Impact of Development On Environment

By Surabhi Tanwar

Human Impacts…

All Species Impact Environment

Understanding how humans interact with the biosphere is crucial to protecting the natural resources.

Humans Impact the Environment more than any species !

HumanActivities

that have changed the biosphere include

may have once causedoften relies on the methods of thehave resulted in

which increased

Food supply Pesticide useMonoculture

use

Hunting andgathering Agriculture Industrial

growthUrban

development

Extinctions oflarge animals

Greenrevolution

High standardof living

Increasedpollution

Industry

Industrial Revolution mid 1800’s.

Economy, Conveniences and Productivity advances

More “Stuff” More Waste

Increase use of Tools, Technology and Sciences

Use of Fossil Fuels Release of CO2 Green House Effect

Chemical and waste by products of manufacturing

Physical change of

Ecosystems.

Soil, Flore and Fauna… Concrete

Suburban Sprawl – Commuters to urban areas

Increase drive time to work & air pollution.

Biodiversity

Oxygen Production

Decreases

Increases

Water Run Off, Pollution, Heat, Habitat Problems

(Destruction, Degradation and Fragmentation)

Urban Development

Green House Effect and Global Warming

CO2 keeps heat radiation in Blanket

Carbon Dioxide is a primary green house gas, responsible for 60% of global warming.

Breathing Problems Irritation of Membranes

Burning Fossil Fuels is the BIGGEST Source (SMOG)

Ozone Layer is being broken down by CFC’s Found in Refrigerators, Coolants; this allows radiation to reach earth, causing genetic defects and cancer.

Air Pollution

Industry Transportation Ore smeltingPower generation

Abiotic and Biotic Issues of Fragmentation

Def.: Breaking up of a habitat into unconnected patches

Some Organisms need large area for gathering food

No migratory routes to reestablish populations lost due to natural disasters.

Climate change

Biological magnification

• Biological magnification– toxins may be concentrated from one trophic level to the next.

• DDT is an example

• DDT is a pesticide that was used extensively

• DDT is not biodegradable

• Organisms do not eliminate it

Fish-Eating BirdsLargeFish

Small Fish

Zooplankton

Producers

Water

10,000,000

1,000,000

100,000

10,000

1000

Magnification ofDDT Concentration

So what do we do?

On an Individual Level

Carefully use both renewable and non renewable resources : SUSTAINABLE USE .

Reduce, Reuse, Recycle.

References

http://www.niehs.nih.gov/research/programs/geh/climatechange/health_impacts/human_developmental/

https://en.wikipedia.org/wiki/Human_impact_on_the_environment

Presentation by: Surabhi TanwarStudent of Masters in Environmental Science- Institute of Science, Mumbai

POPULATION ECOLOGY

Population ecology is the study of populations in relation to environment, including environmental influences on density and distribution, age structure, and population size

By Surabhi Tanwar

Populations have size and geographical boundaries. The density of a population is measured as the number of individuals per unit

area.

The dispersion of a population is the pattern of spacing among individuals within the geographic boundaries.

The characteristics of populations are shaped by the interactions between individuals and their environment

MEASURING DENSITY

•Determination of Density• Counting Individuals• Estimates By Counting Individuals• Estimates By Indirect Indicators• Mark-recapture Method

N = (Number Marked) X (Catch Second Time) Number Of Marked Recaptures

Density – Number of individuals per unit of area.

Measuring density of populations is a difficult task. We can count individuals; we can estimate population numbers.

Fig. 52.1

Density is the result of an interplay between processes that add individuals to a population and those that remove individuals

Patterns of dispersion.

Within a population’s geographic range, local densities may vary considerably.

Different dispersion patterns result within the range.

Overall, dispersion depends on resource distribution.

Clumped. For many animals, such as these wolves, living in groups increases the effectiveness of hunting, spreads the work of protecting and caring for young, and helps exclude other individuals from their territory.

Uniform. Birds nesting on small islands, such as these king penguins on South Georgia Island in the South Atlantic Ocean, often exhibit uniform spacing, maintained by aggressive interactions between neighbors.

Random. Dandelions grow from windblown seeds that land at random and later germinate.

Additions occur through birth, and subtractions occur through death.

Demography studies the vital statistics that affect population size.

Life tables and survivorship curves.

A life table is an age-specific summary of the survival pattern of a population.

Demography is the study of factors that affect the growth and decline of populations

The best way to construct life table is to follow a cohort, a group of individuals of the same age throughout their lifetime.

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin CummingsTable 52.1

A graphic way of representing the data is a survivorship curve.This is a plot of the number of individuals in a cohort still alive at each age.A Type I curve shows a low death rate early in life (humans).

The Type II curve shows constant mortality (squirrels).

Type III curve shows a high death rate early in life (oysters).

Survivorship Curve

Reproductive rates.

Demographers that study populations usually ignore males, and focus on females because only females give birth to offspring.

A reproductive table is an age-specific summary of the reproductive rates in a population.For sexual species, the table tallies the

number of female offspring produced by each age group.

Table 52.2

Reproductive Table

The traits that affect an organism’s schedule of reproduction and survival make up its life history.

Life histories are a result of natural selection, and often parallel environmental factors.

Some organisms, such as theagave plant, exhibit what is known as big-bang reproduction, where large numbers of offspring are produced in each reproduction, after which the

individual often dies. This is also known as semelparity.

Life histories are very diverse, but they exhibit patterns in their variability

Agaves

By contrast, some organisms produce only a few eggs during repeated reproductive episodes.

This is also known as iteroparity.

Most weedy plants, such as this dandelion, grow quickly and produce a large number of seeds, ensuring that at least some will grow into plants and eventually produce seeds themselves.

Some plants, such as this coconut palm, produce a moderate number of very large seeds. The large endosperm provides nutrients for the embryo, an adaptation that helps ensure the success of a relatively large fraction of offspring.

The life-histories represent an evolutionary resolution of several conflicting demands. Sometimes we see trade-offs between survival and reproduction when resources

are limited.

Limited resources mandate trade-offs between investments in reproduction and survival

For example,

red deer show a higher mortality rate in winters following reproductive episodes.

We define a change in population size based on the following verbal equation.

Change in population = Births during – Deaths duringsize during time interval time interval time

interval

The exponential model of population describes an idealized population in an unlimited environment

Using mathematical notation we can express this relationship as follows:

If N represents population size, and t represents time, then N is the change is population size and t represents the change in time, then:N/t = B-DWhere B is the number of births and D is the

number of deaths

We can simplify the equation and use r to represent the difference in per capita birth and death rates.

N/t = rN OR dN/dt = rN

If B = D then there is zero population growth (ZPG).

Under ideal conditions, a population grows rapidly.

Exponential population growth is said to be happening

Under these conditions, we may assume the maximum growth rate for the population (rmax) to give us the following exponential growth

dN/dt = rmaxN

Fig. 52.9

Typically, unlimited resources are rare.Population growth is therefore

regulated by carrying capacity (K), which is the maximum stable population size a particular environment can support.

The logistic model of population growth incorporates the concept of carrying capacity

Example of Exponential Growth

Kruger National Park, South Africa

LOGISTIC GROWTH RATEAssumes that the rate of populationgrowth slows as the population size approaches carrying capacity, leveling to a constant level. S-shaped curve

CARRYING CAPACITYThe maximum sustainable populationa particular environment can supportover a long period of time.

POPULATION GROWTH RATE

Figure 52.11 Population growth predicted by the logistic model

How well does the logistic model fit the growth of real populations?

The growth of laboratory populations of some animals fits the S-shaped curves fairly well.

Stable population Seasonal increase

Some of the assumptions built into the logistic model do not apply to all populations.It is a model which provides a basis from which we

can compare real populations.

Severe Environmental Impact

The logistic population growth model and life histories. This model predicts different growth rates for different populations, relative to

carrying capacity.

Resource availability depends on the situation.

The life history traits that natural selection favors may vary with population density and environmental conditions.

In K-selection, organisms live and reproduce around K, and are sensitive to population density.

In r-selection, organisms exhibit high rates of reproduction and occur in variable environments in which population densities fluctuate well below K.

K-Selected Species

Poor colonizers Slow maturity Long-lived Low fecundity High investment in care for

the young Specialist Good competitors

r-Selected Species• Good colonizers• Reach sexual maturity rapidly• Short-lived• High fecundity• Low investment in care for the

young• Generalists• Poor competitors

Populations are regulated by a complex interaction of biotic and abiotic influences

There are two general questions about regulation of population growth: What environmental factors stop a population from growing?

Why do some populations show radical fluctuations in size over time, while others remain stable?

Density-Dependent FactorsDensity-Dependent Factors

limiting resources (e.g., food & shelter)

production of toxic wastes

infectious diseases

predation

stress

emigration

Density-Independent Factors

Density-dependent factors

increase their affect on a population as population density increases.This is a type of negative

feedback.

Density-independent factorsare unrelated to populationdensity, and there is nofeedback to slow populationgrowth.

Fig. 52.13

A variety of factors can cause negative feedback. Resource limitation in crowded populations can stop population growth by

reducing reproduction.

Negative feedback prevents unlimited population growth

Intraspecies competition for food can also cause density-dependent behavior of populations.

Territoriality.Predation.

Waste accumulation is another component that can regulate population size.In wine, as yeast populations increase, they

make more alcohol during fermentation.However, yeast can only withstand an

alcohol percentage of approximately 13% before they begin to die.

Disease can also regulate population growth, because it spreads more rapidly in dense populations.

Carrying capacity can vary.

Year-to-year data can be helpful in analyzing population growth.

Population dynamics reflect a complex interaction of biotic and abiotic influences

Some populations fluctuate erratically, based on many factors.

Fig. 52.18

Other populations have regular boom-and-bust cycles.

There are populations that fluctuate greatly.

A good example involves the lynx and snowshoe hare that cycle on a ten year basis.

Regional Patterns of Population Change

No population can grow indefinitely, and humans are no exception

To maintain population stability, a regional human population can exist in one of two configurations:

Zero population growth = High birth rate – High death rate

Zero population growth =Low birth rate – Low death rate

The demographic transition is the move from the first state toward the second state

The demographic transition is associated with various factors in developed and developing countries

Bir

th o

r d

eath

rat

e p

er 1

,000

peo

ple

50

40

30

20

10 Sweden

2050

Year

20001900 195018500

18001750

Birth rate

Death rate

MexicoBirth rate

Death rate

Age Structure

One important demographic factor in present and future growth trends is a country’s age structure

Age structure is the relative number of individuals at each age

It is commonly represented in pyramids

Age structure diagrams can predict a population’s growth trends

They can illuminate social conditions and help us plan for the future

Rapid growthAfghanistan

AgeMale

Percent of population

Female

8 6 4 2 2 4 6 80

45–4940–4435–3930–3425–2920–2415–1910–14

5–90–4

85+80–8475–7970–7465–6960–6455–5950–54

Slow growthUnited States

AgeMale

Percent of population

Female

6 4 2 2 4 6 80

45–4940–4435–3930–3425–2920–2415–1910–14

5–90–4

85+80–8475–7970–7465–6960–6455–5950–54

8

Decrease Italy

Male

Percent of population

Female

6 4 2 2 4 6 808

Infant Mortality and Life Expectancy Infant mortality and life expectancy at birth vary greatly among developed and

developing countries but do not capture the wide range of the human condition

Infa

nt

mo

rtal

ity

(dea

ths

per

1,0

00 b

irth

s)

Developedcountries

Developingcountries

Developingcountries

Developedcountries

Lif

e ex

pec

tan

cy (

year

s)

60

60

50

40

4030

20

2010

0 0

Ecological Footprint

How many humans can the biosphere support?

The carrying capacity of Earth for humans is uncertain

The ecological footprint concept summarizes the aggregate land and water area needed to sustain the people of a nation

It is one measure of how close we are to the carrying capacity of Earth

Countries vary greatly in footprint size and available ecological capacity

Bibliography

http://www.cfr.washington.edu/classes.esrm.450/lecture11/harvest.pdf

http://www.csun.edu/~msteele/classes/marine_ecology/lectures/4_population%20ecology%201.pdf

http://warnercnr.colostate.edu/~gwhite/fw662/web_docs/Winkelman%20Lecture%201.pdf

This presentation is compiled by:- Surabhi Tanwar

Masters Student in the Environmental Sciences

Institute of Science, Mumbai