Curly Birch Research
It was in 1759 that Johan Grundberg, a student from western Finland studying at the Turku Academy, presented his thesis on the characteristics and usefulness of birch. In that presentation, drawn up under the guidance of Pehr Kalm, Grundberg deals with topics such as the use of curly birch in those times as the raw material of various utensils. (Kosonen 2004)
The first Finnish researcher to draw attention to curly birch in the early 1900s was T.J. Hintikka, MSc, partly spurred on by the ideas of A.K. Cajander. He went on to give a talk on that topic in 1916 at a meeting of Suomen metsätieteellinen Seura (the Finnish Society of Forest Science). The first scientific research report on curly birch bearing the title “Die Wisa-Krankheit der Birken in Finnland” and authored by the same researcher was published in 1922 in a German scientific journal. Research proper focusing on curly birch and its cultivation got underway in the 1930s at the Finnish Forest Research Institute, when Olli Heikinheimo launched his extensive trials shedding more light on the genetics of this “curly-grain disease” as the phenomenon was referred to by at the time. It was then eventually proven that curly-grainedness is transmitted by seeds to the new tree generation. Controlled experimental plantations enabled this hereditary trait to be transmitted to over 50% of the progeny. Other Finnish curly birch researchers include Saarnijoki, Sarvas, Saarnio, Raulo, and Etholén. A bibliography of curly birch literature published in Finnish is available (Etholén & Huuri 1982).
Finland’s oldest curly birch plantation is located in Padasjoki (village of Vesijako), close to the Romo research facility of Natural Resources Institute Finland (formerly the Finnish Forest Research Institute, a.k.a. Metla). Evo Forestry School’s principal V. T. Aaltonen established the curly birch stand inspired by T.J. Hintikka’s ideas. Seeds were collected in 1920 from naturally-occurring curly birches in forests belonging to the Vanhakartano mansion in the local district of Lammi, and then the seeds were sown into the plant beds of the forestry school’s nursery to produce planting stock. Applying a spacing of 1.25 m x 1.25 m, the transplants aged 2 + 2 years were then planted out on a recently swiddened and prepared site in the immediate vicinity of the experimental station. However, the development of this this plantation has been slow: at one stage, naturally-arisen birches and spruces nearly overcame the young curly birches. Indeed, when assessing the results solely of the Vesijako stand, far-reaching decisions are not possible regarding the development and yield of curly birch. Metla’s best curly birch stands are located at Punkaharju, Kerimäki, Hauho (Vitsiälä), and Aulanko. These plantations were established mostly during the period 1932-1938. The economics and profitability of growing curly birch rest largely on the indicators obtained from examining these stands.