The effects of the drought keep on mounting and it would seem the most recently casualties have been many of our native trees. Many Landcare and community members have reported dead and dying trees, and most have observed it seems to have intensified in recent weeks.
Speaking today with Dr Mason Crane from Sustainable Farms, part of the Australian National University’s Conservation Landscape Ecology group, this dieback we are currently seeing is widespread. North of Sydney, down along the coast and reaching into the far south of the state also.
“Extensive tree dieback was seen during the Millennium Drought”, observed Dr Crane, “however what we are seeing now is possibly on a scale we have not previously observed.”
Weaker trees, due to existing stresses of isolation, stock pressure and shallow soils, are most vulnerable. Particular species like the shallow rooted Stringy Bark, the moisture favouring Blakelys Red Gum, or species on the edge of their range may be the first to go.
Trees become water stressed, and stressed trees tend to send more nitrates into their leaves. Insects are attracted to leaves with higher nitrate levels so concentrate their feeding, overwhelming the tree and compounding the stress it is under. Fertilisers and stock camps also increase the nitrates in tree leaves.
Trees will try and recover using their epicormic re-growth, however if conditions remain dry their reserves eventually become so depleted this is not possible.
The final blow will come after we do receive drought breaking rain. Many trees that have managed to hang on will have suffered extensive root dieback. If strong winds accompany the lifesaving rain, many trees will be blown over.
Saving our trees is not easy. Dr Crane explained “ground cover is the best help. Ground cover helps conserve moisture and regulate soil temperature”.
Trees that are fenced off will have mulch protecting them and greatly reduced stock pressure. Whilst it is not possible to do it for hundreds of trees, putting straw or some kind of mulch around particular trees of concern will help.
For the future, when revegetating is back on the agenda, prioritise protecting as many trees as possible. Paddocks containing lots of trees should be treated differently to others, for example; only used occasionally for off-shears. Where possible, fencing for new plantings can also incorporate some existing trees.
Our resilient landscape has its limits. We can no longer take trees in our landscape for granted.
For more information contact; Ruth Aveyard 0447 242 474 email@example.com
TURNING “DISASTER” INTO DELIGHT AT ILLAWONG
Bryan Ward’s property, Illawong, comprises 160 hectares and carries up to 140 beef cattle at any one time. While this is a relatively small property, it is perhaps typical of thousands of farms producing beef in Australia. There’s a trend to smaller holdings, many operated by people with little farming background.
View The Illawong Case Study here