Polish sausages often seem to be named after their place of origin. If you're making Polish-style sausages outside of Poland, you may have to Polonicise your local place-name.
(pear or plum tree are very good I think)
What about applewood? There are plenty of apple trees in Poland. The country seems to be full of them.
Then what about Alder (olsza)? Is this ever used?