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Planting Acorns- Who does it? Are enough planted?
In
California, the Scrub Jay, Aphelocoma coerulescens (what a name!),
is the primary planter of acorns. At Hastings, individual jays have
been followed and watched. During the fall when acorns are ripe enough
to pick, each jay will pick up to 7,000 acorns. Each acorn is carefully
carried away and packed an inch or two into the ground. A leaf may
be placed over the acorn, or a pebble moved nearby. An adult scrub
jay can remember up to 5,000 such buried acorns, and over the winter,
will fly and walk directly to a buried acorn, dig it up, and have a
quick meal. Certainly mice find and remove a few, but in any event,
the mice and jays miss quite a few. If one jay plants even 1,000 acorns
a year, the oaks should be doing fine.
If you live where the Coast live oak occurs, you will find that jays have buried literally thousands of acorns all around your tree. They sprout and come up by the hundreds after a good year.
So, plenty of acorns get planted by December, and are ready to germinate.
Seedlings from Acorns; Are there enough?
In
studies done at Hastings, many acorn sprouts are found near Valley
oaks and Blue oaks. The oak rapidly sends down a tap root in the fall,
with the first rains, and small shoot goes above ground. Then things
may go dormant for the winter cold. Like other events in the life cycle
of oaks, oaks often appear to be about the same age in a stand, as
if something good happened for a short time. On the Tejon Ranch in
Kern county, more than half the oaks present started in the single
decade of the 1850, while only a small percentage started in the decades
of 1750 to 1990s. We have no idea of what was so special about the
1850s. During the late winter and especially the early spring, the
acorns begin to grow into seedlings. They face almost certain death
within the year. First, gophers are extremely abundant at Hastings
and throughout much of the range of these oaks. By late winter, or
early in the summer, one can walk around under Blue oaks and Valley
oaks and find that most seedlings have been clipped off just above
the old acorn, and just below ground. Chisel-like
cuts suggest gopher teeth. If one digs a trench 6 feet deep, and installs
a boundary of wire cloth in the trench, and extends the wire cloth
above ground for a foot or so, gophers canot tunnel in. All
acorns planted in this "exclosure" (gophers are excluded) grow. All
acorns outside the exclosure eventually are taken by gophers.
This is the size of oak seedling commonly clipped off just underground, and killed, by gophers.