroic feminist re-enactment of The Old Man and the Sea.

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May 2, 2015

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Backyard birds, Climate change, Garden trees, Gardening, Plants that attract wildlife

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Timber!

We’ve had a mob of at least fifteen yellow tailed black cockatoos hanging around in the last few days, mewing like strangled cats and being chased around by magpies and (I think) even noisy minors.  We get the yellow tails quite often around these parts, especially in the winter-time, thanks to the large and sickly but apparently tasty radiata pines that loom over our place.

A male yellow tailed black cockatoo enjoying a pine cone in the neighbours’ yard
Yellow tailed cockatoo tucking in
Silhouette of a yellow tailed black cockatoo

The rule in Hornsby Shire is you can cut down a tree that’s within three metres of the foundations of your house.  If only there was some special by-law where the council chops down the tree for you for free if you can’t slip a paperback book between a towering pine and your bathroom.  One of these days I’ll be communing with nature and the nearest treebole will swell just that tiny bit further and burst straight through into the shower cubicle. That fresh piney smell with not a cent spent on disinfectant.

Two of the less prepossessing pines in our yard
This tree is cold and wants to be inside

It’s been very very very windy in Sydney lately, and quite a few people have been unfortunate enough to experience that piney odour, quickly followed by plenty of refreshing indoor rain. We’ve been pretty lucky, but we’ve spent a lot of time staring anxiously out the window at various ominously swaying monumental specimens.  When I lived in Brisbane I used to be a bit judgey about the lawn to tree ratio in most peoples’ yards.  But if cyclones start creeping their way down the coast I may have to reconsider.

Female yellow tailed cockatoos and a male peeping out of
Yellow tailed black cockatoo enjoying a dead tree at our place
Black cockatoo angel

Yellow tailed black cockatoos are doing pretty well on the east coast, including urban areas, no doubt thanks to their penchant for pines.  But apparently they often struggle to find nesting sites, preferring hollows in trees a century or more old.  They seem to like our senescent radiatas, and spend time perched high on the various dead branches voguing.  I hope, when we finally save enough shekels to pull down the extensive array of dangerous trees in our yard, we still see them.

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November 22, 2014

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anthropocene, Australian natives, Climate change, Ornamental gardens

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Maps in bloom

Angophora costata in bloom seen from Berowra train station

Perhaps I’ve simply been oblivious before, but this year it seems the bush around Berowra is awash with flowers –  white posies crowning the Sydney red gums (Angophora costata) that now appear to be on every street corner, ridgetop and slope.

Gorgeous Sydney red gum in a Berowra street
Sunset from the back deck
Angophora costata in Hornsby Heights
Has Morrisey been performing in Berowra? Angophora blossom hurled away in disgust

There’s something strange about this foam of blossom appearing across our familiar view, as if, while we weren’t looking, a stagehand unrolled a new backdrop to our lives.  I’ve become a tiny bit obsessed by capturing this new scene on camera. Here’s a small sample of my multiples.  Andy Warhol eat your heart out.

Angophora costata in Berowra Valley National Parkbloom in Berowra
Angophora costata at sunset in Berowra Valley National Park
Closer to town, the jacarandas are also out.  I love the way this royal bloom redrafts the map of the suburbs, rerouting your eye from the usual lines of roads and railways and wires, to a new dot-to-dot of superbly laden trees.  The city shifts on its axis.  Or better, the city’s axis, the radial city itself, retreats behind a mist of purple flowers.
 .
Jacaranda and Sydney red gum dot-to-dot
The rhizomatic city of jacarandas

Of course, this new cartography of living things is still a map of privilege, of the breathing space between people.  They don’t call affluent parts of town “the leafy suburbs” for nothing.

Creating and keeping green space gets more urgent as cities get hotter.  An article in the Harvard Gazette reports research on the way inequality, heat and green space correlate.  “Heat” says Joyce Klein Rosenthal, who teaches in Harvard’s School of Design, “is an environmental stressor, unevenly distributed in places where there are less trees, less green space, and associated with poorer housing quality”.   “At every scale” she noted “income levels are associated with surface temperatures. Poorer neighborhoods are hotter; wealthier neighborhoods are cooler”

Gorgeous street trees on my way to work
A magic carpet

Street trees have magic carpets beneath them, not just lilac flowers, but shade.  And on a stifling day the breath of wind across a city park – old-school evaporative airconditioning – is almost as good as the breeze off the water.  Just now, the City of Sydney is trying to green streets and villages, beating the urban heat island effect by shading concrete, weaving plants into walls and sowing seeds on roofs.

But, that hasn’t stopped the chainsaws round here.  New regulations in NSW, created in the name of fire risk-management, let householders rip, at least on trees ten metres or less from their place (oddly, it seems that trees in the middle of spectacular views present the greatest fire hazard).  What an irony: climate change, worsened by tree-felling, makes the Australian weather hotter and extends the bushfire season.  We fear the urban forests, just as we need them the most.

Jacaranda flowers close up
Prepare to stop and marvel at the suburban glories of jacaranda

After years of cultivating a back yard the size of a large picnic blanket (that’s to say, a picnic blanket made of concrete) every day I bless the growing things I see from my window.  I may feel differently one day when the view from my back deck is Sydney red gums topped with flame rather than flowers.  Let’s hope I don’t find out anytime soon.