25 July 2014
Image: AL PAVANGKANAN VIA FLICKR
A pine tree planted in 2004 in honour of Beatles member George Harrison has died after being attacked by pine beetles.
Proving that nature has a sense of humour, a pine tree planted in the garden of former Beatle George Harrison finally succumbed to attack by pine beetles, whose effects were made worse by long term drought in Los Angeles and across California.
George Harrison was an avid gardener and the pine was planted with a small plaque three years after his passing, in his large garden that he restored over many years.
The plaque read "In memory of a great humanitarian who touched the world as an artist, a musician and a gardener."
In memory of a great humanitarian who touched the world as an artist, a musician and a gardener.
Pine Beetles Causing Huge Losses
Beetles are causing enormous damage to pine forests across North America and Canada, causing vast areas of dead and dying forest. Outbreaks of Mountain Pine Beetles are much worse than normal, and the cause is thought to be a combination of warm winters that no longer kill beetle larvae and reduced
rainfall that places additional stress over a long period on trees.
There are also reports of wildfires in beetle-killed forests (opens in a new window) when the dead trees are tinder-dry. Research showed that beetle-killed forests burned two to three
times faster than in healthy forests and with greater intensity, meaning that remaining trees were more likely to be completely killed.
Pine Trees And Drought-Tolerance
Our own experiments are examining the drought tolerance and associated physiology of drought in trees using the unique Large Rainout Shelters and greenhouses to apply combinations of heat and drought.
Our research has shown that pines can survive incredibly long periods with no rainfall at all - nearly nine months in some cases.
This ability to survive drought is due to the complete closure of the tiny pores on the leaves that normally let carbon dioxide into the leaves and also let water escape at the same time.
This comes at a cost, though, when drought periods are long and severe like they have been in North America.
After long periods being unable to fix CO2, the pines begin to starve and this will eventually kill them. Combined with insect attack, vascular damage and defoliation, it is only a matter of time before even the toughest pines succumb.
Large Rainout Shelters are designed to exclude rainfall above and below ground and simulate exposure to drought conditions
Building Our Knowledge Of Beetles' Taxonomy
Australia has not yet faced losses of such magnitude from the changing dynamics of insect ecology but there is continuing concern about exotic insects entering Australia and wreaking damage on our unique forests
Dr Markus Riegler and Dr Shannon Smith are investigating ambrosia beetles and associated microbial diversity to identify critical pests and pathogenic fungi and bacteria.
Ambrosia Beetles have a unique way of ensuring their survival and success in an inaccessible, hidden environment. The beetles actively cultivate fungi which break down wood, using the fungi as their food source (ambrosia - 'food of the gods').
The fungus itself causes the damage to trees but its own success is dependent on the careful cultivation by the beetles. This process is common in the insect world with numerous examples of co-dependent fungi, bacteria and other microbes ('microbial symbiosis').
The project is an international collaboration supported through funding from the Australian Government's Australian Biological Resources Study National Taxonomy Research Grant Program (opens in a new window).
"Invasive bark- and wood-boring ambrosia beetles are emerging destructive tree pests across the world" says Dr Riegler.
"They are destructive not just because of their feeding and tunneling behaviour, but because they can carry fungal plant pathogens that are a threat to Australian and global forestry and timber resources. The more that is known about endemic ambrosia beetles and invasive pests, the better we can manage
the economic and environmental risks."
The Need For Integrated Research
While George Harrison's pine has been replanted, it will be difficult to manage the effects of climate change dynamics on the pine forests that remain in North America, with some estimating that the forests will need more than twenty years to recover.
Our research into drought and heat combined with extensive insect, soil and genomics using large-scale facilities unlike anywhere else in the world will offer a more integrated and comprehensive view into the future of Australia's unique ecosystems.