Day 10: Earthquakes
This was a great day.
If every day were like this, I would do television forever.
Challenges were given and I ended up needing to determine when the last
major earthquake in this area occurred. This seemed impossible until we
got a look into the equipment box tree corers. That's a major
at least the last 15 years, New Zealand scientists have been worried about
their forests. In any given forest here, most all of the canopy trees
the trees that "reach the sky" are old and about the same
age. This is unusual. Most of the time you find trees of all different
ages making up the canopy. Thus, a mature forest in the US can have canopy
trees from 50 to several hundred years old. That doesn't seem to
happen here. First, the common tree species are long-lived (500 to 1000
years old) conifers. Second, they don't survive well as saplings
in the understory waiting for a mature tree to die, so they sprout, grow
for a while and then die waiting to get enough light to become canopy
trees. But why are the canopy trees in an area all about the same age?
for a while that New Zealand forests must be dying that all the forests
were made of old trees that weren't regenerating. Then someone started
aging the trees. Most of the trees in a stand were about the same age,
given or take 50 years. And the dates at which these tree stands began
corresponded to several years after major earthquakes in New Zealand.
Viola! It isn't that the forests are dying out, but that earthquakes
are major factors in shaping forests here.
Basically, New Zealand
earthquakes are big, and they cause massive landslides that can wipe out
entire areas, especially when combined with raging rivers. So, the rock
and gravel carried down by rivers after massive earthquakes decimate previous
forest, covering it with gravel and rock. It is in this new substrate,
"soil", that new trees start to grow, all at approximately
the same time soon after the earthquake.
If we can figure out
the age of these trees, we'll know the approximate date of the last
big earthquake. We are looking for the absolute oldest tree in order to
be the most accurate.
picture-perfect weather, Kate and I went helicopter hiking, as they call
it around here, to find a piece of land out of a big river's normal
flood plain, but within range of a mighty river carrying earthquake landslide
wash. We found such a place, and was it exquisite. I'd never been
in such a wet, mossy, old conifer forest before. Kate joined us for half
of the day. She and I took tree cores.
I came bouncing back
to our base, pleased as pie and ready to count rings. This will be really
tough as slow growing trees have narrow growth rings, which makes them
really difficult to count. At least I am working with plant material
beautiful, interesting plant material. The question remains, did I get
all the way to the center of the trees?
Back to top