Tuesday, 20 February 2007

#8 River Red Gums endangered in Hunter Valley

These massive spreading trees with beautiful multi-coloured trunk and branches are endangered in the Hunter Valley, so I set out to take a look at some and learn a bit about their history and future prospects.

Their history is brutal and their outlook grim

There's something about the greenery of surrounding growth that makes these splendid Hunter Valley giants look a little less majestic when compared to River Red Gums adorning the sparcely grassed red-brown earth of inland Australia, but still a magnificent sight!

A regionally engangered species

The River Red Gum, Eucalyptus camaldulensis, is the most widespread eucalypt in Australia, found in all mainland states and territories. During my travels I have admired these impressive sprawling trees, most notably along the Murray and Macquarie Rivers and dry river banks of far south-western New South Wales.

Eucalyptus camaldulensis, however, has a unique status in the Hunter Valley - the Hunter being the only NSW coastal catchment where the River Red Gum occurs naturally.

It is estimated that numbers of the species have dropped an alarming 99.5 per cent in the region since European settlement.

Pea-sized River Red Gum seed pods

Since European settlement, Hunter floodplains have been extensively cleared to make way for agriculture. River Red Gums depend on permanent or seasonal water for regeneration and optimum health. As the hydrology of the Hunter has been altered dramatically with the construction of dams for flood mitigation, the remaining red gums no longer receive periodic flooding.

Grey-green foliage of the River Red Gum

Today, there are only 19 known stands, mostly occupying private land, with the total number of individuals estimated to be between 600 and 1000 mature or semi-mature trees.

Weed infestation

Grazing and weed infestation are other major handicaps the Hunter's red gums have to cope with. Introduced Kykuyu grass, Pennisetum clandestinum, and the tough spreading ground cover Galenia, Galenia pubescens, are two main culprits. During my on-site investigations recently I also found Balloon Vine and Morning Glory to be rampant amongst the red gum understory, along with African Olive trees and the toxic shrub Green Cestrum.

A Red Gum on the banks of the Hunter River crowded by weeds including Pepper Trees, African Olives, Balloon Vine and Morning Glory, as well as native River Oaks.

Add a lack of local awareness to the woes of the red gum, and extinction looms. There are no known occurences of Eucalyptus camaldulensis in Hunter conservation reserves, but recognition of the rarity and bleak future of the Hunter's River Red Gum population has provided hope.


Under the Threatened Species Conservation Act, the Hunter catchment's River Red Gums have been listed as an Endangered Population. Scientific studies are currently being undertaken to determine whether they are a separate species to that of the Murray/Darling catchment, and also to determine whether previous plantings were established from locally collected seed.

More recently, in 2004, River Red Gum seedlings were planted amongst an existing stand by local environmental groups and community members. These seedlings were propergated by local high-school students from locally collected seed. It is thought that locally collected seed is important to preserve the genetic ingegrity of the Hunter red gum population.

Semi-mature and planted juvenile River Red Gums by the Hunter River

Recently initiated local government planning headed by keen staff hopes to inject renewed interest and enthusiasm into the community to take more responsibility for the future health of these endangered trees. The Hunter Catchment Authority is carrying out on-going work to reduce erosion, and LandCare and Tidy Towns groups provide manual assistance and funds to conservation efforts.

A recent meeting brought these bodies and community members together to discuss the planning of a project that will incorporate the conservation and regeneration of the River Red Gums into an extended vegetation corridor and recreation area. Although numbers were low, it was encouraging to see co-operation and input from all sectors.

The bark falls away from the River Red Gum trunk and branches to reveal a smooth and richly coloured surface

I have enjoyed wandering amongst the two accessible stands of local River Red Gums over the past few weeks, identifying weeds and familiarising myself with habitat and growth habits. I have done as much reading as I can find from reputable sources and spoken to local council and water catchment people. It has been an interesting learning experience.

River Red Gums by the Hunter River surrounded by weedy Balloon Vine.

I am going to take part in the revegetation and conservation program that my local council and community groups are undertaking and I might make a future blog entry to detail progress.

Education can provide awareness, and awareness can promote care and action. If there is an endangered species in your local area, you might find it interesting and rewarding to learn about it, or even become involved in a conservation project.


buffy said...

I'm not accustomed to thinking of E. camaldulensis in an endangered category. Out here in Western Victoria they spring up quite readily. There are many in places that do not inundate - or only very, very rarely. They are indeed magnificent trees. Next time I pull up a seedling in my vegie patch, I'll have to say a prayer for the ones in the Hunter, I guess.

Gaye from the Hunter said...

hi buffy, thank you for your comment.

I am only just beginning to familiarise myself with the Hunter's River Red Gums and their habitat, but will post more on Scribbly Gum when I learn more.

One of the major problems here in the Hunter Valley, as I see it, is the very limited land that is not grazed or farmed, leaving little space for the trees to naturally regenerate.


Esperance Blog said...

Hi Gaye, what you bring to light in your blog is regretfully only too common in farming areas.

Plant species traditionally growing under these large spreading gums tended to be limited to grasses and other herbaceous species, which meant early settlers could just turn their stock out to graze without doing any clearing other than ring-barking to create even more open conditions.

With the continued grazing in the River Red Gum habitats, there has been no regeneration and the only trees left are the old ones now reaching the end of their lives, with no young trees to replace them. Thanks for reinvigorating this problem.


Gaye from the Hunter said...

hi Jack, I am not able to distinguish between many native vs introduced grasses as yet, but plan to get into the field and learn more about what the understory for the Red Gums and other native trees might have consisted of.

The areas of natural vegetation left relatively undisturbed in the Hunter Valley is so minimal that it is just a disgrace.


blogger bill said...

I live in Victoria, and have come to regard the River Red Gum as almost defining my state, if not Australia. Forgive the eastern states bias, but it has the greatest population density.

It's a feature of the landscape that has been immortalized in myriads of paintings and photographs which create an image in the mind of the land in which we live.

My image of my land does encompass the red, stony desert, spinifex, Uluru, Wave Rock and similarly iconic places. But it also has an image of the River Red Gums, almost to the point of them being a place where I would like to be buried.

Although in some recent years I wouldn't mind being interred deep in a Tree Fern forest.

Gaye from the Hunter said...

hello Bill, the colourful sprawling River Red Gums in the damp red sand of a creek that had just emptied after a flow at Silverton (far SW NSW) when we camped there in August 2006 were stunning. It's easy to see why the area is a magnet to artists.


Anonymous said...

Nice stuff Gaye. They truly are a magnificent tree. There was one growing in the grounds of a vineyard I once worked in that was absolutely enormous. We had some botanists doing some research into weed species that invade farmland. These botanists were very taken with this example and estimated that it was at least 500 years old and possibly as much as 700-800 years of age.

I also recall seeing a segment on Landline several years back about the use of this species to restore salt affected land. Apparently they discovered some individuals that had a natural tolerance to salt and were hoping to selectively breed these to be used in land reclaimation works. I haven't heard anything more on this and am not sure what progress has been made since then.

I found it interesting that you mention the fact that there may actually be more than one species. I often thought about this as many of our more widely spread eucalypts can often be further divided into sub-species. I have an article here somewhere in one of my magazines that gives some very interesting details on River Red Gums. I'll see if I can track it down and email it to you.



Gaye from the Hunter said...

hello Peter,

re: the River Red Gum and salt tolerance: I listened to a brief conversation about this last week and found it most interesting. It could be very useful.

I also viewed an article printed from the internet regarding the fatal damage to River Red Gums by possums. I haven't been able to find it on the internet, but will look into it because the longterm field study was apparently pretty conclusive in its findings and I'd like to know more.

I always enjoy your personal accounts and experiences with the environment. Thank you.


Anonymous said...

Hi again Gaye,

I found a link to a blog that has info re: possums and Red Gums that is a very interesting read. Not sure if you may have already seen it.




Gaye from the Hunter said...

hi Peter,

that is precisely the article I was looking for - a field study conducted over time regarding the effect of the brush-tailed possum on the health of the River Red Gum.

It makes interesting reading.

Thank you very much.


buffy said...

I hate bits of information that just simmer to the surface about 20 years after you read them and you can't remember where they came from. I'm sure I read somewhere about River red gums and Forest red gums, both being E. camaldulensis. The leaves of the River ones drooped and were longer and thinnner(at least that was how I remembered they belonged with the water) and the Forest ones stood up more. But it was so long ago that it could easily be an out of date taxonomy. I'll try to remember which publication I read it in...it was definitely not on the internet, must be something I have here in my home library.

Gaye from the Hunter said...

hello buffy,

as far as I am aware, E. tereticornis is Forest Red Gum and is a different species than E.camaldulensis.

I have read that E. tereticornis (Forest Red Gum) was also a widespread species at the time of European settlement in the Hunter Valley, but was also extensively cleared.

Here is a link to E. tereticornis.


I will see if I can find the site I was connecting it to the Hunter Valley.