We know about the critical
life-giving role trees play but the comprehensive spread in shaping life on the planet is what left me in awe. This is one book that kept be riveted,
and changed me significantly in the way I look at trees -and that is something
since I have been observing trees for decades. Imagine never heard about
Rubisco -the most common enzyme on earth, comprising almost 50% of the protein
in leaves! The first chapter is about Tree shaping water. Tree uses solar
energy to split water into hydrogen and oxygen, and transfer electron onto
carbondioxide to make sugar. This means tree needs large quantities of water
and air, and unlike human trees cannot move hence must control their own
environment in dynamic equilibrium. In a sense, trees developed into trees to
gain power over water. Trees grow tall to interrupt air flow with their leaves
and branches, emitting VOCs (Volatile Organic Compounds) to seed clouds,
releasing water vapor out of their stomata, and thus a consistent cycle of
moisture. A recent study has found that trees release more VOCs during drought
conditions to encourage rain. Since trees are exposed to sun they spent as much
as 97% of water to cool itself (as water molecules cools they take sun’s
energy with them), as water rises and cools it condenses, lowering the air
pressure, and if this happens next to moisture laden air from sea they sucked
in by the forest. An unbroken chain of forests can use transpiration to
cycle water deep into inland from coast by setting up pressure gradient, an air
stream laden with water -a flying river, while roots collect and redistribute
water to create water table. All these have significant impact on global water
flow. Gymnosperm ruled earth until about 66m years ago when asteroid impact led to great
extinction after which flowering angiosperm took over to initiate diversity of
life with their ability to produce flowers and fruits, short time scale of
reproduction. They also cycled water quickly, dropping leaves to conserve
energy for next opportunity. Thus, the tree productivity increased dramatically
and unlike gymnosperms, that grew in elegantly spaced forests with an imposing
dominant specie, angiosperm rainforests were crowded, multilayered, packed with
diverse species. How trees shaped distribution of water and help thrive life on
earth is an interesting read. Next chapter is on Trees shaping soil. As tree grew the roots help to anchor as also probe deep to search water. They
grew into rocks and turn it into dust, thus availability of mineral mainly
phosphate (it is essential element for life, forming DNA, RNA, protein so on.
Hunger for phosphorus is reason for tree breaking rock) and others like iron,
zinc, magnesium so on, and these extracted minerals can be seen on the top of canopy
of the tree 60m above ground! Importantly trees also convert this dust into soil
-a chain of carbon sequestered from air, to trap water as also by addition of nitrogen (as the tree became
dominant in carboniferous period there was shortage of nitrogen which was fixed
by cycads -they produced oxygen free areas to nurture nitrogen fixing bacteria)
thus making it fertile. Studies show that older and larger trees trap exponentially more
carbon into earth as they mature. As rocks weathered phosphate were hard to
find, and trees shifted to breaking limestone as also evolved strategies to
recapture (while gymnosperms were eaters of rocks angiosperms evolved diverse
strategies as competitive recyclers). Through shaping soil trees make essential
mineral available for life to thrive. Trees shaping fire is an
exceptionally interesting chapter, and did change many of my understanding of
trees. Trees manipulating fire is a crazy thought but that is genius of trees,
indeed life. Some species of trees have managed to get fire on their side. Take
the case of how a specie of Pine actively help start fire, indeed self-immolate, to burn
away its neighbor- a Fir specie. Some trees encourage mock fire at low temperature
to prevent real hot fire from happening. And if fire does go out of hand and
reaches trunk (of say chir pine) they turn mock fire into real fire, slow burning hot
fire that clears everything and allows the pines to start again from seeds. There are many species of trees that need catastrophic fires to regenerate,
they use fire to create chaos. Some trees fill itself with volatile resin up to
the brim particularly at the upper canopy waiting for lighting to strike and inflame. There
is mention of devastating impact of eucalyptus trees that is being used for
afforestation, not only they grow fast, burn easily and poison anything that
tries to eat them (except koalas) they also lower water table – an adaptation
mechanism to kill nearby trees. There is a ominous warning that climate change
fueled forest fires are causing fire adapted trees not to burn but explode, fires are
becoming too hot for seeds to germinate, underground re-sprouting mechanism to
work. Trees shaping air gives some practical insight that helps us
understand the role of trees on the air we breathe. Carboniferous period (a
warm wet period between the end of Devonian -358m years ago, and the beginning
of Permian -300m years ago) was characterized by gigantism of insect life -when
you see reference of large dragonflies or gigantic millipedes you can associate
it to this period. The reason for this was content of oxygen in the air -35%,
allowing this gas to diffuse into body and power its muscles that is not
possible with 21% oxygen we have now. Trees not only release oxygen but also compounds
to seed clouds and attract animals and communicate with other trees. Locking
away of carbon dioxide and release of oxygen changed the atmosphere to an
extent that it led to dramatic global cooling (temperature fell by as much as 20degree
centigrade) to carboniferous rainforest collapse. Trees also lessen
impact of wind, for instance, shape of tulip tree leaves curl up into a tube
thereby lessening the force. Araucarias are one of my favorite trees for the
reason that they were munched on by dinosaurs, what I didn’t know was they evolved
their shape to manipulate wind for complex pollination. Just like human trees
also enlist bacteria to perform sophisticated function. There is mention of
enigmatic Lynn Margulis and her brilliant contribution to understand
biochemistry of life particularly endosymbiotic theory -bacteria being
enveloped and enslaved into symbiosis and cooperation. Trees shaping fungi
talks about mycelium network, and awkward interface of trees with fungi as it
balances support (nitrogen and phosphorus source) and harm, some evolved to so
much sophistication as to mete out right carbon reward to the right fungus
(trees have evolved a plant hormone specifically meant to control and shape
fungi). Trees balance nutrient from roots with sugar from the shoots, by
directing growth of both root and shoot. There is also constant mycelium
interaction that connects trees in an underground network proposed as 'wood
wide web'. There is richness to the diversity in an old forest that implies
connected systems based on feedback. The author has problem with these and
faults it for anthropomorphizing, there are overwhelming evidence of
mycorrhizal connections but the trees connecting through these suffer from
confirmation bias is the stand taken. …a tree’s ability to be dispassionate -to
think and feel like wood -is one of its greatest wonders (arguably one of the
best sentences in the book, later in the book author mentions animist communities who do
not anthropomorphize -there is an aesthetic appreciation of what a tree is and
acute observation of how they function). Trees shaping plants provides insights
into areas I wasn’t aware of. The author quotes writer Zoe Schlanger ‘What if,
instead of hunting, our food was sunlight that rained down on us, so we were
bathed in it and we had to evolve only to be prepared to receive it?’. To
understand life of plants author adds to the quote ‘what if all the sunlight is consistently
blocked off?’. Majority of plants are angiosperms that evolved under conifer
canopies that were rapidly losing diversity and eventually devastated in the
aftermath of KT extinction event 66m years ago. Like the case of mammals this event boosted angiosperms while severely restricting gymnosperms. Plants were
foremost shaped by trees (specifically gymnosperms) as they absorb much of
carbon and sunlight, and then adapting out from under them. Specific
adaptations like coping to constant disturbance, creeping phase along forest
floor and waiting for opportune circumstance to shoot up, there roots and
shoots could layer and root again making them extremely resistant to trampling
(Mesozoic forest frequented by dinosaurs), they had many possible shoots and
could respond to damage as also adaptation to absorb light better. Angiosperms
were thus intrinsically flexible, adaptable and creatively chaotic. The cataclysmic
asteroid impact and intense dust and ash led to two years of no photosynthesis,
soon open forest of gymnosperms turned into multilayered forest of angiosperms
and became basis for stupendous evolution of modern day terrestrial
biodiversity. Many angiosperms rose to become tall canopy trees but not as
structurally shaped or tall as gymnosperms. Tree shaping animals is
penultimate chapter that starts with example of sloths that are completely
shaped by trees to the extent that they have almost become tree. Another
interesting example is that of a specie of bats that is so manipulated that its
nose can only be used to access nectar thus blocking them from any other source
of food and so completely dependent on the tree thus transporting pollens over
long distance and optimizing genetic flow. Bees are modified by trees to see
only UV rays, blue and green (wavelength longer than purple) and no red. There
is discussion on relationship between birds and trees, and how birds were manipulated to distinguish red and green hence ripeness of fruit. Pollination and seed dispersal are
two main reasons why tree shape animals. I found large seeded fruit adaptation to allow only large animal access so that seeds can be carried to
farther distance quite interesting particularly example of cocoa, the toxicity
of which will knock off small monkeys as it prefers larger monkeys, high fat
content of cocoa butter ensures physical energy to travel long distance. The
book ends appropriately with how Trees shaping people. Human history, the
human brain, the human hand and human leg, all start in the forest canopy. Primate
brains developed by sensing and balancing on trees. Our ability to stand
upright negotiating branches, desire to build nests and the compelling scent of
wood (hence books or even cupcakes), are all adaptation of primates shaped by
trees. Trees and tree dwelling shaped the physical evolution of early humans. Shifting
from leaf eating to fruit eating impacted development of intelligence and
memory. In the safety of nest deep REM sleep resulted in development of brain,
enlarging and shaping our brain. Cells of humans and trees diverged 1.7b years
back (and we do share 30% of genetic code), the shared lifestyle ended when one
daughter cell engulfed a photosynthetic bacterium and became a light eater
while the other remained an amorphous blob hunting for food. Trees pathway of development
is therefore creative as they produce more and more inventive molecules while
human pursued path of avarice by taking these molecules for own use. Trees therefore
are shaping humans chemically for last 500,000years by providing compounds we
cannot make -medicines, supplements, vitamins, spices to antioxidants are provided
by trees. Trees shape us through what we eat and air we breathe. Take for
instance the case of cocoa (source for chocolates that we crave). Is it that as
the world warmed up cocoa and humans expanded their range together? That the
seeds of interdependence survived in our DNA, encoding a human protein (an
adenosine receptor) that was chemically reshaped by the rings and oxygens of
theobromine (alkaloid found in cocoa)? It is speculated by the author that some
of our rootedness as humans, our wish to temper the excitement of technological
advances with a grounding in nature by planting trees around our newest cities,
is part of how trees shaped us. The book ends poignantly with the mention of
last painting by Van Gogh (Tree Roots) -throughout the book there are many
literary references that makes it quite interesting. The author writes, the
painting is his last masterpiece, gnarled bright blue tree roots and green
foliage bursting out of a taupe bank. It is a picture of trees holding it all together,
making sense out of a bewildering world.
