Lecture 4: Renewable Resources Flashcards
renewable resources=
can be replenished over short periods of time
- sunlight, wind, organic matter, groundwater
To be renewable:
- must be capable of ___ after harvest
- must be harvested at a rate ______ to regeneration
- can be _____ harvested
- regeneration
- less than or = to
- sustainably
T/F
all water is a renewable resource
false
groundwater/ surface water= renewable
aquifer= non-renewable
- aquifers can dry up if we use the water & don’t let them refill
physical water scarcity=
water is not available for use
- more than 75% of river flows have been withdrawn
- has exceeded sustainable limits
approaching physical water scarcity=
more than 60% of river flows have been withdrawn
- will experience physical water scarcity in the near future
economic water scarcity=
water is available for use, but inaccessible (due to infrastructure etc)
if we can’t use water (due to lack of supply, or poor quality), then neither can the ___
environment (usually!)
List 4 causes of water scarcity
briefly explain/ give an example for each
- irrigation
- growing crops that require too much water
- solution= GMO plants to make them more drought resistant - hydroelectric dams
- eg. Great Ethiopian Renaissance Dam: Egypt & Sudan (downstream) have a reduced water supply - 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) - Too many people!
- especially in dry places
___% 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)
70%
- cotton, rice, sugarcane, wheat
Why can soil be classified as a renewable resource?
- fertility (nutrient constant) cycles
- organic matter cycles- organisms are replaced
Why is soil sometimes considered a non-renewable resource?
- 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
Erosion is leading to soil becoming non-renewable. What are 3 causes of erosion?
- 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)
What are some good farming practices to promote nutrient and organic matter cycling?
- 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)
explain why salinization of soils is occurring
- accumulation of salts in the soil due to excessive irrigation (water evaporates and leaves behind salts to form) and/ or excessive fertilizer use
List 4 agriculture practices that should be more widely implemented to protect our soils
- terracing (step shape)- decreases erosion
- shelter belts (wind breaks= decrease erosion)
- intercropping- plant different crops together
- leave residuals behind
logging can be sustainable if done properly, but what is our main problem?
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
_____ is the permanent removal of trees (by humans, wildfires etc)
deforestation
*not always done by humans
clear-cutting=
deliberate removal of all trees in an area by HUMANS (for use in economy etc)
nutrient sink=
reservoir that provides storage for a nutrient
* ocean= greatest carbon sink, but plants are also a C sink
silviculture=
the study of growing and logging forest
List 3 problems with silviculture and provide solutions
1.
Problem= harvesting the entire tree depletes nutrients
Solution= only harvest the stem, leave residuals
- Problem= short rotation (50yrs) depletes soils
Solution= use longer rotations- 100yrs (lets soil and tree recover) - Problem= big cuts can lead to mass leaching of nutrients
Solution= harvest smaller areas mixed with untouched areas (buffers)- decreases erosion
The harvest of old-growth forests should be limited.
One reason: Lots of endemic species live there. What is an endemic species?
species that only lives in these forests
bycatch=
the catch of non-target fish/ ocean wildlife
- includes that’s brought to port & what’s thrown overboard at sea (dead or dying :( )
____is one of the largest threats to maintaining healthy fish populations and marine ecosystems
bycatch
this affects foodchains!
What is bottom trawling?
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
fishing ___ the foodweb is problematic
down
What is the precautionary principle?
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!
aquaculture=
the farming of fish & other aquatic animals (fresh or saltwater)
- includes restocking and decreasing destructive fishing processes
what are some risks with aquaculture (high impact aquaculture) - list 4
- 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
What are examples of low-impact aquaculture (less risky)
- recirculating aquaculture systems (pool indoors- no risk of escaping)
- include the whole food chain to mimic natural enviro
IMTA systems=
integrated multi-trophic aquaculture
= include the whole food chain in fish farms to mimic natural enviro
