rock that has slowly been broken down due to chemical or physical weathering and by organisms creates this
general deterioration of land, decreasing its productivity and biodiversity
arrival of eroded material at a new location
What are the 3 types of soil? List them in order from largest to smallest
the wearing away or removal of soil from the land, natural process accelerated by humans
3 causes of soil erosion
overcultivating fields, overgrazing rangeland, clear-cutting forests
cation exchange capacity
a soil's ability to hold positive ions in turn, making them available to plants
an increased level of salt in soil
degradation of once fertile rangeland or farmland into unproductive desert
traditional method of farming, labor intensive, plows pushed by farmers
in the 1930s drought and erosion caused "black blizzards" of sand
livestock lives on land too arid for successful crop growth, must continually move stock to find food
the technology in which the genetic material in a living cell is modified for medical or industrial use
example of invasive species
conservation reserve program
policy where famers are paid to put high erodible land in conservation reserves
3 examples of chemicals used to kill pests
a biofuel derived from corn
uses a pest's predators to control the pest
huge warehouses or pens deliver food to animals living at extremely high densities
large field of a single crop type
- DNA combined from different sources (or different species) into a single DNA molecule
- GMO's have recombinant DNA
3 examples of GMO's and what they are modified for
- golden rice- rice that produced vitamin A
- Bt crops (apples, broccoli)- produce their own pesticides
- freeze resistant strawberries- protected from frosts
- roundup ready crops- withstand the herbicide Roundup
clearing and loss of forests alters landscapes and ecosystems
maximum sustainable yield
resource managers attempt to maximize the amount of resource harvested while keeping the harvest sustainable by keeping the population at half the carrying capacity
Uneven aged tree stand
A tree planation that maintains a mix of tree ages to mimic a natural forest
Prescribed burn (controlled burn)
Forest Services will burn areas of forest under controlled conditions in an effort to clear away underbrush and prevent massive uncontrolled forest fires
National wildlife refuge
US Fish and Wildlife Services administer havens for wildlife and permit hunting, fishing, observation and photography
Result from habitat fragmentation whereby organisms along a fragment’s edges experience different conditions than in the interior
The farther an island from the mainland, the fewer species tend to colonize it
Private, nonprofit organizations purchase land and preserve its natural conditions (ex. Nature Conservancy)
The upper level of leaves in a forest, home to many insects, birds and arboreal mammals
Natural forests uncut by people (very little remain today)
Creates uneven aged tree stands as only some trees are cut at any one time (small patches of trees or single widely spaced trees are harvested)
Removal of dead trees (snags) following a natural disturbance
Warmer, milder summers cause this insect to feed on the bark of conifers, killing the trees (climate change alters forests!)
Compare traditional with industrial agriculture
- Traditional agriculture is biologically powered agriculture, using human animal muscle power.
- Industrial agriculture uses large-scale mechanization and fossil fuels to boost yields. Also uses pesticides, irrigation and fertilizers
What was the Green Revolution? When did it start? What are the benefits and negatives of it?
- Beginning around 1950, the GR introduced new technology, crop varieties, and farming practices to the developing world.
- Pros: increased yields and helped millions avoid starvation
- Cons: hard on the environment, can degrade the integrity of soil, the very foundation of our terrestrial food supply
How is soil formed
- the formation of soil begins when the lithosphere's parent material is exposed to the effects of the atmosphere, hydrosphere, and biosphere
- parent material is broken down by weathering that converts large rock particles into smaller particles
- once weathering has produced fine particles, biological activity contributes to soil formation through the deposition, decomposition, and accumulation of organic matter
- as plants, animals, and microbes die or deposit waste, this material is incorporated amid the weathered rock particles, mixing with minerals
- weathering and the accumulation and transformation of organic matter are the key processes of soil formation
physical weathering, ex
- no chemical changes in the parent material
- ex: wind, rain, thermal expansion, contraction, water freezing
chemical weathering, ex
- substances chemically interact with parent material
- ex: water and gases
biological weathering, ex
- organisms break down parent material
- ex: tree roots and lichens
Describe each soil layer
- O horizon (Organic)- or litter layer consists of organic matter deposited by organisms
- A horizon- or topsoil consists of some organic material mixed with mineral components
- E horizon (Eluviated)- or leaching layer is where minerals and organic matter tend to leach out
- B horizon (Subsoil)- where leaching accumulates
- C horizon (Rock, parent material)- weathered parent material R horizon- consists of pure parent material
- mineral particles: 50%
- organic matter: 5%
- air/water: 45%
How would the soils’ composition change if we were in different biomes?
Different biomes are under different conditions. Tropical rainforests have bad soil, because it rains so much which increases the leaching. Iowa has less rain, so there are more nutrients for things to grow.
- soil's color can indicate its composition and fertility
- black or dark brown soils are usually rich in organic matter, whereas a pale color often indicates leaching
- determined by particle size
- Silty soils with medium-sized pores, or loamy soils with a mix of pore sizes, are best for plant growth and agriculture.
- a measure of the clumpiness of soil
- An intermediate degree of clumpiness is generally best for plant growth.
- Repeated tilling can compact soil, reducing its ability to absorb water
- influences the availability of nutrients for plants’ roots
- soils of intermediate pH values are best for most plants since plants can die in soils that are too acidic or too alkaline.
How is a soil’s cation exchange capacity a measure of its fertility?
- soil particle surfaces that are negatively charged hold positively charged ions
- in cation exchange, plant roots donate hydrogen ions to the soil in exchange for nutrient ions, which the soil particles replenish by exchange with soil water
- soils with fine texture and soils rich in organic matter have high cation exchange capacity
Compare soil characteristics of tropical rainforests with temperate grasslands.
- tropical: enormous amount of rain leaches minerals and nutrients out of the topsoil and E horizon and down to the water table, below the reach of plants' roots. at the same time, warm temperatures speed the decomposition of leaf litter and the uptake of nutrients by plants, so the thin topsoil layer contains very little humus.
- temperate: less rainfall ann less leaching, so nutrients remain within reach of plants' roots. plants return nutrients to the topsoil as they die, maintaining its fertility. the think, rich topsoil of temperate grasslands can be farmed repeatedly
What is desertification? What areas are more prone to it? What causes it
- a loss of more than 10% productivity
- arid areas, places with over-farming
- Erosion, soil compaction, forest removal, overgrazing, drought, salinization, climate change, water depletion
What was “the dust bowl?” And how did this event occur?
- 1930s drought & erosion caused “black blizzards” of sand
- over grew wheat and over grazed cattle; removed vegetation
- alternating crops from one year or season to the next
- Benefits: return nutrients to the soil, break disease cycles associated with one type of crop, minimize erosion that comes from empty fields, reduces insect pests that feed/lay eggs on one type of crop
- furrows are plowed sideways across a hill and follows the natural contours of the land to prevent gullies from forming; the side of each furrow acts as a small dam
- Benefits: furrows capture soil and prevent erosion
- level platforms with raised edges are cut into steep hillsides to contain precipitation and irrigation water
- Benefits: allows farmers to cultivate steep hills without losing soil due to water erosion
- planting different types of crops in alternating bands
- Benefits: slow erosion with more ground cover than a single crop, reduces pests & disease, if a legume is used, they can replenish N to the soil
- rows of tree or tall shrubs that are planted along edges of field to slow wind
- Benefits: reduce erosion from wind
- limited tilling that leaves no more than 30% of crop residue after harvest
- Benefits: reduces soil erosion, improves water quality, increases organic matter
How do each of the following degrade soil quality? Overgrazing
- too many animals eat too much of the plant cover and impedes plant regrowth
- -Erosion of soil= positive feedback cycle: erosion prevents regrowth and lack of plant cover causes further erosion
How do each of the following degrade soil quality? Salinization
the buildup of salts in surface soil layers; as water evaporates salt is pulled from lower to higher horizons, salts precipitate and turn the soil surface white as the water evaporate
How do each of the following degrade soil quality? Irrigation
- Artificially providing water to support agriculture
- -Waterlogging: over-irrigated soils; water suffocates roots, low O2 accelerates denitrification
How do each of the following degrade soil quality? Fertilizer application
- substances containing essential nutrients
- -Eutrophication: N/P runoff from cropland cause algae blooms and low oxygen “dead zones” with fish fills
How is overgrazing a tragedy of the commons issue?
range managers establish and enforce limits on grazing on publicly owned land. US ranchers have traditionally had little incentive to conserve rangelands bc most grazing has taken place on public lands leased from the government and because US taxpayers have heavily subsidized grazing. overgrazing has resulted in extensive environmental impacts across the American west.
What is malnutrition? What diseases can this lead to?
- a shortage of nutrients the body needs
- Kwashiorkor: diet lacks protein or essential amino acids
- –Occurs when children stop breast-feeding
- –causes bloated stomach, mental and physical disabilities
What are the positive and negatives associated monocultures?
- large expanses of a single crop
- –More efficient, increases output
- –Susceptible to disease and pests
Why does pesticide effectiveness reduce over time?
Some individuals are genetically immune to a pesticide, they pass these genes to their offspring and immunity increases in the population
What is biocontrol? Why do we use it? What are the possible negative consequences?
- uses a pest’s predators to control the pest
- may have “nontarget” effects on the environment and surrounding economies
What is integrated pest management?
Sustainable and cost effective techniques to suppress pests
Explain the process of recombinant DNA technology.
- 1.Isolate a desired gene
- 2.Cut the gene using restriction enzymes so as to produce sticky ends 3.Cut a plasmid with the same restriction enzyme producing sticky ends
- 4.Fuse the gene and plasmid with the enzyme ligase
- 5. Insert the recombinant plasmid back into a bacterial cell which will divide and make more copies of that gene, simultaneously expressing that gene
- Reduced use of chemical insecticides
- Reduced strain on nonrenewable resources
- Improved crop quality
- Improved nutritional quality
- No long-term research has been done
- Insects might develop resistance to pesticide-producing GM crops "superweeds"
- Certain gene products may be allergens
pests dont ruin plants
insects might develop resistant
Why is it better for the environment to eat less meat?
- Land and water are needed to raise food for livestock
- Producing eggs and chicken meat requires the least space and water than producing beef
- produce manure, which causes eutrophication
- Air pollution
- Crowded, dirty housing causes disease
What can you do to make “greener” food choices?
eat less meat, go organic
What are the benefits and negatives with feedlots?
- += don't take up as much space that could be used for agriculture
- produce huge amounts of manure- Causing eutrophication
- Crowded, dirty housing causes disease
- pollutes water and air
What is sustainable agriculture? What methods does it use?
- agriculture that does not deplete soils faster than they form
- no till farming, reducing fossil-fuel
What are a few characteristics of organic food?
- no genetic modificaiton
- no hormones
- no synthetic fertilizers
How do you know a food is “organic”?
Compare forests to woodlands.
any ecosystem with a high density of trees
Describe 4 ecosystem services provided by a forest.
- –Plant roots stabilize soil and prevent erosion–
- Leaves slow runoff, prevent flooding and recharge aquifers
- –Plants filter pollutants, purify water during transpiration
- –Absorb CO2, release O2 gas, influence weather patterns, and moderate climate
Describe 4 reasons forests are considered one of the most diverse ecosystems.
- structural complexity
- their capacity to provide many niches for organisms
- furnish food and shelter for an immense diversity of animals
What negative consequences occur because of deforestation?
- –Changes landscapes and ecosystems
- –Reduces biodiversity
- –Promotes desertification in arid regions
- –Worsens climate change
- –Disrupts ecosystem services
How does deforestation worsen climate change?
- –Dead plants decompose and release CO2
- –Combustion of forests releases CO2
- –Fewer trees soak up less CO2
Compare primary with secondary forests.
- p= natural forest uncut by people
- s- trees at partial maturity because people cut them down
Describe three solutions to deforestation.
- some conservation proponents are pursuing community-based conservation projects that empower local people to act as stewards of their forest resources
- conservation organizations are buying concessions and using them to preserve forest
- a project called POTICO aims to reduce deforestation and illegal logging
Name three methods of resource management. Describe each.
- maximun sustainable yield - achieve the maximum amount of resource extraction without depleting the resource from one harvest to the nest
- ecosytembased management- aims to minimize impact on the ecosystems and ecological processes that provide the resource
- adaptive management- systematically testing different approaches and aiming to improve methods through time
Why were national forests established? What do they do?
- to protect public lands from resource extraction and development
- –Open to nature appreciation and recreation
Compare even and uneven aged tree stands.
- Even-aged stands: all trees are the same age
- Uneven-aged stands: mixed ages of trees and species
- More similar to natural forests
- More diverse
4 methods of tree removal
- Seed-tree approach
- Shelterwood approach
- Selection systems
- Salvage logging
- a few seed-producing trees are left standing to reseed the logged area
- Leads to even aged stands
- some trees are left to provide shelter for the seedlings as they grow
- Leads to even aged stands
- only select trees are cut
- leading to uneven aged tree stands
Removal of dead trees following a natural disturbance
What did the National Forest Management Act of 1976 do?
- –Consider both economic and environmental factors
- –Ensure research and monitoring of management
- –Permit only sustainable harvest levels
- –Ensure that profit alone does not guide harvest method
- –Protect soils and wetlands
- –Assess all impacts before logging to protect resources
Why are prescribed burns used?
- clear away fuel loads
- nourish soil
- encourage growth of new vegetation
What is habitat fragmentation? What causes it? What occurs as a result?
- habitat is chopped into small pieces
- Logging, agriculture, and residential development fragment habitat
- animals do not have enough area to roam
What patterns can we see with larger islands with respect to distance from the mainland, extinction rates and immigration rates?
- –large islands have more species than small
- They have more habitats, environments, and variety
- –the farther an island is from the continent, the fewer species find and colonize it
- Less immigration and gene flow