Olli-Pekka Tikkanen

Senior researcher, forest zoology and pathology

Adjunct professor (docent) in Forest Ecology (School of Forest Sciences/UEF)

School of Forest Sciences,
Faculty of Science and Forestry
University of Eastern Finland, Joensuu Campus
PO Box 111 (Yliopistokatu 7), FI-80101 Joensuu, Finland
Tel +358 46 921 0746, e-mail: firstname.lastname@uef.fi
Office: Borealis building, room 271B, www.uef.fi/fi/web/forest/tikkanen-olli-pekka

Current Research projects

Warming climate and distribution of natural enemies of trees

It is assumed that, in future, the climate of southern Finland will become similar to that currently found in Northern Poland. According to recent climate change scenario (RCP 4.5 – intermediate increase of CO2 in atmosphere) the effective temperature sum in southern Finland will be 1600 day degrees, in the period 2020-2049, which equals the temperature sum of accumulated normally in Northern Germany, Poland and southern Lithuania. Simultaneously, average winter temperatures will increase with 2.3 °C by 2020-2049 and with 4.3 °C by the end of the century.  In the summer 2018, the record high temperature sums over 1800 dd were measured in the southern Finland.
Warming will change the distribution of species. The extreme cold periods are milder and less frequent providing better winter survival. The warmer summers enhance the reproduction of species. Because natural enemies of trees reproduce and disperse faster than trees, northern forests may receive new enemies and threats in future. Also previously less harmful organisms may become a problem to forest health. Warming climate also cause stress to trees, which may make them more susceptible to outbreaks.

Recent publications

Other research projects

  • Environmental variability and enemy pressure of insect herbivores in Pine dominated ecosystems.

  • Ecology of endangered great crested newt Triturus cristatus in boreal forests of Eastern Finland

  • Landscape history of Eastern Fennoscandia

Dispersion ecology of subspecies of European mistletoes, Viscum album album and V. a. austriacum

Mistletoes are common parasitic epiphytes of trees in temperate zone of Europe. There are two common subspecies; V. a. austriacum, which is specialized on pines, and V. a. album which grows on deciduous trees of several genera. V. a. austriacum is considered as a problem to silviculture and forest health in many parts of Central Europe. In recent decades, both subspecies of mistletoes have increased their area of distribution. V. a. album has spread on new areas in north. In 2005 it was found from Estonia and in 2016 from Finland. V. a. austriacum have not shown similar fast movement to northwards, but in montane pine forests, it has increased in numbers causing deaths of trees. Also, it has spread in higher altitudes.
In this project, we study, firstly, what is the freeze tolerance of the seeds of two subspecies of Viscum album, and secondly, can difference in freeze tolerance explain differences in their distribution pattern.
Research partners: Białowieża Geobotanical Station of University of Warsaw, Swedish Agricultural University in Uppsala, Swiss Federal Institute for Forest, Snow ad Landscape Research WSL, University of Granada.

Monitoring of abundance and northern distribution limit of nun moth (Lymantria monacha)

Nun moth is the most damaging insect defoliator of coniferous trees in Central Europe. The cold tolerance of eggs of is approximately -30 C. Since 1990’s the periods of extreme cold winter weather has become less frequent. As a result, the northern distribution limit of nun moth has moved 200 km northwards in past two decades. In this project, starting in summer 2018, we have created a pheromone trap network, which covers a large part of Southern and Central Finland extending to province of Kainuu in north.
The aim is to study the effect of climate on distribution and abundance of this potentially extremely damaging forest insect. As a control, we also monitor the populations pine beauty moth (Panolis flammea) that is a native and common herbivore of pines in Finland.
Research partners: Finnish Natural Resource Institute.

Environmental variability and enemy pressure of insect herbivores in Pine dominated ecosystems.

Environment quality may have great impact on presence of outbreaks of insect herbivores. It is commonly assumed that pine (Pinus sylvestris) forests growing on poor sites are more prone to herbivory than stands growing on fertile soils. One potential mechanism is the increased predation pressure of herbivores in more productive environments.
We have been testing empirically the pupal predation pressure of insect herbivores on xeric, sub-xeric and mesic pine stands. The preliminary results from two successive seasons strongly indicates that top-down mechanisms of herbivore control are stronger in mesic stands than in sub-xeric or xeric stands. In our study sites, in pine forests of North Karelia, Finland, the small mammals seems to be the main regulatory agents of defoliating insects.
Vole cycles may cause fluctuation in the predation pressure. We continue the predation experiments and study the multiannual variation in the pupal predation of pine insect herbivores.

Publications of the project:

Ecology of endangered great crested newt Triturus cristatus in boreal forests of Eastern Finland

Populations of great crested newt are living in forested environments in Eastern Finland. We have been studying the terrestrial habitat use of the newt and made a predictive model of its reproductive success in relationship to the environmental properties of the breeding ponds.
Currently the aim is to evaluate the population size of the great crested newts in forest ponds applying mark-recapture analyses. For this purpose we are developing Photo ID methods together with I3S team.

Publications of the project:

Landscape history of Eastern Fennoscandia

The northern forests have provided only narrow opportunities for agriculture and in many areas the area of permanent agricultural land has been very small. However, the local populations have used forests and timber in several different ways. We have been studying the effect of past human populations in current forest structure in remote areas of Republic of Karelia, Russian Federation, in co-operation with the researchers from the Petrozavodsk State University and from the Karelian Research Centre of the Russian Academy of Science.
Our main research areas are Kalevala National Park and Kostomuksha Strict Nature Reserve and their surroundings on Russian side of the Finnish-Russian border. These parks belong to the core protected areas of the Green Belt of Fennoscandia. In addition to past, present and future ecological values, the importance of this area on cultural and historical heritage of Karelia and Finland is of its own class. The villages which are now largely abandoned, are the source of the runes of Kalevala and the landscape has strongly inspired the artists of the "L'Age d'Or" of Finnish Culture in the late 19th century.

Publications of the project: