Unit 5 Test Flashcards
Tragedy of the Commons
the tragedy of the commons suggests that individuals will use shared resources in their own self-interest rather than in keep with the common good, thereby depleting the resources
Classic example is sheep on pasture in a society that is agricultural
Commons is any resource that is not owned by any one individual person, family, company, interest group, etc.
Personal net benefit = personal benefit - cost
In this case, benefit would be healthy sheep to produce wool or meat, and costs would be degradation of the pasture
In commons, BENEFITS go to individuals but COSTS are shared among everyone
Good ex. Traffic in NYC
Clearcutting
Highly invasive forestry technique that involves removing all or nearly all trees at once
Often done for lumber or to clear land for other uses (eg. mining or grazing).
Associated with many negative effects Can be economically advantageous but leads to soil erosion, increased soil and stream temperatures, and flooding.
What effect does clear cutting have on a forest?
may increase water availability, but also:
Depletes groundwater storage
Increases erosion and runoff, possible landslides
Degrade Soils
Increase Flood Risk
Seed Tree Harvesting
Leaves some trees left as ‘seed’ for regrowth
Better than clear cutting, I guess, but still contributes significantly to erosion, makes habitat unsuitable for most organisms, and degrades soils
Selective Cutting
Only certain trees are cut down
Could be species, size, location based
This is probably better than clear cutting, but might alter forest structure significantly by removing species (especially ecologically impactful ones) or shelter for some species (eg. if large trees are removed).
Does not create runoff/erosion problems associated with clear cutting
Expensive and not favored by logging companies except in rate cases
Shelterwood
All trees are eventually cut down, but in a staggered fashion so that some regeneration occurs before the next cut
Can actually benefit biodiversity in some cases by promoting succession
If done properly, can reduce runoff and erosion normally associated with logging
Slash and Burn
Awful. Air pollution, carbon dioxide sequestration undone, soil runoff, and many more issues. Burning small plots of land ever hundred years can revitalize soils and be good for agriculture, but this is absolutely terrible if done on large scale.
Strip Cutting
Strips of land clear cut in intervals- can be better for biodiversity, but still terrible for erosion and soils- and creating even aged stands in strips is not the best for biodiversity either.
methods for mitigating deforestation
reforestation, using and buying wood harvested by ecologically sustainable forestry techniques, and reusing wood.
Demand for lumber leads to logging- reducing demand via reuse or efficiencies may help
To promote biodiversity- trees should not be all of the same age, and should be of various species- sometimes timber companies plant monocultures.
Trees stands with varying ages can promote habitat- dead trees should be left standing. Trees should be harvested and re planted in a staggered fashion
Methods to protect forests from pathogens and insects
integrated pest management (IPM) and the removal of affected trees.
Pests in forests can threaten biodiversity and the economy- tree pests are common and include things like:
Dutch Elm Disease
Chestnut Blight
Emerald Ash Borer
Beech Leaf and Beech Bark Disease
Hemlock Wooly Adelgid
Spotted Lanternfly
Brown Marmorated Stinkbugs
Integrated Pest Management
Managing a forest with the threat of disease requires a few mitigation strategies:
Regular monitoring of forest stands for diseases trees or pests, may include national or regional monitoring
Knowledge of pests and the threshold at which they threaten forests (for some pests, their mere presence is a critical threat)
Trapping or removing of pests
Biological Control
Chemical Control
IPM- A case study- EAB
7% of NY Trees are ash
ALL ash trees threatened by Emerald Ash Borer (EAB), an insect from Asia that cuts off the tree’s phloem (nutrient supply)
EAB control methods include biological controls (see right) and herbicidal injections
Injections work, but are not scalable. Biological controls might slow the spread, but do not stop it
What will replace Ash trees? Important question not only for biodiversity, but also for logging industries!!
Chemical Controls- EAB and other diseases
Insecticides can be injected into ash trees to ‘save’ them from EAB- this actually does work and is kind of like vaccinating the tree
Cost can be high (a few hundred dollars minimum per tree)- not terrible if you want to preserve the tree in your front yard- but what about for the forest as a whole or logging industry?
Other drawbacks? Try to think of some…..
IPM- A case study- Spotted Lanternfly
Invasional meltdown- when multiple invasive species have a combined effect greater than their individual parts- this is the case with Tree of Heaven and Spotted Lanternfly- removing Tree of Heaven might help!!
SLFs should be managed like other pests- where monitoring can sometimes lead to effective, targeted treatment
This problem is still relatively new!
Prescribed burn is a method by which forests are set on fire under controlled conditions in order to reduce the occurrence of natural fires.
Fire is a natural part of any landscape- fire helps promote succession, diversify forest age stands, and ultimately increase biodiversity. However, fire suppression, or human behavior that has led to a lack of fires, can promote megafires.
Controlled burns, where parts of the forest are allowed to burn (or in some cases actually set on fire) can reduce occurrences of natural fires, especially megafires.
Green Revolution - advantages
Green Revolution is shift away from small farming to what Pollan talks about in Omnivore’s Dilemma - ;large scale, industrial farming
GMOs, irrigation, fertilizers, pesticides
MAJOR increase in food production -land can produce several times more food under these new ‘technologies’
Decrease in world hunger, increase in human population carrying capacity
Perhaps ties up more land for conservation, housing, mining, or other uses because agriculture becomes that much more efficient
Green Revolution - Consequences
New technologies come at a significant cost to the environment
Pesticides, excess fertilizer and associated runoff, erosion, soil degradation
Biodiversity loss
Lands are being increasingly devoted to one crop - economies are based on specific crops and food becomes commodified like never before
Cost to human social order
Farming became a business, not a way of life, displacing many
Wealth inequality can grow if large corporations or certain countries control seed supply
Health impacts
Unknown effect or disputed effect of many chemicals and pesticides
Overconsumption of particular products (eg. corn)
Green Revolution - MEchanization
Machines largely replaced human end even animal labor in farming settings
Unemployment and social displacement for farm workers
This ‘prices out’ more farmers and favors large, industrial operations
Machinery is reliant on fossil fuels, and carbon footprint of agriculture grows
Tilling
mixing/breaking up/loosening soil to make planting easier
Incorporates fertilizer into soil better
Often done to prevent or kill weed growth
Allows more moisture to reach soil
Porosity increases, usually permeability does too
Commonly done in industrial agricultural settings
Tilling - Disadvantages
Increased erosion is the most obvious negative
Topsoil loss is also possible - long term degradation fo soil
Nutrient runoff with heavy fertilizer
Carbon losses to increase soil aeration are significant - medium term soil carbon storage is turned into short term carbon shortage
No till agriculture can save farmers money and be better for long term soil but can certainly make it more difficult to achieve large yields
Increases runoff
Fertilizer, other stuff gets into water, can increase turbidity
Most of the time not that abd because agricultural land is flat, eventually a significant amount of soil will be lost to water and create bad conditions there, and lose top soil
