Written by Caroline Greiser
The hot and dry summers of the recent years (particularly 2018 and 2019) caused an attack wave of the European spruce bark beetle (Ips typographus), killing many spruce trees in Europe. Large parts of the managed boreal forest in Sweden is dominated by spruces, so the beetle attacks changed the landscape significantly. We want to know, how microclimate changes under trees that have been killed. We - that is Philipp Lehmann and Mark Ghaly from the Zoology Department and me.
The tasks sound simple: Put up microclimate loggers in a number of attacked forests and in a number of healthy forests and compare microclimate between the two groups.
But:
1) Sites can differ along other gradients that affect microclimate, so preferably one needs to find pairs of near-by sites (attacked and healthy) with similar topographic setting and similar forest type (age, proportion of spruce, density, etc).
2) In order to prevent further spread, newly attacked trees are normally felled. One finds attacked dead stands (where the trees were left standing) only in nature reserves. Nature reserves often do NOT involve homogeneous spruce stands, thus finding similar and representative sites was tricky.
3) Dead trees are easily wind-felled, creating huge canopy gaps, thus obviously affecting microclimate. Yet we want to capture the more subtle changes caused by decreased evapotranspirative cooling.
... and so on and so far...
I did some very sophisticated site selection at my computer, following advice from Martin Kopecký from the microclimate group in Prague (they have similar projects), but I had to improvise a lot in field. This will not be the most amazing dataset ever, but at least I am finally using the best affordable loggers available on the market right now.