Definitions

Agriculture Systems of using the land and the life it supports for producing food and other goods such as timber, drugs etc., to satisfy human 'needs'. Always involves fundamental changes in the ecology where it is practiced.

Alien In a natural system, a plant or animal not evolved in that system and to which the system is not adapted.

Bio-dynamic farming A system of farming and gardening in which organic farming is supplemented by an awareness of planetary and seasonal cycles.

Biomass Energy-rich substances which come from of make up living organisms. Examples include plant and animal tissue. All living things and their remains are part of the planet's biomass.

By-products Products of industry other than the ones which the industry is intended to produce. Often (but not always) necessary to making the main product, industrial by-products are often harmful and almost always hidden or not noticed. They are seldom adequately dealt with.

Cash crops A crop grown mainly for sale and usually for export rather than feeding local populations.

Co-dependent Depending on each other - as when soil, for example, depends on a variety of animals to remain as a functioning system, and the animals in turn depend on the soil system.

	A Contentious term for countries (usually in the South) which are considered to lack the sophistication and access to goods and technology of more developed countries in the North, but which are attempting (usually without success) to achieve them.
	The process of moving towards genuine democracy, understood as the ever more just sharing of political and economic power.
	A term used in so many contexts and with so many implications that it has often become almost meaningless. (John Button)

Ecology The study of the interconnectedness of living systems, including humans and their activities.

Ecological system An interconnected living system consisting of many living beings and possibly including humans. Also sometimes called an ecology (e.g.: Fynbos Ecology)

Environment Conditions or surroundings: According to the Brundtland Report, "The environment is where we live..."

Food Chain The way in which food passes through living systems - usually by organisms eating each other. Many poisonous substances (pesticides, industrial by-products etc.) don't break down as they pass through the food chain, but accumulate until, near the top of the chain, they reach toxic concentrations.

Gaia Hypothesis Gaia is the Ancient Greek name for Mother Earth. James Lovelock used it to mean: "The complex living being involving the Earth's biosphere, atmosphere, oceans and soil. The hypothesis is the idea that we can regard the earth as such a being.

Green Revolution The short-term increase in crop yields made possible by the use of pesticides, fertilizers and high-yield varieties of plants.

Mitochondria Small structures within animal cells responsible for the animal's energy metabolism, they convert food into chemicals which cells can use. Originally thought to be part of the cell, they are now seen as specialised bacteria, with their own DNA, which have co-operated with animal cells for untold ages.

Monoculture Growing a single crop over a large area of land. Problems with monoculture include short-lived resistance to pests and lowered plant diversity.

Non-renewable energy Energy from sources which cannot be replaced. Examples include coal, oil and naturel gas as well as nuclear fuel.

Ozone A gas consisting of molecules made of three oxygen atoms (O3.) It is highly toxic at ground level but in the upper atmosphere it shields the surface from harmful ultra-violet radiation.

Permaculture (Permanent agriculture) A system of sustainable agriculture intended to enrich local eco-systems.

Photochemical smog A haze which happens in hot dry weather (common in South Africa) caused by the action of sunlight on pollution from Nitrogen Oxide and organic chemicals, and producing, among other things, toxic ozone. Kills trees and causes lung complaints and other health problems.

Photosynthesis The way that green plants use the sun's energy to power the change of carbon dioxide and water into living (organic) chemicals. The origin of almost all living substances on the planet.

Renewable energy Energy from sources which can be replaced. Examples include the burning of wood and the use of muscle power, solar, wind and tidal energy.

Soil A complex living system consisting of weathered rock, organic matter and small living organisms. It holds water and nutrients used by plants.

South The poorer "developing" countries of the world, mostly, but not exclusively, in the Southern Hemisphere. Most of the world except Northern Europe, North America and the more prosperous Pacific Rim countries.

Stochastic Goal-seeking, though not necessarily in a purposive way. Any syste3m which modifies itself by means of feedback to its environment in order to attain certain "goals". For a plant, "goals" might be light, water, nutriments, reproduction - the conditions of survival.

Sources include John Button's Dictionary of Green Ideas and The Earth Report. These and many other books define some of the key concepts used here at much greater length.