Metla Project 3332

The influence of the water budget on tree growth and site productivity in forests on mineral soils in Southern Finland

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Duration: 2002-2006   Keywords: climate, growth, paludification, site produvtuvity, soil, water budget, yield
Research Programme: Alternatives of silvicultural practices in forest management and their effects on forest production

Objectives

A central hypothesis for this project is that different factors in the water bugdet is causing most of the differences between forest development at the coast compared to the inner parts of Finland. Thus, a lot of the analyses are about comparing tree growth, site productivity and growing conditions from the coast of Finland to for example those in central Finland.

Research Topics

The research consists of three different approaches, each with different scale, point-of-view and methods...

  • In south-western coastal areas and archipelago we shall construct models for dominant tree height development in order to predict site productivity. Other analysis with deal with the relationship between site index and regional differences in growing conditions emphazising those connected to the water budjet.

  • In the second part of the project the goal is to describe how site productivity is depending on topography and soil in some stand treatment experiments along the coast of the Gulf of Bothnia. Here, coastal area conditions might also affect for example thinning and fertilisation reactions of forest trees and this could call for regional adaptation of general silvicultural guidelines.

  • Short term tree growth and its dependence on growth factors during the growing season will be measured in intensive monitoring sites at the coast and compared to the equivalent in central Finland. Additional treatment will be implemented in order to extract the role of soil frost (winter-spring-early summer conditions). Measurements of stem circumferences, temperatures and water availability will be collected on an hourly basis by dataloggers during a couple of years.
You can get more information about coastal area forests and growing conditions from the web-pages of earlier projects, for example...


Results

A short overview 12/2004

  • Constructing height development models has not progressed as well as expected. We did implement a new way of getting stem analysis data which makes the field work quite easy, but measuring tree discs indoors has been a very large task. At the moment we only have new material from Metla owned forest areas of Vilppula and Vesijako. We will try to construct models for the southwestern archipelago using NFI data combined with old stand measurements from that area.

  • The basic measurements of our coastal area experiments with different stand treatment have been made according to plans. Results have been presented at excursions and other occasions. They have mostly consisted of basic information about the effects of stand treatment on growth and yield as well as economical result. Comparisons have often been based on additional stand development predictions using the MOTTI simulation system.

    To get a better picture of how previuous soil development (land uplift; rising shorelines) is affecting site productivity in the area we are still collecting more precise data of elevation and topography. Our national DEM has a pixel size of 25x25 m and is not good enough to describe the small scale variation we find in coastal area forests.

  • In our intensive monitoring forests we have succeeded in changing growing conditions with respect to soil frost conditions quite drastically. Still, the area with applied treatment was quite small and it is difficult to interpret the growth reactions of the trees. Measurments also need to be continued for longer periods and should include sap-flow measurements. Irrigation and/or roof construction (drought) could be good complementary treatments in order to achieve extreme variation in growing conditions. Direct comparison of short term tree growth between different regions does not seem to lead to any conclusive results.


    • Project leader: Karlsson, Kristian
    The Finnish Forest Research Institute, Kannus Office, Silmäjärventie 2, FI-69100 KANNUS, FINLAND
    Phone: +358 29 532 3413
    E-mail: kristian.karlsson@metla.fi


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    Updated 12.06.2012
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