ECHO LAKES -- On an early Thursday afternoon, one might expect a Bay Area architect to be in a hurried office setting, perhaps wearing a shirt and tie with the sleeves rolled up, poring over plans or blueprints or other architect-type documents.

Over time, humankind has counted all sorts of things. Insomniacs enumerate their sheep, government census bureaus their homo sapiens. Dieters take stock of their calories, campers their 99 bottles of beer on the wall. And these days, a small group of volunteers is devoting itself to tabulating the Sacramento region's trees.