IB Environmental systems and societies Topic 5: Land Key Definitions

Aeration is the exchange of gases between soil and the atmosphere.

Agricultural system refers to the combination of crops, livestock, technologies, and management methods used by farmers under specific environmental and socio-economic conditions.

Biomass is the total mass of living organisms in a given area or volume.

Bioturbation is the mixing and disturbance of soil by living organisms.

Carbon sequestration is the process of capturing atmospheric carbon dioxide (CO₂) and storing it in solid or liquid form.

Cation-exchange capacity (CEC) is the ability of a soil to hold positively charged ions due to negatively charged particles like clays and humus.

Compost is partially decomposed organic matter produced from kitchen, garden, and farm waste.

Decomposition is the breakdown of organic nitrogen in dead organisms and waste products into ammonium (NH₄⁺).

Denitrification is the conversion of nitrates (NO₃⁻) back into nitrogen gas (N₂), which is released into the atmosphere.

Erosion is the removal of soil particles by wind or water.

Eutrophication is a process where excess nutrients, primarily nitrates and phosphates, enter aquatic ecosystems, triggering a cascade of ecological changes.

A lack of reliable access to enough safe, nutritious food to meet dietary needs, caused by problems of availability, affordability, or distribution rather than by a global shortage of calories.

Food miles are a proxy for the carbon emissions associated with the movement of food through the supply chain.

Food security is defined as the physical and economic availability of food, ensuring all individuals can access the balanced diet necessary for a healthy and active life.

Gleying is the formation of waterlogged soils due to prolonged saturation, resulting in greyish or bluish colours.

Greenhouse gases are atmospheric gases that absorb infrared radiation emitted from the Earth’s surface and re-radiate it back, contributing to atmospheric warming.

Habitable land is land not covered by glaciers or classified as barren, and that can support ecosystems and human use.

Humus is a dark, crumbly substance that retains waterand nutrients, improving soil fertility.

Infiltration is the process by which water enters the soil from the surface.

A keystone species is an organism that has a disproportionately large impact on its ecosystem relative to its population size.

Leaching is the downward movement of dissolved minerals and nutrients through the soil.

Low-productivity food systems are farming methods that maintain high environmental sustainability but generate relatively small amounts of food.

Malnutrition is the condition of having an inadequate or unbalanced diet, including both insufficient intake (undernourishment) and excessive intake (overnourishment).

Marginalized groups are communities with limited political power, limited resources, or restricted legal rights.