"Eucalyptus: Friend or Foe?"

[Antonino Giglio]

I've just read an article in the winter edition of The Digger's Club, signed Clive Blazey, at page 2.

As someone read it?
I actually find it very interesting and challenging and, on my opinion, it is a mind opener.

I was particolarly stunned to read about the agressivness and fierce competitive nature of eucapyptus "...but once the eucalyptus becomes the dominant sepecies and replaces the rain forest it completely alters the ecology to create conditions in which it trives. The leaves of eucalyptus hang vertically to reduce evaporation and letting through light that rises soil temperatures and reduces soil moisture wich destroys shade loving ferns and mosses The eucalypt also produces chemicals to prevent plan competition whcih assists it to become the dominant species. Its leaves are inflammable so its litter of leaves will ignite destroying all living things - soil carbon, soil biota, animals, plants and, of course, us..."

Has anyone read it? What do you guys think about this "hot" topic?

[gardenlen]

simply put for me it means, any plant that is planted outside its indemic region has the potential to become a weed, now the way i see it the uec's in question are probably no more aggressive as weed status where they are exotics than what lantana and slash and radiata pines are over here. in california in particular and madagascar also they are taking over their habitats, that is mainly due to better growing conditions and that they have no natural balancer, so they thrive.

len

[milifestyle]

I reckon it means Eucalyptus have evolved to be a dominant species.

However i also reckon the Human species has evolved to become the dominant destroyer of Eucalyptus.

[geoff]

Antonino, I haven't read the article but I agree with the idea. Not sure if it's mentioned in there, but eucalypts also have waxy leaves, so their litter is waxy and water repellent, and so are the soils beneath them. Essentially they are creating a situation that reinforces the dry nature of our country. They don't produce deep layers of humus in the same way that non-eucalypts will, so they are not creating deep moist soils that hold water and increase growth of other plants. It's a bit like the chicken and the egg, which came first, the environment or the climate? I think that eucalypt forest is creating the dry climate, just as much as the dry climate has favoured the eucalypt forest. It's a self-reinforcing feedback.

If we want to live well here we should be planting deciduous trees, which shade the soil, produce humus and deeper soils, and transpire more water therefore creating more rain. A house surrounded by eucalypts et al is going to be hot in summer, one surrounded by deciduous broadleaf trees is going to be cooler and moister, therefore more pleasant, so there are direct advantages in terms of reducing energy use required to maintain comfort levels. I imagine this would translate to other areas of our immediate environment. If the whole productive area of a household is surrounded by cool, moist forest it's going to be much more productive than one surrounded by hot, dry land.

[pebble]

Is there evidence that gums will replace rain forest without human intervention? There are natives in NZ that will take over and area and become the dominant, only, species for several hundred years at a time eg manuka and kanuka. But they don't do that to existing bush, they do it on land that has been cleared (by humans or fire).

I'd want to know if gum forests last forever. Do they always outcompete other plants after a fire? Under what conditions do other plants succeed?

I can think of small stands of gums in NZ that are a hundred years old and they haven't taken over. Hardly aggressive especially when you compare them to pines.

[Burra Maluca]

I'm in Portugal, not Australia, but we have huge areas of land planted up with non-native eucalyptus here, mainly for paper production. My experience (mostly just walking through the forests and observing) is that they produce a total monoculture, virtually nothing else will grow near them, the soil is even worse than normal beneath them and they are an extreme fire risk. But they don't seem to spread - they stay where they are planted, so no I don't believe they are aggressive invaders, at least, not the type they grow here.

By the way, does anyone here know if it's possible to compost eucalypt leaves? And how long it takes after cutting one down until you can grow anything else in the area? Or even, what else *can* you grow - I know acacia will, and 'snotberries', but is there anything else I could try?

[milifestyle]

Yes, Eucalypt leaves can be composted. It can take a while for the oils to leach out though. I occassionally get a load of shreeded eucalypt from the tree loppers clearing around power lines. Its a coarse mulch so i like to put it through the flails on my own shredder after a month or so aging.

LOTS of moisture is good.

[ecodharmamark]

G'day All

The Blazey 'article' can be viewed here:

http://www.diggers.com.au/articleEucalyptus.shtml

Not quite sure what Clive is 'digging' at with regards to the above, but lumping all spp. of Eucalypt into one of two categories, either 'friend or foe', is really not helping to further the debate re: to burn or not to burn. The genus Eucalyptus, of which there are more than a thousand species/sub-species, have evolved over millenia to deal in there own unique way (and often within their own unique ecological niche) with fire.

Last week I spent 3-days in Kakudu, and during my time there studied much of the Eucalypt escarpment country. No evidence of rogue Eucalypts trying to storm the wetter environments at the base of the escarpments propper. Indeed, most of my life has been spent living in or near a Eucalypt forest of one description or another, and likewise I have never seen a Eucalypt forest self-regenerating in any way other than nature intended. The only time Eucalypts pose a threat to other non-Eucalypt ecologies is when those same ecologies have been bulldozed and replanted with Eucalypt mono-cultures, also known as plantations (and never as an ecologically-diverse forest). In this point, I agree with Clive.

Eucalypts do not kill people; people kill people. We have irrovociably-altered our forest ecologies, and now we have to learn to live with the outcomes. We reap what we sow.

For those who are interested in the vast field of science known as 'fire ecology', particularly as it pertains to maybe 60,000-plus years of human-induced/influenced change in an Australian context, you could do a lot worse than read the following:

http://www.publish.csiro.au/samples/Aus ... Sample.pdf

For expert information/advice concerning the beautiful genus Eucalyptus, check out one of the world's brightest stars in the field of Eucalypt ecology, Dean Nicolle:

http://www.dn.com.au/index.html

Cheerio, Mark.

[Antonino Giglio]

Antonino, I haven't read the article but I agree with the idea. Not sure if it's mentioned in there, but eucalypts also have waxy leaves, so their litter is waxy and water repellent, and so are the soils beneath them. Essentially they are creating a situation that reinforces the dry nature of our country. They don't produce deep layers of humus in the same way that non-eucalypts will, so they are not creating deep moist soils that hold water and increase growth of other plants. It's a bit like the chicken and the egg, which came first, the environment or the climate? I think that eucalypt forest is creating the dry climate, just as much as the dry climate has favoured the eucalypt forest. It's a self-reinforcing feedback.

If we want to live well here we should be planting deciduous trees, which shade the soil, produce humus and deeper soils, and transpire more water therefore creating more rain. A house surrounded by eucalypts et al is going to be hot in summer, one surrounded by deciduous broadleaf trees is going to be cooler and moister, therefore more pleasant, so there are direct advantages in terms of reducing energy use required to maintain comfort levels. I imagine this would translate to other areas of our immediate environment. If the whole productive area of a household is surrounded by cool, moist forest it's going to be much more productive than one surrounded by hot, dry land.

Thanks Geoff! Great imput, very balanced and true...

[duanejen]

The Weeds of National Significance Act is about to be lobbied to put the whole Genus Eucalyptus on the WONS list.

It is the greatest environmental weed this country has!!!

WHY should it be declared??

It is invasive.
It burns.
Its alleolopathic
It's residue fails to break down.
Its a monoculture.
It's poisoning and killing ALL of our catchments.
It prevents biodiversity from growing beneath it.

It ticks ALL the boxes as the reasons for putting it on the WONS list.

Anyone wanting to join the debate can contact the Bureau of Rural Sciences at DAFF (Dept of Ag, Forestry and Fisheries) and participate in their survey.