Adapted from Afoot & Afield in Orange County by Jerry Schad

Distance: 0.7 mile
Hiking time: 1/2 hour
Optional map: USGS 7.5-min Wildomar
Best times: All year
Agency: SRPER
Difficulty: easy

The self-guiding Oak Tree Trail (a loop trail with leaflets available at the start) takes you through what is billed as the only protected, self-reproducing stand of Engelmann oaks remaining on Earth. The Engelmann oak (or mesa oak), native to the coastal foothills of Southern California and far-northern Baja California, is rapidly being displaced by urbanization and other forms of habitat degradation. These trees are easily distinguishable from their botanical cousins and frequent neighbors coast live oaks — by their grayish scaly bark (especially on young specimens) and by their grayish-blue-green leaves. Ranging in age up to about 300 years, these particular thick-trunked Engelmanns have real character. Their multifarious, wandering limbs divide into innumerable branches, and their dense foliage spreads outward to cast black pools of shade upon the ground.

There's much more to see along this little trail than the oaks. Purple needlegrass — a native, fire-resistant and drought-resistant bunchgrass that survives by sending down roots several feet deep — thrives in the meadows. The native grasses growing on the Santa Rosa Plateau, in fact, comprise the largest bunchgrass prairie in Southern California. Prescribed burning is used as a tool here to maintain the native grasses and suppress nonnative, invasive species.

Cole Creek trickles alongside the first part of the trail, its bed sculpted with small ponds (or tenajas) that support frogs, pond turtles, and newts. California sycamores twine upward among the oaks. One of these oaks has a hollow interior, providing nesting habitat for birds such as woodpeckers and screech owls.