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Silva Fennica 1926-1997
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Acta Forestalia Fennica
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Articles containing the keyword 'cone crop'.

Category: Research article

article id 131, category Research article
Timo Pukkala, Tatu Hokkanen, Teijo Nikkanen. (2010). Prediction models for the annual seed crop of Norway spruce and Scots pine in Finland. Silva Fennica vol. 44 no. 4 article id 131. https://doi.org/10.14214/sf.131
Many studies indicate that the flowering abundance of boreal trees strongly correlates with the weather conditions of the previous summer. This study developed prediction models for the seed crops of Norway spruce and Scots pine using weather variables one and two years prior to flowering year as predictors. Weather data, systematically recorded at many weather stations, were obtained from the Finnish Meteorological Institute. Seed crop monitoring data came from 22 spruce stands and 44 pine stands. In every stand, seed crop has been monitored for many years, the longest continuous period being 45 years. Monthly mean temperatures, monthly rainfalls, and periodical temperature sums were used as predictors in the seed crop models. Generally, both tree species flowered abundantly one year after a warm summer and two years after a cool summer. While the models only explained about 45% of the variation in the annual seed crop, they accurately predicted good and bad seed years: when the models predicted good seed crops the likelihood to have at least a medium seed crop was very high and when the models predicted small seed crops, the likelihood to obtain medium or good seed crop was very low. Therefore, the models reliably predict if a particular year will be a good seed year or a poor seed year. These predictions can be used in forestry practice for proper timing of natural regeneration activities, and when activities in seed orchards are planned.
  • Pukkala, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: timo.pukkala@uef.fi (email)
  • Hokkanen, Finnish Forest Research Institute, P.O. Box 18, FI-01301 Vantaa, Finland ORCID ID:E-mail:
  • Nikkanen, Finnish Forest Research Institute, Finlandiantie 18, FI-58450 Punkaharju, Finland ORCID ID:E-mail:

Category: Article

article id 7432, category Article
Ukko Rummukainen. (1954). Männyn ja kuusen käpysadosta ja sen arvioinnista vuosina 1950-1953. Acta Forestalia Fennica vol. 61 no. 20 article id 7432. https://doi.org/10.14214/aff.7432
English title: Estimation of Scots pine and Norway spruce cone crop in 1950-1953.

The cone crop of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) has been assessed in Finland since 1930 annually by sending a questionnaire to forest professionals around the country. Based on the result it is decided if the crop is good enough for collection of the cones next winter. This article presents the results of cone surveys in 1950-1953, and suggest improvements in the method of the investigation.

According to the survey, Scots pine crop was best in 1952, when the crop was intermediate in the whole country, and relatively abundant in the county of Lapland. Norway spruce crop was best in 1951, when the crop was better than in average in the whole country. The evaluators had variable opinions whether the crop was good enough for cone collection or not. They assessed the pine cone collection more often as profitable than the spruce cone collection. Usual reasons to regard spruce cone collection as unprofitable were seed damages and the sites being too far away. To make the results more uniform and accurate, a suggestion to change the evaluation method is presented. The evaluation should be focused on the cone crop of mature stands.

The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.
The PDF includes a summary in German.

  • Rummukainen, ORCID ID:E-mail:

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