25.10.2019 change 25.10.2019
Anna Ślązak
Anna Ślązak

Białowieża Forest’s ‘Natural Value’ Not Effected by Humans - But Global Warning Could Change That, Warn Experts

Białowieża Forest. Credit: PAP/Wojciech Pacewicz 01.01.2018 Białowieża Forest. Credit: PAP/Wojciech Pacewicz 01.01.2018

Nature in the Białowieża Forest is thriving both because of, and despite, humans, a new study has found.

But it warns that because of climate change, there will be ‘unpredictable consequences.’

Scientists from four different institutions cited nearly 200 case studies in which they highlighted the balance between natural and manmade influences on the diversity of the forest’s growth.

The research presented in the journal ‘Forests’, found that the forest is home to over 11.5 thousand animal species and 1.2 thousand species of vascular plants.

As such, a large part of the Białowieża Forest meets the criteria of natural forest "undisturbed by man", as defined by the European Environment Agency.

Main author of the study, Prof. Bogdan Jaroszewicz, head of the Białowieża Geobotanical Station UW and former deputy director of the Białowieża National Park, said: "Most of the forest complexes in Europe were cut down in the Middle Ages and transformed into arable fields. In many Western countries, ancient forests are those visible on the oldest maps made 300 or 500 years ago... Here, we are talking about a natural object, for which the continuity of existence is almost 12 thousand years!"

The report goes on to point out that although people have been present in the Białowieża Forest since prehistoric times, their density was smaller than on most of the Central European Plain, and periods of settlement activity and human absence alternated, allowing the forest to regenerate. Even those parts of the forest that were transformed as a result of forest management in the 20th century still have a chance to return to a near-natural state.

Prof. Jaroszewicz added that many species appeared in the Białowieża Forest because of humans. Where river valleys were mowed, meadows were created that enriched the ecosystem with species typical for open areas.

He said: ”We believe that such places, rich in species associated with man, should be actively protected, as opposed to the Białowieża Forest in general, where protecting processes should be a priority, allowing nature to take its course.”

However, the report also focuses on exceptional ecological processes, including the formation of forest soils, undisturbed for centuries. No less important is the impact of natural, processes, "destructive" from the human point of view, such as insect activity or storms. As a result, the forest is rich in old and hollow trees and dead wood.

Due to the continuity of natural processes, elements rare or absent in modern-day managed forests have always been present in the Białowieża Forest, including dead wood and associated species. This translates into great richness of species, primarily mushrooms and invertebrates.

"Such organisms cannot be protected without protecting the entire process, because many of them require dead wood in an advanced state of decay, e.g. 20-30-year-old decayed logs. Other unique organisms require trees that are still alive, but decayed and old, several hundred years old," says Prof. Jaroszewicz.

According to scientific data, there are 1070 vascular plant species in the Białowieża Forest, of which approximately 670 are typically forest species, and almost 400 are synanthropic (associated with human presence). "The actual number of species in the forest is greater, if only because about 400-500 alien species have spread there. But there is no current publication that would summarize it," says Prof. Jaroszewicz.

In addition, there are about 200 species of mosses and 63 species of liverworts. The Białowieża Forest is also one of the places with the largest variety of fungi in Europe. In the strict reserve, scientists counted nearly 1380 species, although they estimate that their number in the entire forest may exceed 5 thousand. Many are endangered species.

The review shows that over 11.5 thousand animal species also live in the Białowieża Forest (most of them are invertebrates), but their actual number can be even twice as high. This diversity is incomparable to other European forests of similar size. They include species that are extinct or extremely rare in the forests of Western Europe, such as lynx, bison, Laxmann`s shrew, white-backed woodpecker or three-toed woodpecker. In the last two decades, several hundred species of previously undetected insect have been found in the Białowieża Forest.

However, the report warns that climate change, brought about by man, will lead to changes in nature that we cannot predict based on historical knowledge. There are certain scenarios which seem more likely than others, though.

The scientists predict that the natural range of beech will shift to the north and east, which means the final colonization of the Białowieża Forest. The situation is different for spruce, one of the main tree species there. As the climate warms, it will probably "retreat" to the north, beyond the borders of the Białowieża Forest, which could mean extinction of spruce and closely associated species. These changes mean a change in the structure of the entire forest, its biodiversity and functions, the authors of the analysis write.

According to the researchers, the changes have already begun, and the course of some of them is fast and worries forest management services. The share of spruce significantly decreased in the years 2013-2018. The share of boreal species associated with the temperate climate zone, e.g. spruce or pine, within the strict reserve in the Polish part of the Białowieża National Park is decreasing. Deciduous species have been replacing them for several decades.

Professor Jaroszewicz said: "In addition to hornbeam and linden, we are also beginning to observe the spontaneous renewal of beech, which appears here beyond its natural range," he says.

The shape of the Białowieża Forest largely depends on the future water situation. Professor Jaroszewicz points out that the last two years were extremely dry, which can significantly change the direction of changes taking place in forest stands. "Beech, which shows the tendency to expand, does not like drought, so its future is not certain. The Białowieża Forest could change in a direction that we cannot imagine at this point. We do know one thing: a change is coming," he says.

In addition to Professor Jaroszewicz from the Białowieża Geobotanical Station of the University of Warsaw, the research was carried out by scientists from the Forest Research Institute in Białowieża, the Institute of Mammal Biology PAS in Białowieża and the Laboratory of Paleoecology and Archaeobotany of the Faculty of Biology of the University of Gdańsk.

The full report can be read here: (https://www.mdpi.com/1999-4907/10/10/849).

PAP - Science in Poland - Anna Ślązak

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