Answer: I wish there were an easy way to tell which plants like which kind of soil, but the truth is, you'll have to look up individual plants in a good horticultural encyclopedia to discover their growing requirements. Generally speaking, most cultivated plants are happy in soils with a pH of 6.0 to 7.5. Since 7 is neutral on the pH scale, anything slightly more acidic or slightly more alkaline shouldn't make much difference to most plants. There are some real acid-lovers, such as blueberries, azaleas and rhododendrons, and there are some plants that prefer alkaline soils, such as lilac and cacti. Most areas with high rainfall will have acidic soils and areas with little rainfall will have alkaline soils. That's just a general observation, and your mileage may vary.
A potential problem you should be aware of is that pines have shallow feeder roots. Because the trees are larger than any annual or perennial you can plant, the tree roots will outcompete with smaller roots for available water and nutrients. You'll need to be attentive to your new plants, making sure they get enough moisture to survive.
An excellent resource for plants that thrive in your gardening region, plus those that do well in acidic soils is Sunset Western Garden Book. It's full of ideas for special planting situations such as yours, and most libraries carry a copy.
Hope this answers your question!
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