The doctoral dissertation in the field of Forestry will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus and online.
What is the topic of your doctoral research? Why is it important to study the topic?
In my doctoral research, I examined the natural regeneration of Scots pine and Norway spruce and the growth of seedlings under continuous cover forestry (CCF) following selection, small gap, and shelterwood cuttings. The study focused on northern Finland for pine and southern Finland for spruce.
The topic is important because successful natural regeneration and sufficient seedling development are essential for continuous cover forestry, where a new tree generation is not established artificially through sowing or planting as is often the case in rotation forestry. In CCF, there must be enough naturally regenerated seedlings to replace the harvested trees, and the seedlings should also grow into trees as quickly as possible.
Doctoral research investigated the conditions under which natural regeneration is most abundant and seedlings grow best. CCF is becoming increasingly popular year by year, and it is important to understand how its practices can be carried out sustainably in a way that supports natural regeneration.
What are the key findings or observations of your doctoral research?
It was found that both Scots pine and Norway spruce regeneration were more abundant and seedling growth was faster under a sparser overstory, in some cases even at basal area levels lower than those recommended in current silvicultural guidelines.
Ground- and field-layers also played an important role in the number and growth of pine seedlings: a thinner or exposed humus layer predicted higher seedling densities, whereas a dense moss cover and bilberry were associated with lower numbers of seedlings. In other words, the study indicated that site preparation supported pine regeneration, even though it is not commonly applied in CCF.
Conversely, the presence of herbs and bilberry was associated with faster-growing pine seedlings in northern Finland, indicating more fertile sites. The study also found that small gap cuttings were the most effective method for promoting natural regeneration of pine.
In addition, one of the sub-studies successfully predicted the number of naturally regenerated seedlings using remote sensing data.
How can the results of your doctoral research be utilised in practice?
In practice, the results of the doctoral reserarch can be applied by selecting the CCF method and possible site preparation technique that best support natural regeneration, as well as by managing stand to a density that most effectively promotes natural regeneration and seedling development.
What are the key research methods and materials used in your doctoral research?
The factors influencing seedling density, height, and other seedling attributes were examined by predicting these variables using linear mixed-effects models and extensive field inventories. The study sites were established and the data collected in collaboration with Metsähallitus and the Natural Resources Institute Finland.
The doctoral dissertation of Petra Peltola, MSc (Agr & For) entitled Natural regeneration success of Scots pine and Norway spruce in continuous cover forestry in Finland will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus. The opponent will be Professor Emeritus Tomas Lundmark, Swedish University of Agricultural Sciences, Sweden, and the custos will be Professor Heli Peltola, University of Eastern Finland. Language of the public defence is English.
For further information, please contact:
Petra Peltola, [email protected], p. 050 575 3343
