Popular Science: Tree-rings – a live chronicle of forest management
Knowledge of the forest’s history is very important in order to acknowledge causes of the contemporary plant composition, but also because of learning the successes and mistakes of the methods. We can use historical sources and/or tree-ring width, which show the tree’s years of “abundance” and “poverty”. We can research the influence of diverse events on the tree’s growth and at the same time we can successfully reconstruct these events by analysing the tree-ring width.
People have been using forests since time immemorial. One of most important management styles was coppicing. Coppicing consisted of cutting trees close to the ground, letting them resprout from the cambium or dormant buds, and cutting the shoots repeatedly at short intervals. Coppicing created space for the heliophile plants, hence as soon as sunlight reached the ground, tree seedlings grew as fast as possible. This management style was especially good for oaks. The first preserved note about coppicing in the Pálava forests is from the 14th century. In these times coppicing was done in seven-year-long intervals. This interval, however, was prolonged to up to 30 years during the 19th century and in the 20th century, when typical coppicing only happened in the year 1935. In the 1970s and in the 1990s only the strongest trunk was left and the canopy had changed into the “high forest”, which dominates the countryside nowadays.
The authors concentrated on the influence of diverse management styles on Sessile Oak (Quercus petraea). They researched if oaks reacted to coppicing by increased diameter growth, then the influence of the surrounding canopy on oak growth and how the forest is in development nowadays. They took and compared samples of the tree-rings in 90 chosen oaks. Therefore they gained an overview of the oak’s reaction to particular events dating back to the 19th century. Then they compared their data with the archive records of forest management.
Their results corresponded with the archive records very well. The growth of the oak trunk increased rapidly after the coppicing. It is interesting that oaks in the Pálava region still show increased growth 22 years after the coppicing, which is much longer than the 6-7 years recorded in other studies. The authors explain this phenomenon by the richness of the soil and water regime in the forest. Thanks to these special conditions oaks are able to compete for sunshine and water.
However, the situation nowadays is not good for the oaks. Pálava became a nature reserve in 1946 and the forests were left to develop without any care. This logically led to the higher density of the canopy, to a decrease in the amount of light and therefore to a decrease in diversity. This situation is catastrophic for the oaks, because the seedlings have no chance to grow. Hence, the forest composition will completely change after the old oaks die. It depends only on us. Either we want to have the forest as it was for centuries – hence coppiced, rich in species and managed by man, which is also a great source of firewood and nature friendly. Or we can have a high forest that is created by man to gain economical profit without respect to the natural wealth.
Altman J, Hédl R, Szabó P, Mazůrek P, Riedl V, Müllerová J., Kopecký M, Doležal J (2013) Tree-Rings Mirror Management Legacy: Dramatic Response of Standard Oaks to Past Coppicing in Central Europe. PLOS ONE 8(2): e55770 doi: 10.1371/journal.pone.0055770.g001
Question for the author:
In the article you ask yourself how the oaks could have survived before the coppicing. Could it be similar as e.g. in Yellowstone? Could there have been fires in this region sometimes? Fire would not threaten old trees, but would also give a chance for seedlings to grow. Could coppicing kind of simulate these fires? I expect that nowadays nobody would give permission for fires in the Pálava region, but there could have been quite regular fires in prehistory.
This is an interesting question, which is not so simple to answer. Prehistory was a very long time period and our knowledge about vegetation goes back to its final 12 000 years (Holocene). Oaks spread in our area just at the end of this period. I do not generally suppose that fires could be the cause predominantly forming this society and helping oaks to survive. Nevertheless, there were definitely many more fires than today according to the dominating steppe vegetation. Another factor that maintained more open forest societies were large ungulates such as European bison. We cannot imagine prehistorical forests as dark and deep forests. To the contrary, forest ecosystems were more open and maintained by the wide scale of factors, which were damaged by human intervention. Coppicing and other forms of traditional management only compensate for what was destroyed by man in a relatively short time.