Research data about the operation of root systems is needed to understand tree growth and matter and energy fluxes in a forest ecosystem under changing environmental conditions.

Pine roots. Photo: Anna Korhonen.

The biomass production and carbon storage of forests in a boreal ecosystem are based on tree growth processes and survival strategies. High production requires that annual tree growth and any related aboveground and underground growth phenomena are synchronized with changes in environmental conditions.

During the long lifecycle of trees, there can be various extremes in growth conditions to which trees must be able to adapt. Climate change adds yet another challenge.

Root research offers valuable information about boreal tree growth in changing climate conditions

Considering tree growth, the impact on fine roots is important as they carry the water and nutrients that trees need. The nutrient uptake of plants also reduces the nutrient load passing from the soil to watercourses, causing eutrophication. A significant portion of the annual primary production of trees is consumed by their relatively short-lived fine roots.

Factors affecting the phenology of tree roots and shoots, the impact of which can be either direct (external drivers) or indirect (internal drivers). External drivers can be targeted at roots or shoots.

Root growth processes and their growth dynamics are not understood nearly as well as aboveground plant parts. The understanding of causal relationships in root growth mechanisms requires experiments in controlled environments in which soil and air conditions can be regulated independently, while monitoring the responses of roots and aboveground parts.

Responses develop as a consequence of any changes in the root growth environment, including soil moisture and temperature, soil freezing, snow cover, groundwater level and related soil oxygen rate, as well as the composition of the substrate. Studies aim to identify phenomena related to roots and shoots and interaction between them at different stages of the annual tree cycle.

A unique infrastructure for root research 

The Natural Resources Institute Finland (Luke) has a globally unique special laboratory for root research. It enables research on the phenology and growth of tree roots and shoots.

Laboratory experiments are mainly conducted in specially made root chambers, or dasotrons. They are rooms several metres tall in which soil and air conditions can be regulated independently. By changing conditions, the annual cycle of tree growth and rest periods can be accelerated. During a single calendar year, it is possible to simulate up to two growth periods.

The laboratory is located in jointly used facilities at the University of Eastern Finland in Joensuu.