Local activists in Serra Mesa are rehabilitating Ruffin Canyon, a finger canyon of Mission Valley.

"Think globally, act locally." The Friends of Ruffin Canyon group in Serra Mesa have taken this slogan to heart by launching a prototypical effort to preserve one of San Diego's several dozen undeveloped urban canyons. On weekends you can find these folks out clearing away nonnative vegetation and restoring and enhancing the sage scrub and riparian native habitats of Ruffin Canyon, a mini-chasm leading downward from the south end of Ruffin Road toward Friars Road and Qualcomm Stadium.

The group has persuaded San Diego's city council to designate 84 acres of property here as the Ruffin Canyon Open-Space Preserve. This means that unneeded road projects such as a planned southward extension of Ruffin Road down along the canyon floor will never occur.

Hikers will find a short network of trails to explore in Ruffin Canyon, with access at three principal points: the south end of Ruffin Road at Gramercy Drive, west of Taft Middle School on Gramercy Drive, and the east end of Shawn Avenue. Volunteers have recently been busy working at the first two trailheads, restoring the landscape, laying out graded trails that descend into the canyon, and (at Ruffin Road) installing a small native garden accessible to wheelchairs.

You can glimpse the wild character of the canyon by descending to the bottom, where rough and often steep pathways, some worn in by neighborhood kids over the years, dart up and down through a tangled array of shrubs like lemonade berry and holly-leafed cherry -- the latter currently bearing marginally edible, dark-red fruit. Willows and cottonwoods grow along a dry streambed, as do undesirable, invasive nonnatives (slated for removal) such as fan palms and pepper trees. In the future, a more easily followable trail system will be built; for now it takes a bit of slip-sliding over cobbles and dodging bushes to negotiate your way in some spots.

Naturally, you won't see much in bloom here until the autumn or winter rains arrive. Once they do, the canyon will turn into a fragrant garden of two dozen or more species of annual and perennial wildflowers.

The Friends of Ruffin Canyon group meets on the fourth Monday each month at 6:30 p.m., generally at Taft Middle School. For more information, search "friends of ruffin canyon" at www.yahoogroups.com.