D. Suzuki_ Salmon and the forest
Summary
TLDRNorth America's temperate rainforests, a rare and endangered ecosystem, host the world's highest biomass due to its giant trees. Despite poor soil nitrogen levels, these forests thrive thanks to salmon, which carry nitrogen-rich nutrients from the ocean. After spawning, salmon are consumed by wildlife, particularly bears, who disperse nitrogen throughout the forest. This nutrient cycle supports tree growth, creating a symbiotic relationship between the ocean, rivers, and the forest, highlighting the interconnectedness of ecosystems.
Takeaways
- 🌳 North America is home to half of the world's temperate rainforests, which are incredibly rare and endangered ecosystems.
- 🌍 These rainforests cover less than 1% of the Earth's terrestrial area, yet they have the highest biomass weight of any ecosystem.
- 🌲 The large trees in these forests are a mystery given the nitrogen-poor soil, which is typically not conducive to such growth.
- 🐟 The key to the growth of these large trees is the salmon, which play a crucial role in the ecosystem despite the rain washing nutrients away.
- 🏞️ Salmon are born in the forest's freshwater rivers and are dependent on the forest for various stages of their life cycle.
- 🌊 After maturing in the ocean, salmon return to the rivers loaded with nitrogen-15, a heavier isotope that is abundant in the ocean.
- 🐻 Bears are significant contributors to the distribution of nitrogen in the forest, as they eat salmon and spread their waste, rich in nitrogen-15, throughout the area.
- 🦟 Flies and their maggots also play a role in the nitrogen cycle, as they consume salmon carcasses and then drop to the forest floor, enriching the soil.
- 🌱 Tree growth rings show a correlation between the presence of nitrogen-15 and periods of significant tree growth, indicating the importance of salmon as a fertilizer source.
- 🔄 The script describes a complex and interconnected system where the health of the ocean, salmon, rivers, lakes, and forests are all interdependent.
Q & A
What is considered one of the most rare and endangered ecosystems on the planet?
-Temperate rainforests are considered one of the most rare and endangered ecosystems on the planet.
How much of the world's temperate rainforests are found in North America?
-North America has half of all temperate rainforests in the world.
What is the significance of the temperate rainforest ecosystem in North America?
-The temperate rainforest in North America, which runs from Southern Alaska to Northern California, has the highest biomass weight of living things of any ecosystem on the planet.
Why are the soils in temperate rainforests considered poor in nutrients?
-The soils in temperate rainforests are considered poor in nutrients because the frequent rainfall washes a lot of the nutrients out of the soil.
How do large trees in temperate rainforests obtain the nitrogen they need if the soil is nitrogen-poor?
-Large trees in temperate rainforests obtain nitrogen through the salmon, which bring nitrogen from the ocean when they return to spawn.
What role do salmon play in the nutrient cycle of the temperate rainforest ecosystem?
-Salmon play a crucial role in the nutrient cycle of the temperate rainforest ecosystem by returning nitrogen from the ocean to the forest when they come back to spawn.
How do bears contribute to the distribution of nitrogen in the forest?
-Bears contribute to the distribution of nitrogen in the forest by consuming salmon, and their feces spread nitrogen-15 throughout the forest.
What is the relationship between the nitrogen content in tree rings and salmon runs?
-There is a clear relationship between the nitrogen content in tree rings and salmon runs, with wider tree rings corresponding to years with a large salmon run, indicating that salmon are a major source of fertilizer for the trees.
How do the nitrogen levels in salmon affect the food chain in the forest?
-The nitrogen levels in salmon affect the food chain in the forest by providing a rich source of nitrogen-15, which is then consumed by other animals such as bears, birds, and insects, supporting the entire ecosystem.
What is the significance of the timing of the salmon runs and the hatching of flies in the forest?
-The timing of the salmon runs and the hatching of flies is significant as it ensures that the flies, which are loaded with nitrogen-15, are available to feed the birds migrating from South America, thus linking the food chains across different ecosystems.
How does the script describe the interconnectedness of the ecosystems mentioned?
-The script describes the interconnectedness of the ecosystems by highlighting how the ocean nourishes the salmon, which in turn fertilize the forest, and how this system is linked to the rivers, lakes, and even to the southern hemisphere, forming a single, complex system.
Outlines
🌲 The Secret of Temperate Rainforests' Fertility
The first paragraph introduces the rarity and endangered status of temperate rainforests, highlighting that North America hosts half of the world's temperate rainforests. These forests, despite being less than 1% of the planet's terrestrial area, have the highest biomass due to the presence of large trees. The mystery of how these trees thrive in nutrient-poor soil, especially in nitrogen, is revealed through the life cycle of salmon. Salmon are born in freshwater rivers within the forest, and their journey to the sea and back is crucial for the ecosystem. They accumulate nitrogen-15 from the ocean, which is then reintroduced into the forest ecosystem when they return to spawn and are consumed by predators like bears and birds. This process fertilizes the forest, particularly evident in the tree rings' nitrogen-15 content, which correlates with years of abundant salmon runs.
🐟 The Salmon's Role in Ecosystem Connectivity
The second paragraph emphasizes the interconnectedness of the ecosystem, where the salmon play a pivotal role. The salmon, after being born in the forest and spending time in the ocean, bring back nitrogen-15 when they return to spawn. Their bodies, once consumed by predators, fertilize the forest floor, providing a rich source of nutrients for the trees. This cycle not only supports the growth of trees but also sustains a complex food web involving insects, birds, and other animals. The paragraph illustrates how the health of the forest is tied to the health of the ocean and how the salmon act as a vital link between these two ecosystems, creating a harmonious and self-sustaining cycle.
Mindmap
Keywords
💡Temperate Rainforests
💡Biomass
💡Nitrogen
💡Salmon
💡Nitrogen Isotopes
💡Spawning
💡Bears
💡Invertebrates
💡Fungus and Bacteria
💡Interconnectedness
Highlights
Temperate rainforests are among the rarest ecosystems globally, covering less than 1% of the Earth's terrestrial area.
North America hosts half of the world's temperate rainforests, stretching from Southern Alaska to Northern California.
These rainforests have the highest biomass weight of any ecosystem due to the presence of large trees.
The soil in temperate rainforests is poor in nitrogen, a critical nutrient for tree growth.
Salmon play a key role in the ecosystem, being born in freshwater rivers within the forest.
Clear-cutting forests leads to a significant decline in salmon populations, highlighting the interdependence between salmon and the forest.
Salmon require cool waters and food from the forest during their early life stages.
The forest also helps to maintain the quality of the spawning gravel, crucial for salmon reproduction.
Salmon accumulate nitrogen-15 from the ocean during their time at sea, which is different from the nitrogen-14 found on land.
When salmon return to spawn, they bring a rich source of nitrogen-15 to the forest ecosystem.
Predators such as bears, eagles, and wolves consume salmon, spreading nitrogen-15 through their feces in the forest.
Bears, in particular, are significant in distributing salmon-derived nitrogen throughout the forest.
Flies and their larvae (maggots) also play a role in spreading nitrogen-15 by consuming salmon carcasses.
The timing of salmon runs coincides with the arrival of migratory birds, providing a critical food source for them.
Tree growth rings show a correlation between wide rings (indicating growth) and years with abundant salmon runs.
Salmon that spawn and die in the water contribute to a nutrient-rich mat of fungus and bacteria, feeding the next generation of salmon.
The ecosystem demonstrates an intricate web of connections between the oceans, rivers, lakes, forests, and migratory birds.
Transcripts
one of the most rare and endangered
ecosystems on the planet are temperate
rainforests North America has half of
all temperate rainforests in the world
it's less than 1% of the land the
terrestrial area of the planet and in
North America we have pinched between
the Pacific Ocean and the coastal
mountains we have a temperate rainforest
that runs from Southern Alaska to
Northern California has the highest
biomass weight of living things of any
ecosystem on the planet and that's
because we have big trees and one of the
mysteries has always been how can we get
such big trees when it rains a lot it's
a rain forest and the rain washes a lot
of the nutrients out of the soil the
soil in fact is very poor in nitrogen so
how can you have a nitrogen poor
ecosystem and yet these gigantic trees
that are built on nitrogen and carbon
well it turns out the secret is the
salmon you see the salmon are born in
the forest in in freshwater rivers and
we know that the salmon need the forest
because if you clear-cut a watershed
where the salmon spawn salmon
populations plummet and usually
disappear the salmon need the forest for
the canopy to keep the waters cool
because the babies are very sensitive to
temperature there we need the forest to
provide the feed when the babies are are
getting ready to go down to the ocean
they need to feed and we need the forest
to hold the soil so that doesn't spoil
the spawning gravel so we knew that but
now the interesting thing is if you look
at the nitrogen on the land it's almost
exclusively nitrogen-14 which is a the
normal isotope of nitrogen when you look
in the oceans the nitrogen has also has
a large component of nitrogen 15 which
is slightly heavier it's got extra
Neutron in it and you can tell nitrogen
15 from nitrogen 14 in your in your
instruments so baby salmon born in the
forests protected by the forests they go
out to sea there are five species of
salmon on the coast and depending on the
species they stay out to sea for two to
five years all the while growing and
loading up with nitrogen
theme from the oceans so when they come
back to spawn they are loaded like
little bullets of nitrogen 15 fertilizer
and as they come into the estuaries is
the killer whales and the seals are
eating them then they hit the river and
the Eagles in the way and the Bears and
the wolves are all eating the salmon and
as they poop in the woods they're
spreading nitrogen 15 throughout the
forest and one of the major vectors are
bears the Bears
they'll fish together they're a solitary
animal but when the salmon are running
they'll fish together in the same pool
but the minute they grab one they take
off they don't want to eat it with the
other bears around and they'll go up 150
meters on either side of the river they
sit down they eat the best parts which
you all know is the brains and the belly
and the eggs and usually they'll leave
the carcass the rest of the carcass so
about half the salmon is left there they
go back for another one
and a bear will take about 600 salmon
out of the river in a year and that
salmon carcass it's left is immediately
pounced on by salamanders and beetles
and Ravens and everything but the major
vector is flies so the Flies lay their
eggs on the carcass within a few days
that carcass will just a seething mass
of maggots which are consuming that
flesh loading up with nitrogen 15 and
then they drop to the forest floor and
over winter as pupae and the next spring
as they hatch in the trillions it's just
at the time that the birds from South
America are coming through on their way
to the Arctic to have their babies so
the timing is that the salmon are now
feeding the Flies which are programmed
then to hatch just at the time that they
will feed the the birds from South
America when you look at the trees you
can take a core of the trees and pull it
out you can show there our fat rings
which is a lot of growth or skinny rings
you can measure the amount of nitrogen
15 in the Rings and show when there's a
fat ring there's way more nitrogen 15
and then we've got government records
going back 50 years and you can show
when there's a fat ring that was the
year that was
big run of salmon so it's very very
clear the salmon are the major pulse of
fertilizer that the trees are getting
the trees respond to that many of the
the salmon spawn and then die in the
water they sink to the bottom and if you
come up a stream a few weeks later the
bottom is covered with a thick mat of
fungus and bacteria that are consuming
the flesh and the fungus and bacteria
are eaten by by invertebrates insects
and things when the babies emerge from
the gravel for months later the baby
salmon the water is filled with food
that is loaded with nitrogen 15 that
comes from the parents bodies so you see
this unbelievably beautiful system of
interconnectedness where the oceans give
burped you don't feed the salmon and
their oceans are linked to the rivers
and lakes which are linked to the the
forests and are linked to the southern
hemisphere all of that is a single
system
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