We know that there are species that are under the threat of extinction. What can we do to
conserve them? What are the ecological processes that we can use? Or what are the
conservation strategies that we can use to protect those species to save them from the brink
(Refer Slide Time: 00:33)
In this context, we have two different kinds of strategies which are In-situ conservation
and Ex-situ conservation. And, in today’s lecture we will have a look at In-situ
(Refer Slide Time: 00:43)
As always, we begin with the word roots; in situ means on site. So, this is conservation
that is done within the natural habitat. On the other hand ex situ conservation, ex situ means
off site, which is conservation that is done outside the natural habitat. In situ conservation
would be conservation that you are doing within the natural habitat. So, things such as
national parks wildlife sanctuaries come under in situ conservation, because you already
have organisms that are living in those areas and so, you are conserving the organisms on
Ex situ conservation is when you are trying to conserve the organisms outside their natural
habitat. If you are setting up a seed bank, and taking out seeds from the natural habitat,
and storing them there in the seed bank. So, that if something happens to the natural habitat
you can use the seeds bring them to the natural habitat and you can regrow the plants back.
So, that would be an example of an ex situ conservation or things such as zoos.
You have a zoo in Delhi. So, those animals are not naturally living in Delhi, but they have
been brought from different areas of India, in different areas of the world, and then they
are kept in the Delhi zoo. So, zoos are an example of ex situ conservation.
(Refer Slide Time: 01:53)
The process of in situ conservation would be that areas in the national habitat are
designated as reserves, national parks or protected areas. So, you classify the natural
habitats or you look for those areas in the national habitat, that you can classify as reserves,
national parks or protected areas. And, then in these areas ecological monitoring and
interventions that is active management are done and legislations are required to maintain
these areas as protected areas.
What you are doing is you are taking out some areas of the natural habitat. And, you are
saying that these areas will be protected areas, you are putting up some legislation. So, that
people are not able to intervene into these areas, or people are not able to divert these areas
for some other applications. And, once you have done that you do habitat monitoring and
some amount of interventions.
Now, these interventions could be say if you are observing that the wild dog population in
your area in that actual habitat is going down. So, then you would ask the question what
is the reason. Probably your wild dogs are not getting enough amount of food or probably
they are suffering from some disease. So, the intervention in this case would be to intervene
at the level of food or at the level of disease.
Suppose they have some disease. So, you might give them some antibiotics or maybe you
could try to vaccinate them if that diseases leading to a high amount of death rate and so
on. So, that is the process of in situ conservation.
(Refer Slide Time: 03:25)
Whereas, in the case of ex situ conservation you designate areas with suitable conditions
and facilities are created in those areas. So, when you are setting up a zoo, you designate
certain area in your city or outside your city and you say that ok, we are going to construct
this zoo here, then you create facilities in those areas. So, you create enclosures, you create
pathways so that people can come visit these areas. You create pathways through which
feed will be brought for these animals; you create pathways so, that where you can bring
in more animals from outside or maybe take some animals outside. You create facilities in
terms of veterinary care, what are those designated areas in your zoo where if an animal is
suffering from a disease, you can take it out and give it some amount of veterinary
All these facilities are created and once you have these facilities, the species are moved
into this designated areas for their survival in breeding. In a number of areas you also do
captive breeding of these animals. And, then the third stage is optional when the species
are later released into their natural habitats. So, that is the ex situ conservation.
(Refer Slide Time: 04:37)
Now, in situ conservation gives a certain amount of advantages over the ex situ
conservation. And, at the same time it also suffers from certain disadvantages as compared
to the ex situ conservation. So, when we are talking about in situ conservation you can
think about say a tiger reserve. Should you keep a tiger in a tiger reserve or should you
keep a tiger in a zoo? In both the instances we are trying to conserve the tiger. Now, in the
if you are keeping it in a tiger reserve it would give you certain advantages.
Species continue to live in their natural environment a zoo is an artificial environment
whereas, a tiger reserve is a natural environment, it is less disruptive and less costly. So,
you are not required to take the animal away. So, if you are taking a tiger out of a forest
area and to keep it into a zoo, you need to engage a number of people, this tiger will have
to be immobilized and then put into a cage, and then transport it to another location, and
then once it has been moved into a zoo then, it will have to be fed. And, all these feeding
arrangements will also require quite a lot of cost whereas, if you are keeping it in the
natural environment, the tiger is going to hunt by itself, you do not have to go there and
feed this tiger everyday.
So, it is less disruptive and less costly. Also natural behaviors are maintained. If, you have
tigers that are living in the wild conditions, in those situations, the cubs that are born will
be trained by their mothers on how to hunt? They will remember and they learn these
processes of hunting whereas, if you are keeping a tiger in a zoo so, a tiger will vary easily
forget how to hunt and because it is getting a food in a premade format. So, the animals
are already killed and probably already cleaned before giving it with the tiger. So, it will
lose out it is natural behaviors very easily.
Protection of natural habitat provides protection to other species as well. In the case of a
tiger reserve, when you are protecting the tigers you are at the same time also protecting
the Chitals, the Sambars and a number of other species leopards and so on by protecting
the tigers. Whereas, in the case of ex situ conservation, if you are keeping it in the zoo. So,
if you are only keeping a tiger in the zoo, then in that case you are not protecting the other
Now, even in the case of ex situ conservation, the animal will need to be released
somewhere. Because, if you are keeping tigers in a zoo, you are doing captive breeding
and from say 5 tigers, now you have 50 tigers. Now, if you have 50 tigers, what do you do
with these 50 tigers? They will have to be released somewhere, because keeping a tiger is
If you have in situ conservation sites, then these sites will provide suitable areas for such
releases later on; so which is also why you need to maintain in situ conservation areas as
well. And, also reserves double as places for scientific studies and public awareness, which
is also why we keep in situ conservation methods.
(Refer Slide Time: 07:27)
However, it also suffers from certain disadvantages. It requires very large areas. So, in the
case of tiger reserves, it will have tens or even hundreds of square kilometers of area.
Whereas, to have a zoo, you might set up set up a zoo in a very small area, say a few square
kilometers. So, in situ conservation has this disadvantage that it requires the very large
area. Also less intensive protection and management, because the areas may be enclosed
upon or the animals poached.
So, here we have the classic example should you keep all your eggs in one basket or should
you keep your eggs in different baskets. In the case of a zoo when you have all the animals
in a very small area, you can give a very good amount of protection to those few number
Whereas if you are keeping the animals in very large size forests. So, you cannot be there
in the forest at all places at all times. So, it is possible that some poachers might get inside
and poach some of the animals, or maybe some people would try to encroached upon some
areas of the forest, but that is a possibility. So, which is there in the in situ conservation.
Then, there is a threat of diseases and disasters. Because your level of intervention in the
case of in situ conservation will not be very high whereas, in the case of a zoo a diseases
much easily controlled because you have access to all the different animals. So, you can
give medicines to all different animals on all days whereas, in the case of in situ
conservation that is not possible. And, also large establishment is required in each case, if
you want to maintain a tiger reserve. So, you will require a large number of forest cards a
large number of rangers some SDOs, some DFOs and so on. Whereas, in the case of a zoo
the level of establishment is not that high, because it is a smaller facility.
(Refer Slide Time: 09:13)
Now, if we are trying to go with in situ conservation. So, in this lecture we will concentrate
on in situ conservation. If you are going with in situ conservation, what should be our
strategies? So, basically we are asking the question, where should we make these reserves?
We said that we wanted to create these in situ conservation reserve, we want to make a
tiger reserve. Where should we have this tiger reserve?
Second, what should be the size and shape of these reserves? Is there any ecological
concept through which we can determine what should be the shape and size of this reserve?
Should we have large reserves, should we have smaller reserves, or should we have
reserves that are say linear, or reserves that are circular, or reserves that are square in size,
or square in shape, what should be the size and shape of the reserves?
What are the ecological principles through which these would be guided? And, third
question is how are we going to manage these reserves? So, we begin with where to make
(Refer Slide Time: 10:11)
Traditionally reserves have been created in areas that are beautiful areas. So, areas that
have lush green mountains, lakes, beaches, example the Dachigam National Park in
Srinagar, it is a very beautiful area.
Earlier, when kings wanted to make a reserve they would choose a very beautiful serene
environment and create a reserve or we could create reserves in those areas that have a
high species diversity. So, we can use our knowledge of ecology or our understanding of
ecology to say, that we should create a reserve in an area that has a high species diversity.
So, that we can conserve a large number of species if you create a reserve an example is
the Silent Valley National Park in Kerala. So, this area has a very high species diversity or
another way of creating a reserve is those areas that harbor unique animals.
For instance, we have this Gir National Park in Sasan Gujarat, because we have lions there.
The only reason we have this natural park there is that we have this unique animal lion that
has not found anywhere else. So, these were three ways in which traditionally we have
been creating reserves, but then these could become very haphazard and based on the
whims and fancies of the reserve creator.
For instance, if I am not interested in lions and probably I had to set up this reserve, I could
even say that lions are not important for us. Let us create a reserve for say gharials. Now,
gharials are also important species, lions are also important species, but then I can make a
decision that I should have a reserve where we have gharials and not lions and somebody
else may say that we should have a reserve where we have lions and not gharials.
Now, is there a way? Can we use our ecological understanding to reduce this amount of
whims and fanciness so that everybody can come to a common platform? And, so, the
process of reserve creation becomes more and more systematized.
(Refer Slide Time: 12:11)
Now we look at the scientific ways of creating reserves. Scientifically or ecologically we
can say that we should have reserve in those areas that have high species richness, because
in that case when you construct a reserve, you will be conserving a large number of species
automatically. We also require an area that have a high degree of endemism.
(Refer Slide Time: 12:37)
Because, if we have an area in which you have a particular species say lions. So, if lions
are only found in this area and not found anywhere else if we construct a reserve in this
area, will be conserving this population of lions, because if we lose our population of lions
in this particular area, will lose the lions completely forever.
We also require need to have reserves in those areas that have a high degree of species
endemism. And, also we require reserves in those areas that have a high number of species
that are under threat. Threat, richness and endemism are three things that should guide our
process of selecting areas where the reserve should be set up.
(Refer Slide Time: 13:25)
How do we begin with that? We will begin by plotting where different species are found.
So, things such as global mammalian richness can be plotted to see, what are the areas
where we have a larger richness of mammalian species.
(Refer Slide Time: 13:39)
Or we could do it for amphibians species, or we could look at the IUCN lists of which
different species are under threat.
(Refer Slide Time: 13:47)
And, we can plot those species. So, global mammalian species that are under threat. So,
here again we can see for instance that the areas in Southeast Asia have a larger amount of
threat or a larger number of species that are under threat.
Probably we require more amount of conservation in that area or amphibian species under
(Refer Slide Time: 14:05)
We can use our knowledge of the concepts of biogeography to state that, because different
species are found in different areas, because different areas have different habitats, and
because the species under threat are found in different areas. So, which are the areas in
which we need to set up our reserves.
(Refer Slide Time: 14:31)
One way in which we can collate all of this different information is by looking at
biodiversity hotspots. So, as we have defined before biodiversity hotspots are areas that
have high species richness, high degree of endemism and high degree of threat.
(Refer Slide Time: 14:49)
We have quantified all three of these, we have plotted these things together to look at the
areas that have theta Biodiversity hotspots. So, even in our country we have this Tarai
region, we have the western ghats and we need more amount of conservation in these areas.
Now everybody can come to this platform and say that yes, we need to conserve more and
we need to construct more and more reserves in these particular areas.
(Refer Slide Time: 15:11)
When we are talking about threat, there is this other concept of setting up a triage. Now,
triage; ‘tri’ is three. So, triage says that we need to look at the level of threat that can be
perceived by us.
If there is an area that has a very high degree of threat. So, there is a very small piece of
forest. Suppose, this is a very small piece of forest and this forest is surrounded on all sides
by different villages, and all of these villages are putting a very high amount of influence
on to the small piece of forest.
(Refer Slide Time: 15:35)
There is a very high degree of threat that this forest is perceiving. So, should we set up a
reserve here? Well the answer would be yes and no, yes if this area has some endemic
species that we need to protect at all cost, but then we could even go for the answer of no,
because we already have such a huge amount of human influences then probably it is
already a lost cause. Because, even if we set up this reserve, we cannot remove all of these
humans from these surrounding areas. So, this is already a lost cause.
(Refer Slide Time: 16:31)
Secondly, if the level of threat is very less so, why can we have situations say do we have
the level of threat that is very less, we have a very large size forest. And, in this forest there
are only these areas that have the villages. So, the amount of threat that is in this forest is
very less and especially in these areas, it is extremely less. There is practically no amount
of human influence in these areas. Should this area be a priority area for us, should we set
up a reserve in this area?
So, the principle of triage would say that, no, we should not set up a reserve in this area,
because this particular area can wait for a while. Even, if we do not set up a reserve in this
area, the species in this area are already protected, because there is a very less amount of
threat that we have in this area. So, which areas should be should be preferred for making
a reserve, that should be the areas that have a medium level of threat that is where most of
the focus is or should be.
Essentially, in this particular forest if you need to set up a reserve, it should not be in this
area, because this area already has a very high amount of human influence, it should not
be in this area. Because, here as well we have a very less amount of threat, but a reserve
should preferentially be constructed in these yellow areas, which have a medium level of
threat. Because, if you do not set up a reserve in this area, then probably with time, the
human influence that is now concentrated in this area would then move into this area.
Now, if we are setting up a reserve in this area, because currently these areas are not being
used by human beings. So, it becomes much more easy to convince the policy makers or
the administrators, that we need to set up these areas as it reserves. And, probably there
would be a very little amount of opposition from humans that are living in these areas,
because they are already not using these areas. And, if we are setting up a reserve in this
area because these are already a very high human use area then there would be an
The principle of triage tells us created in those areas that have a medium level of threat in
the highest preference. On the other hand if you have some area that has a high level of
threat or a very low level of threat and there is some other factor. There is some amount of
endemism or there is some policy issue, that after a while we might lose these areas as
well, then it would make sense to create a reserve in those areas as well because they would
also move into the medium threat category in that respect.
(Refer Slide Time: 19:17)
Another way in which we can look for areas where to set up a reserve is through the process
of gap analysis. Now, this approach tries to identify holes in the existing network of
protected areas that are primarily in locations that are or were historically uninhabitable
for humans due to their high prevalence of diseases etc.
Now, creating some protected areas in human dominated areas may fill the gap allowing
a different set of species to thrive. Now, what it says is that consider a hill.
(Refer Slide Time: 19:51)
Now, in this particular hill, those areas that were say on the very top and were very cold.
So, these are the coldest areas. So, these were not used by human beings. And so, probably
there was a reserve that was set up in these areas. Then, on though low lying areas, suppose
there were a number of marshes so, this was a marshy area. So, it had a very high amount
of infestation because of mosquitoes and so, because this area was not being used by
humans that was also a reserve that was historically set up in this area.
We have 2 reserves one is this reserve and the second one is this reserve that already exists.
Now, if we have another hill nearby should we also construct a reserve in this area and in
these areas? Now, gap analysis would say that no, because we have seen in the case of
biogeography that different species have different requirements. Hence, by constructing
these 2 reserves, we are conserving those species that live in cold areas and that live in
marshy areas, but what about those species that are living in these areas; they have not
been given any amount of protection so far, because these areas are extremely human
If we could take some area out of here and probably convert that into a reserve, then there
is one school of understanding that says, that this would be the most preferred location
where we should be setting up a reserve. Because, if we do that we would not only be
providing a continuity between both of these existing reserves, but at the same time this
would be an area whose habitat has not been afforded any amount of protection so far.
So, gap analysis says that we should identify the gaps in the existing network of protected
areas and set up a reserve in those areas where we can see a gap.
(Refer Slide Time: 22:03)
An example is the Khangchendzonga National Park in Sikkim.
(Refer Slide Time: 22:11)
If you look at the area and if you look at this area in 3 dimension, we will see that most of
the area is a very great height and so is very cold and so, this area has been set up as a
national park. But, then those areas that are not at that great height and are not set up as a
national park, probably those are the areas where we should also devote some amount of
(Refer Slide Time: 22:41)
Once we have decided what are the areas where we should have the reserves, the next
question is what should be the shape and size of those reserves? Are there any ecological
principles that should guide the shape and size of those reserves. Now, let us look at the
principles of reserve design.
(Refer Slide Time: 22:57)
The first principle is that big is better than small. If you have a larger size reserve, then
probably that is better as compared to a smaller size reserve; now, Why? Again, because
if you have a larger sized reserve then probably you will have a greater amount of habitat
(Refer Slide Time: 23:19)
Because, if you have a smaller size reserve, that will have say ‘N’ number of habitats, if
you have a larger sized reserve, you will have more number of habitats. More number of
habitats would then support more number of organisms, more amount of species diversity,
which is why we should have larger size reserves. Also, in the case of larger size reserves
you can even protect those species that have a large home range requirement, which is not
possible in the case of smaller sized reserves.
And, also administratively it is more secure and easier to manage per unit area, because
one larger populations are less susceptible to extinction. Because, in the case of larger
reserves, if we have larger populations, you only have deterministic factors that are playing
a role, but stochastic factors will not be playing a role, but in the case of a smaller reserve,
if you have a smaller population, then a stochastic factors will also be playing a role.
Second, when you go for a larger sized reserve, you have a small parameter per unit area,
which means that you have a less cost of protection. What does that mean?
(Refer Slide Time: 24:27)
Let us consider a circular reserve of say radius r. Now, the area of this reserve will be given
by π r 2 and the circumference of this reserve or the perimeter of this reserve will be given
by 2 π r.
Now, the most amount of protection that we need to do is on the circumference, because
it is on this circumference that people will come and get into the reserve. So, if there is
some person who wants to come into the reserve for poaching, he or she will have to cross
this perimeter. So, all of this perimeter needs to have a high degree of protection. So, our
costs are proportional to the perimeter of this area.
Now, if we look at cost per unit area, will find that it is proportional to 2 π r which is the
perimeter divided by π r 2
. So, π / π get cancelled out. And so, this is equal to 2 / r. So,
your cost per unit area is proportional to 2 / r. Now, if you increase r, this value of 2 / r
reduces. So, if you have more r. So, 2 / r is less, which means that you will have a lesser
cost per unit area, if you have a larger amount of r.
So, larger the reserve is, it means that you have less cost of protection per unit area. And,
third is that it is less vulnerable to catastrophes since smaller catastrophe will not impact
the whole area.
(Refer Slide Time: 26:21)
If you have a very small size reserve, this is the reserve and if you have a fire the whole of
the reserve might be lost to fire, but then if you have a large size reserve, and then you
have a fire here a probably a larger sized fire, then you might be able to save the other
areas. So, there was a fire that destroyed this much of portion, but then these areas would
still be saved.
In that case, we say that the larger size reserve is less vulnerable to catastrophes, because
you will not lose the complete population. The population that is left or that you were able
to protect in the case of a larger size reserve might be sufficient in most cases to restock
the whole reserve later on. So, smaller catastrophes do not impact the whole area. So, this
is also another reason why we prefer to have large size reserves.
(Refer Slide Time: 27:07)
Now, it is not just a area, but also the connectedness; one big reserve is better than then
several smaller reserves of the same total area. So, here you have one big reserve here you
have 4 smaller reserves. And, the total area of these 4 smaller reserves is equal to the area
of the big green size reserve green colored reserve.
In this case also we will see that this reserve is better than having these 4 smaller size
(Refer Slide Time: 27:41)
Why? Because here we are saying that you have this one big reserve and then you have
these 4 smaller sized reserves. In the case of smaller sized reserves, because the
populations are not connected with each other. The animals that are here will not be able
to move to this other area. So, they will behave as small populations. And, again in the
case of small populations will have more amount of stochasticity.
In the case of the one large reserve in this reserve will only have deterministic factors that
will play a role in extinction, but in the case of these reserves will have the stochastic
phenomena, that will also play a role alongside the deterministic phenomena. So, the
chances of all these four suffering from local population extinctions is very high.
At the same time if you have these 4 smaller reserves, the total cost of maintaining these
results will also be very high, because here again if you have a smaller size. So, the
parameter per unit area is very high.
(Refer Slide Time: 28:49)
Next, if you cannot have a situation where you have a large sized reserve, you have to go
with smaller size reserves. In that case we say that closer reserves are better because they
minimize isolation. So, this left side, green colored four reserves, this configuration is
better than having this reserve why, because if you have these reserves that are close by.
So, there the animals will be able to move from one area to the other area. Because, there
is a very small amount of patch that has anthropogenic influences whereas, if you have
this population and this probably needs to move to this area, then it will find it very much
If these populations are able to mix with each other. In that case these reserve, if it suffers
from local extinction you will have animals that are coming from this small reserve, this
reserve and this reserve that will restock this population. The amount of stochastic
population loss that you will observe when the reserves are close by will be less.
Similarly, not only should these reserves be close together, but then in place of having
them in a linear fashion, we should have them in the form of a cluster. Because, in the case
of a linear fashion, if this portion suffers from an extinction, a local extinction only animals
from here will be able to come here, but animals from here will find it very difficult route
to reach this reserve.
Whereas, if you have it in the form of a cluster, if you have local extinction here the animals
from here will be able to repopulate, the animals from here will be able to repopulate. So,
cluster is always better than having a linear arrangement. This is also another learning that
we are learning from ecology.
(Refer Slide Time: 30:33)
Circular reserves are preferred as compared to linear reserves, because they have less
amount of biotic pressure.
(Refer Slide Time: 30:45)
What do we mean by that? If you have this reserve. In this case and you have say villages
in the periphery. In this case, the central portion of this reserve will have a very less amount
of biotic influence, because it will be protected from all of these using all of these buffer
areas. Whereas, if you have a reserve that is linear in shape and suppose you have the
villages here like this. In this case, the influence of these villages would be much higher
as compared to when it was a circular reserve, or to put it in other words suppose, from
any village the cattle are able to go say 10 kilometers inside.
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