World population will swell to 9 billion by the middle of the century
Agricultural land covers 38% of earths land surface
Agriculture: Practice of raising crops and livestock for human use and consumption
Cropland: Land use to raise plants for human use
Rangeland: land used for grazing livestock
Agriculture first appeared 10,000 years ago and was invented independently by different cultures.
Agriculture is a form of intensification – a way to increase the productivity and carrying capacity of given unit of land
Traditional agriculture = biologically powered agriculture, using human and animal muscle power
Subsistence agriculture = families produce only enough food for themselves
Industrialized agriculture = a more recent form of agriculture using large-scale mechanization and fossil fuels to boost yields
Monoculture = vast fields of single types of crops – occupies about 25% of the world’s croplands
Food Security = the guarantee of an adequate reliable and available food supply to all people at all times. There is no guarantee that agriculture production will continue to outpace population growth as it depends on water resources and crop diversity and the ability of soils to support crops and livestock.
Undernourishment = people receive less than 90% of their daily caloric needs
Overnutrition = receiving too many calories each day
In Canada, 48% of adults exceed their healthy weight and 14% are obese
Malnutrition = a shortage of nutrients the body needs
The diet lacks adequate vitamins and minerals
Green revolution = increase in agricultural productivity during mid to late twentieth century including: increased food production, devoting more energy and greatly increasing use of irrigation, fertilizers and pesticides
Extensification = bringing more land into production
Intensification = better productivity per unit of land
Positive effects of on natural resources of Green revolution: reduced pressure to convert natural lands, prevented deforestation and habitat conversion
Negative effects on natural resources of Green revolution: Intensive use of water, fossil fuels, chemical fertilizers and pesticides (pollution, erosion, salinization and densification)
Fertilizer Impacts: Inorganic and Organic
Inorganic – or industrial fertilizers are mined or synthetically manufactured mineral supplements (nitrogen, phosphors and potassium)
Organic – natural materials such as animal manure, crop residues, fresh vegetation, compost
Runoffs can lead to phytoplankton blooms and pose human health risks
Irrigation Impacts
Agriculture main reason for extraction and use of fresh water worldwide
Efficiency is quite low as only 43% of the water applied gets used by plants
Can lead to waterlogging and salinization of soils
Drip irrigation is one possible solution
Monoculture Impacts
Large expanse of a single crop
More efficient, increases output
Devastates biodiversity
Susceptible to disease and pests
Contributes to a narrowing of human diet: 90% of our food comes from 15 crop species and 8 livestock species
Pesticide Impacts
Poisons that target pest organism
Pest organisms pose greater threat in a monoculture situation
Annual cost of pesticides is about $45 billion
Concerns about cumulative effects of pesticide use (i.e. killing pest you weren’t intending too)
Monoculture and organic fertilizers can cause various fatal impacts on the environment
Pest = any organism that damages valuable crops - a bigger problem in monoculture.
Weed = any plant that competes with crops
Insect, fungi, viruses, rodents and weeds that eat or compete with our crops have taken advantage of the ways we cluster food plants into agricultural fields.
Pesticides = positions that target pest organism
Insecticides = target insects
Herbicides = target plants
Fungicides = target fungi
91% of pesticides sales are for agricultural purposes
85% of pesticides sold in Canada are herbicides
Usefulness of pesticides tends to decline with time:
Pests evolve resistance to pesticides
Small fraction of insects and microbes have genes that confer some degree of immunity to a given pesticide
If an insect survives pesticide, resistance is passed through their genes to insect offspring.
Biological control (Biocontrol) = uses a pest’s natural predators to control the pest
No one can predict the effects of an introduced species
The agent may have “nontarget” effects on the environment and surrounding economics
Removing biocontrol agent is harder than halting pesticide use.
Due to potential problems, proposed biocontrol use must be carefully planned and regulated
Integrated Pest Management (IPM) – uses multiple techniques to suppress pests
Biocontrol
Chemical, when needed
Population monitoring
Habitat alteration
Crop Rotation and transgenic crops
Alternative tillage methods
Mechanical pest removal
We are critically dependent on insects to pollinate crops
Male plant sex cells fertilize female sex cells
1500 crop species depend on insect pollination (3-8% of global crop populations)
Pollinators are at risk for various reasons
Conservation of pollinators is vital
Bees devasted by parasites and colony collapse disorder
North American farmers regularly hire beekeepers to bring colonies to their fields
To conserve bees and other pollinators: reduce or eliminate pesticide use and plat flowering plants
Genetic Engineering = laboratory manipulation of genetic material
Creates a genetically modified (GM) organism
Recombinant DNA = DNA patched together from the DNA of multiple organisms
Biotechnology = material application of biological science to create products derived from organisms
Biotechnology has helped us create medicines, clean up pollution, understand the causes of cancer, dissolve blood clots after heart attaches and make better beer and cheese
Transgenic organism = an organism that contains DNA from another species
Transgenes = genes that have moved between organisms
Genetic engineering is like and unlike traditional breeding
Similar: 1) both alter gene pools for preferred characteristics and 2) both apply to plants and animals
Different: 1) traditional breeding uses genes from the same species (selective breeding deals with whole organism, not just genes) and 2) in traditional breeding, genes come together on their own
Most GM crops today are engineered to resist herbicides, others to resist insects
Three-fourths of the world’s soybean plants are transgenic
As are one out of every four corn plants and over half of all cotton plants
Globally, in 2013, GM foods grew on 175 million hectares of farmland, producing $10.5 billion worth of crops
Impacts of Gm crops:
As GM crops expanded, scientists, citizens and policy makers have become concerned because: 1) pests could evolve resistance 2) could ruin the integrity of native ancestral races 3) interbreed with closely related wild plants
Evidence of negative ecological effect is limited
Numerous mechanisms whereby genes can “escape”
Critiques argue that we should adopt the precautionary principle: the idea that one should not proceed until the ramification of an action are well understood
Debate over GM foods involves more than science
Ethical issues play a large role
People don’t like “tinkering” with “natural” foods (why are we playing god?)
With increasing GM use, people are forced to use GM products or go to special efforts to avoid them
Crops that benefit small, poor farmers are not widely commercialized
The future of GM foods seems likely to hinge on social, economic, legal, political and scientific ones
Consumers and the government of the worlds developing nations could exert the worlds developing nations could exert the most influence in the end
India and Brazil approve of GM crops
China is expanding use of transgenic crops
Crop diversity provides insurance against failure
Preserving native variants protects against crop failure
Genetic diversity in crops has decreased in the last 40/50 years
Market forces discourage diversity in food’s appearance
Consumers prefer uniform, standardized food
Seed Banks = preserve seed types as a living museum of genetic diversity
Seeds collected and preserve and periodically planted
Hand pollination preserve genetic distinctiveness
The Royal Botanic Gardens Millennium Seed Bank in Britain aims to bank 20% if the worlds plant by 2020
Norway has started a “doomsday vault” seed bank
As wealth and commerce increase, so does consumption of meat, milk and eggs
Global meat production has increased fivefold since 1950
Per capita meat consumption has doubled
High consumption has led to feedlot agriculture
Concerted Animal Feeding Operations (Factory Farming) = Huge warehouses deliver energy-rich food to animals living at extremely high densities
Necessary to keep up with meat consumption in Canada and the United Stated
Over ½ of the world’s pork and most of the poultry come from feedlots
Benefits of feedlots: 1) greater production of food 2) keeps up with high meat consumption 3) reduces the impact of livestock on land (use less space) – no overgrazing and soil degradation
Cons of Feedlots: 1) contribute to water and air pollution 2) poor waste containment may cause human disease (e. coli, salmonella). 3) cattle: steroids used to stimulate growth 4) heavy use of antibiotics to control disease
90% of energy is lost every time energy move from one trophic level to the next
The lower on the food chain from which we take our food sources, the more people the earth can support
Producing eggs and chicken requires the least space and water; beef requires the most
Aquaculture = raising aquatic organism for food in a controlled environment (open water pens or land based ponds) and is the fastest growing type of food production (provides a third of the world fish for human consumption).
Benefits of Aquaculture: 1) reliable protein source 2) sustainable 3) reduces fishing pressure on overharvested wild fish stock 4) energy efficient
Cons of Aquaculture: 1) diseases can occur, requiring expensive antibiotics 2) reduces food security 3) large amounts of waste 4) farmed fish may escape and introduce diseases into the wild.
Sustainable Agriculture = does not deplete soil, pollute water or decrease genetic diversity.
No-till agriculture = depth and frequency of ploughing and tilling is kept to a minimum to protect soil moisture and compaction.
Low-input agriculture = uses smaller amounts of pesticides, fertilizers, growth hormones, water and fossil fuel energy than industrial agriculture.
Organic agriculture = uses no synthetic fertilizers, insecticides, fungicides or herbicides (relies on biological approaches – composting and biocontrol).
Fresh water = relatively pure, with few dissolved salts – only 2.5% of earths water is fresh, most is tied up in glaciers and ice caps
Water is constantly moving among the reservoirs via the hydrologic cycle
As water moves through the hydrologic cycle:
Stores and distributes heat
Erodes mountain ranges
Builds river deltas
Maintains ecosystems
Supports civilization
Gives rise to political conflicts
Residence times = storage time for water
Reservoirs differ in resident times and amount of water they store
Climate change will affect the hydrologic cycle:
Shift northward in mid-latitude rain belt
Earlier snowmelt and spring run off
More transpiration
Drier summers in the interior continental region
Additional impacts
Warmer rivers (impacting fish)
Lower water levels in great lakes
Higher ocean water levels
Tributary = smaller river that flows into a larger
Drainage basin /watershed = the area of land drained by a river and tributaries
If there is a large bend in the river, the force of water cuts through the land:
Oxbow = an extreme bend in a river which can transform into a;
Oxbow lake = the bend is cut off and remains as an isolated, U-shaped body of water
Floodplain = areas nearest to the rivers course that are flooded periodically (frequent deposition of silt makes floodplain soils fertile)
Riparian = riverside areas that are productive and species-rich.
Wetlands = systems that combine elements of freshwater and dryland
Freshwater marches = shallow water allows plants to grow above the water’s surface
Swamps = shallow water that occurs in forested areas (can be created by beavers)
Bogs = ponds covered in thick floating mats of vegetation (a stage in aquatic succession)
Wetland > March >
Wetlands are extremely valuable for:
Wildlife
Slowing runoff by reducing flooding, recharging aquifers and filter pollutants
People have drained wetlands mostly for agriculture
Southeastern (Potholes region) Canada has lost more than half of their wetlands
Prairie Pothole Region = an entire region that should have multiple little “prairie potholes” that are ecological diverse havens. They help fertilize the surrounding areas.
Lakes and ponds are bodies of open, standing water
Littoral zone = region ringing the edge of a water body
Benthic Zone = extends along the entire body of the water body (home to many invertebrates)
Limnetic Zone = open portions of the lake or pond where the sunlight penetrates the shallow waters (I.e. Lake Winnipeg)
Profundal zone = water that sunlight does not reach (supports fewer animals because there is less oxygen) (i.e. west hawk lake)
Oligotrophic lake and ponds = have low nutrient and high oxygen conditions – not a lot of primary production going on, very clear lake (i.e. Lake Superior)
Eutrophic lakes and ponds = have high nutrient and low oxygen conditions (i.e. lake Winnipeg)
Water bodies fill completely in through the proves of succession
Ground water plays key roles in hydrologic cycle
Confined / artesian = water-bearing, porous rocks are trapped between layers of less permeable substrate – under a lot of pressure (i.e. clay)
Unconfined aquifer = no upper later to confine it = readily recharged by surface water
Groundwater becomes surface water through springs or human drilled wells
Groundwater may be ancient; the average age is 1,400 years