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Articles containing the keyword 'frost damage'.

Category: Research article

article id 175, category Research article
Heikki Hänninen, Jaana Luoranen, Risto Rikala, Heikki Smolander. (2009). Late termination of freezer storage increases the risk of autumn frost damage to Norway spruce seedlings. Silva Fennica vol. 43 no. 5 article id 175. https://doi.org/10.14214/sf.175
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 (email)
  • 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:
article id 242, category Research article
Jyrki Hytönen, Paula Jylhä. (2008). Fifteen-year response of weed control intensity and seedling type on Norway spruce survival and growth on arable land. Silva Fennica vol. 42 no. 3 article id 242. https://doi.org/10.14214/sf.242
The effects of seedling type (2-year-old container seedlings vs. 4-year-old bare-rooted seedlings) and post-planting vegetation control intensity on the growth and survival of Norway spruce (Picea abies (L.) Karst.) seedlings were compared based on 15-year data from a field experiment established on arable land. Vegetation control treatments with terbuthylazine and glyphosate were carried out 1–3 times on successive years, either as overall or spot applications. The highest stand volumes were obtained with the combination of large bare-rooted seedlings and effective vegetation control. Volume of bare-rooted seedlings was greater than that of container seedlings in all treatments (e.g. on the control plots 9.5 m3/ha vs. 4.1 m3/ha). The best results were obtained with the most intensive weed control treatments (spot treatment repeated twice and overall application repeated three times). These treatments increased both bare-rooted and containerised seedlings’ survival by 33–40% units and their height, breast height diameter, and volume by 45–49%, 17–47%, and 249–279%, respectively. In terms of survival, the container seedlings, in due part to their smaller size, benefited from vegetation control more than the bare-rooted seedlings. Successive early summer frosts damaged the seedlings and significantly retarded their growth. The frequency of frost damage was not affected by vegetation control nor was it attributed to seedling type.
  • Hytönen, Finnish Forest Research Institute, Kannus Research Unit, P.O. Box 44, FI-69101, Kannus, Finland ORCID ID:E-mail: jyrki.hytonen@metla.fi (email)
  • Jylhä, Finnish Forest Research Institute, Kannus Research Unit, P.O. Box 44, FI-69101, Kannus, Finland ORCID ID:E-mail:

Category: Research note

article id 534, category Research note
Ilkka Leinonen, Heikki Hänninen. (2002). Adaptation of the timing of bud burst of Norway spruce to temperate and boreal climates. Silva Fennica vol. 36 no. 3 article id 534. https://doi.org/10.14214/sf.534
The adaptation of the annual cycle of development of boreal and temperate trees to climatic conditions has been seen as a result of stabilizing selection caused by two opposite driving forces of natural selection, i.e. the tolerance of unfavorable conditions during the frost exposed season (survival adaptation) and the effective use of growth resources during the growing season (capacity adaptation). In this study, two theories of the effects of climate on the adaptation of the timing of bud burst of trees were evaluated. This was done with computer simulations by applying a temperature sum model for predicting the timing of bud burst of different Norway spruce genotypes on the basis of air temperature data from various climatic conditions. High geographical variation in the temperature response of bud burst, typical for Norway spruce, was included in the theoretical analyses. The average timing of bud burst and the corresponding risk of occurrence of damaging frost during the susceptible period after bud burst were calculated for each genotype in each climate. Two contrasting theories of the stabilizing selection were evaluated, i.e. the overall adaptedness of each genotype was evaluated either 1) by assuming a fixed threshold for the risk of frost damage, or 2) by assuming a tradeoff between the risk of frost damage and the length of the growing season. The tradeoff assumption produced predictions of between provenance variation in bud burst which correspond more closely with empirical observations available in literature, compared to the fixed threshold assumption.
  • Leinonen, University of Oklahoma, Department of Botany and Microbiology, Norman, OK 73019, USA ORCID ID:E-mail: leinonen@ou.edu (email)
  • Hänninen, University of Helsinki, Department of Ecology and Systematics, FIN-00014 Helsinki, Finland ORCID ID:E-mail:

Category: Article

article id 7377, category Article
S. E. Multamäki. (1942). Kuusen taimien paleltuminen ja sen vaikutus ojitettujen soiden metsittymiseen. Acta Forestalia Fennica vol. 51 no. 1 article id 7377. https://doi.org/10.14214/aff.7377
English title: Frost injuries of Norway spruce seedlings and their effect on afforestation of drained peatlands .

The aim of the investigation was to study natural regeneration of Norway spruce (Picea abies (L.) Karst.) in drained peatlands and frost injuries in seedlings, and to compare microclimates of the regeneration areas. The experiments included peatlands in Satakunta in Western Finland. Restocking of the areas with seedlings and their survival was followed in 1935-40 at sample plots that were mainly 1 are large.

Susceptibility to freezing was shown to be dependent on the stage of development of the shoots. Shoots that have just begun to grow contain little water, and withstand better freezing temperatures than shoots in later stages of growth. Damages to the seedlings were observed when the temperatures decreased to -2.8–-4.3 °C. The most severe damage to a seedling was caused by the death of the leading shoot by spring frost.

Norway spruce regenerates easily on moist peatlands, but peatlands with dry surface tend to have little or no seedlings. The species regenerated better in marshy sites than correspondingly fertile mineral soil sites. However, it needs shelter to avoid frost damage. On clear cut spruce swamp the undergrowth spruce seedlings that were left in the site got severe frost damage. If the site had birch (Betula sp.) coppice or undergrowth, spruce seedlings survived in their shelter depending on the height and density of the birch trees. To be effective, the protective forest should have relatively even crown cover. Young spruce seedlings could grow well even under relatively dense birch stand.

The PDF includes a summary in German.

  • Multamäki, ORCID ID:E-mail:
article id 7343, category Article
S. E. Multamäki. (1939). Kuusen kylvöstä ja istutuksesta metsitettävillä soilla. Acta Forestalia Fennica vol. 47 no. 3 article id 7343. https://doi.org/10.14214/aff.7343
English title: Sowing and planting of Norway spruce in drained peatlands in Finland.

The drained peatlands regenerate usually well, and artificial regeneration by sowing or planting has been rare. Field trials of Norway spruce (Picea abies (L.) H. Karst.) were established in northern Satakunta in Western Finland in three drained peatlands in 1934. Sowing trials of Norway spruce consisted of patch and broadcast sowed sample sites in treeless bogs and under protective forest. The seedlings of spruce were planted either under protective forest or in treeless peatland.

The results show that artificial regeneration of Norway spruce succeeds best under protective forest. The best tree species for upper storey is Betula sp. which grows fast and controls growth of ground vegetation. The peat is relatively decomposed on those peatlands that are suitable for spruce, and breaking of the surface of the peat is not recommended. In the sowing trials, breaking of the upper layer of the peat caused frost heaving, cracking of the dried surface and sticking of mud in the seedlings in the patch sown sample site. The shoot and root growth of seedlings of the broadcast sown site was better than seedlings of the patch sown site. The planted spruce seedlings seemed to be more susceptible for spring frost than the seedlings in the sown site. The plants of seed origin succeeded in general better than the planted seedlings.

The PDF includes a summary in German.

  • Multamäki, ORCID ID:E-mail:
article id 5590, category Article
Heikki Hänninen, Seppo Kellomäki, Ilkka Leinonen, Tapani Repo. (1996). Overwintering and productivity of Scots pine in a changing climate. Silva Fennica vol. 30 no. 2–3 article id 5590. https://doi.org/10.14214/sf.a9235

The productivity of Scots pine (Pinus sylvestris L.) under changing climatic conditions in the southern part of Finland was studied by scenario analysis with a gap-type forest ecosystem model. Standard simulations with the model predicted an increased rate of growth and hence increased productivity as a result of climatic warming. The gap-type model was refined by introducing an overwintering sub-model describing the annual growth cycle, frost hardiness, and frost damage of the trees. Simulations with the refined gap-type model produced results conflicting with those of the standard simulation, i.e., drastically decreased productivity caused by mortality and growth-reducing damage due to premature dehardening in the changing climate. The overwintering sub-model was tested with frost hardiness data from Scots pine saplings growing at their natural site 1) under natural conditions and 2) under elevated temperature condition, both in open-top chambers. The model predicted the frost hardiness dynamics quite accurately for the natural conditions while underestimating the frost hardiness of the saplings for the elevated temperature conditions. These findings show that 1) the overwintering sub-model requires further development, and 2) the possible reduction of productivity caused by frost damage in a changing climate is less drastic than predicted in the scenario analysis. The results as a whole demonstrated the need to consider the overwintering of trees in scenario analysis carried out with ecosystem model for boreal conditions. More generally, the results revealed a problem that exists in scenario analysis with ecological models: the accuracy of a model in predicting the ecosystem functioning under present climatic condition does not guarantee the realism of the model, nor for this reason the accuracy for predicting the ecosystem functioning under changing climatic conditions. This finding calls for the continuous rigorous experimental testing of ecological models used for assessing the ecological implications of climatic change.

  • Hänninen, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Leinonen, ORCID ID:E-mail:
  • Repo, ORCID ID:E-mail:
article id 5518, category Article
Heikki Hänninen, Seppo Kellomäki, Kaisa Laitinen, Brita Pajari, Tapani Repo. (1993). Effect of increased winter temperature on the onset of height growth of Scots pine: a field test of a phenological model. Silva Fennica vol. 27 no. 4 article id 5518. https://doi.org/10.14214/sf.a15679

According to a recently presented hypothesis, the predicted climatic warming will cause height growth onset of trees during mild spells in winter and heavy frost damage during subsequent periods of frost in northern conditions. The hypothesis was based on computer simulations involving a model employing air temperature as the only environmental factor influencing height growth onset. In the present study, the model was tested in the case of eastern Finnish Scots pine (Pinus sylvestris L.) saplings. Four experimental saplings growing on their natural site were surrounded by transparent chambers in autumn 1990. The air temperature in the chambers was raised during the winter to present an extremely warm winter under the predicted conditions of a double level of atmospheric carbon dioxide. The temperature treatment hastened height growth onset by two months as compared to the control saplings, but not as much as expected on the basis of the previous simulation study. This finding suggests that 1) the model used in the simulation study needs to be developed further, either by modifying the modelled effect of air temperature or by introducing other environmental factors, and 2) the predicted climatic warming will not increase the risk of frost damage in trees as much as suggested by the previous simulation study.

The PDF includes an abstract in Finnish.

  • Hänninen, ORCID ID:E-mail:
  • Kellomäki, ORCID ID:E-mail:
  • Laitinen, ORCID ID:E-mail:
  • Pajari, ORCID ID:E-mail:
  • Repo, ORCID ID:E-mail:
article id 5355, category Article
Halvor Rostad. (1988). Frost resistance during shoot elongation in Picea abies seedlings in relation to the growth environment of the previous growing period. Silva Fennica vol. 22 no. 3 article id 5355. https://doi.org/10.14214/sf.a15512

Frost resistance during shoot elongation in seedlings of Norway spruce (Picea abies (L.) H. Karst.) was studied in two experiments. The aim of the first study was to evaluate the effect of varying mineral nutrition. Except for potassium, only minor differences in mineral elements concentrations were established, presumably due to low levels of irradiance and thus a low rate of dry matter production. No significant differences in frost injuries were found between the treatments in the experimental series, but the control seedlings were significantly less injured. It is assumed that poor hardiness development at the end of one growth period resulting from low levels of irradiance may decrease the frost resistance during the next shoot elongation phase. Observations from the second experiment with Norway spruce nursery stocks representing different seedling ages and production systems, support this assumption.

The PDF includes an abstract in Finnish.

  • Rostad, ORCID ID:E-mail:
article id 5352, category Article
Lars Christersson, Heinrich A. von Fircks. (1988). Injuries to conifer seedlings caused by simulated summer frost and winter desiccation. Silva Fennica vol. 22 no. 3 article id 5352. https://doi.org/10.14214/sf.a15509

Visible frost damage to forest trees in Sweden seldom occurs in winter but is frequent in late spring, summer and early autumn. Frosts are frequent in all seasons in various parts of Sweden, even in the southernmost part (lat. 56°, N) and temperatures may be as low as -10°C even around mid-summer. Ice crystal formation within the tissues, which in most seedlings takes place at around -2°C, causes injury, not the sub-zero temperatures themselves.

The apical meristem, the elongated zone, and the needles of seedlings of Picea abies (L.) H. Karst. in a growing phase were damaged at about -3°C and those of Pinus sylvestris L. at about -6°C. Other species of the genus Pinus were tested and most were found to be damaged at about -6°C, with some variations. Picea species tested were damaged at about -3°C to -4°C.

A method has been designed to compare the response of different species to winter desiccation, which occurs under conditions of (1) low night temperature, (2) very high irradiation and increase in needle temperature during the photoperiod, (3) frozen soil, and (4) low wind speed. There were differences in response to winter desiccation between pine and spruce species. Seedlings of Pinus contorta tolerated these winter desiccation conditions much better than those of P. sylvestris or Picea abies. Picea mariana was the least tolerant of the species tested.

The PDF includes an abstract in Finnish.

  • Christersson, ORCID ID:E-mail:
  • Fircks, ORCID ID:E-mail:
article id 5350, category Article
Heikki Hänninen, Paavo Pelkonen. (1988). Frost hardiness and over-wintering of forest trees. Silva Fennica vol. 22 no. 3 article id 5350. https://doi.org/10.14214/sf.a15507

This issue of Silva Fennica consists of eight articles, which are based on a co-nordic conference ”Frost hardiness and over-wintering in forest tree seedlings”, held in Joensuu, Finland, during December 1–3, 1986. The whole annual cycle of the trees is considered. Emphasis is given on methods for the study of frost hardiness, genetic variation in frost hardiness, nitrogen metabolism, bud dormancy release, and joint effect of natural and anthropogenic stress factors in the winter damage of forest trees. Practical implications for tree breeding and nursery management are discussed.

The PDF includes an abstract in Finnish.

  • Hänninen, ORCID ID:E-mail:
  • Pelkonen, ORCID ID:E-mail:
article id 5233, category Article
Leo Heikurainen. (1985). Verhopuuston vaikutus kuusitaimikon kehitykseen. Silva Fennica vol. 19 no. 1 article id 5233. https://doi.org/10.14214/sf.a15412
English title: The influence of birch nurse crop (Betula pubescens) on the growth of Norway spruce (Picea abies) seedling stands on drained peatlands.

Young Norway spruce (Picea abies (L.) H. Karst.) are susceptible to early summer frost damage. Birch (Betula pubescens Ehrh.) naturally colonize rich or fairly rich drained peatlands after clear cutting, and can provide protection for developing seedlings. The report describes the development of spruce stands after various types of handing of the birch nurse crops.

Different proportions of birch and spruces did not have any influence on the spruce stand production. In cases where the nurse crop stand is removed when the spruce stand age was 20 years and height 4 m the spruce suffered badly but recovered with time, reaching the spruce stand growing under a nurse stand within the next 20 years. The height growth of spruce depends on the density of the nurse stand, especially on fertile sites. The development of diameter growth also depends on the density of the nurse trees. Removal of the nurse stand in spruce stands on the sites concerned should be done when the spruce stand is 20 years old and at the height of 4 m.

The PDF includes a summary in English.

  • Heikurainen, ORCID ID:E-mail:
article id 4840, category Article
Paavo Yli-Vakkuri. (1971). Havaintoja latvakasvainten pakkasvaurioista kuusen taimistoissa Itä-Savossa. Silva Fennica vol. 5 no. 2 article id 4840. https://doi.org/10.14214/sf.a14642
English title: Winter frost damages to the leaders of Norway spruce saplings in Eastern South-Finland.
Original keywords: Itä-Savo; kuusi; pakkasvauriot; pääverso

In the eastern parts of South-Finland the growing season of 1967 was highly favourable, which resulted in good height growth during the following year. During the summer 1968, temperature conditions were unfavourable, while the middle of summer was cold and the later part of the growing season unusually hot. The following winter had exceptionally cold spells from January to March, which caused Norway spruce (Picea abies (L.) H. Karst.) abundant winter frost damages such as dead shoots and buds, and destroyed needles.

These damages occurred particularly in stands with height of 0.5–3 m, and the occurrence of damages seemed to concentrate to the parts of saplings that had been immediately above the snow cover. Detailed observations on spruce plantations growing under a dense nurse stand of alder (Alnus sp.) indicated that explicitly the top shoots suffered from damages and not so much the laterals. When the needles of the leader suffered from minor damages, the shoot continued to grow normally. Still, sometimes a branch took over and became a new leader. If only the leader bud was killed, further stem development became dependent on one of the topmost lateral buds. When the upper part of the leaded died, one of the lateral shoots at its base usually became the new leader.

The PDF includes a summary in English.

  • Yli-Vakkuri, ORCID ID:E-mail:

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