Lake sediment reveals political regime change impacts
Sediment gathered from a lake in Romania has recorded the environmental changes linked to changes in the political landscape, a study shows.
Analysis of the deposits revealed higher erosion rates of topsoil, linked to intensive farming, during the post-war Communist era.
Changes to the cores' pollen signature also showed that woodlands were felled in order for more land to be farmed.
The 1986 Chernobyl accident was also recorded in the samples, it added.
The samples, collected from Lake Stiucii in Transylvania's lowlands, central Romania, showed how the collapse of President Ceausescu's Communist regime in 1989 was also recorded in the cores.
Simon Hutchinson from the University of Salford, UK, one of the scientists involved in the research, explained that the 40cm lake cores provided evidence of land use over the past 100 years.
"By looking at the rate of sedimentation you could identify different periods," he told BBC News.
"You could see when rates were quite low and quite stable, then there was a big increase in sedimentation - when the lake was infilling - from the 1950s onwards during the state socialism period.
"Then the sedimentation rate tails off again when you get into the late 1980s and more so during the early 1990s following the fall of Ceausescu when a lot of agriculture in the region changed."
President Ceausescu was Romania's last Communist leader. He was overthrown and executed in a revolution in late 1989.
Dr Hutchinson observed: "If you look at the sediments' properties in more detail, by looking at the magnetic and the geochemical signals you can usually start to differentiate between surface and sub-surface erosion."
He explained that intensive farm practices, favoured by Communist regimes, led to topsoil (surface erosion), adding that geochemical analysis revealed the presence of metals, which was an indication of pesticide use.
"This area of Transylvania was very heavily farmed. I am told that it was effectively the bread basket for eastern Europe," he said.
Dr Hutchinson's colleague, Dr Angelica Feurdean from Germany's Senckenberg Biodiversity and Climate Research Centre, examined the cores' pollen records, which revealed a change in the balance between tree and non-tree pollen.
He explained this indicated when and to what extend the woodlands had been cleared for agricultural use.
"You can start to link together a broad change in what has happened in terms of erosion, and then more subtle things going on in the landscape in terms of what people were doing and what they were farming, by the pollen spectrum, for example," said Dr Hutchinson.
He added that samples taken "in this part of the world" often contained a "big spike" of radiocaesium, a product of human activity such as nuclear reactors or nuclear weapons testing, as a result of the 1986 Chernobyl nuclear power plant accident.
He added that it provided a good marker in the cores for the period that pre-dated the end of the region's state socialism political regime.
The data gathered from the core samples allowed the team to plot a timeline that showed how there was a link between changes in the political landscape and changes in the physical landscape.
Dr Hutchinson said: "Basically, during the socialist period the grasslands expanded and the woodlands crashed or disappeared. Since that (socialism) system collapsed, the woodlands have started to come back."
He explained that the landscape currently contained a lot more diversity as a result but added: "It is probably a short-term gain because if this environment continues then the trees will crowd out the grassland and a new status quo will be established.
"It is a window of opportunity for conservationists to make some decisions about what we want to do with this landscape.
"In a sense it is man-made landscape, but in terms of biodiversity it is really diverse. Now, it is about how we would like to manage that.
"If we leave it then it would return to woodland. That's fine but then we'll lose a lot of species associated with grassland.
"It will be about whether or not the conservation strategies are appropriate and whether they also consider the socio-political driver behind these changes to the landscape."