IB Environmental systems and societies 2.5 Zonation, Succession and Change in Ecosystems Key Definitions

A climax community is the final, stable community in succession, in equilibrium with its environment and characterized by high biodiversity, complex food webs, and efficient nutrient cycling.

Ecosystem resilience refers to an ecosystem’s ability to recover from disturbances and return to its original state or adapt to a new equilibrium.

Gross Primary Productivity (GPP) refers to the total amount of energy captured by producers (typically plants and algae) through photosynthesis.

Species that reproduce slowly, producing few offspring but investing heavily in their survival.

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

A kite diagram is a graphical representation of species distribution along a transect.

Net Primary Productivity (NPP) refers to the amount of carbon that is captured by plants through photosynthesis and is available for growth and reproduction after subtracting the energy used by the plants for cellular respiration.

Net Productivity (NP) is the amount of biomass remaining after the losses due to cellular respiration have been subtracted from the gross productivity.

Nitrogen fixation is the conversion of nitrogen gas (N₂) from the atmosphere into ammonia (NH₃).

pH measures hydrogen ion concentration, influencing chemical reactions in water.

Plagiomax is an ecosystem that is arrested in an earlier stage of succession due to human interference.

A seral community (sere) is a stage in the process of succession, where one community modifies the environment, making it more suitable for the next community.

Stability is the ability of an ecosystem to maintain structure and function over time, even in the face of stress or disturbances.

Succession is the gradual process of change in ecosystems, where one community replaces another due to shifts in biotic and abiotic conditions.

Topsoil is the upper mineral-organic layer of soil where most nutrient cycling, decomposer activity, and root growth occur.

A transect is a straight line or path across an environmental gradient along which samples are taken at regular intervals.

Weathering is the process of breaking down rocks and minerals into smaller particles, forming the inorganic component of soil.

Zonation refers to the gradual change in species composition along an environmental gradient.