The chilly day after Thanksgiving, Susie Kocher and her family, who live in the Lake Tahoe Basin, set out on their annual tradition of 28 years: the Christmas tree hunt in a local national forest.

They packed the truck, put on their layers, and drove a few miles away to a spot forest staff had marked, where they scouted out a little white fir. About six feet tall and straggly but pencil-straight, it was short enough to fit under the low ceilings of their cabin and charming enough to love.

Kocher knows that most of the forests in the basin are overgrown with small conifers that contribute to fire danger and sap forest health, a problem across the United States but particularly