Evidence for multiple ring growth per year in Bristlecone Pines
by Mark Matthews
The great ages claimed for certain individual Bristlecone Pine trees (Pinus longaeva)
and the Bristlecone Pine master-chronology, conflict with biblical earth history.
The ages, however, are based on the assumption that the trees grew no more than
one ring per year. Creationists have proposed that these supposed old Bristlecone
Pines (BCPs), including the ones that make up the master-chronology, have grown
more than one ring per year. If these trees did grow more than one ring per year,
the conflict between the ages of these trees and the biblical record is resolved.
This paper compiles and examines some of the evidence for multiple ring growth per
year in Bristlecone Pine, including observations which don’t make sense under
the assumption that all these rings are annual, but are compatible with the creationist
hypothesis. Evidence claimed to support the annularity of these rings is rebutted.
In addition, a hypothesis is put forward that multiple ring growth per year (known
as ‘multiplicity’) may benefit these trees under certain environmental
conditions, and a hypothesis is offered to explain the observation that all BCPs
with thousands of rings exhibit a strip growth habit. In conclusion I suggest ways
that creationists can collect more decisive substantiation of multiplicity in BCPs.
Photo by John Woodmorappe
Figure 1. Bristlecone Pine growing in less than ideal conditions.
Growing in the White Mountains of eastern California are what are thought to be
some of oldest living trees on Earth. The tree with the most rings, dubbed ’Methuselah’,
is thought to be about 4,600 years old. One might expect then that the White Mountains
host some of the best growing conditions on Earth. In fact, the opposite is true.
Ironically, the alleged oldest trees grow in some of the worst imaginable conditions.
Conditions are so bad that few other plants can survive: short cool summers with
a growing season thought to be only several weeks long; desert-like aridity (250
mm of precipitation per year, mostly as snow); many trees grow out of little more
than cracks in dolomitic rocks. Strong winds coupled with air that in the summer
is said to be the driest on earth,1
and the rocky ‘soil’ (where there is any ’soil’), means
that what little rain does fall will evaporate or drain away quickly (figure 1).
It may be that these exceptionally harsh growing conditions are the key to understanding
why some of these Bristlecone Pines have so many rings that they appear to live
about ten times longer than BCPs which are growing in comparatively good conditions!
The thesis of this paper is that, under conditions where water is scarce, BCPs grow
multiple thin rings per year rather than one thick ring (as has been documented
in other species of gymnosperms and angiosperms2
). Further, I hypothesize that the multiplicity growth habit and the strip-growth
habit conserve a tree’s resources, especially water.
Multiplicity is common under the right conditions
It may be that these exceptionally harsh growing conditions are the key to understanding
why some of these Bristlecone Pines have so many rings that they appear to live
about ten times longer than BCPs which are growing in comparatively good conditions!
Perhaps the best evidence that some BCPs can grow multiple rings per year is the
fact that it has already been demonstrated. Lammerts, a creationist, induced multiple
ring growth in sapling BCPs by simply simulating a two week drought.3 Some dismiss this evidence, saying that while multiplicity
has been demonstrated in young BCPs, it hasn’t been demonstrated in mature
BCPs and therefore may not occur in mature BCPs.4
While this hypothesis could be true, surely the burden of proof should be on those
who propose that what happens in immature trees doesn’t happen in mature trees.
An expert in the genus Pinus didn’t seem to have any problem believing
that White Mountain BCPs grew multiple rings per year. In his book, The Genus
Pinus, Mirov states, ‘Apparently a semblance of annual rings is formed
after every rather infrequent cloudburst.’5
If an expert like Mirov readily accepted multiplicity in these BCPs, then perhaps
the doubters of this notion should at least give the evidence a serious examination.
It is important to understand that the idea that mature trees can grow more than
one ring per year is not a highly speculative hypothesis. It is well established
that mature trees of many species of both angiosperms and gymnosperms, including
other species of the genus Pinus, can grow multiple rings per year, especially
under the types of conditions in which some of the BCPs in the White Mountains grow.
Glock et al. published a large study in 1960 documenting the common occurrence
of multiple ring growth per year, under conditions similar to those in the White
Mountains.2 They found that multiplicity was more than twice as common
as annularity, and conclude that probably very few annual increments, over the entire
tree, consist of only one growth layer6
(that is, only one ring).
In addition to solid direct evidence that these BCPs may be capable of growing multiple
rings per year, there is abundant indirect evidence of multiplicity.
Indirect evidence of multiplicity
To build a master-chronology of BCPs believed to extend back over 8,700 years,7 researchers must use wood
from dead trees to extend the chronology beyond the lifetime of currently living
trees. The older parts of the chronology come from dead wood found lying on the
ground near the living trees. This means that some pieces of wood in the earliest
part of the chronology would have had to lie around on the ground for more than
7,000 years!8 Immediately,
one wonders how wood can lay on the ground for 7,000 years without rotting, eroding
away or otherwise disintegrating. Some have speculated that the cool, dry climate
and high resin content of the wood preserve it against fungal rot, insect attack,
and weathering. But this explanation doesn’t make sense given the disintegration
that has occurred in the dead portions of living strip-growth trees.
Figure 2. Left picture (A) shows strip-growth; in this case spiral
strip-growth (live bark is the darker strip spiraling up trunk). (B) depicts the
cross-section of a tree that has been growing in a strip-growth habit for many years.
Notice that the cross-section has become more rectangular than circular. (C) depicts
the cross-section of a strip-growth tree where the wood not directly beneath the
strip-growth has decayed away over time. How could this wood decay away in a fraction
of the time that wood on the ground has lain un-decayed?
Strip-growth is a peculiar phenomenon found in all BCPs with more than about 1,500
rings. In strip-growth trees, most of the tree has died, but there remains one thin
strip of living bark running up the side of the tree providing water and nutrients
to the small portion of the tree’s crown which is still living. The added
growth layers in strip-growth trees cause the tree to become slab shaped instead
of cylindrical. Schulman says (speaking of the oldest of the White Mountain specimens
found at the time), that in the strip-growth trees, the dead portion of the trees
has been eroded down to the pith (centre), ‘… erosion of the barkless
areas had been proceeding for one to two millennia and had reached to the pith or
near it’.9 How can
dead wood lay on the ground for up to 7,000 years while the dead wood in strip-growth
trees completely disintegrates in a fraction of that time? Perhaps the wood on the
ground isn’t nearly as old as thought (figure 2).
Figure 3. This photo shows John Woodmorappe holding a piece of
downed BCP while a cross-section is being sawn for further study. This tree was
sampled at a prior unknown date. The fingers of John’s left hand appear to
be resting on the old sawn surface—probably where a previous cross-section
was taken (although John couldn’t verify this). There are some obvious signs
of decay on this old sawn surface that have occurred since the time it was freshly
sawn. (Compare the surface that the fingers are resting on to the freshly cut surfaces).
(After Woodmorappe,10 p. 126).
Also consider that in the climate of the White Mountains, these dead pieces of wood
are subjected to many freeze/thaw cycles during the year which would tend to tear
the wood apart through mechanical freeze/thaw processes. It seems strange, then,
that researchers looking for old wood can’t get any clues about the age of
a piece of dead wood just by looking at it.10
The pieces of wood which have been lying on the ground dead for supposedly thousands
of years don’t typically show any more signs of ageing/decay than wood which
has supposedly been laying there only several hundred years. In figure 3, dead BCP
wood shows some obvious signs of decay. Why, then, do these ‘younger’
pieces of wood show just as much decay as pieces of wood which have been decaying
for thousands of years? Shouldn’t the supposed decay inhibitors at work in
the ‘old’ dead pieces be effective in the ‘younger’ pieces
of dead wood?
One would also expect more dead wood lying on the ground from all those supposed
past millennia if the wood is capable of surviving on the ground for thousands of
years. Woodmorappe and others have found that dead wood dating to the earliest millennia
is very rare.11 If this
‘ancient’ dead wood is so resistant to decay processes that it looks
as fresh as wood only a few hundred years old, then it would seem it should be about
as abundant as wood from more recent millennia; or, at a minimum, that there should
be an approximately linear relationship between the amount of wood remaining on
the ground and the millennia in which it grew. In a limited study, Woodmorappe didn’t
find such a linear relationship but more of a log-normal distribution of ages with
the distribution skewed toward the younger ages.11 On the other hand
if these trees, living and dead, are all about the same maximum age, but some grew
more rings per year than others, then Woodmorappe’s observations begin to
make sense.
The claim that wood can lay on the ground undecayed for 7,000 years is even more
fantastic when one considers the rate at which the mountains that these trees are
growing on are eroding away. LaMarche12
has found an erosion rate of about 1 foot (30 cm) per 1,000 years in the White Mountains
in general, and a higher rate in the areas where the oldest trees grow. (The actual
erosion rate may be much higher than LaMarche reports because he derived these erosion
rates based on the tree-ring records of living trees assuming annularity of rings—an
assumption that this paper contests). How is it possible that seven feet (213 cm)
of dolomitic surface, can erode away over the course of 7,000 years, while dead
wood could remain essentially in place on the surface of the ground over that same
period? Can the dead wood really be that much more resistant to destruction than
the rocks are?
We find more evidence for multiplicity of rings when comparing the growing environments
of BCPs having thousands of rings with those having only a few hundred rings. The
White Mountains afford the BCPs growing there numerous ‘micro-environments’
(that is conditions in the immediate vicinity of an individual tree). It is therefore
baffling that the trees with thousands of rings grow only where water and soil are
most scarce! After studying the environment of ‘old’ BCPs, LaMarche
notes, ‘Comparative aridity thus seems to be an important characteristic of
the “old-age habitat”’ and ‘Thus, high life expectancy is
apparently related to the frequent occurrence of sub-optimum moisture conditions.’
Consequently, ‘There is a large concentration of ancient trees on arid sites
at the lower forest border in the White Mountains.’13 Conversely, LaMarche found that where moisture
conditions were better, as in valley areas where a decent soil can accumulate, none
of the BCPs reach the ancient ‘ages’, ‘No old bristlecone pines
are found in the valley bottom, which is a sheltered area with deep colluvial soil
and gentle surface slope.’14
Strange—trees in decent growing conditions only live to several hundred years,
similar to the maximum age of many other tree species, but trees growing nearby
in a microenvironment with little water can live to several thousands of years.
These observations would make more sense if both sets of trees actually live to
about the same maximum ages, but the trees growing where water is scarce grow multiple
thin rings per year rather than one thicker ring. One explanation is that such a
growth habit conserves water.
Similarly, researchers have found that in the central area of a stand of BCP trees,
where growing conditions are the best, the trees do not have more than several hundred
rings. But at the margins of the stand, where the soil thins and growing conditions
become progressively poorer, the trees with the most rings are found.15 It seems more probable that all the trees in the
stand are about the same age, but that the trees growing at the margins are starved
for water and grow multiple rings to conserve water. If there are no truly ancient
BCPs—only BCPs which grow multiple rings per year—then Woodmorappe’s
observation that ‘old BCP trees do not seem to show some typical biomarkers
of ageing’ also makes sense.16
Figure 4. Typical tree cross-section, Ring B is the growth layer
that grew over the layer represented by ring A.
Consistent with the above observations are the observations of Larson et al.17 In their study of US and
western European trees that grow out of cliff faces, they found many ancient trees
with exceptionally thin rings, and often exhibiting strip-growth. Again, it’s
likely there isn’t much soil on a cliff face to provide for water storage
between precipitation events, so the cliff trees may be using multiple ring growth
per year to conserve water.
Can multiplicity conserve water?
If the basic proposition of this paper is correct—that there are no truly
ancient BCPs, only BCPs which have grown multiple rings per year under xeric (dry)
conditions—what is the connection between multiplicity and water scarcity?
Could it be that multiplicity somehow conserves water, thereby allowing a tree to
survive? To understand how multiplicity may help a tree conserve water, it is necessary
to understand some tree anatomy.
Figure 5. The dark-wood is caused by the wood cells becoming gradually
smaller. When growth begins again the first cells formed are large; this makes the
outer edge of the dark-wood sharp and the inner edge diffuse. Wood growth is to
the right in both frames. The ring widths are about 0.5 mm.
Tree growth can be conceptualized as a tree continually adding one layer of wood
after another to itself, over its entire surface area. It is as if thick coats of
paint are added over the surface of the whole tree one at a time. This method of
growth causes the wood of the tree to have the distinctive pattern seen on a stump
when a tree is cut down. The basic pattern that we see is of concentric circles
like the cross-section in figure 4. Each ring in the figure represents the cross-section
of one growth layer that grew over the surface of the whole tree but which we are
now seeing only in cross-section. In figure 4, ring B is the growth layer that was
added on top of the growth layer that grew right before it, represented by ring
A. Not all trees exhibit this growth-ring habit, but most species in temperate zones
of the world do. For trees that do exhibit growth rings, it is normal for them to
grow one ring per year under normal growing conditions.
In BCPs each growth-layer or ’tree-ring’ (the terms are synonymous),
consists of a light coloured band of wood coupled with a dark coloured band. The
radial growth in a tree occurs due to a thin layer of cells just under the bark,
called the cambium. As the cells in the cambium divide, they add wood to the outer
surface of the tree just under the bark. The light coloured wood is often called
the ‘early-wood’ because, under the assumption that each growth layer
represents one year’s growth, the light coloured wood represents the growth
that happens earlier on in the growing season. The dark coloured wood is called
the ‘late-wood’ or ‘dense wood’. The cells that make up
the late-wood are smaller, the cell walls are usually thicker, and there is a higher
resin content in these cells. Since the cell walls appear dark and more of the late-wood
consists of cell walls, the late-wood has a darker appearance and is more dense
(figure 5). (Throughout the remainder of this paper I use the terms ‘light-wood’
and ‘dark-wood’ rather than the conventional ‘early-wood’
and ‘late-wood’, because these terms describe the wood rather than reinforce
the idea that these kinds of wood only grow during certain times of the year—which
is incorrect in some cases).
Figure 6. Trees with only one growth increment per year (top) have
sap-filled wood in constant contact with the bark throughout the growing season.
In trees growing multiple rings per year (bottom) the dark-wood layers may serve
as barriers to radial movement of water during the growing season, thereby reducing
water loss through the bark.
Trees lose water naturally from their leaves or needles during photosynthesis. Trees
can also lose a significant amount of water vapour through the bark.18–20
Any mechanisms that slow the rate of water loss out through the bark would be a
great advantage to the trees in xeric conditions. Since the dark-wood has thicker
cell walls, higher resin content, and smaller and fewer pits for conducting water,
it is possible that the dark-wood retards the movement of water in the radial direction
better than the thin-walled, low-resin, heavily pitted, light-wood cells. Perhaps
this is why during the winter dormant season a tree has a layer of dark-wood right
beneath the bark; it may be a design feature of the tree to help prevent water loss
out of the bark during the winter dormant season. If this hypothesis is correct,
and the dark-wood slows the radial movement of water and reduce the rate of water
loss out of the bark, then a BCP having just one thicker layer of highly conducting
light-wood in constant proximity to the bark throughout a growing season will loose
more water through the bark than a tree which grows multiple thin rings, because
each dark-wood layer would serve as a barrier to the radial movement of water (figure
6). A possible test of this hypothesis might involve measuring rates of water loss
through the bark of thick-ringed BCPs and thin-ringed BCPs to see if the thin ringed
BCPs lose less water than thick-ringed ones.
Conserving resources, mainly water, may also explain the mysterious strip-growth
habit of the trees with thousands of rings. LaMarche notes that ‘Attainment
of an age greater than about 1,500 years apparently depends on the adoption of a
strip-growth habit.’21
This ‘strip growth’ habit is caused by the cambium dying around most
of the circuit of the tree such that there is only one long living strip of bark
running up the side of the trunk. The added growth layers cause the tree to become
slab shaped instead of cylindrical. Strip growth allows the surface area of the
bark to be minimized and resources to be conserved.
A tree growing in a normal manner (that is, adding growth layers around its whole
circumference) requires that each centimetre of increase in trunk or branch radius
adds about 6 cm of circumference, and a corresponding increase in surface area.
added surface area increases water loss through the bark. It also means that as
the tree gets older and bigger, an ever-increasing amount of wood has to be added
for each ring of the same width. To keep up this rate of wood addition would require
that the tree have basically unlimited access to resources needed to grow—including
water. But under strip growth, the tree doesn’t use an ever increasing amount
of resources to add each new growth layer; it takes about the same amount of resources
each year to add each new growth layer (figure 7). Perhaps the switch to strip-growth
takes place when the tree has reached a point that it can no longer add complete
new growth layers because of resource limitations.
Figure 7. When a trunk or a branch is adding an increment of growth
around its whole circumference (left), the addition of increment B takes more resources
than the addition of the previous increment A of the same thickness. But under strip-growth
(right) increment B takes about the same amount of resources to grow as the previous
increment of the same thickness A.
Most of the water is conducted up the tree in the ‘sapwood’, which comprises
the rings just underneath the bark; the ’heartwood’ does not conduct
much water up the tree. When strip-growth occurs (as is the case with the White
Mountain BCPs with thousands of rings), the strip of live bark and associated sapwood
in the rings immediately beneath it only feed one or a few main branches; the rest
of the tree dies because there are no more conducting tissues to feed it. The dead
part of the tree begins to dry out and eventually decays. When the water conducting
cells of the tree become dry (a condition known as cavitation) they serve as an
effective barrier to water movement. Thus, the many rings consisting of cavitated
cells would serve as a very efficient barrier to water loss from the relatively
small portion of conducting sapwood beneath the live strip-bark. In this way very
little water would be lost from the dead portion of the strip-growth tree.
Support for the hypothesis that strip growth allows for better survival when resources
are limited can be seen in the BCP cross-section of figure 8. The tree experienced
cambial die-back over about a fourth of its circumference, after which it immediately
started growing thicker rings than before the die-back occurred. Because the tree
had less surface area to cover during its growth increment after die-back, a thicker
increment could be grown even though the accessible resources remained the same.
Figure 8. This cross-section demonstrates that after die-back (when
strip-growth begins) a tree has enough resources at its disposal to grow thicker
rings than before die-back. The upper-left frame is a scan of the whole cross-section.
The upper-right diagram shows where part of the circumference experienced die-back
allowing more vigorous growth around the remaining live part of the circumference.
The bottom frame shows the last 12 rings formed before die-back (left) and first
12 rings formed after die-back (right). Note that the average ring is much thicker
after die-back occurred. The cross-section is about 24 cm at its widest point. The
bottom frame is about 0.64 cm wide.
This leaves open the possibility that BCPs under certain conditions may switch between
annual growth rings and multiple growth rings per year several times during its
life. For example, when the tree is young and its circumference is small, it may
have access to enough water to meet its basic needs, so it grows only one ring per
year. As it ages and the surface area of the tree expands it loses more and more
water out of the bark, but by switching to a multiplicity growth habit it can conserve
water. As the tree continues to expand in surface area a point is reached where
the tree can no longer sustain growth over its whole surface area. By switching
to strip growth it reduces drastically the surface area of tree which is a pathway
for water loss. Growing in a strip-growth habit, the tree may now have access to
enough water that it can maintain its growth using only a single ring each year.
If for some reason the water supply is no longer sufficient, the tree can begin
growing multiple thin rings per year again.
Rebuttal to claimed evidence for annularity
The initial reason that scientists studying BCPs in the White Mountains thought
that they were growing only one ring per year is because they believed it was fairly
easy to tell when a tree was growing more than one ring per year. As seen in figure
5, the beginning of the dark-wood is usually a zone that is somewhat fuzzy; that
is, the light-wood grades gradually into the dark-wood. This is because the light-wood
cells gradually becoming smaller as new cells are added. However the dark-wood band
usually ends abruptly, producing a distinct line which marks the outer edge of the
dark-wood. This results from the cells of the dark-wood typically getting smaller
and smaller until they stop and are followed by distinctly larger cells making up
the light-wood of the next ring. So, the inner edge of the dark-wood is usually
gradual, fuzzy and indistinct; but the outer edge of the dark-wood is usually abrupt
and distinct. This was interpreted as meaning that late in the growing season of
each year, a tree would slow down its growth until it gradually came to a complete
stop (this stop corresponded with the last latewood cells that were added to the
circumference of the tree). No further growth would take place until the beginning
of the next growing season; at that time the tree began vigorous growth again and
the cells which began to grow were the large early-wood kind.
Sometimes dark-wood is produced which does not have a distinct outer boundary, but
a fuzzy one, like the inner boundary. Under the microscope it can be seen that the
cells of dark-wood do not end abruptly but gradually start getting bigger again.
This is usually interpreted as the tree, for some reason, slowing down its growth
during the growing season, but then picking up its growth again before beginning
the final slow down that occurs at the end of a season. The entire growth band for
that year would then include a ‘false’ band of dark-wood (such dark
bands are designated as ‘false’ because they did not occur at the end
of the growing season as ‘true’ dark bands should). If not detected,
false bands would lead one to believe that two rings were present, representing
two years, rather than one year’s worth of growth with a ‘false’
dark band in the midst of that year’s light-wood. So it was assumed that ‘false’
rings (and thereby multiplicity) could be easily detected because the outer edge
of the dark-wood would be less distinct than the outer edge of normal annual rings.
Later, however, Glock et al. demonstrated that in dry climates, not only
are ‘false’ rings common in many species, but the bands of ‘false’
dark-wood can have outer boundaries that are every bit as distinct as the outer
boundaries of a true annual ring.2 Therefore, ‘false rings’
can be indistinguishable from ‘true’ annual rings; ‘ …
the growth layers resulting from intra-annual flushes [of growth] may, and commonly
do, possess outer borders indistinguishable from the borders terminating the annual
increment … .’22
So we see that ‘false’ dark-wood does not always have a fuzzy outer
boundary.
Figure 9. Photo of thin-ring dark-wood with diffuse inner and outer
boundary. It is difficult to tell which is the inner, and which is the outer boundary.
The frame is about 0.1 mm wide.
LaMarche and Harlan see four lines of evidence as supporting the annularity of rings
in BCPs.4 The first is that the dark-wood bands in BCPs do not have diffuse
outer boundaries, implying that none of the rings are ‘false rings’.
Glock et al. showed that at least some species can have ‘false rings’
that are indistinguishable from the annual rings.22 It may well be that
White Mountain BCPs have false rings which are indistinguishable from annual rings.
It is also often the case that extremely thin rings have inner and outer boundaries
which are virtually identical (figure 9). Additionally, Glock et al. found
that about 99% of the extremely thin rings and partial rings were ‘false’
rings.23 White Mountain
BCPs with thousands of rings abound in thin and partial rings.24,25
In fact, some ring sequences consist of rings so thin (averaging 0.1 to 0.2 mm and
less26) that a microscope
is needed to distinguish one ring from another. Some ring bands are the thinnest
possible, being only one cell thick!27
(Figure 10 shows a thin ring with a light band only two to three cells thick.) Finally,
further evidence of ‘false’ rings can be seen in figure 11 which shows
three distinct BCP dark-wood bands that are all connected together, strongly indicating
that they were all formed during the same growing season.
Figure 10. Photo of a ring where the light-wood is only 2 or 3
cells thick. The frame is about 0.2 mm wide.
The second line of evidence comes from a 3-year study by Fritts where continual
growth measurements were taken on a few Bristlecone Pines in the White Mountains
of California.24 However, these measurements were taken from trees in
a valley-like area where the soil was substantial enough that soil moisture measurements
could be taken (the ‘soil’ is too rocky in most of the ‘old’
tree areas to allow moisture level measurements), and all these trees were deemed
‘young’. As discussed above, BCPs in decent soil may not grow multiple
rings per year, as a general rule, because they have access to enough moisture in
the soil. Also, the trees are deemed to be ‘young’ because they don’t
have thousands of rings, which, according to my hypothesis in this paper, means
they are probably not growing multiple rings per year.
With respect to the third line of evidence, LaMarche and Harlan claim that samples
obtained in 1971 cross-match with White Mountain Bristlecone Pines sampled in 1954
by Schulman.9 They found that most trees have formed exactly 18 rings
in the period 1954–197128
(a few formed only 17 rings, none formed more than 18 rings) indicating that the
BCPs did not grow more than one ring per year. The argument hinges on a claimed
cross-match that can’t be verified and could be incorrect given the inherent
subjectivity of cross-matching. Beyond that, it appears that none of the living
trees sampled in 1971 were ‘ancient’ ones (i.e. with thousands of rings),
so it is possible that the trees in this study were growing only one ring per year.
The fourth line of evidence has to do with frost markers found in a number of trees
in the 87th ring before the ring representing 1971. If each ring represented
a year, then this frost would have occurred during the growing season of 1884. After
finding these frost markers, LaMarche and Harlan went back through weather records
and try to make the case, based on sketchy weather data, that there could have been
a frost around 9–10 September 1884 which caused the frost damage in the trees
rings.
Figure 11. Three dark-wood bands tied together. B continues to
the right of A with the black vertical line at approximately the same location.
If traced to the left, the dark-wood band in A indicated by the white arrow merges
completely with the dark-wood band above it. Likewise, the same dark-wood band in
B (again indicated by the white arrow) if followed to the right blends in completely
with the dark-wood band below it, giving the strong indication that all three dark-bands
were grown during the same growing season. The total length of A and B together
is about 2 cm.
The argument is unconvincing for a number of reasons. Fritts25 found
that Bristlecone Pine in the White Mountains stopped growing in late July to early
August. The trees would still have to be growing when the freeze supposedly occurred
⅓ of the way through September (LaMarche and Harlan don’t actually mention
where in the growth ring the damage occurs, but even if it were in the very last
formed part of the ring, 9 September seems like an unlikely date for the trees to
still be growing). In addition, it goes against the general rule that frost damage
usually occurs early in the growing season due to a late frost.29 LaMarche and Harlan claim that the 87th
ring was the first ring with frost damage encountered when counting back from 1971.
This means there shouldn’t have been any other unseasonably cold spells between
1884 and 1971 that could have caused frost damage, but LaMarche and Harlan don’t
address this question. The frost could have occurred much more recently if the trees
have grown extra rings per year. Lastly, there apparently isn’t good weather
data available for the White Mountains back in 1884. LaMarche and Harlan end up
having to rely on weather data that is vague and over 400 miles away for making
a weak case that there could have been a frost around September 9, 1884.
Another idea encountered in the literature is that the cross-datability of BCPs
somehow negates the possibility that the rings involved aren’t annual. I have
never seen the logic behind this contention explicitly stated, but perhaps the thinking
is that if trees were putting on extra rings per year more or less randomly, then
we shouldn’t be able to match the patterns between two trees because one tree
might have grown one ring in a year and another tree might have grown two or more.
However, if the timing of the growth layers is triggered by environmental factors
(like rain events), it could very well be that all trees growing in a similar environment
behave similarly. So, for instance, if there were two large precipitation events
and one smaller one in a particular year, then it might be expected that all the
trees growing near each other in similar growing conditions would grow two larger
rings and one thin ring that year. In this way the ring-width sequences would be
similar, but not every ring would represent an annual increment. Glock et al.
concur that cross-dating doesn’t prove annularity, ‘The fact that the
thin, entire growth layers or lenses match from one tree to another does not prove
their annual character.’30
Suggestions for demonstrating multiplicity
The following are some ways that additional direct evidence for BCPs growing multiple
growth layers per year can be obtained (remembering that trees growing in water
scarce conditions are the ones most likely to grow multiple rings a year):
- Find old photos (from perhaps a private land owner, nature photographer, the National
Park Service or the US Forest Service) of individual Bristlecone Pine trees or stands
of trees, where the date (or year) that the photograph was taken is known, and the
location of trees is known. Go to where the original photo was taken and try to
find new trees or new branches that have grown since then. Get permission to core
the tree or branch (or better yet see if the whole tree or branch can be cut, special
permission may be needed on public land). The age of the photo will provide the
maximum age that the branch or tree can actually be—see if the number of growth-rings
exceeds this maximum age. A slight variation of this method would be to find a private
individual or public servant who knows (and can preferably document) exactly when
a certain Bristlecone Pine tree was planted or a certain road was built or land
cleared.
- Place time tags in the trees by freezing with dry ice to produce ‘frost’
damage or by watering with a dye that is transferred to the sap wood. It is possible
that nuclear bomb testing or other events have put radioactive or, for example,
trace element tags into wood that can be used to verify multiplicity.
- Locate dated old photos of dead standing BCP snags and logs laying on the ground
to determine if the rate of wood decay matches what it should be if these dead pieces
of wood are thousands of years old. This could offer indirect evidence of multiplicity.
Conclusion
The great ages claimed for individual BCPs are based on the assumption that the
trees grew no more than one ring per year. These ‘ages’, generating
a master chronology of 8,700 years, are plainly contradictory to the biblical timeframe.
Upon close scrutiny there is strong evidence that multiplicity of ring formation
is common under the environmental conditions where the trees grow that are used
in the master chronology. Thus the assumptions behind the great ages are not correct.
The number of growth rings produced by BCPs seems to be more a function of the soil
water status of the area in which the BCPs grow: the drier the environment, the
more rings are produced. Multiplicity of growth rings and the strip growth habit
are possibly physiological mechanisms for conserving water in dry conditions. Studies
that have sought to prove annularity in BCPs have not used a correct methodology
or timeframe, and more suitable experimental methods have been proposed. In investigating
direct evidence for multiplicity, the effect of environmental conditions needs to
be accounted for. Once again, uniformitarian assumptions about the constancy of
rates in the past are shown to be too simplistic, and the biblical timeframe can
accommodate the data.
Acknowledgements
I wish to thank Mark Armitage for the photomicrographs in figures 5, 9, 10 and 11.
Mark wasn’t given enough time to do the pictures properly, so he is not satisfied
with their clarity. I think they are fantastic and thank him for them. I also thank
Tom Willis, Wes Bartley and Tony Wells for their comments and suggestions on the
paper.
Related articles
Related resources
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