FAQs - Plantations and Greenhouse
The following is a list of FAQs developed by Graeme Anderson, manager of the Plantations for Greenhouse Program. Plantations for Greenhouse was a $1.5M Victorian Government Greenhouse and Private Forestry initiative which aimed to establish over 1500 hectares of new longer-term timber and greenhouse plantations across Victoria in partnership with local farm forest growers. Graeme spent much of his time answering questions from landholders about plantations and greenhouse. Here are some of the most frequently asked questions.
Q. Can you briefly explain the concept of carbon sinks?
A.Climate change or the ‘enhanced greenhouse effect’ is caused by the increased concentration of greenhouse gases (such as CO2) in the atmosphere. Reducing greenhouse gas emissions is a fundamental task, however the planting of new forests can sequester (absorb) greenhouse gas from the atmosphere and serve as a valuable “sink”. The stored carbon in these new greenhouse plantings will become a saleable commodity in future.
Q. What’s the use of planting trees as a greenhouse sink if they will eventually be cut down?
A. Most people think that planting trees as a carbon sink that will eventually be harvested defeats the purpose. Why not plant the trees and just leave them there?
Surprisingly, a plantation established on cleared farmland that is managed for longer term production of renewable firewood and timber has even greater greenhouse benefits than a tree planting that is just left alone to grow old. This is because there is generally a limit to the amount of carbon that a forest can absorb, and at full maturity the forest will be at an equilibrium. However, a forest/plantation managed to produce a sustainable (ongoing) supply of greenhouse friendly products such as timber helps to free up the forest to grow and store more carbon (until it reaches equilibrium again).
Q. Doesn’t burning firewood increase our greenhouse emissions?
A. The burning of most fuel to produce energy (oil, coal, gas, wood) releases greenhouse emissions. One critical difference is that firewood that is sourced from a renewable plantation is actually greenhouse neutral – this means the carbon released from burning the wood is taken back (sequestered) by the plantation as it regrows. It’s basically a greenhouse gas recycling program.
Q. Is wood really a greenhouse friendly product?
A. If wood is taken from renewable sources such as plantations, it is a very greenhouse friendly option when compared to other materials.
For example, imagine the construction of 1000 metres of transmission line – the greenhouse emissions for construction (to last 60 years) are:
Tubular steel poles = 38 tonnes emissions
Concrete poles = 17 tonnes of emissions
Timber poles = 4 tonnes of emissions
That’s why growing of new carbon sink plantations that can provide ongoing supplies of wood products (paper, timber, flooring, construction etc) are a very useful activity. Not only does the new forest estate create increase stores of carbon, but the wood produced can go to displace many other products that have much higher emissions associated with their production.
Q. How can a renewable plantation that produces firewood actually provide a net greenhouse carbon sink whilst still producing an energy resource at the same time?
A. It’s all about the change in land use from cleared agricultural land (with low carbon storage) to a new sustainable plantation based land use. Over the longer term (repeated rotations) the plantation goes on to produce a plentiful supply of wood products such as fuelwood (energy) - while at the same time substantially increasing the overall carbon levels that are stored on site. The key aspect is the change to a forested land use which increases longer term carbon usage and storage.
Q. Are Sugar Gum plantations good for greenhouse?
A. A recent report by the Australian Greenhouse Office (AGO) looked at the greenhouse emissions from woodheating resulting from various firewood production systems.
The report found that there is actually a net sequestration of carbon per unit of energy produced from burning firewood collected from a coppiced short rotation Sugar Gum plantation.
However, the AGO report showed that collecting firewood from the thinnings, harvest residues and other material from beneath a plantation grown for sawlog production (long rotation Sugar Gum) provided the greatest benefits in terms of carbon sequestered per unit of energy produced.
Q. What happens to the greenhouse benefit if I grow the trees, cut them down and then return the land to pasture?
A. If at the end of the day you harvest all the trees and return the land to the original agricultural land use – the final carbon stored on the land is likely to return to the very low carbon levels found initially. While this may not result in a net carbon sink, if all of the wood grown was used as a fuel source it would have provided a greenhouse benefit due to the fact that an equivalent amount of other greenhouse emitting fuel (and thus emissions) was not required.
This outcome is still better than no plantation at all. However permanent land use change towards plantations has much better outcomes for greenhouse.
Q. Do plantations provide other benefits aside from greenhouse?
A. Well designed plantations can provide many other benefits such as salinity control, farm shelter, biodiversity and improved catchment health as well as producing fuelwood and timber.
Recent studies by Victorian fauna scientists are showing that the diversity and abundance of native birdlife is vastly improved in areas where new eucalypt plantations have been established. Their studies are showing that the even a single species eucalypt planting can greatly benefit birdlife populations when compared to the pre-existing cleared land. The fact that the new planting produces nectar, provide protection, increased insect diversity and partially recreates habitat - all contribute to improving the value of the area for native wildlife. These benefits can be increased further by designing woodlots that have special features such as areas of shrubs or mixed tree species.
For more information about Plantations for Greenhouse contact your regional DPI Private Forestry Officer or Graeme Anderson at DPI Geelong on 5226 4821.