The "spikning" is an academic ritual in Swedish universities, and a part of the publication of PhD theses. Researchers and doctoral students at the University of Borås "spikar" their theses at the birch trunk in the library.
In Sweden, a dissertation, or doctoral thesis, is a publication submitted by researchers when they finish their four-year doctoral studies. A licentiate thesis is submitted after two years of doctoral education. A doctoral thesis may be published as a book (monograph thesis), or as a compendium consisting of a number of shorter scientific papers (compilation thesis).