Readers of Mary Rosenblum’s popular novel, The Drylands, have asked her what will become of the forests in that future—does she envision the entire country as a desert? Ms. Rosenblum replies, “Well no, I don’t. So I took a look at the forests of southern Oregon, and what happens to the trees, in ‘The Botanist.’ ” The author has just sold her first mainstream mystery, Blood Work, and she is working on Black Sheep—the second book in the series