Above and below ground interactions affecting tree growth and susceptibility

All species are embedded in complex webs of interactions. Large damage events as we have seen following the drought of 2018 is contributed to the reduced vitality of spruce trees because of water stress which were efficiently utilized by the spruce bark beetle (Ips typographus) to increase it reproduction success. In 2019 the population densities of the spruce bark beetle, and thus the damage, increased further plateauing in the following years and declining population densities observed from 2023. The question that we ask in our project is: how do below and above ground processes interact to affect tree growth and vitality. We start with the mycorrhiza and look at how their communities vary under different growing conditions and how the mycorrhizal communities respond to drought. At tree level we look at the growth of trees, and the responses of the fine roots to drought. We also investigate the sap flow and stem water potential. At the same time, we want to investigate whether or not and at what stage, stress can be detected in the canopy. The last component of our study is to investigate the chemical composition of the bark in defence to spruce bark beetle and to establish a relationship between carbon allocation to defence and tree susceptibility to spruce bark beetle. There are many thoughts on how tree allocate carbon to the root system, to growth and to defence and how this is influenced by nutrient and water availability. Imposing drought simulation through the use of rain-out shelters, we aim to elucidate some of the possible interactions between mycorrhiza, the tree and its enemy, the spruce bark beetle. 

Project members: 

Core members:

Maartje J Klapwijk (SLU) 
Petra Fransson (SLU)
Sigrid Netherer (BOKU)
Danielle Creek (NMBU)
Celina Nilsen (SLU; PhD student)

Tree chemistry: 

Erika Wallin (MidSweden University)
Seda Nematipour (MidSweden University)

Tree physiology:

Leonie Schönbeck (SLU)
Jose Lopez (SLU)

Stress detection;

Langning Huo (SLU)

Stress acoustics;

Jonatan Klaminder (SLU)
Tamara van Steijn (SLU)