Lecture 5 - Renewable Resources Flashcards
Definition and examples of renewable resources
Renewable
- Capable of regeneration after harvest
- Must be harvested at a rate less than or equal to regeneration
- Can be sustainably harvested
Definition of Sustainability
Sustainability is the process of living within the limits of available physical, natural and social resources in ways that allow the living systems in which humans are embedded to thrive in perpetuity.
Difference between surface water and groundwater
Surface water: lakes, ponds, streams, rivers
- Renewable
Groundwater: underground reservoirs that accumulate in so-called aquifers
- Non-renewable
Water scarcity: what is it, what are its causes, and how to reduce it?
What is it:
- Surface water scarcity; water resources development is approaching or has exceeded sustainable limits
Causes:
- Irrigation; water needed for the production of food
- Hydroelectric dams; water used to produce electric energy
- Bad planning; ex. Las Vegas
- Too many ppl; unbalanced demand (especially in dry places)
Reduce:
- We need better agriculture; 70% of all freshwater on the planet is used for growing food; change needed at the gov level not individual
Causes of soil erosion and salinization
Erosion: process of removal and transport of the topsoil by action of water, wind, and mass movement that causes its deterioration in time
- when erosion rates are high we lose the resource
Causes of erosion:
- Over-cultivation
- Over-grazing
- Poor forestry practices
Salinization: accumulation of salts in soils due to excessive irrigation and/or excessive fertilizer use.
Improving soil use through better agricultural practices
Best Practices:
- Cycle fields + fallow yrs
- Plant cover cropping
- Leaving crop residuals
- No-till farming
Deforestation problems
Problems caused by deforestation:
- soil loss
- nutrient leaching
- loss of biodiversity
- decreased CO2 sequestration
- hydrological disruptions
Clear-cutting
- deliberate removal of all tress in an area by humans
- usually for harvesting and trees are allowed to regrow
- problems can be similar to those for deforestation if not done properly
Silviculture
Growing and harvesting of trees
Problems
- whole-tree harvest depletes nutrients
- short rotation depletes soils
- big cuts can lead to mass leeching of nutrients
- logging roads disrupt streams, cause erosion
Solutions
- stem-only harvest, leave residues
- implement longer rotations
- harvest smaller areas mixed with untouched areas (buffers)
- plan roads around streams, install appropriate sized culverts
Importance of Old Growth Forests
Very high biodiversity and number of endemic species
Problems of bottom trawling
- Bycatch: the catch of non-target fish and ocean wildlife; one of the largest threats to maintaining healthy fish populations and marine ecosystems
- Fishing down the food web: start w fishing top predators, once those are depleted, go to next trophic level
Aquaculture (high impact vs. low impact)
Aquaculture = cultivation of fish in semi-domestication; potential solution to the increasing need of food
High impact: create the culture in the natural habitat using nets
- risks: overuse of antibiotics, fish eat plastic net, invasive species introduced, waste products, diseases and parasites
Low impact: integrated multi-trophic aquaculture systems (IMTA); created in a huge tank outside of the enviro water
The Precautionary Principle
Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.
AKA when in doubt, protect ppl and environment.
