Download 3.2 Sustainability

How Humans Influence
Ecosystems
Objectives
q I can define sustainability and identify how
traditional ecological knowledge can support
sustainable initiatives
q I can explain how land and resource use negatively
affect ecosystems
Vocabulary: contamination, deforestation,
extinction, habitat loss, soil degradation,
resource exploitation, sustainability,
traditional ecological knowledge
Sustainability
—  Sustainability is a word that is used often and can be
defined in more than one way; however the main
concept is to maintain biodiversity and
ecosystem health over time so that it will still be
available for future generations.
Sustainability
—  This requires balancing human economic activity
(i.e. our demand on nature) with nature’s ability to
meet that demand.
—  Requires sustainable practices that maintain or
increase the sustainability of an ecosystem while
providing economic opportunities for people.
Sustainability
—  Current sustainable approaches often make use of
Aboriginal traditional ecological knowledge of
local environment resources, factors, and cycles that
has been built up over centuries of experience and
passed on through rituals, songs, stories, and beliefs
Land Use
—  Land use is defined as the ways in which humans use
land for
—  Forestry
—  Agriculture
—  Urban development
—  Industry
—  Mining
Human Encroachment on Natural Systems
Negative Effects of Land Use
Over the past 150 years humans have aggressively
encroached on natural ecosystems.
—  The results of these activities are:
A)  HABITAT LOSS
—  Destruction of habitats so that they
can no longer support the organisms
that once lived there à most significant
cause of loss of biodiversity
Human Encroachment on Natural Systems
Negative Effects of Land Use
B) HABITAT FRAGMENTATION
—  Division of habitats into smaller, isolated sections
à impacts plant pollination, seed dispersal,
wildlife movement, and plant and animal
reproduction.
Human Encroachment on Natural Systems
Negative Effects of Land Use
DEFORESTATION
—  Practice in which forests are logged or cleared for
use and never replanted
—  The negative effects of deforestation include:
i. 
ii. 
iii. 
iv. 
Habitat loss & fragmentation
Decreased biodiversity
Soil degradation (topsoil is lost due to erosion à harder
for plants to grow)
Decreased removal of atmospheric CO2
Human Encroachment on Natural Systems
Negative Effects of Land Use
AGRICULTURE
—  Refers to the clearing of land for crop
growth or for rearing livestock
Human Encroachment on Natural Systems
Negative Effects of Land Use
—  As well as having the above
negative effects for deforestation,
agriculture has the additional
negative effects of:
i. 
Pesticide/Herbicide Use à
leads to bioaccumulation &
biomagnification of toxic chemicals
Human Encroachment on Natural Systems
Negative Effects of Land Use
ii. 
Soil Compaction à farm animals and equipment
squeeze air out of the soil, which can result in run-off
& leaching (since water can’t soak in), which reduce
plant growth
÷ 
The process of aeration can be used to counteract soil
compaction by removing plugs of soil and therefore
loosening it ! puts air into it so that water can be absorbed
and therefore so leaching and run-off can be reduced
Human Encroachment on Natural Systems
Negative Effects of Land Use
iii.  Excess nutrients à overuse of fertilizers
containing nutrients like P and N can lead to
eutrophication in water bodies
Resource Use
—  Resource use refers to the ways we obtain and use
naturally occurring materials, and is also referred to as
resource exploitation.
The main natural resources of BC include: (DO NOT COPY)
Metals
Lumber
Fish
Hydroelectri
Coal, Natural
(Cu, Zn, Au,
city
gas, Oil Ag, Ni, Fe) Resource Exploitation
—  The good news: provides us with everyday items (ex.
food and shelter) and jobs
Resource Exploitation: (continued)
The bad news: has many negative effects, including:
i.  Habitat loss & fragmentation
ii.  Decreased biodiversity
iii.  Soil degradation
Resource Exploitation: (continued)
The bad news: has many negative effects, including:
iv.  Contamination of soil and water, in which pollutants or
microorganisms are introduced into the environment (ex.
mining introduces cyanide, a lethal chemical, into
ecosystems)
à A method to counteract contamination is the process of
reclamation, which tries to restore the land to the way it
was before exploitation à ex. water treatment facilities
remove heavy metals from mine sites are they close,
certain species of plants are used as stabilizers
(bioremediation!)
Resource Exploitation: (continued)
The bad news: has many negative effects, including:
iv.  Overexploitation, in which a resource is used or
extracted until it is depleted
à Results in loss of genetic diversity, making a population
more susceptible to disease and less adaptable to
environmental changes
à May even result in extinction (complete disappearance of a
species from Earth) à if a keystone species is depleted or
driven to extinction, this has a major impact on the
ecosystem
Resource Exploitation (cont)
—  Overexploitation is the second largest threat to
organisms after habitat loss.
Read “Keystones in a Kelp Bed”
—  On the back:
1. 
2. 
3. 
Define keystone species
Explain why otters are an example of keystone species (how
do they fit within a kelp ecosystem?)
How do you expect the following to be affected as sea otter
populations rebound in the future?
÷  Kelp
biomass
÷  Abalone populations
÷  Sea urchin populations