Ashe Juniper Age Estimation for Comal
Bill Holliday 3/04
This chart should be good for estimating ages of a number of junipers
when a good average is needed. It will not be reliable on each and
A quote from Andrew Smith states this very well."...size by
itself, is the worst indicator of tree age. If a two inch diameter pine
is 100 years old, then how old is a four inch diameter pine? I’d say
between 50 and 500 years would be a safe guess.”
It is important to use the correct column for this chart. Even
then, microsite differences such as pavement nearby deflecting
rainwater towards a tree will throw expeced age far off the true age.
Seventy two trees from eighteen sites were used for this growth model.
Most showed about a six percent error in placing the draught of the
1950s. Slow growing areas such as deep shade, steep slope or bare rock
caused many more false rings and missing rings increasing error to ten
or twelve percent for those categories. Shade and competition from
nearby trees for water and nutrients are both dealt with as “shade”.
deep soil: two feet or more, no rocks in sight
average soil: some rocks in sight, 6 inches to two feet of soil
shallow soil: bedrock outcroping 10% to 50% of the area, one to six
inches of soil bare ground: mostly bedrock, less than two inches of
soil or litter on rock in places
shade: complete shade, under closed canopy. Does not include little
trees under a lone tree in open. flat: less than eight degrees slope
slope: eight to fifteen degrees of slope
steep slope: more than fifteen degrees, usually more than 20 degrees of
for flat ground, sun, deep soil, use column A
for flat ground, sun, average soil, use column B
for flat ground, sun, shallow soil, use column C
for flat ground, sun, bare ground, use column D
for flat ground, shade, deep soil, use column E
for flat ground, shade, average soil, use column F
for flat ground, shade, shallow soil, use column G
for flat bare ground, shade, unfinished
for sloping grouncf, sun, average soil, use column B
for sloping ground, sun, shallow soil, use column C
for sloping ground, sun, bare ground, use column H (this column is
extrapolated, not from actual data)
for steep sloping ground, sun, deep soil, use column I (very uncommon
but some river cutbanks)
for steep sloping ground, sun, bare ground, use column J
for sloping ground, shade, shallow soil, use column K
for sloping ground, shade, bare ground, use column L (uncommon but some
for trees less than 10’ tall in poor soil; or less than 15’ in good
soil, lean heavily on height for age.
for trees more than 10’ taIl in poor soil; or more than 15’ in good
soil, lean heavily on trunk diameter for age.
for light colored soil, add 20 percent to the age estimate
for dark colored soil, subtract 20 percent from the age estimate
On "Mail Route Road" subtract 30 percent from the expected age.
That soil, although shallower than the river floodplain, is as fertile.