Nauka Przyroda Technologie

2018 volume 12 issue 4 #29 , DOI: 10.17306/J.NPT.2018.4.29

Władysław Danielewicz, Adam Hruzik, Blanka Wiatrowska

The extinction of shrubby birch (Betula humilis Schrank) in the Wielkopolska region and adjacent areas

Summary.

Background. In Poland Betula humilis is a unique, rare late-glacial relict threatened with extinction. The largest number of localities of this species was recorded in the north-eastern part of Poland, the Lubelszczyzna and the Pojezierze Południowopomorskie regions. Many of these localities have already disappeared. In the Wielkopolska region, marking the southern limit of its range, and in the areas adjacent to that region it has been recorded in approx. 30 localities. The aim of this study was to present the history of adverse changes in the local distribution of shrubby birch, to characterise its current localities and make an attempt at the identification of causes for these changes.

Material and methods. The analyses were conducted on localities of shrubby birch reported from the Ziemia Lubuska, Pojezierze Wielkopolskie and from the Thorn-Eberswalde Urstromtal. The search for this species in most of these localities, particularly those unconfirmed in literature, was conducted in various periods starting from the 1980's to the year 2017. In sites where this species was not found, the current environmental conditions were determined in order to compare them to the status when the plant species had been recorded. Existing localities were described including the characteristics of local shrubby birch population. Local observations were used to investigate factors, which may have contributed to extinction of B. humilis in a given area.

Results. From the 25 previously known localities of shrubby birch investigated in this study only 4 were confirmed. The largest locality is found in meadows at the Bydgoszcz Canal at Ślesina near Nakło, while three, much smaller localities were reported from Łochowice near Bydgoszcz, the Puszcza Bieniszewska forest near Konin and Brzozówiec near Trzemeszno. In most historical localities the environment was found to be unsuitable for this species. In sites of former exten-sively managed meadows, moist transitional mires and low Betulo-Salicetum repentis fens, most frequently we may observe expansion of tall and dense shrubs, and occasionally also forest communities.

Conclusions. Disappearance of shrubby birch in the area of the study is a phenomenon, in view of which this species needs to be classified to the group of vascular plants critically endangered in the region and in the western part of Poland, particularly when considering the group of woody plants. Most of the shrubby birch population in the analyzed area died out in the course of several decades of the 20th century, mainly due to anthropogenic changes in soil moisture content and spontaneous transformation of natural peatbog communities and semi-natural meadows into thickets and forests that are excessively shaded for this species.

Key words: shrubby birch, distribution, Wielkopolska region, historical localities, environmental conditions, causes of extinction

Full text available in Polish in Adobe Acrobat format:
https://www.npt.up-poznan.net/pub/art_12_29.pdf

Streszczenie w języku polskim:
https://www.npt.up-poznan.net/tom12/zeszyt4/streszczenie-29.html

Corresponding address:
Władysław Danielewicz
Katedra Botaniki Leśnej
Uniwersytet Przyrodniczy w Poznaniu
ul. Wojska Polskiego 71 d
60-625 Poznań
Polska
e-mail: wladyslaw.danielewicz@up.poznan.pl

Accepted for print: 30.11.-0001