At nine a.m. on a perfect late summer day in a series of perfect late summer days, the temperature is starting to climb from a 65-degree low, the dew point is low, and the sky is merry with clouds. As the day goes on, the chirruping crickets will be joined by whining cicadas and the high might touch 80 degrees. It is a good day to go for a hike at southeastern Wisconsin’s Lulu Lake Preserve, and to learn about preserving biodiversity.