ES chap 15
Terms in this set (56)
what are some factors that can contribute to an area of food shortage?
soil fertility-soil erosion will reduce, climate- temperature and rainfall, pests
what is plants greatest stressor?
natural selection keeps pests abundant
one of mandkinds greatest accomplishments, 12,000 years ago in Nile River Valley(cross bred wild varieties of crops)
depends on domesticated animals to pull plows
amount of food produced per acre-11% of the earths surface is under agriculture
supports crop growth
marasmus & kwashiorkor: deficiencies of calories and protein
-goiter: caused by iodine deficiency
-anemia: caused by iron deficiency
-blindness: caused by vitamin A deficiency
limited to meeting the demand of a family's needs
primary cause for world hunger
many poorest nations don't rely on machine bc of fossil fuels
most common cause for starvation worldwide
1-4 years of age/ most important bc of developing brain
how many essential amino acids do humans need
8-leads to lower productivity and mental capacity
what requires the least amount of energy for production
allowed chemists to increase the amount of an essential nutrient involved in plant growth -Nitrogen (occupies 78% of atmosphere )
natural ways to create nitrogen
lightning strikes and bacteria
Mexico increased it wheat production and India doubled its production of rice without increasing the amount of farmland used
plowing, fertilization, irrigation, pest control
-plowing helps by mixing soil nutrients, loosening soil particles, uprooting weeds
how long is soil generated
slowly- 1 cm needs 100 years
soil formation involves the decomposition of..
organisms break down nitrogen
when human activities or natural processes damage the lands so that it can no longer support the local ecosystem. In areas with dried climates, desertification can occur
when human activities or climatic changes make arid or semiarid areas more desert like. Because of overgrazing, the land has fewer plants to hold the top soil in place *get less than 10 in of rain each year
why is there more livestock on the planet
because of increased socio- economic status
built across hillside to prevent downhill erosion
plowing across the slope of the hill instead of up-and-down the slope
no till farming
A crop is harvested without turning the sale over as into the small farming leaving the previous crop to decay slowly
how many inches of rain will Chester County receive each year
by incorporating new crop varieties that grow faster and demand more water in order to produce higher yield farmers must use more water
how much percentage of crops does NA lose
how much % does worldwide damage to crops lose in yield
how do organophosphates Impact humans?
impaired memory & concentration
species that perform valuable services such as polinayion
what is pesticide persistence?
they do not break down rapidly into harmless chemicals
what chemical was banned bc of the biomagnification of the chemical food chain
DDT, a persistent prsticde
using the enemies of the pests so farmers can reduce the use of chemical pesticides
organisms that can cause
Most common: bacillus thuringiensis
concentrated plant chemicals used as a biological pesticide *buodegradable
integrated pest management
multistep process to reduce pest populations with little use of chemical (last resort) farming technique *involves use of biological controls
unsustainable method that has reduced the overall fish populations in ocean ecosystems
any organism that exists where you do not want it or is large enough to cause economic damage
what are three types of pest populations that humans try to control?
plants, fungi, microorganism
how much % of insect damage does Africa face?
more than 25%
why do crop plants have less protection from pests than do wild plants?
wild plants grow throughout a landscape, so pests have a harder time finding and feeding on a specific plant
grow throughout a landscape, have evolved defended against many pests, are protected from pests by pest predators that live on or near them
provide pests with a one stop food source, grow together in large fields
why do crops in tropical climate suffer greater Damage than crop in North America ?
bc the insects grow and reproduce faster in tropical climates
why do humans try to control pests?
so their crops aren't destroyed. if they are, then the farmer will suffer economically
what is the most common method of aquaculture
each individual pond on a fish farm contains what?
fish at a specific stage of development
where do salmon live until they reach adulthood
on a ranch
where do salmon live after they leave their birthplace until they reach adulthood?
in the ocean
how does circulation clean water contribute to the open at of a fish farm?
the clean water brings in oxygen while sweeping away CO2 and fecal waste
why do salmon return to their birthplace after they mature?