How is the pH of bark determined? I know how this is done for soil, but am curious as to how this is done for bark.
Remember that pH is a purely aqueous concept, so the standard method for most materials is to prepare a suspension or solution of it in water.
The trick will be setting a standard: how much bark is suspended in how much water, and for how long. Also, should the mixture be stirred/agitated?
If it is anything like my line of work, there will probably be more than one standard method, and it is important to specify the one used; as it will influence the result to some extent.
One method is described at:
That is very interesting and clear. Thank you very much for your helpful information and taking the trouble to find that link for me. Checking bark pH doesn't sound quite as easy as testing soil with a bought kit!
Using a soil test kit may well not give exactly the same result as another method, but if you are interested in trends or comparisons, then as long as you keep to the same method, weights, and volumes, then the results are going to be useful. If (say) you find a lichen that flourishes on bark that your test says is pH 5.0, or higher, but not on bark with pH 4.5 or lower, then a trend is clear.
For confidence in the method, try repeat assays on the same bark. If all the results are close to each other, then at least you know that the method is reasonably valid.
If you want to get serious, lab suppliers can provide buffer solution mixtures of known pH, to test your method. Or you can do some browsing and brew your own - the components are usually low toxicity and fairly cheap.
It is more curiosity about how bark could be tested than anything serious at this stage. Your very helpful information has intrigued me and I may now go and do some browsing and see if I can brew my own buffer solution.
Who knows, maybe it will tell me why, when everything else seems to be the same, some birch trees in the woods nearby host lichens and yet some of the neighbouring birches don't.