Over the last few years it has become increasingly common in artificial forest regeneration to extend the planting period by using freezer-stored seedlings for early summer plantings. Developmentally, however, planted freezer-stored seedlings lag behind seedlings planted earlier in the spring. As freezer-stored seedlings also start hardening later, they are more susceptible to early autumn frosts, especially in years when the thermal growing season ends and the first autumn frosts come earlier than usual. By means of computer simulations with a simple temperature sum model and long-term air-temperature data from three locations in Finland, we examined the effect of the freezer-storage termination date on the risk of autumn frost damage to the seedlings. The long-term simulations revealed a drastic effect of year-to-year variation in the thermal conditions during the growing season on the occurrence of autumn frost damage. Such results provide crucial information complementary to those obtained in field experiments, which are always restricted to a relatively short time period. Together with earlier field data, the present results suggest that at an average regeneration site in central Finland, the planting of seedlings whose storage has terminated on 15 June and 22 June involve autumn frost damage every tenth and every fifth year, respectively. The sensitivity analysis revealed that the temperature sum requirement of maturation has a great effect on the risk of autumn frost damage, thus pinpointing the need for experimental studies addressing this ecophysiological trait of the seedlings.

Hänninen, Plant Ecophysiology and Climate Change Group (PECC), Department of Biological and Environmental Sciences, Box 65, FI-00014 University of Helsinki, Finland ORCID ID: – E-mail: heikki.hanninen@helsinki.fi
Luoranen, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID: – E-mail: –
Rikala, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID: – E-mail: –
Smolander, Finnish Forest Research Institute, Suonenjoki Research Unit, Juntintie 154, FI-77600 Suonenjoki, Finland ORCID ID: – E-mail: –

Category: Article

article id 7231, category Article

Martti Hertz. (1929). Huomioita männyn ja kuusen pituuskehityksen "vuotuisesta" ja vuorokautisesta jaksosta. Acta Forestalia Fennica vol. 34 no. 18 article id 7231. https://doi.org/10.14214/aff.7231

English title: Observations on annual and daily cycles in the height growth of Scots pine and Norway spruce.

Original keywords: mänty; kuusi; taimet; pituuskasvu; lämpötila; vuotuinen vaihtelu; kasvukausi

English keywords: Pinus sylvestris; Picea abies; height growth; seedlings; temperature; growing seasons

Abstract | View details | Full text in PDF | Author Info

The height growth of Scots pine (Pinus sylvestris L.) seedlings were observed in Korkeakoski and Evo in Southern Finland in 1925-1928. The growth was slow in the beginning of the growing season, increased after that to decrease again towards the end of the growing season. The height growth begun in May, reached the fastest growth rates in June, and ended in June-July. According to the earlier studies, the length of the height growth of Scots pine is dependent on the temperature of the previous summer. This study showed that warm temperatures of the same summer promote height growth, and low temperatures slow it down. Also the daily growth fluctuates, being highest during the afternoon and slowest during the early morning. The daily growth is dependent on temperature.

Norway spruce (Picea abies (L.) H. Karst.) begin the height growth in average 9 days later than Scots pine. Compared to pine, the speed of growth in spruce decreases slower towards the late summer.

The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander. The PDF includes a summary in German.

Hertz, ORCID ID: – E-mail: –

article id 5178, category Article

Reijo Solantie. (1983). "Mereisyyden - mantereisuuden" ja "humidisuuden" käsitteistä erityisesti tammen luontaisen levinneisyyden perusteella. Silva Fennica vol. 17 no. 1 article id 5178. https://doi.org/10.14214/sf.a15093

English title: Concepts of continentality-oceanity and humidity especially in the light of the natural distribution of Quercus robur.

Original keywords: tammi; levinneisyys; mereisyys; mantereisuus; levinneisyysalue; kasvukauden pituus; lämpösumma; ilmasto; ilmankosteus

English keywords: oak; Quercus robur; distribution; northern boundary; oceanity; continentality; growing season; northern distribution limit; humidity; climate

Abstract | View details | Full text in PDF | Author Info

Climatological factors determining the natural northern boundary in Europe of oak (Quercus robur L.) were investigated. The natural northern boundary of oak corresponds in detail to the curve at which the growing season, beginning at +5°C in spring and ending at +10°C in autumn, is of a certain constant length. The northern boundaries for more oceanic plants can be explained by prolonged autumn activity. This is obviously the general explanation or the concept of oceanity. Oak spread markedly in Finland in the summers during 1961–1975, which on an average were as warm but much dried than those during 1931–1960. The importance of humidity for oak was discussed.

The PDF includes a summary in English.

Solantie, ORCID ID: – E-mail: –

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