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Scientists from the Institute of Mathematical Problems of Biology of the Russian Academy of Sciences and the Institute of Physicochemical and Biological Problems of Soil Science of the Russian Academy of Sciences (Pushchino, Moscow Region) conducted a study of abandoned arable lands
central European part of Russia (temperate forest zone). It turned out that abandoned fields are covered with forests about five times faster than previously thought, in just two decades.
Their findings were presented in the journal Ecological Processes.
https://ecologicalprocesses.springeropen.com/articles/10.1186/s13717-018-0150-8
"The resettlement of forest species without fires occurs very quickly if this field is located next to a forest rich in different species. In the literature, you can find estimates at the level of 100, 200 and 300 years. On protected lands, we saw that after 20 years, forest flora is restored on former arable lands," said Larisa Khanina, head of the laboratory of computational ecology at the Institute of Biodiversity of the Russian Academy of Sciences in Pushchino.
The clearing of forests for new fields and pastures, as well as the reverse process - their overgrowing with young tree growth, have long been of interest to a very wide range of scientists, from specialists in the field of ancient and medieval history to climatologists, ecologists and economists.
For Russia, this issue has become especially relevant in the last three decades due to the fact that huge areas of arable land were abandoned along with collective farms and extinct villages in the early and late 1990s. Ecologists have long been trying to find out how quickly they are overgrown with forest and how this process is affected by fires that periodically occur in such fields overgrown with weeds and grass.
As reported by the press service of the Institute of Mathematical Problems of Biology of the Russian Academy of Sciences, Khanina and her colleagues gave a somewhat unexpected answer to this question, observing what was happening on one of the abandoned fields with an area of 265 square kilometers, located several hundred kilometers south of Moscow, from 1998 to 2014.
By observing how often fires broke out on these patches of soil, biologists and soil scientists calculated how they change the nature of flora growth and the transitions between different types of ecosystems.
As these observations and calculations showed, the classical ideas about how abandoned fields become overgrown and how fires affect their condition turned out to be fundamentally incorrect.
Firstly, scientists found out that forests begin to appear on their territory almost immediately after the field is withdrawn from agricultural use, bypassing the stages of their overgrowth with grass and shrubs, for which scientists previously allocated 5-10 years.
Secondly, it turned out that the speed of this process and the time of its onset depended very much on how often fires occurred in their territory. In their complete absence, the forest regenerated in about 20 years, and frequent fires pushed this date back by decades and radically changed the species composition of the flora.
The frequency of the fires themselves was extremely uneven - in some regions they occurred every 1-2 years, while in other areas of the Serpukhov region they occurred once every five years or less often. These differences were mainly due to human activity, since the most frequent fires occurred near villages and other settlements, as well as local climate fluctuations.
Interestingly, the appearance of forests on former fields led to a sharp depletion of the soil due to the fact that the trees pumped out all the nitrogen, organic matter, phosphorus and other useful substances from them. This situation was completely uncharacteristic for already established forest areas - their soil, on the contrary, was rich in nutrients and balanced from a chemical point of view.
Scientists believe that such information will be useful not only for employees of environmental agencies, but also for potential buyers of abandoned lands planning to clear them of forest for agricultural use.
Based on materials from RIA Novosti https://ria.ru/20190122/1549720544.html and the Scientific Russia portal https://scientificrussia.ru/articles/zabroshennye-pashni-zarastayut-lesom-v-pyat-raz-bystree-chem-dumali
Photo "Overgrowing arable lands", press service of the Institute of Mathematical Problems of Biology of the Russian Academy of Sciences
