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Previously, global climate debates focused primarily on the deforestation of tropical wetland forests. Until now, only few are aware that the destruction of tropical dry forests also heavily impacts on our climate. In examining the South-American Gran Chaco forest, Matthias Bauman, PostDoc at the Humboldt-Universität zu Berlin (HU), shows the negative effects of its deforestation and the expansion of grazing and soybean acreages. In an interview with the HU press office Matthias Baumann talks about the core findings of his study.
Mr Baumann, what made you choose to examine a tropical dry forest in terms of climate impact?
Previously, global climate debates focused on the deforestation of tropical wetland forests for the most part and the Amazonas in particular. Accordingly, efforts were made to limit deforestation here and thus reduce the emission of greenhouse gases - in some cases with enormous success.
Until now, only the scientific community was aware that the destruction of tropical dry forests also impacts on our climate. To this effect, barely any measures were taken to protect such forests in the past.
Please generally explain again: Why does the deforestation of the forest have a negative impact on the climate?
The forest is burned after forest clearance in order to create agricultural land and this is especially the case when the wood cannot be used for further processing. That is more cost-effective and faster than transporting it. During the burning process, carbon which is stored in the vegetation in leaves, branches, logs and roots, is released. As a result of deforestation, the same greenhouse gas is produced as that during coal combustion, for example.
Due to the large quantities which are released, we now know today that the land-use change in addition to the combustion of fossil energy sources, is one of the driving factors of climate change.
What role does the Gran Chaco play in this context?
In our study, we identified the Gran Chaco as a hotspot of global deforestation. We have been able to point out two developments that occurred during the last 30 years: On the one hand, more than 20 percent of the forest in the Chaco has been lost. That is twice the surface area of Bavaria. Cattle now graze there for meat production, monocultures are mostly cultivated on the rest of the land. On the other hand, 40 percent of the grazing areas which already existed have been transformed into crop areas – particularly for soy. The soy is shipped to Europe and China and here it is primarily used for animal fattening so as to satisfy the constantly increasing hunger for meat.
So there are two developments in the Chaco: The expansion and intensification of agriculture. With what effect?
In essence we were able to demonstrate that the resulting greenhouse gas emissions in the Chaco are of a similar magnitude as those in the neighbouring deforestation hotspots in the tropical rainforest.
That alone astounded us because in the latter case, there is significantly more carbon stored in the vegetation. In this respect, our results are also an indicator for how fast deforestation is progressing in the Chaco.
The main problem with 60 percent of the collective emissions is the transformation of forest into cattle pastures but the subsequent transformation of grazing areas into soy bean fields also has a strong influence.
How did you proceed in the study and how did you calculate the emission levels?
We evaluated satellite images in the period between 1985 and 2013. This way we were able to reconstruct the course of the deforestation front, so we could see how the core of the Chaco has been cleared from various external positions. The outcome was maps and graphs which, in turn, enable conclusions to be drawn about the causes and solutions. We then calculated, by mean of a carbon model, how the land-use change contributes to the carbon balance.
So what can be done?
Clarification and information, describe the problem and bring it to the attention of the public. We have a clear objective of using the study to point out the danger posed by the disappearance of tropical dry forests. That is relevant to us all.
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About :
Matthias Baumann is a postdoc at the Geographical Institute at the Humboldt-Universität zu Berlin (HU). After completing his degree at the HU he went to the University of Wisconsin-Madison and he returned with a PHD in 2014. Since then he has been doing research under the supervision of Prof. Tobias Kümmerle in a team of approx.10 researchers at the Conservation Biogeography Lab. Here the focus is on questions pertaining to global land-use change and coupled human-environment systems.
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Please put a reference to the source of the interview on publication. For more pictures contact the HU press office: pr@hu-online.de
http://onlinelibrary.wiley.com/doi/10.1111/gcb.13521/abstract;jsessionid=BAA32CF...
https://www.geographie.hu-berlin.de/en/professorships/biogeography/people/curren...
The current situation of the Chaco region. Dark green: deforestation for farming, violet: deforestat ...
Quelle: private/ HU
Deforested Chaco area in Argentina: Only three weeks prior of talking this picture the area was cove ...
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Biologie, Geowissenschaften, Umwelt / Ökologie
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