September Visit (9/8/2017): View from the Trailhead

Just over two years after the fire, here is the view from the old trailhead.  Trees and hillsides are looking considerably greener, even at the end of summer.  Some of this is due to the wetter winter last year, but shrub and tree regrowth is also responsible.  Vines of wild cucumber and wild grape are taking advantage of the shrub skeletons that remain bare – many vines are visible in the middle distance in this painting – but shrub resprouting and reseeding is also widely in evidence throughout the reserve.

TrailheadView_2017Sep08_sm

The view in April 2017:

TrailheadView2_2017Apr01_sm

The view in September 2016:

closedtrailhead2_2016sep29_sm

The view in March 2016:

coldcanyonclosedtrailheadv2_2016mar23_sm

The view in September 2015:

coldcanyonclosedtrailheadv2_2015sep11_sm

September Visit (9/29/2016) 2 of 3

It’s oak gall season!  I spotted the leaf below right in the middle of the trail, with galls from two different wasps.  The urchin gall wasp (Antron quercusechinus) makes the spiny pink galls and the crystalline gall wasp (Andricus crystallinus) makes the furry pink galls.  These wasps, in the family Cynipidae, lay their eggs in oak leaves (in this case a blue oak), and the eggs secrete plant hormone mimics which cause the leave to form the spectacular gall.  The larvae grow and feed in the gall for weeks to years, depending on environmental conditions, and then pupate within the gall and emerge as adults.

oakgalls_2016sep29_sm

Continuing the oak theme, I looked carefully at oak regrowth along Cold Creek.  Interior live oak, an evergreen oak, is generally a more vigorous basal sprouter, as observed below:

liveoakgrowth_2016sep29_sm

Blue oaks, which are deciduous, generally do not resprout from their bases, but show regrowth in their crowns:

blueoakgrowth_2016sep29_sm