Autumn in terminal decline?

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”.

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.

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?

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.

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)

Let them eat light!

It’s persimmon season, but, natch, nothing doing on my little Nightingale tree, despite a grand show of weird naked-looking flowers in the spring.  Two fruits nearly made it to the finish line, but the possums got there first.

Gorgeous as the golden fruits are reputed to be as they hang on the leafless trees, 2016, I have decided, will be the year of picking green. The persimmons may well be mouth-puckeringly unripe but as human overlord of this place, I insist that it is I who will enjoy their high-tannin nastiness, and not some upstart marsupial.

In fact, my tree is an old fashioned astringent persimmon: the fruits need to be “bletted” to go super soft and sweet. This can happen far from fruitflies and other critters, deep in the pantry, in the comforting darkness of a paper bag, with only an ethylene-emitting banana for company.  I have days when crawling in next to the banana to be bletted myself sounds like a good gig.

In theory, me and my persimmons can hole out for a few weeks in an undisturbed corner and it should work out delectably for both of us.

But, really, I don’t care! Harvests mean nothing to me! A barren tree is a beautiful tree.

For now, it’s all about the komorebi, a Japanese word I encountered for the first time a few days ago in the marvellous nature blog, Mildly Extreme.

Because who needs food when you can have sunlight filtering through though autumn leaves?*

*Love those leaves… but thank god for the Freemont mandarins

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.

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.

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.

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.

Ecosystems of evil

Okay, I know there’s no such thing as evil ecosystems.  You create plenty, and things come.  Plenty of chicken food and regular eggs, you get nine teenaged brush turkeys, slouching around your backyard, eating anything that’s not nailed down.  Lots of grapes vines and your resident possums bite their way through the mesh exclusion bags and let in the fruit flies.  A yard littered with the sulphurous fermented droppings of a cocos palm (not to mention the ordure of those brush turkeys), you get loads and loads of flies.

I’ve had a red hot go at taking an aesthetic approach to the flies, with their sparkling metallic blue and golden armour and crazy eyes.  I’ve tried to think about them as simply part of the cycle of life, but I am starting to stare pointedly at my watch, waiting for the arrival of the cavalry, a wheeling flock of insectivorous SBBs (small brown birds) that will weave through the undergrowth and snatch the pests from the air without breaking formation.  I want one of those neat and tidy ecosystems, the ones where the annoying insects become a food source for endangered and good-looking avian visitors.

But no – desite my native shrubs and the absence of a horde of noisy miners, our place is rich in  bombastic generalists and SBBs are thin on the ground.  Your kookaburra – good for tidying up your left over sausages. Your cockies will make short work of the peach crop.  But both of them bloody useless at disposing of flies.  The garden skinks have been a disappointment as well.  Allegedly they are avid carnivores, and flies are a favourite treat, and we’ve got more Lampropholis guichenoti in the backyard than we have five cent pieces rattling around in the bottom of the washing machine.  But they, too, have failed to come to the party.  Once again, Gaia appears to be napping on the job.

While the Cocos palm absolutely and definitively a weed (I like the nuggets of invective in the Grow Me Instead Brochure – “a blot on the landscape” “can give the appearance of a garden planted with telegraph poles”) my hatred for this vermin-attracting plant was masked for a while by a sense of gratitude.  After all, it did save the house and possibly the family from being crushed under a giant gum tree.

I was at work one day when RB called.  “I don’t want to worry you but a tree’s just fallen on the house”.

The SES was summoned: a marvellous mob of guys and gals with chainsaws who belayed themselves to the wonky car port and swarmed over the roof of the house, making short if noisy work of the tree.  The big gum had lost its grip on the ground and fallen sideways towards our verandah.  Fortunately a forked branch wedged itself across the Queen palm, holding the eucalyptus suspended just a smidgen above the roof. The sum of the damage: one branch lightly brushed a gutter and gave it a bit of a bend.

So, thanks for that, Queen palm (and, needless to say, the SES. You are legends.).  We’re grateful for the structural integrity of our roofline.

But if you think it’s going to stop us chopping you down, you couldn’t be more wrong. The possums might view your fruit as ideal picnic food but you’re a hazard for the flying foxes.  It’s a worry when you rely for 30% of your diet on something that gives you acid reflux, damages your teeth, chokes you and leads you to stumble around on the garden being mauled by suburban dogs.  Even Maccas isn’t that bad.  That’s an evil ecosystem if ever there was one.

And that’s leaving aside the trip hazard for someone as poorly coordinated and lazy with the garden broom as I am.  So unless I hear about a recipe for cocos palm wine before I afford a tree surgeon, Cocos palm, you’re cactus!

Pomegranates: a Christmas star turn

My little pomegranate, a variety called “Wonderful“, is living up to its name. The flowing scarlet flamenco skirts of the flowers don’t last very long, but in a kind of floral Eurovision stunt, once the maxidress is off, there they are in their nifty stellar mini.

Of course, just because they’re looking gorgeous now, doesn’t mean any of these beautiful budlets will go on to become proper grown-up fruit.  The tree struggled on for a few years in a pot, and only gave us our first taste of success when it finally went into the ground last year.  And festive as it is, I’m not sure what to read into the flurry of fallen starry frocks underneath the tree.

Apparently pomegranates don’t like humidity much, especially in the spring time. The rigorous raking its roots were getting from feathered visitors up until recently probably didn’t do much for it either.  I sorted out that problem by piling rocks and tiles on them – the pomegranate roots, that is, not the brush turkeys, although the thought of burying a turkey or two under an avalanche of bricks is pretty appealing.

I’m hopeful we’ll see a better crop this year.  A tree with a 5,000 year old history of cultivation has got to be tough as old boots, I reckon. Unsubstantiated rumour has it that the pomegranate may even have been the “apple” that Eve was tempted with by the diamond python of the Garden of Eden.  Surely a participant in that epic contest between good and evil (or at least, between nudity and a well supplied fruit bowl) will be able to handle a tussle with a chook or two.  With luck, in the spirit of this year’s glamorous bearded Eurovision winner Conchita Wurst, our feisty femme will “rise like a phoenix” above her stack of stones and discarded finery.

The waste management business

Heavy rubbish day.  Or as it’s known locally, the council cleanup.  No words strike more fear into the hearts of your loved ones, if you are a gardener with an ample shed and an insatiable love of junk.

I was left momentarily unsupervised today, and all the good work of a weekend of chucking stuff out began to go into reverse.  I know it’s a sign of my hoarding pathology, but I really struggle to imagine why someone would ditch a barely scratched inch-thick slab of gorgeous red gum about half as long as my kitchen.

Here’s the only plausible explanation I could come up with: it had been used in the commission of a mob murder.  “I know, I know, Vinnie had to go… he knew too much… but since he “went on holiday” I just don’t feel the same about that big chopping board…”

Another road-side acquisition of the last 48 hours (the coffin-sized item pictured below) also suggests restless nights and guilty secrets.  I swear the pruning saw was in-situ before I even considered taking this photograph.  Such measures may be necessary when “spring cleaning” for those of us who only have possession of an electric mulcher, suitable strictly for lighter duties.

Okay, not quite long enough, but there's always the pruning saw.

Okay, not quite long enough, but there’s always the pruning saw.


All this “waste disposal” has perhaps been a bad influence, since today I had to do a piece of work.  I got a place ready, somewhere nice.  No need for concrete boots (or indeed blood and bone) just a very old pair of Blundstones and some hair clippings at the bottom of a hole.  We had a problem: our new associate, low-chill Tropical Sunshu nashi pear, had to be put in the ground.

We put her in the ground, and we put her in a box.  In that order, suggesting I’m no wise guy.  Though I can say, hand on heart, that she’s gone to her narrow bed, to sleep the Big Sleep, since the box we put her in was constructed of not merely one, but two bed frames.  Those beds may never have concealed any horses’ heads, but they were absolutely and definitely products of the waste management business, a business I should clearly for the sake of my family (and my shed) try to leave behind.

Day of the Dead Bugs

It’s a pity the internet isn’t scratch and sniff.  The citrus flowers were splendiferous this year – the place was suffused with perfume for weeks.  And now there are lots of baby fruit on the trees – not only on the lemon, mandarin, oranges and grapefruit down in the veggie garden but even on the limes and the kumquat suffering in pots by the back door.

But there’s a nasty smell taking over the garden these days. The stinkbugs are back.

I’ve spotted bronze orange bugs in the garden before but never quite got around to doing anything about it.  I’ve gone for a bit of a Darwinist approach with insect pests in the past.  Organic Tough Love, we might call it.  “Deal with it!  I’m busy!” has worked okay with the Eureka lemon and the Freemont mandarin (and the ruby grapefruit seems to be doing alright too).  But the poor baby blood orange has only grown about 5 cm since I planted it, thanks to sooty mould and aphids (… okay, thanks to neglect).  The one mature fruit tree that was here when we arrived has been smothered by potato vine, scratched by chooks, starved of water and fertiliser, permanently shaded and, of course, parasitised by the odd citrus bug.  No wonder we’ve only seen 3 rather unpleasant oranges in the last 5 years.

So, bugs, it’s time.

There’s something of a 60s Bond film about these pics – I think it’s the Chromakey background.  But maybe it’s also the general Bondishness of stink bugs.  You can imagine a cable car zipping up to their citadel at the top of the lemon tree.  And 007 would need any number of secret weapons from Q’s underground lab to deal with that nefarious blinding spray.  There’s Sean Connery converting a dapper hat into an oxygen mask before fighting off the green and orange horde.

No fancy equipment for Uncle Harry and I when we set out on our mission this morning, just protective glasses, ill fitting rubber gloves and a trug of boiling hot waterNo-one lost an eye, though by the time the bucket was filled with colourful corpses we both smelled atrocious and Harry had a mysterious brown stain on his beetle-pinching fingers.

Despite being a vegetarian for a quarter of a century, I’m not sure I’d make much of a Buddhist.  Meat-loving Harry felt guilty about the citrus beetle death toll whereas I wielded the seccateurs gloating “Die, bugs, die!!”.  While I was up a stool lopping the most heavily infested branches off the lemon tree (it needed a haircut anyway), I spotted a Halloween-themed scene which made me feel less unnaturally ghoulish.  I particularly like the bit of fly viscera splattered on the right hand side of the frame: Spidey was obviously scuttling from the scene of the crime.  We killed a lot of bugs today but at least we didn’t paralyse them, regurgitate stomach acid onto them and then suck their corpses dry.

Although strictly speaking, if you could face a meal of stinkbug entrails, this probably would probably be a more sustainable alternative to death by washing up liquid. On that funereal note, enjoy All Soul’s Day, folks.  Let’s hope we don’t see any stinkbugs returning from the grave.