OOS 16-1
From soil to canopy warming in temperate forests in Hokkaido, Japan: It’s all ecology
Temperature is increasing worldwide and in particular in the temperate zone where also large temperature changes occur during the year. To understand the effect of higher temperature on temperate forest ecosystems in Hokkaido Japan experimental warming was applied to the soil and canopy of adult tall oak and birch. Hereby we focused on soil N pools, leaf phenology, physiology and herbivory. Temperature was elevated 5 degrees above ambient by electric heating cables in the soil surrounding the trunk and of selected branches in the top of the canopy, furthermore selected branches were passively warmed up by open top canopy chambers. Access to the top of the canopy was provided by a construction crane or scaffolding towers.
Results/Conclusions
The warming of the soil prevented freezing and solute N pools were lower in winter as compared to control sites in the forest surrounding oak trees with freeze-thaw circles during winter. With soil warming leaf phenology of understory herbs altered depending on the leaf habit of the species. In the canopy of the oak trees branch warming extended the leaf life span and only small effects were found in physiology. Also herbivory of the canopy leaves showed no significant changes with branch warming however leaf herbivory decreased with soil warming in oak. This response was opposite in birch where warming increased leaf herbivory. The direct and indirect effect of the results above will be discussed as well as the methods used. The soil and branches around and in tall trees, respectively, were warmed up successfully with species specific responses to higher temperatures.