AP Environmental Science Unit 2 Review (Everything you Need to Know!)
Summary
TLDRMr. Smeads' AP Environmental Science review covers Unit 2, focusing on biodiversity's three levels: genetic, species, and ecosystem. He explains how biodiversity benefits ecosystems and humans through ecosystem services. The video also discusses island biogeography, ecological tolerance, natural ecosystem disturbances, and adaptations, like Homo habilis' opposable thumbs. It concludes with ecological succession and keystone species, emphasizing their roles in maintaining ecosystem balance.
Takeaways
- 🌿 Biodiversity encompasses three levels: genetic, species, and ecosystem diversity, each nested within the other.
- 🧬 Genetic diversity is crucial for species' adaptability to environmental changes, as it provides a range of traits that may help some individuals survive.
- 🌳 Species diversity, including species richness and evenness, is beneficial for ecosystems' resilience, as it ensures that if one species declines, others can fill the gap.
- 🌍 Ecosystem diversity is important for biomes' health, with higher diversity supporting more species and functions.
- 💰 Ecosystems provide valuable services to humans, known as ecosystem services, which are categorized into provisioning, supporting, regulating, and cultural services.
- 🏝 The theory of Island biogeography suggests that island species richness is influenced by proximity to the mainland and island size.
- 🕊 The dodo bird's extinction illustrates the vulnerability of specialist species on islands to invasive species and environmental changes.
- 🌡 Ecological tolerance refers to the range of conditions an organism can tolerate; genetic diversity can provide a buffer against environmental disturbances.
- 🌪 Natural events, such as seasonal changes, hurricanes, and forest fires, can disrupt ecosystems, but they also drive natural selection and adaptation.
- 🌎 Earth's climate naturally changes over tens of thousands of years due to variations in its orbit, known as Milankovitch Cycles, affecting sea levels and ecosystems.
- 🦍 Adaptations, like opposable thumbs in Homo habilis, provide a survival advantage and can lead to new species' evolution, demonstrating how genetic mutations can be advantageous.
- 🌲 Ecological succession involves the gradual change in species composition over time, with primary succession starting on bare rock and secondary succession following a disturbance.
Q & A
What is the main focus of Unit 2 in the AP Environmental Science course?
-Unit 2 focuses on biodiversity, including the three levels of biodiversity and how biodiversity benefits ecosystems.
What are the three levels of biodiversity mentioned in the script?
-The three levels of biodiversity are genetic biodiversity, species biodiversity, and ecosystem biodiversity.
How does genetic diversity benefit a species?
-Genetic diversity benefits a species by increasing the likelihood that some members will have traits that allow them to adapt to environmental disturbances or changes.
What is species richness and how does it relate to species diversity?
-Species richness is a measure of the total number of different species found in a given ecosystem. However, a higher species richness doesn't necessarily mean more species diversity; species evenness, which is the balance of population sizes, is also considered.
How does ecosystem biodiversity benefit biomes?
-Ecosystem biodiversity, which refers to the variance in different ecosystems found in a given area, benefits biomes by supporting a greater species richness and providing a wider variety of habitats.
What are ecosystem services and how do they benefit humans?
-Ecosystem services are the direct or indirect contributions of ecosystems to human well-being, including provisioning services (like wood for furniture), supporting services (like pollination), regulating services (like carbon sequestration), and cultural services (like tourism and recreation).
What is the theory of Island Biogeography and what are its two simple rules?
-The theory of Island Biogeography suggests that the number of species on an island is related to its distance from the mainland and its size. The closer an island is to the mainland and the larger its area, the higher the species richness.
How does ecological tolerance relate to an organism's survival?
-Ecological tolerance refers to the range of conditions an organism or species can tolerate before death or serious injury occurs. It's a measure of how much an organism can adapt to changes in its environment.
What are the three main levels of frequency for natural events that disturb ecosystems?
-The three main levels of frequency for natural events that disturb ecosystems are periodic events (like seasons), episodic events (like hurricanes), and random events (like asteroid strikes).
How do Malankovic Cycles contribute to natural climate change?
-Malankovic Cycles, which include changes in Earth's orbital eccentricity, axial precession, and obliquity, contribute to natural climate change by altering Earth's distance from the Sun and the tilt of the Northern Hemisphere towards the Sun.
What is the difference between primary and secondary ecological succession?
-Primary succession occurs on a bare surface like bare rock, starting with pioneer species like moss and lichen, while secondary succession occurs in areas where soil is already present, often following a disturbance that clears out existing vegetation.
What is a keystone species and why is it important?
-A keystone species is a species that has a disproportionately large effect on its ecosystem relative to its abundance. Removing a keystone species can cause the ecosystem to undergo dramatic changes or even collapse.
Outlines
🌿 Introduction to AP Environmental Science Unit 2
Mr. Smeads introduces the review of Unit 2 for the AP Environmental Science course and exam. He emphasizes the importance of understanding the concepts of biodiversity, which includes genetic, species, and ecosystem diversity. The instructor encourages students to practice their writing skills for the exam, specifically for the mini FRQs at the end of each unit. The video aims to help students think critically about environmental science topics and prepare for the AP exam.
🌍 Biodiversity and Its Impact on Ecosystems
This section delves into the concept of biodiversity, explaining the three levels: genetic, species, and ecosystem diversity. It discusses how genetic diversity within a population can help species adapt to environmental changes, while species diversity contributes to the health of an ecosystem by ensuring resilience against disturbances like disease. Ecosystem diversity, in turn, benefits entire biomes by supporting a variety of life forms. The paragraph also touches on the idea that biodiversity provides ecosystem services that are valuable to humans, such as provisioning, supporting, regulating, and cultural services.
🌱 Ecological Tolerance and Natural Ecosystem Disruptions
The paragraph explores ecological tolerance, which is the range of conditions an organism can tolerate before facing death or serious injury. It uses human body temperature as an example to illustrate the concept of optimal range and the zones of physiological stress and intolerance. The discussion extends to natural events that can disrupt ecosystems, categorized into periodic, episodic, and random events. It also covers the concept of Malankovitch Cycles, which are natural variations in Earth's orbit causing gradual climate change over tens of thousands of years, leading to changes in sea levels and ecosystems.
🦸♂️ Adaptations and Evolution in Ecosystems
This part of the script discusses how organisms adapt to environmental disturbances, using the opposable thumbs of Homo habilis as an example of an adaptation that provided a survival advantage. It explains that genetic diversity allows for a range of traits, which can lead to beneficial mutations like the opposable thumb that enabled early hominids to use tools more effectively. The paragraph also covers how species like Homo erectus adapted to new environmental conditions by evolving traits such as the ability to stand upright and use more efficient tools.
🌳 Ecological Succession and Keystone Species
The final section reviews ecological succession, distinguishing between primary and secondary succession. It describes the process by which pioneer species colonize bare or disturbed areas, leading to the development of soil and the eventual establishment of a climax community. The paragraph also introduces keystone species, which are crucial to the functioning of an ecosystem, and explains how the removal of such a species can lead to ecosystem collapse. Examples of keystone species include wolves and ecosystem engineers like beavers and mangroves, which create habitats that would not exist without them.
Mindmap
Keywords
💡Biodiversity
💡Ecosystem Services
💡Species Richness
💡Species Evenness
💡Ecosystem Diversity
💡Island Biogeography
💡Ecological Tolerance
💡Adaptation
💡Ecological Succession
💡Keystone Species
Highlights
Introduction to Unit 2 of the AP Environmental Science course and exam preparation.
Emphasis on the importance of understanding the concepts in Unit 2 for the AP exam.
The necessity of practicing the writing style required for the AP Environmental Science exam.
Overview of biodiversity as the first topic in Unit 2, including its definition and importance.
Explanation of the three levels of biodiversity: genetic, species, and ecosystem.
The nested relationship between the levels of biodiversity and their benefits.
Discussion on genetic diversity and its role in species adaptation to environmental changes.
Species diversity and its measurement through species richness and evenness.
The concept of ecosystem biodiversity and its impact on biomes.
Introduction to ecosystem services and their categorization into four key groups.
Examples of how ecosystem services benefit humans financially.
The impact of human activities on disrupting ecosystem services, using the Deepwater Horizon oil spill as an example.
Introduction to the theory of Island Biogeography and its two simple rules.
The relationship between island distance from the mainland and species richness.
The relationship between island size and species richness.
The vulnerability of specialist species on islands to invasive species.
The concept of ecological tolerance and its importance for species survival.
The role of genetic diversity in allowing species to adapt to environmental disturbances.
Natural events that cause ecosystem disturbances, including periodic, episodic, and random events.
The Malankovitch Cycles and their influence on Earth's climate and sea levels.
Adaptation as a response to natural ecosystem disturbances, exemplified by Homo habilis and opposable thumbs.
The process of ecological succession, including primary and secondary succession.
The role of keystone species in maintaining ecosystem stability.
Conclusion of Unit 2 review and encouragement for students to think critically and apply their knowledge.
Transcripts
hey everybody it's Mr smeads and today
we're going to be reviewing unit 2 of
the AP environmental science course and
exam if you're ready to think like a
mountain and write like a scholar let's
get started before we go any further
with unit 2 today make sure you've got
your ultimate review packet study guide
printed out and ready to go as we go
through this video you want to answer
the practice questions make sure that
you really understand the concepts that
are covered in unit 2. that exam I may
is just too tough to go into without
practicing the writing style that you
need in Apes so make sure you're
practicing with the mini frqs at the end
of each unit so on we go into unit 2
with a short but sweet look at
biodiversity many of these Concepts
would be familiar already from your
biology classes so if you want to see
where we cover specific Concepts make
sure to take a look at the video time
stamps here that way you can pop down to
those sections if you just need A Brief
Review now the first Topic in unit 2 is
biodiversity and it's one that students
think they understand but often don't
fully grasp and that's because the basic
definition is really simple it's just
the diversity of different life forms
found in an ecosystem but what we really
need to make sure we have down are the
three different levels of biodiversity
and why biodiversity is so beneficial
remember that the three levels of
biodiversity are genetic biodiversity
ecosystem biodiversity and species
biodiversity and these three levels are
nested within each other which helps us
remember why they're so beneficial
genetic diversity is the variance of
genes or traits found within individuals
of a population so high genetic
diversity or a wide range of different
traits is beneficial to species because
it increases the likelihood that if
there's an environmental disturbance or
a change in that ecosystem some of the
members will have genes or traits that
allow them to adapt so if you have a
population of sparrows and then there's
a drought that causes the seeds they eat
to become dry and harder High genetic
diversity in that population will
increase the likelihood that some of
them have bigger beaks that can still
crack those harder seeds open species
diversity is the diversity of different
types of organisms found in an ecosystem
now there's a really simple way to
measure and there's a more complex way
to measure it now the easy way to
measure is species richness this is just
a count of the total number of different
species found in a given ecosystem but a
higher species richness doesn't
necessarily mean that an ecosystem has
more species diversity we also want to
consider what's called species evenness
this is the distribution or the balance
of the population sizes of all the
different populations present so if we
look at this diagram we can see that
even though the two forests have the
same species richness Force number one
will have a higher species evenness now
this higher species evenness is
beneficial to the whole ecosystem of
forest number one that's because if
there were disease that spread among one
deciduous tree species in that ecosystem
there would still be plenty of conifers
or other deciduous species to repopulate
that Forest now if the same disease were
to strike in force number two that force
would have the potential to lose 70
percent of its tree cover if this
dominant tree species were susceptible
to that disease now that would devastate
the forest in a way that Forest number
one wouldn't be so just like genetic
diversity is beneficial to populations
and species diversity is beneficial to
ecosystems ecosystem biodiversity is
beneficial to entire biomes an ecosystem
diversity just refers to the variance in
the different ecosystems found in a
given area so the tropical rainforest
would have a really high ecosystem
diversity you're going to find Rivers
different types of tree stands Edge
habitats where a forest meets an open
area whereas a desert biome is going to
have a lot lower ecosystem diversity and
be able to support less species richness
because of that so now that we
understand why biodiversity benefits
ecosystems let's take a look at how
ecosystems benefit humans by making us
richer now I know what you're probably
thinking wait uh what is going on here
the vegan bike riding carbon emission
cutting environmental science teacher is
talking about exploiting nature for
money but remember many of the things
that we attach monetary value to
ultimately come directly from or are
dependent on the natural function of
ecosystems now these Financial benefits
that we get from ecosystems are called
ecosystem services and in Apes we
categorize the different type of
services into four key categories
provisioning services are the easiest to
remember and that's because these are
things provided directly to us by
natural ecosystems examples would
include things like wood for furniture
or houses that can be harvested and sold
for a profit supporting services are
processes done by ecosystems that
support a valuable Human Action such as
agriculture for example insects like
bees and moths May pollinate a farmer's
crops increasing the amount of produce
they can sell now the farmer could still
produce some food without those
pollinators but not nearly as much so
their profits or their yields are
supported by those pollinators
regulating Services refer to the fact
that ecosystems often regulate or
stabilize climate or other environmental
factors which saves US money from having
to pay to clean up unstable conditions
so the fact that trees sequester carbon
dioxide can save us money because it
reduces some of the expensive
consequences of climate change this
could be things such as droughts which
damage Farmers crops or storm damage
which could damage your home and finally
we have cultural Services which are the
recreational or intellectual benefits we
get from nature so a tourist going to
visit the Grand Canyon is going to pay a
park fee and stay at a local hotel which
generates Revenue scientists research
ecosystems and they might write books or
reports that lead to valuable products
being created in addition to being able
to identify the four categories of
ecosystem Services we also want to
understand how humans can disrupt
ecosystem services so great example
would be drilling for and transporting
crude oil so when the deep water Horizon
oil spill happened in the Gulf Coast of
Mexico a ton of ecosystem Services were
disrupted fishermen weren't able to
catch as many fish and their profits
suffered mangrove swamps and salt
grasses died which destabilized the
coastline and led to more storm damage
and the tourism industry was impacted as
beaches were covered in oil and tourists
were less likely to come visit and on
topic 2.3 we'll take a look at the
theory of Island biogeography this can
sound like a super complex topic but it
really just boils down to two Simple
Rules so let's say we have two islands
of equal size but one is closer to the
mainland than the other the closer
Island would be likely to have a higher
species richness just because there are
more species capable of migrating to the
island from the mainland the further
away from the mainland island is the
fewer species that are able to fly or
swim there so if we plot distance from
the mainland and number of species on a
graph we'll see an inverse relationship
between the two now if we look at two
islands that are the same distance from
the mainland the larger Island would be
likely to have a higher species richness
this is due to the fact that it's going
to have a higher ecosystem or habitat
diversity with more space there's a
greater variety of Landscapes like
forests or grasslands or ponds this
means that we can have a wider variety
of plant and animal species supported in
this ecosystem so if we plot Island area
and number of species on a graph we'll
see a direct relationship between the
two as the Island area increases so too
does the number of species supported by
this island we also need to remember
that Island ecosystems are somewhat
unique in that they're going to offer a
narrow range of food and habitat choices
to species this often leads to really
specific adaptations where species are
adapted to the conditions of these
narrow food and habitat choices take the
dodo bird for example this large
flightless bird species evolved from a
member of the pigeon family some 20
million years ago now because it only
inhabited the small island of Mauritius
it didn't have a lot of competition from
other herbivores or pressure from
predators this led to an increasing body
size and the loss of flight because a
small flight worthy body wasn't
advantageous anymore without competitors
or carnivores to fly away from and the
problem for these highly specialized
species is that because they're uniquely
adapted to these narrow conditions
they're often unable to adapt to or
compete with invasive species that show
up on their Island and this is precisely
what happened to the dodo bird when the
most invasive species of all time showed
up on their Island the humans now
without getting too graphic suffice it
to say that the dodo bird is not around
anymore and the big takeaway here is
that islands are going to have a higher
percentage of specialist species than
the mainland and those specialist
species are going to be more vulnerable
to invasives because they're so uniquely
adapted to the narrow conditions of
those islands
dodo brain
so as good as DW is at cooking Arthur
this one doesn't really add up
definitely didn't go extinct because
they were dumb they just evolved on an
island with no natural predators and so
they weren't afraid of the humans when
they showed up so maybe the real dodo
brains were the Dutch Sailors who hunted
dodos at a way faster rate than they
could repopulate and somehow didn't
think that would lead them to Extinction
so moving on from islands and dodo
brains we'll take a look at a really
simple concept called ecological
tolerance this just refers to the range
of conditions an organism or species can
tolerate before death or Serious injury
ensues so let's start with an easy
example that we're all really familiar
with and that's human body temperature
most of us are sitting somewhere between
a comfortable 97 and 99 degrees
Fahrenheit now there are a few outliers
with especially high or low body
temperatures and this is a great example
of genetic diversity but in general
humans have an optimal range for body
temperature of about 97 degrees to 99
degrees this is the range where bodies
function most optimally we're able to
survive grow and develop so what happens
if an organism moves outside of its
optimal range the first thing that
happens is it enters What's called the
zone of physiological stress so let's
return turn to this human body
temperature example if your body goes
above 99.5 or below 95 degrees you're
going to enter a stressed physiological
State you're not going to think or move
as quickly as you would normally and
you're not going to be able to remain
here for long without serious
consequences if you move even further
from the optimal range so above 106
degrees or below 86 degrees you're going
to leave the zone of physiological
stress and enter what we call the zone
of intolerance which quickly leads to
death now this is a great time to review
why genetic diversity is so important
there's a general range of tolerance
that all the members of a given species
share such as this optimal range for
human body temperature but there's also
some variation between individuals and
that's due to genetic diversity so some
individuals may have a wider range of
tolerance or a wider optimal range than
others and this is how genetic diversity
can act as sort of a buffer against
environmental disturbance so if the
environmental conditions of a population
change such as the temperature or the pH
of their environment some of the members
are going to have a wider range of
tolerance due to genetic diversity they
can survive the environmental change and
pass on these tolerant genes to their
offspring which allows a new population
to evolve that is now adapted to this
new condition speaking of environmental
disturbances we need to take a minute to
review the non-human or natural events
that can disturb ecosystems now before
you start thinking I'm letting humans
off the hook for disturbing the
environment with five whole units
dedicated to the different ways that we
impact the environment so don't worry
but for natural events that cause
ecosystem disruptions there's three main
levels of frequency we need to
understand first we have periodic events
these are things like rainy Seasons or
dry seasons that happen with some
regularity then we have episodic events
these occur less regularly but they're
still occurring with some regularity
especially when the environmental
conditions are right great examples of
these events would be hurricanes and
forest fires they don't happen super
regularly but they are more likely to
occur when the environmental conditions
are right and finally we have random
events which as their name implies occur
with no Rhyme or Reason whatsoever these
are things like an asteroid striking
Earth or volcano erupting however
ecosystems can also will be disrupted by
slow gradual changes in Earth's climate
over time the reason Earth's climate
change is naturally over time is because
the orbit that the Earth takes around
the Sun changes naturally over time the
first way that the Earth's orbit around
the sun changes is called eccentricity
this refers to the shape of the orbital
path that the Earth takes around the Sun
sometimes this shape brings the earth a
bit closer to the Sun in its orbit and
sometimes a bit further away the second
is called axial precession where how
much the Earth wobbles on its axis and
the third is the change in Earth's
obliquity or tilt we call these
variations in Earth's orbit malankovic
Cycles since each of these Cycles
happens with a regular frequency they
produce regular changes in Earth's
climate as a result notice on the x-axis
of these graphs that we're talking about
cycles that unfold over tens of
thousands of years so they produce
really gradual climate change not the
type of change we're seeing right now
which is easily observable in one human
lifetime what scientists have learned
from lining up the timing of these
malakovich Cycles with ice core
temperature data is that these Cycles
impact the temperature versus climate by
bringing closer or further away from the
Sun or tilting the Northern Hemisphere
closer or further away from the Sun now
don't worry about understanding the
intricacies of the malakovich Cycles you
don't need to go this in depth in Apes
what you do need to know is that earth's
climate changes naturally over time over
the course of tens of thousands of years
as Earth's orbit brings Earth either
closer or further away from the Sun or
tilts the Northern Hemisphere closer or
further away from the Sun the other
thing we need to remember about Earth's
natural gradual cycling of climate
change is that it causes a change in sea
level as we can see here there's a
really clear link when we look at the
last 400 000 years worth of data on
global temperature and sea level during
periods where earth's climate is warmer
sea level rises due to both the melting
of glacial and polar ice sheets and also
the thermal expansion of water molecules
in the ocean now in the context of
ecosystems let's think about what this
rise in sea level and change in
temperature can mean low-lying Coastal
ecosystems like estuaries may be
completely flooded and may disappear
during periods of high sea level shallow
ocean waters that provide tons of
sunlight to Coral Reef ecosystems may
become deeper and light may not
penetrate to the bottom which completely
changes those ecosystems these are the
types of ecosystem disturbances we need
to think about when we're talking about
this slow gradual cycle of natural
climate change now you may be thinking
poor manatees or Coral or other species
that are impacted by natural ecosystem
disturbance but don't forget that
ecosystems and organisms can adapt in
fact every species on Earth is the
result of adaptation on the part of some
ancestor species forced to change based
on natural ecosystem disturbances and
environmental upheaval so the next time
you catch a dub in Call of Duty or
fortnite don't forget to thank homo
habulous for those opposable thumbs in
all seriousness though let's take a
closer look at how this trait of
opposable thumbs may have Arisen in
ancestors of Homo habilis first we need
to think back to the genetic diversity
concept that we reviewed in the
beginning of this video because of
genetic diversity there's a range of
traits even thumb muscle arrangement in
all members of a population so some
early members of the homo habulous
species randomly developed an new thumb
muscle Arrangement roughly 2 million
years ago this thumb muscle Arrangement
allowed for a tighter more nuanced grip
that ultimately led to the ability to
manipulate and create stone tools now
the prevailing scientific consensus is
that this new thumb muscle Arrangement
enabled homo habulous to create and
wield more efficient stone tools for
cracking open animal bones this gained
them access to the energy-rich marrow
inside and gave them a huge energetical
advantage over similar primates that
didn't have this same access to bone
marrow now because of this big
energetical Advantage the opposable
thumbs brought members that had this
adaptation survived longer due to access
to more marrow and passed on those
traits to more offspring an adaptation
is just a genetic mutation like a new
thumb muscle Arrangement that gives an
organism a higher likelihood of
surviving and reproducing as we wrap up
our review of adaptations here the
important thing to remember is that
organisms are either able to adapt to
environmental disturbances or they're
unable to adapt to environmental
disturbances and then they go extinct
some of the environmental changes that
early hominids adapted to were moving
out of dense forests and into grasslands
in these new grassland conditions it
became advantageous to be able to stand
up so we see Homo erectus with the
ability to stand upright look around and
Survey the environment it was also
advantageous to be able to wield more
efficient tools to break open animal
bones to get more energy all of these
are great examples of adaptations that
allowed species like Homo habilis to
adapt to new environmental conditions
survive and pass those traits onto
Offspring and speaking of surviving look
at you surviving all the way to the end
of the unit 2 review as we wrap up our
review of ecosystems we'll review
ecological succession and keystone
species first of all we have to remember
that there are two types of ecological
succession that's primary succession and
secondary succession in primary
succession pioneer species like moss and
lichen start to colonize a bare rock
ecosystem when the wind transports their
seeds or their spores there now they're
able to grow on bare rock because they
can secrete acids which release the
nutrients and minerals they need from
The Rock through a process called
chemical weathering this chemical
weathering process combined with a death
and regrowth of the Moss and lichen
slowly lead to the formation of shallow
rocky soil this in turn allows other
pioneer species like grass wildflowers
and shrubs to colonize the area
eventually the continual death and
regrowth of these early successional
plants adds more and more organic matter
and depth to the soil this then enables
intermediate successional species like
shade intolerant fast-growing trees to
come and colonize the area over time
slower growing shade tolerant species of
trees like Oak and Maple grow up and
replace the intermediate successional
trees and trucks we call this community
that has progressed through these stages
of succession in climax community these
ecosystems typically have large amounts
of biomass and support a high species
richness secondary succession follows a
really similar progression of changes
with one key difference there's already
soil present instead of moss and lichen
being blown in by the wind and
colonizing bare rock you have pioneer
species like grass and wildflowers being
blown in by the wind and they're
colonizing Disturbed soil you see
secondary succession tends to take place
after a disturbance that clears out the
existing vegetation this could be a
forest fire a glacial Retreat or even
humans abandoning an agricultural field
the pioneer species in secondary
succession are still fast growing and
Sun tolerant and typically they have
their seeds dissers by either the wind
or by animals and finally we'll review
keystone species now remember a keystone
species is more than just an important
species every species has some level of
function in its ecosystem but a keystone
species is one that's so vital to its
ecosystem function that if it's removed
the entire ecosystem can collapse so if
we were to lose a keystone species like
wolves from a forest ecosystem the deer
and Alchemy overpopulate this would lead
to over grazing of the vegetation of
that ecosystem and this could be so
intense that other organisms would lose
those trees and food and habitat
resources this could even lead to the
reshaping of the landscape as the tree's
roots would no longer be there to hold
the soil intact and the banks of rivers
might erode without those plants
stabilizing the soil along the banks
other keystone species examples include
ecosystem Engineers like beavers and man
groceries these species shaped landscape
so dramatically that they create
habitats That Couldn't exist without
them the mangrove swamp would be
impossible without those stilt-like
roots of the mangrove tree and the
Beaver Pond would be impossible without
the Beaver Dam and that is unit two
in the books hopefully you feel like the
vocabulary richest of your mind has
increased maybe you even have some fast
growing mid-successional Apes ideas
taking root in the soil of your brain
thanks for watching today ape Scholars
as always think like a mountain and
write like a scholar
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