Lecture 4: Renewable Resources

Question 1

renewable resources=

Answer 1

can be replenished over short periods of time
- sunlight, wind, organic matter, groundwater

Question 2

To be renewable:
- must be capable of ___ after harvest
- must be harvested at a rate ______ to regeneration
- can be _____ harvested

Answer 2

• regeneration
• less than or = to
• sustainably

Question 3

T/F
all water is a renewable resource

Answer 3

false

groundwater/ surface water= renewable

aquifer= non-renewable
- aquifers can dry up if we use the water & don’t let them refill

Question 4

physical water scarcity=

Answer 4

water is not available for use
- more than 75% of river flows have been withdrawn
- has exceeded sustainable limits

Question 5

approaching physical water scarcity=

Answer 5

more than 60% of river flows have been withdrawn
- will experience physical water scarcity in the near future

Question 6

economic water scarcity=

Answer 6

water is available for use, but inaccessible (due to infrastructure etc)

Question 7

if we can’t use water (due to lack of supply, or poor quality), then neither can the ___

Answer 7

environment (usually!)

Question 8

List 4 causes of water scarcity
briefly explain/ give an example for each

Answer 8

1. irrigation
   - growing crops that require too much water
   - solution= GMO plants to make them more drought resistant
2. hydroelectric dams
   - eg. Great Ethiopian Renaissance Dam: Egypt & Sudan (downstream) have a reduced water supply
3. bad planning
   - eg. Las Vegas= too many people, so built the Hoover dam, which uses water from the Colorado river (had dried up, and no longer reaches the ocean)
4. Too many people!
   - especially in dry places

Question 9

___% of all freshwater on the planet is used for growing food
- which 4 plants make up 58% of all irrigated farmland? (require lots of water)

Answer 9

70%

• cotton, rice, sugarcane, wheat

Question 10

Why can soil be classified as a renewable resource?

Answer 10

• fertility (nutrient constant) cycles
• organic matter cycles- organisms are replaced

Question 11

Why is soil sometimes considered a non-renewable resource?

Answer 11

• erosion (removal of topsoil)
• fertilizers etc are causing nutrient/ organic matter cycles to become unbalanced
• it’s drying up! (water overuse/ shortage)
• it’s getting salty
• soils are under pressure & competing uses of forestry, crops/ pastures, and urbanization

Question 12

Erosion is leading to soil becoming non-renewable. What are 3 causes of erosion?

Answer 12

• over-cultivation (soil is lost every time the field is ploughed- exposed to rain/ wind etc)
• over-grazing (plants hold the soil in place, but not when they’re gone!)
• poor forestry practices (removing trees= erosion)

Question 13

What are some good farming practices to promote nutrient and organic matter cycling?

Answer 13

• cycle fields (crop rotation) and fallow years (no crops)
• leaving crop residuals- added back to the soil
• no-till farming (tilling mixes nutrients but causes erosion)

Question 14

explain why salinization of soils is occurring

Answer 14

• accumulation of salts in the soil due to excessive irrigation (water evaporates and leaves behind salts to form) and/ or excessive fertilizer use

Question 15

List 4 agriculture practices that should be more widely implemented to protect our soils

Answer 15

1. terracing (step shape)- decreases erosion
2. shelter belts (wind breaks= decrease erosion)
3. intercropping- plant different crops together
4. leave residuals behind

Question 16

logging can be sustainable if done properly, but what is our main problem?

Answer 16

we are cutting down trees for the wrong reasons!
- we don’t always use the wood we cut
- clearing forests just to plant crops etc

Question 17

_____ is the permanent removal of trees (by humans, wildfires etc)

Answer 17

deforestation
*not always done by humans

Question 18

clear-cutting=

Answer 18

deliberate removal of all trees in an area by HUMANS (for use in economy etc)

Question 19

nutrient sink=

Answer 19

reservoir that provides storage for a nutrient
* ocean= greatest carbon sink, but plants are also a C sink

Question 20

silviculture=

Answer 20

the study of growing and logging forest

Question 21

List 3 problems with silviculture and provide solutions

Answer 21

1.
Problem= harvesting the entire tree depletes nutrients
Solution= only harvest the stem, leave residuals

2. Problem= short rotation (50yrs) depletes soils
   Solution= use longer rotations- 100yrs (lets soil and tree recover)
3. Problem= big cuts can lead to mass leaching of nutrients
   Solution= harvest smaller areas mixed with untouched areas (buffers)- decreases erosion

Question 22

The harvest of old-growth forests should be limited.
One reason: Lots of endemic species live there. What is an endemic species?

Answer 22

species that only lives in these forests

Question 23

bycatch=

Answer 23

the catch of non-target fish/ ocean wildlife
- includes that’s brought to port & what’s thrown overboard at sea (dead or dying :( )

Question 24

____is one of the largest threats to maintaining healthy fish populations and marine ecosystems

Answer 24

bycatch

this affects foodchains!

Question 25

What is bottom trawling?

Answer 25

a method of fishing: drag a net along the bottom of the ocean, catch whatever you catch (targets certain fish though)
- lots of bycatch :( problematic

Question 26

fishing ___ the foodweb is problematic

Answer 26

down

Question 27

What is the precautionary principle?

Answer 27

where there are threats of serious/ irreversible damage, lack of full scientific certainty should not be used as a reason for postponing measures to prevent environmental degradation

(tend to do years of research to “prove” damage before doing anything about the problem)
This applies to fisheries!

Question 28

aquaculture=

Answer 28

the farming of fish & other aquatic animals (fresh or saltwater)

• includes restocking and decreasing destructive fishing processes

Question 29

what are some risks with aquaculture (high impact aquaculture) - list 4

Answer 29

• overuse of vitamins
• fence= plastic that the fish ingest & then we eat
• in enclosed water: stagnation and O2 is a risk
• non-native fish are problematic if they escape

Question 30

What are examples of low-impact aquaculture (less risky)

Answer 30

• recirculating aquaculture systems (pool indoors- no risk of escaping)
• include the whole food chain to mimic natural enviro

Question 31

IMTA systems=

Answer 31

integrated multi-trophic aquaculture
= include the whole food chain in fish farms to mimic natural enviro