I cut down two conifers and a eucalyptus on a small new plot I will start using for growing vegetables. I had them chopped down in small pieces and made a separate pile for it. I know from experience that the conifers will compost, even though it will take more time. I will mix it with other compost when it’s ready.
Perhaps I’d be more worried about the eucalyptus. The tree has an allelopathic effect on other plants. The internet is full of opinions whether or not eucalyptus can be used as a mulch, and I don’t know myself whether or not it is a good idea. I did notice that vegetation around the eucalyptus tree was “suffering” compared to other spots in the plot, but on the other hand, since a chopped down eucalyptus can’t produce anymore allelopathic substances, I believe that allowing the mix to compost will also get rid of them over time.