Thursday, September 23, 2010

Playing with Fire in Order to Save the Eucalyptus Trees

A recent article written by Wendi Zukerman published in the magazine “New Scientist,” highlights the research done by D. C. Close, N. J. Davidson, D. W. Johnson, M. D. Abrams, S. C. Hart, I. D. Lunt, R. D. Archibald, B. Horton and M. A. Adams on the premature decline in the number of eucalyptus trees in Western Australia related to the suppression of fires in recent years. The paper written by Close et al., illustrates a possible explanation for the decrease in eucalyptus trees due to the increase in number of fire intolerant and shade tolerant plants.

(Image: Melanie Stetson Freeman/Getty)

The article states that without regular low-level fires, the eucalyptus tree cannot survive because these are the conditions it has needed to survive in the past. It then goes on to explain that without regular fires, dry rainforest type species are allowed to grow beneath the canopy of the eucalyptus trees which compete with the eucalyptus trees for water as well as contribute to a thick layer of litter that changes the chemistry of the soil which stresses the trees even further (Zukerman, 2010). There is a severe lack of evidence to support these statements. For example, there is no mention of any evidence that would explain why a layer of litter may affect the chemistry of the soil or how a thick layer of litter could changes the chemistry of the soil. It only tells the reader that it does. In the paper (primary source), there are specific examples of experiments done by other scientists that indicates “seedlings planted in plots that had been experimentally burnt by Withers and Ashton (1977) had survived, indicating that recruitment was possible where the thick litter layer was eliminated” (Close et al. 2010). The paper continues to explain that because of the thick layer of litter, “eucalypts have less access to P and/or cations as these elements become locked up in soil, litter and midstorey biomass.” (Close et al. 2010). This evidence that supports the statements made by the authors of the paper helps to increase the strength of their claims.
Also included in the paper was a table that illustrated the increased density of fire tolerant species and the decreased density of eucalypt species in Temperate Australia in the absence of fire.
The paper gave a wide variety of references to support the claims it was trying to make. The list of references to other research to back up the hypothesis of the paper is staggering which made the strength of the claim much greater. However, the article did not quite reach the standard that was set by the primary source it was based off of. The article did reference the paper written by Close et al. as well as two more sources to support any information that was not found in the primary source such as research from 2004 that states the eucalyptus trees need neutral to acidic soil in order suck up nutrients such as iron and manganese (Zukerman, 2010). Although the secondary source did not have nearly the amount of references to support its findings as the primary source did, the article did cover all its bases by referencing each paper it extracted information from.
Both the paper and the article spoke of a similar situation involving the North American pine. However, the primary source goes much more in depth by describing the situation in North America as well as giving references to further information on the research. The parallels between both the situation in Australia and that of North America are clearly stated in the primary source. An example of this could be “the increased development of midstorey vegetation resulting in the decline of fire tolerant tree species and the dominance of shade tolerant species and altered soil microclimate and microbial dynamics” (Close et al. 2010). The secondary source does not mention any of the reasons that the two situations are similar just that they are similar. This lack of evidence does not aid in strengthening the claims that are made in the article.
The limitations of the primary source are clearly stated in the introduction of the paper as well as in the conclusion. As stated in the paper by Close et al., “although anecdotal reports from forest and fire management authorities, coupled with our own observations, indicate that overstorey eucalypt decline is widespread in some forest types across temperate Australia, we currently lack quantitative information on the extent of decline and there is a clear need to investigate both the scale of the phenomenon and the ecological processes that underpin it. Emphasise is made on the fact that the research reported is site and species specific and that the model is thus applicable to only a sub-set of Australian ecosystems. For example some eucalypt species growing in relatively fertile soils and under high rainfall do not appear to exhibit premature decline with the development of a dense, shade adapted midstorey.“ (Close et al. 2010). As you can see, all the limitations of the paper are clearly stated allowing for no misunderstandings when someone reads this paper. However the article does not discuss or even mention any limitations of the work.
It is clear that there is a price to pay when moving from primary source to secondary source. Information supporting the main points is lost in order to create a shorter version of the original source. Media has to make the information more public friendly, that is to target a general audience and make the information easy to understand. In a primary source the information is targeted for a more specific group of individuals allowing for all the information to be included. A secondary source can allow for the reader to make assumptions about the information that is given due to lack of information about the limitations of the work and the strength of the claims is clearly compromise. However, a secondary source is a good place to learn a little about a subject of interest and intrigue the reader to learn more but if you want to understand it fully, getting all the correct facts, a primary source is the only way to do so.

Close, D., Davidson, N., D. Johnson, D., Abrams, M., Hart, S., Lunt, I., Archibald, R., Horton, B. and Adams, M. (2009, April 3) . Premature Decline of Eucalyptus and Altered Ecosystem Processes in the Absence of Fire in Some Australian Forests.
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Zukerman, W. (2010, September 16) . Receding gums: What ails Australia's iconic trees?.
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