APES Test 7

Major limiting factor for human population growth

Food supply

Percent of world land used for agriculture

11%

Percent of human food from land vs. water

95% from land

Main global staple crops

Wheat, rice, corn, potatoes

Number of plant species supplying most of human food

14

Undernourishment

Not enough calories

Malnourishment

Enough calories, not enough nutrients

Marasmus

Severe deficiency of calories

Kwashiorkor

Protein deficiency, causes edema (swollen belly)

Famine

Mass starvation over a large area for limited time

Chronic hunger

Enough to survive but not enough to be healthy or productive

Food desert

Area with limited access to affordable, healthy food

Subsistence agriculture

Small scale farming where crops feed family & community

Cash crop agriculture

Crops grown for sale in markets (ex. coffee, tobacco)

Traditional (resource-based) agriculture

Uses local resources, polyculture, long fallow periods, low external inputs

Demand based agriculture

Market driven monocultures, heavy external inputs, responds to global demand

Organic agrilculture

Minimal synthetic fertilizers/pesticides; emphasis on soil health, biodiversity, IPM

Agro-ecosystem

Human managed ecosystem for food production (ex. fields)

Key traits of agro-ecosystems

Lower diversity, simpler food chains, open nutrient cycles, reduced stability

Monoculture

Large area planted with a single crop

Main problem with monocultures

Very vulnerable to pests/disease

Limiting factor

Limits growth or productivity

Macronutrients needed by plants

N, P, K, Ca, Mg, S, C, H, O

Micronutrients definition

Nutrients needed in tiny amounts

Main goal of adding fertilizer

Supply limiting nutrients to increase crop yield

Green Revolution

Mid-1900s shift to high yield crop varieties with heavy use of water, fertilizers, and pesticides

Benefits of Green Revolution

Dramatic increases in food production and yields per acre

Enviornmental cons of Green Revolution

High water use, fertilizer runoff (eutrophication), pesticide pollution, energy-intensive

Why eating lower on food chain helps food supply

Less energy loss between trophic levels; more people fed per unit of land

Why vegetarianism alone doesn't solve world hunger

Distribution, poverty, and politics still limit access (problem isn't amount of food but access to food)

GMO definition

Organism whose DNA has been altered with genetic engineering

Common GM crop traits

Pest resistance, herbicide tolerance, weather resistance, improved nutrition

Golden rice

Genetically modified rice with increased vitamin A (beta-carotene)

Main GM crops in agriculture

Corns and soybeans

Benefits of GM crops

Higher yields, less pesticides, better nutrition, lower costs

Concerns of GM crops

Superweeds, harm to non-target species, health questions, ethical/economic issues

Aquaculture

Farming of aquatic organisms in both freshwater and marine habitats

Mariculture

Aquaculture specifically in marine (saltwater) enviornments

Benefit of aquaculture

High yield, reduces pressure on wild fisheries

Concerns of aquaculture

Waste accumulation, disease, escape of farmed species, habitat damage

Main categories of enviornmental impact from agriculture

Soil degradation, water pollution, air pollution, biodiversity loss, climate impacts

Soil erosion definition

Removal of topsoil by wind or water

Effects of soil erosion

Loss of fertility, sedimentation in water, reduced crop productivity

Desertification definition

Turning productive land into desert-like conditions, usually from overgrazing and poor practices

Salinization

Build up of salts in soil from evaporation of irrigation water

Consequence of soil salinization

Reduced crop yields, soil can become unusable

Nutrient pollution from agriculture

Fertilizer runoff (N, P) causes eutrophication and hypoxic dead zones

Nonpoint source pollution from agriculture

Diffuse runoff from fields, hard to trace to one location

Major greenhouse gas sources in agriculture

Fossil-fuel use, nitrous oxide from fertilizers, methane from livestock and rice paddies

Biodiversity impacts of agriculture

Habitat loss, fragmentation, monocultures, pesticide impacts

Pest definition

Any organism that competes with humans for resources or threatens human health

Weed definition

Plant growing where humans don't want it

Broad-spectrum pesticide

Kills many species, not just target pest

Narrow-spectrum pesticide

Targets a specific pest or small group

Persistent pesticide

Breaks down slowly, remains in enviornment for long time

Biomagnification

Increase in pollutant concentration at higher trophic levels in food chain

Pesticide treadmill

Cycle of pest resistance --> more pesticide use --> new pesticides needed

IPM (Integrated Pest Management)

Pest control strategy using multiple tactics to minimize pesticide use and enviornmental damage

IPM goals

Reduce artificial pesticide use, control pests economically, protect enviornment

IPM example techniques

Biological control, crop rotatioon, resistant varieties, monitoring, targeted pesticide use

Forage definition

Crops grown specifically to feed domestic animals

Rangeland definition

Land providing food for grazing animals without plowing or planting

Pasture definition

Plowed and planted land managed to grow forage for livestock

Overgrazing definition

Grazing more animals than land can support, vegetation can't recover

Effects of overgrazing

Soil compaction, erosion, desertification, loss of plant diversity

CAFO (Concentrated Animal Feeding Operation)

Large-scale facility where many animals are raised in confined spaces for meat/dairy

Major advantages of CAFOs

High production efficiency, cheap meat, consistent supply

Waste problem in CAFOs

Large manure lagoons can leak/overflow, causing water contamination

Antibiotic concern in CAFOs

Routine use promotes antibiotic-resistant bacteria

Hormone concern in CAFOs

Growth hormones may affect human health and animal welfare

Animal welfare issue in CAFOs

Crowded, stressful conditions; limited mobility; ethical concerns

Largest global user of freshwater by sector

Agriculture

Major irrigation problem in arid regions

Salinization of soils

Drip irrigation benefit

Minimizes evaporation and runoff; delivers water directly to plant roots

Environmental issue with flood or furrow irrigation

High water loss and risk of soil salinization

Tragedy of the commons

Overuse of shared resources when individuals act in self-interest

Externality definition

Cost or benefit of a good/service not included in its market price

Maximum Sustainable Yield (MSY)

Largest harvest that can be taken indefinitely without depleting a resource

Multiple-use lands definition

Public lands managed for several uses (timber, grazing, recreation, habitat)

Approximate percent of U.S. land publicly owned

Roughly 42%

Approximate percent of U.S. land managed by federal government

About 25% of total land area

BLM - Bureau of Land Management primary uses

Grazing, mining, timber, recreation on public rangelands

USFS - U.S. Forest Service primary uses

National forests; timber harvest, recreation, habitat

NPS - National Park Service primary mission

Protect national parks/monuments for conservation and public enjoyment

USFWS - U.S. Fish and Wildlife Service main role

Manage wildlife refuges, protect endangered species and habitats

Wise-use movement

Political push to increase resource extraction and reduce regulation on public lands

Silviculture

Practice of controlling forest growth, composition, and quality (forest management)

Stand (forestry)

Group of trees of same species and age in a forest area

Even-aged stand

Trees all about the same age

Uneven-aged stand

Mix of trees of different ages

Plantation forest

Managed, usually even-aged monoculture stand grown like a crop

Old-growth forest

Undisturbed forest with very old trees, complex structure, high biodiversity

Second-growth forest

Forest that has regrown after logging or disturbance

Rotation time (forestry)

Time between harvests in a managed forest

Forest canopy

Upper layer formed by tree crowns

Forest understory

Layer beneath canopy; shrubs, young trees, small plants

Clear-cutting definition

Removal of all trees in an area

Main advantage of clear-cutting

Economically efficient, easy and cheap logging

Ecological impacts of clear-cutting

Erosion, habitat loss, fragmentation, altered microclimate, changed water runoff

Strip-cutting

Clear-cutting in narrow strips, leaving forest between strips