Lecture 41 Biodiversity, population and ecological principles


So, in the last class, we looked at the organization
of matter in nature at different levels and ecology that is focusing on organism, population,
community, ecosystem towards biosphere. And when it comes to organisms and population,
we were discussing the population dynamics and how it is controlled in a population or
in a community. So, there are various models which controls,
which gives us an idea of the population that is in a community that is growing. So, the logistic model of population growth
essentially defines the growth of population in the absence of competition, so it is a
sigmoidal curve which tappers of to an equilibrium level which is limited by the resources or
some other external factors. So, the sigmoidal growth histories reflect
changing intensities of competition. Fecundity or the rate at which individuals
produce offspring should be high when there is plenty of food supply that is high intrinsic
rate of increase. And fecundity, survival or both should drop
when there is crowding or when the population is increases, and population growth would
slow until it ceased altogether. So, in logistic model also the population
cannot go on growing indefinitely it will crash at some point when it is exceeding the
carrying capacity of the ecosystem. So now when it comes to, when there are two
multiple species exist in an ecosystem, the Lotka-Volterra model defines the competition
between species. If populations of 2 species compete for a
resource, it must follow that the carrying capacity of habitat for each is reduced from
what it would have been if one species were in sole occupancy. So, if only one species was there that would
have been using all the resources but now into 2 species comes into the population that
is competition and the carrying capacity gets reduced because of the competition between
the 2 species. This will result in the elimination of one
species eventually if it carries on the competition stuff. So, the Lotka-Volterra model is the simplest
model which actually also can be used for prey-predator relationships or interactions
in a particular habitat or an ecosystem. The model was developed independently by Lotka
and Volterra in 1925-1926 period, it has 2 variables P and H and several parameters that
affect the equation. So it is defined by two independent equations,
so the first equation is the variation of the density of the prey that is defined as
dH by dt which is given by rH minus aHP where H is the density of prey, r is the intrinsic
rate of prey population increase, that is in the absence of any predator how much population
of that prey can grow with given resources in the ecosystem. Then similarly P is the density of predators,
so to determine r the intrinsic rate of prey population growth, we need to consider that
predator population is zero. a is the predation rate coefficient that also
determines how much in the presence of predator how the prey population is changing. b is the reproduction rate of predators per
1 prey eaten, so that dictates how many predators will be there, so dP by dt is the rate of
increase of the predator by eating the prey. So, b gives the reproduction rate of predators
per one prey in the eaten. And m is the mortality rate of the predators,
so these two equations are used for defining the, interspecific competition or the interaction
between prey-predator population. So, there are different parameters that are
used in this Lotka-Volterra model and how one measures this parameters are the following
set of experiments can be done, for example, keep prey population without predators and
estimate the intrinsic rate of increase, that we have done in the case of logistic model,
you give enough resources to the prey species and then keep counting the number of individuals
in the community as with time and that gives the intrinsic rate of increase of the population
of the prey. Then put one predator in cages with different
densities of prey and estimate prey mortality rate and corresponding K-value. So, this experiment can be done in lab using
small insects like lady-beetle and aphids, so, for example, lady-beetle eats aphids,
an example is that lady-beetle kill 60 aphids out of 100 in 2 days. Then, for example, we can determine the K
value as equal to minus ln of (1-60/100) which is equal to 0.92, and a, in this case, is
equal to 0.92/2, that is the K value equals instantaneous mortality rate multiplied by
time. Thus, the predation rate equals to the, that
is the a which is the predation rate equals to the K value divided by the duration of
experiment. So now if it is 2 days that is 0.92 by 2 that
is given for, so that gives us the value for per day, predation rate. So, if a value is estimated in different prey
densities are not close enough to each other then the Lotka-Volterra model will not work. So, you can change the prey densities and
then estimate whether the values that we get, value of a that we get is close to each other. So, then that says that whether the model
will work to define the relationship between the prey-predator composition in an ecosystem. However, the model can be modified to incorporate
the relation of the prey density in this case. Similarly, parameter such as b and m, how
do we determine that? So, what you do is keep constant density of
prey, example H=0, 5, 10, 20, 100 prey per cage, and estimate the intrinsic rate of predator
population increase. So, you just keep, let us say 5 preys or 10
preys in a particular cage and then estimate how many of those the lady-beetles are growing
at what rate, and then that will, or the predator is growing at what rate and that at these
densities of prey. Plot the intrinsic rate of predator population
increase versus prey density, so one can get a linear regression from this and that gives
us the, which is an rP equal to bH minus m that if you plot this graph we can get the,
which is, it is a straight line, and then from there you can get b and m values and
which can be used in the Lotka model for to get these two. So, the first equation is to get, first experiment
was to get r and H, and the second experiment is to get b and m which is, which are parameters
affecting the predator population growth, r and a are the values which affect the prey
population growth, so these two values will decide how the interaction between these two
species happen in the system. So, now we will summarize what we have looked
at so far, and the important concepts that one needs to look in ecology. Ecology is the vast subject which requires
as it is the science of the universe or somebody has defined earlier and, but it requires a
lot of detailed time and analysis to study that the interactions of different species,
different communities and how they coexist or and how life exists on earth itself. So, we are summarizing some of the important
points here, so one of the questions that we ask is what keeps us and other organisms
alive on earth. The earth’s life support system has four
major components that interact with each other that we have to take into account, and we
have to remember that is the atmosphere that is air, hydrosphere the water, the geosphere
which is consisting of rock, soil, and sediment, and the biosphere which is the, which consisting
of the living things. So, we have defined that you know how life
and this, and also, we remember that life exists in land and water. Terrestrial, so we classify this life that
is existing on terrestrial systems into biomes which are nothing but large region such as
forest, so the term biomes is used to classify large region such as forest, deserts, grasslands
etcetera with distinct climates and species that particular species that exist in those
biomes. The three major factors that sustain life
on earth are one-way flow of quality energy from the sun and through living systems through
the process of food web or the second is the cycling of nutrients and matter in the living
systems and the nonliving systems. And third is the gravity which allows the
planet to hold on to its atmosphere which is very important for us to have the living
condition being established here and also the movement of organisms on earth etcetera
are also dictated by the gravity. Similarly, what are the major components of
an ecosystem? So, when we define ecosystem, ecosystems we
have defined earlier as consisting of living and nonliving components, which interact and
forms the ecosystem and abiotic factors can limit the population growth, because this
is the nutrient cycling that is important which has to reach the living systems by nutrient
cycling, we will soon see what are the nutrient cycles and so that limit, that can limit the
population growth, for example, if nitrogen is in limited supply in an agriculture field
we know that the production will reduce. So, similarly, there are vital nutrients,
micronutrients, and macronutrients which are needed for the growth and wellbeing of organisms. For example, vitamins are very important for
the wellbeing of humans, it is not the food that we eat alone which gives us energy alone
is not sufficient for our biomass growth, we need also some vital supplements of micronutrients,
elements like metals and other thing, other elements like calcium, magnesium, and some
other trace elements sometimes Zinc, all these are required for the wellbeing and for the
living systems. So, abiotic factors can limit population growth
due to these aspects. Similarly, producers which are also known
as autotrophs, which means they can produce their own energy, and consumers are heterotrophs,
which feed upon others, are the living components in this ecosystem. Energy flow and nutrient cycling sustain ecosystems
and biosphere. These are the important points that we have
to remember about ecosystems, it is nothing but a mechanism for energy flow which is coming
from the solar system or the sun, from the sun to reach organisms and then maintain life
on earth. So, what happens to matter in ecosystems? We have discussed energy flow in ecosystems
and the efficiency with which energy flows in living systems, so which can be calculated
using in the case of plants it is estimated using net primary productivity and the efficiency. And the efficiency varies according, in different
ecosystems that we have looked at and we said, we have also seen that the efficiency of certain
ecosystems are much higher than others because of probably the biodiversity that exists there. So, similarly matter also flows in the ecosystems,
so mostly matter in the form of the nutrient cycle, what we call as biogeochemical cycles
within and among ecosystems and the biosphere. So, that is how the matter gets circulated
in the ecosystem and between ecosystems and the biosphere, so certain components have,
when you look at hydrology cycle or when you look at carbon cycle, or most of the cycles
have both atmosphere as well as living systems are involved. Human activities are majorly altering these
biogeochemical cycles, we will soon see those cycles. So, the cycles which we are aware of that
controls life on earth are water or hydrologic cycle, the carbon cycle, nitrogen cycle, phosphorous
cycle, and sulphur cycle. Let us take a look at, for example, nitrogen
cycle, so in this diagram, there are natural pathways in which nitrogen is, so nitrogen
cycle operates on earth, and red arrows indicate the pathways which are affected by human activities. So there are many of this natural biogeochemical
cycles are affected today by human activities, example is given in the case of this nitrogen
cycle here. So, for example, nitrogen oxides which are
from burning fuel and using inorganic fertilizers are released into the atmosphere, and that
affects again the other natural flow of nitrogen into the environment. So, there are processes and reservoirs one
can see in different colours, the blue colours indicates processes that go on in regenerating
the nitrogen and back into the cycle, and reservoirs are where nitrogen is stored for
certain time period. For example, nitrogen lost to deep ocean sediments,
nitrogen in ocean sediments, ammonia in soil etcetera are examples of reservoirs. And processes like electrical storms or lightning,
for example, volcanic activity, decomposition by microbes, uptake by plants etcetera are
processes which go on in converting one form of nitrogen to another form, or it is taken
up by plant, so one can see and nitrogen in plants and animals are also considered as
reservoirs because they may take time before they can get back into the system. Similarly, if you look at the phosphorous
cycle which is also again affected by human activities, some examples are mining waste,
sewage, fertilizers, detergents, all these, for example, can sewages recently because
of detergents that we use sometimes have polyphosphates which are used as builders which comes into
the water body, and then it runs off and reaches water bodies, so again these are reservoirs
of the phosphates, so in the water bodies they get again converted. So, the pathways are affected by human activities
by excessively releasing certain phosphates into the water bodies and it affects the biological
cycle in the aquatic as well as in the terrestrial ecosystems when water is consumed by organisms
and water is also used by aquatic organisms. Similarly, sulphur also the pathways are again
affected by smelting, burning coal and refining fossil fuels or use of fossil fuels also release
sulphur dioxide into the atmosphere and so basically you can see, it affects the sulphur
cycle as well. Carbon is a major cycle which is affected
by human activities, and one knows that the carbon dioxide in the atmosphere is one of
the reason for the maintaining the temperature, maintaining the temperature and it forms only
0.03% by volume in the atmosphere. However, it affects, or it dictates the temperature
control of our planet, so we all know that the climate changes one of the factors which
are affected by the carbon cycle in a major way, and also the hydrologic cycle. So, all these biogeochemical cycles can affect
climate as well as the existence of life on earth, so it is important for us to take into
account how this nonliving part or the abiotic part of ecosystem affects life cycle on, life
itself on earth and how it affects ecosystems and their maintenance. Similarly, another point that we need to summarize
this about biodiversity and evolution, so these are two points we touched upon, what
is biodiversity and why is it important? So biological diversity is the variety of
earth species, the genetic diversity, the ecosystem they live in, and ecosystem processes
such as the energy and material flow that sustains all life. So, this is essentially not just the diversity
of the living beings that we see around are is not the only way to explain biodiversity,
it is given here there are four major components for earth’s diversity which can be called
as ecological diversity that is the variety of terrestrial and aquatic ecosystems that
we see around. Second is functional diversity because there
are many functions by the ecosystems. Genetic diversity, so the genetic pool of
different organisms, for example, if you take, if you consider fish there are different species
of fish which are genetically different in a particular pond or a lake that we take as
a example ecosystem. Species diversity, so these are the four major
components that we see on earth as we go from one region to another or when we consider
biomes, so you can see different forms of life exist, and this diversity is that is
contributing to biodiversity. So, the biodiversity is the vital renewable
resource for all life on earth, so that is the most important message that we have to
keep in mind and to make life sustainable on earth, biodiversity is very necessary. And as far as our human understanding is concerned
of all the research that we have done so far with the scientist finding out how many species
are there, out of the 4 to 100 million species on earth, we have only identified 1.8 million
species, and there are 1000s of species discovered every year or identified every year which
we do not know what their functions are, what exactly their contributions are etcetera,
but is it important for us to know it? No, each of them have a unique function to
serve on the planet, and that is why it is important to have each and every species. So, and where do species come from? So, the definition or the understanding of
species, where do species originate or the everyone is aware of the book origin of species,
so which tells us that evolution by natural selection explains how life changes over time
or different species come into existence. So, populations evolve when genes mutate,
and that is the slight changes in the genetic makeup is what or when we have seen in the
first slide that is essentially telling us. So, this slide for example, tells us that
at the cell level, whatever changes that happens affects the organism and runs through the
population, community, and the ecosystem, and that is essentially what we mean by the
mutation that can happen at the molecular level which changes the cell and the organism
and then how the community get affected. So, basically the natural selection is the
process which happens at the molecular level of the DNA and that or the genetic the gene
of the organism and that gets transferred to the, in the flow of the organization of
life on earth. So that is one can see how species evolve
in this process itself. So, the species diversity is nothing but the
variety and abundance of species in a particular place that we see, what is meant by varieties,
the number of species that you see abundances nothing but the number of members of a particular
species that you see. So, the species diversity or biodiversities
expressed using a quantity that has both the components that is the number of species as
well as the number of members in each species that have to be taken into account to estimate
the biodiversity. Species-rich ecosystems, why are they important? They are important because they are more biologically
productive and also sustainable in under circumstances such as disturbance happens, or some chemical
pollution happens or let us say storm or a flood or drought happens, in all this cases
species-rich ecosystems are more stable when it comes to stability of ecosystems, when
it comes to stability of ecosystems. And the important thing that we have to remember
is that that is nothing unwanted on earth. So, each species has a unique role in its
ecosystem which is known as ecological niche. And there are generalist and specialist species
in an ecosystem, but at the same time each species has a unique role to play in that
ecosystem and which cannot be underestimated or under, we cannot disregard the role played
by that particular organism or particular species in an ecosystem. So, the niche can be occupied by that particular
place in the ecosystem can be occupied by native and non-native species. So, when it comes to what is meant by native
and non-native is that based on species roles, we can classify species into different types,
so that is why we call them native species, native species means species which are native
to that region or that native to that habitat. And non-native species which maybe migratory
or brought by humans or brought in by some other means, mostly humans have introduced
many species as non-native species which may not belong to that particular area. Sometimes food, for example, potato which
could have come from a different continent because it was you know considered as a good
food item, or it could be any other plant or organism that were brought to various parts
of the planet by human beings. So, they are all non-native species, but they
form major part of food today for human beings, so that is one of the reasons why many non-native
species can be found in many different places. Then there are indicator species, so they
indicate the healthiness of a particular ecosystem, examples are fish or frog, birds, bees, they
all tell us how, what is the health of an ecosystem. Let us take the case of a frog or a pond for
example, how do we know that the pond is in a healthy state or is it in a, for example,
the water in the pond can be, can we drink the water, is it healthy system? So many indicator species can be found for
example, in a pond or a lake in a freshwater system which can point the fact that the water
quality is very good, so for example, frog, frog is an amphibian, and it has life in the
water as well as on the land. So, frog lays eggs in the edge of water and
the land, so for example, it is very sensitive to the quality, the nature of water, for example,
the surface extension of water can be altered by let us say adding surface active agents
or surfactants into water, we all know that the surface tension will decrease. So, if the water quality is different, surface
tension can be different, pH can be different, the oxygen in dissolved oxygen water can be
different, all these affects. For example, the existence of let us say fish,
frog etcetera in water, and that actually indicates whether the water for example is
or that ecosystem where they are living is healthy or not. So, it is good to see the species like frogs
around us and to tell us that you know the ecosystem is healthy, so frogs egg as I said
is actually made of a membrane which is semipermeable in nature and any change, any certain changes
in its environment can affect the integrity of that membrane and the frog can be either,
it can die in the egg state itself or it can be born with some defects and which can be
observed in the case of any disturbances in its, in the environment or in the ecosystem. So, it gives us a kind of indication for the
quality of the ecosystem that it lives. Similarly, birds, world over it is seen that
the population of birds in many species are declining drastically due to various factors
such as atmospheric pollution, climate change, global increase in temperature, various other
human contributed factors, habitat loss, and lack of food all this are contributing to
the decline of birds, bees, etcetera all over the world. So, these are indicator species which tells
us that all is not well with the earth and its biomes, and it is time for us to wake
up and then act on these issues. Then there are two more classes which is keystone
species and foundation species, so these determine the structure and function of their ecosystem,
that is why they are called keystone species and foundation species. Keystones we all know that when buildings
are constructed there is a keystone that starts, that is laid where you start the construction
of the building, so that is considered as the first stone that determines the rest of
the alignment of every other stone that is used in the construction. Similarly, the species determines the structure
and function of their ecosystem, so they have a major role to play. So, any given species may play one or more
roles in a particular community, we will take a little-detailed look at keystone and foundation
species. Keystone species are they maintain and create
habitats, and several critical roles they can play such as pollination of flowering
plants, example keystone species are bees, butterflies, sunbirds, bats, these are all
examples of keystone species. For example, without the contribution of bees
or many insects which can pollinate a plants, the food availability to major part of the
planet will, especially to humans will be constrained to a large extent and human species
can face a large humungous problem if bees, butterflies and all these birds disappear
from the planet. So, for example, these species are getting
drastically affected by some of our activities, for example, when we see a mosquito or when
we see some adverse insects we use insecticides, and you know herbicides and other weed killers
and other plants, other chemicals which can harm these organisms which are playing a vital
role in our existence on earth. So, we are compromising the quality of existence
and compromising the quality of ecosystem services provided by these organisms towards
or to the species towards life on earth, and especially to human beings life as well, and
the quality of life that we have. Then we also have top predator keystone species,
examples are wolf, tiger, leopard, that we hear always or like certain sharks, etcetera,
they are predator species which are on the top of the food chain and also they are keystone
species, how do they affect the ecosystem is by regulating the population. So, their important role is in controlling
the population of the different species which they feed upon, so that is very important
role in so that for example a health of a forest ecosystem will be dictated by the tiger
or let us say leopard or a lion in that ecosystem. And which is important for let us say introducing
the number of herbivores species there, and the herbivores otherwise could increase in
number and could feed upon all the plants which are, which they can eat up, so which
can result in the collapse of a system for you know certain time before it recovers back. So, their top predator keystone species are
required for controlling the population of herbivore species and other plant and other
links in the food web below. Similarly, foundation species is as plays
a major role in shaping communities by creating and enhancing their habitats in the ecosystem,
an example is elephants, elephants when they move around they uproot trees and plants and
then trample the soil, they also turn around the grass many times, so the changes that
they inflict into the habitat helps in, for example, when trees are uprooted, grasses,
when sunlight can reach the lower bottom of the forest canopy, and this helps in grass
to come back and or start growing in an area where there was no grass before and herbivores
will get benefited greatly by this activity, or for example, fruit bats, so these for example
fruit bats can, for example, help create forest back, rejuvenate forest back in a place where
there is degraded forest land because they spread, they are very good dispersal agents
for seeds and that is how they can bring back forest in places which are degraded in nature. So, their role is very important, so we should
not be like considering them as pests or disturbance just because some angle of it is not acceptable
to us is not what the role in on earth in ecosystems, so it is very important for us
to consider these facts before we act upon certain things with humans and relook at the
living systems. So, the biodiversity is also species interaction
and population control are interconnected, so the species interaction can be of various
kinds which you have studied in school itself, which are interspecific and can be classified
into based on predation or that could be parasitic relationship which means one is exploiting
the other one. Mutualism means both are benefited from each
other which you would have seen, many species have this helping each other by, for example,
controlling the say certain insects let us say which you know troubles certain animals. So, in the process, for example, you would
have seen when buffalos and cows are moving in a field you can see certain birds like
herons or other birds may go along with them, so this could be an example where both animals
are benefited by the process. When animals are moving some flies are flying
around, or insects are flying which helps the bird feed upon, and also the animal also
gets help from the birds in turn by removal of the nuisance of the insect which are biting
them. So, similarly commensalism, where an example
is crow, which is commensal bird which lives along with us and sometimes lives on the leftover
food and other things and so there are species which are living based on human beings, which
is an example of commensalism or many other species also could be just living on the scrap
which is left by one species could be used by another one. And one more important thing when it comes
to species interaction is that predators and prey species can drive each other’s evolution,
how is this done? So, when predators hunt a prey, the prey’s
instinct for escaping from the predator will help it evolve better strategies, for example,
a prey species may evolve to become a faster runner by evolving to escape from the predator. Similarly, the predator will also evolve because
it is constantly strategizing to you know inventing strategies to get the prey which
it can feed upon. So, both are evolving in the process over
a long time period, and that is how evolution happens in such circumstances when there is
prey-predator relationships. Similarly, natural selection how it reduces
competition between species. So that is another question that comes to
us, so adaptation is the answer to this, so adaptation means how, if you look at many
different water birds, so if you go and look at marsh or a swamp area there will be so
many different species of birds which are feeding there in the marsh. So, what are the adaptations for these birds
if you look at, they will have, different birds will have different length of stock
of, the height of their legs will be different, the length of the beak will be different,
the kind of food they may be eating will be very different so you can see that a variety
of food habits they will evolve as well as different strategies to get the food will
also be evolved in the same place to see, so these are known as adaptations. Or for example in a canopy if there are birds
which are feeding in the canopy itself, they may also restrict themselves to certain regions
of let us say top, very tall trees if they are predating so, if they are finding food
from let us say insect-eating birds, they are finding food let us say in a canopy of
particular tree, so they will evolve eventually to specialize maybe in different heights of
the same tree itself, so there may be difference species locating and looking at food, looking
for food at different heights of the tree itself. So, this is an example of how adaptation,
would adaptation to a particular stress that is evolved in the environment could lead to
some form of survival strategy. So, that helps them survive in a situation
where there is interspecific interest, or intraspecific competition between species
is happening And in the absence of any competition what
limits the growth of population that we have seen is that resources especially the food
availability is one of the important things, food availability as well as for example if
it is birds or other species, where do they nest or where do they home? That is also an important parameter, so nesting
facilities, resources, when we say resources, it could be food, home, everything that comes
into the picture. So, with the constraints given no population
can grow indefinitely, this is applicable to human population also because the resources
will be shrinking as our population keep on increasing. And population can grow shrink or remain stable
depending upon the availability of resources, and when population exceeds a carrying capacity
it can crash, so this is the summary of what we have land in this course. So, there are certain principles in ecology
that we can carry home that is ecosystem structure and functions are determined by the forcing
functions of the system, that is based on mass and energy flow into the system. So, this how in ecosystem evolves and what
is its structure, how it functions etcetera are determined by the energy flow and the
material flow into the ecosystem. And the energy inputs to the ecosystems and
available storage of matter are limited, so based on the conservation of matter and energy. So, all ecosystems function based on the first
and second law of thermodynamics, so the energy inputs and how the energy is getting transformed
into material or storing, how it can be stored as matter are limited, based only in which
can be stored. And similarly, we have to remember that ecosystems
are, when we consider them as thermodynamics systems, they are open systems and dissipative
systems that means there is loss always from the system to the environment, it is not something
that is, it is not a closed system, so all ecosystems, if you look, are open systems
thermodynamically. Similarly, ecosystems also have a property
called homeostatic capability, that results in smoothing out and depressing effects of
strongly variable inputs. Which means, for example, if a flood or a
drought or a fire happens, forest fire happens, eventually through ecological succession of
the disturbed land they can come back to normal, some normalcy, though the homeostatic capability
is limited, and it is not necessary that none of the ecosystems will go back to a particular
state in or you know a particular stable state that we call, it is continuously influx and
continuously evolving, so it is a dynamic state that it is achieving. And one more thing that we have to remember
is these are ecosystems are self-designing systems. So, the processes of so of ecosystems have
characteristic time and space scales that should be accounted for environmental management,
so there is something that we have to remember always. That the ecosystem, so it is unlike or many
human device processes whether a mechanical system like a watch or a clock or a helicopter
or a ship works unlike that, an ecosystem is something has, it has its own characteristic
time. So, an ecosystem will evolve over a long period
of time, it is not something that happens which with short time scales which we can
observe and analyze, and their space scales are also different. So, they can be as small as my few micron
scales to, it could run into kilometer scales. The space scales are can be very, very large
or it could be very, very small under which it can operate, the ecosystems can operate,
so it has to be accounted for when we are considering management of ecosystems. Similarly, when we are considering ecosystems
as they said they are open systems and not only that they do not have clear boundaries,
so basically, we need to consider the ecotones or the transition zone, these are important
areas of an ecosystem, they work as membranes for cells. So, if you take biological cells, there is
a membrane which is surrounding the cell. Similarly, each ecosystem has what is known
as an ecotone area or a transition zone, for example, if you take a pond, the immediate
surroundings of the pond, for example, can get flooded during you know excess rains or
it could withdraw it a smaller area pond when there is no rain or a drought happens. So, there is no clear line that you can draw
it to say what is the area of that pond or a lake or a river or an ecosystem that we
are considering or a forest for example also. So, what is the exact you know boundary for
it? There is no boundary, so there is a, so we
need to take into account that transition zones, for example, seashore, it is a transition
zone or river banks they are transition zones. So that is why it is very important to consider
coastal regulations and regulations in constructing away from ecologically sensitive zones and
also ecotones and transition zones because animals and birds and other living creatures
do not see these boundaries as we see as walls and roads are such constraints that we put
in place. Other creatures require to crossover to this
different places, and that has to be kept in mind anytime when we are considering ecosystems. And so for example, considering construction
of roads through forest patches, so which will result in fragmentation of ecosystems
or habitats and animals will be in distress. And many different species can become you
know suffer because their water bodies or water access points could be elsewhere, so
these are all problems that could happen also because of this lack of this considerations. The components of an ecosystem are interconnected,
interrelated and form a network implying that direct as well as indirect effects of ecosystem
development need to be considered. So, every component in an ecosystem are interconnected,
and interrelated and forms a network. So, it is like if you are looking at a spider’s
web, so if you go and disentangle one of the legs of those, one of the strings of the web
it becomes less functional, and it can actually damage the web itself. So, similar implications can be thought about
in ecosystems also where we may not visualize, or we may not always see all the connections
which are existing there which can have catastrophic effects. An ecosystem has history of development, it
should be taken into account while doing anything with ecosystems. So this is also other important factor that
ecosystem is something, not that has not come about overnight. It has happened over millions of years and
including its nutrients cycling, the soil formation, the different species that has
come about there, all this has happened over millions of years of time, so that has to
be taken into account while we are doing any projects or any activities in this on earth. Ecosystems and species are most vulnerable
at their geographical edges, this is also another important factor or principle that
we need to think about or consider, an example as I said is the coastal zones or banks of
rivers or for example so, water channels, all this are or for example even when we are
considering a pond or a well where we have fresh water, and then, for example, it has
a boundary, a geographical edge or a boundary, so how do we treat those boundaries, I mean
you can go and impact those boundaries by let us say you know put concrete and then
concretize the boundary, which may not be a good idea at all because there are so many
living organisms like frogs which actually have life which is between the water and the
land. So, by concreting you may be affecting their
life cycle and also affecting the wellbeing of that ecosystem itself, so there are many
other species which are also making use of such areas which are very, very vulnerable
and ecosystems are more vulnerable at that geographical edge, so that needs to be taken
into account and though we consider them as we do not take into account this facts many
times when we look at ecosystems. Similarly, ecosystems are hierarchical systems
and are parts of a larger landscape. So it is not that they are isolated systems
which are sitting somewhere, and we can tamper with it, or we can do what we would like to,
they are just part of a larger landscape, and this is just a small part of the system
itself. So it is important to maintain landscape diversity
rather than looking at in a smaller and smaller unit such as ecosystems or individual species
and their protection and you know the aspects of protecting those habitats, so it is important
to consider maintenance of the larger landscape itself which it forms a part of. Similarly, physical and biological processes
are interactive, it is important to know them to interpret them properly. It is not that we can isolate physical processes,
for example, there is a climate change it will affect the biological processes as well,
or if there is a temperature change in the atmosphere, it affects our wellbeing or the
biological systems which are dependent on them. Or, so there are different physical processes
that we have discussed especially the nutrients cycles and the biogeochemical cycles, all
these are affecting the biological processes. So with this certain guidelines about ecology
and how we protect ecosystems, so there are various measures which are put in place for
protecting ecosystems and biodiversity on earth, and the different countries have different
protocols. India also has different protocols to protect
the biodiversity, so and the ecosystems which are very, very important for the wellbeing
of not only human beings but also other organisms which serve us lot of ecosystems functions
and ecosystem services as we have described in this class. And that is one of the major reasons why we
need to have an understanding of ecology, and I would suggest reading of good books
on ecology that is available, many books are available on web also, and many resources
are available on the web to understand more about ecology and concepts in ecology. And so I would stop at this point, in that
recommending, reading more about ecology and understanding ecosystems and their importance
in our lives. Whether we are doing in different profession
of engineering or science, it is important for us to understand the living system or
the living biomes where we are located ourselves and how our activities are disturbing the
different ecosystems and our own existence on earth.

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