Conifers do not make the soil acidic, but poisoning the stumps could present problems depending on what you used. In any case, a soil test should clarify the soil pH.

Are you in Australia? I would imagine there is some way to get a soil test there just as there is in the states.

Agree with the above......plants of any kind have minimal impact on soil pH. That is primarily a factor of the underlying mineral content of the soil and the amount of rainfall received.

But a quick overview of Australian native plants reveals that for the most part, they prefer a slightly acidic to nearly neutral soil pH (5.5 to 7.0), which is entirely in keeping with the vast majority of plants grown anywhere, as that is the soil pH that allows most necessary plant nutrients to be most readily available.

If soil testing services in your area are difficult to locate, self testing for pH is extremely doable. You can get test strips at most pharmacies or even the DIY garden center kits will provide reasonably accurate results, providing you use distilled water.

Most conifers don't sprout from stumps. Exceptions being certain particular ones like redwoods and yews.

Thanks for getting back to me. I haven’t tested anything as yet and apologies in thinking this was an Aussie forum, very helpful regardless.