Definitions of key terms and words used used by the CASCADE project and in this website.

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catastrophic shift

An ecosystem may suddenly shift to a new state, characterized by a different structure, species composition and/or functioning. This phenomenon is referred to as a “catastrophic shift” in ecology. Such shifts to a degraded state (e.g. occurring in drylands) can lead to dramatic economic as well as ecological consequences. A catastrophic shift, according to the mathematician René Thom’s catastrophe theory, is an abrupt change in the state of a system, which suddenly shifts from one stable state to another stable state, separated by a tipping point. Catastrophic shifts are usually associated with hysteresis. Catastrophic shifts may either have positive consequences (shifts to the “healthy” state) or negative consequences (shifts to the “degraded” state) for the ecosystem functioning and related services. In physics catastrophic shifts are known as first-order phase transitions, and in mathematics they are subcritical bifurcations.


A repeated sequence of soil profiles that is geographically related to and associated with relief features.

climate scenarios

Internally consistent pictures of a plausible future climate, not predictions of future climate.

Common Agricultural Policy (CAP)

Agricultural policy of the European Union.


The development of a dense, compact surface soil layer (e.g. due to cultivation with heavy machinery, overgrazing), characterised by a much lower permeability so impeding the movement of water and air, and the growth of plant roots (see also crusting)

complex adaptive system

A dynamic network of many agents (e.g. cells, species, individuals, firms, nations) acting in parallel, constantly acting and reacting to what the other agents are doing (cited in Waldrop 1992).


11th Conference of Parties of the UNCCD

cost-effective measures

A favourable relationship of benefits over monetary and non-monetary costs of establishing and maintaining the measure.

critical transition

Large and persistent response in an ecosystem corresponding to a change in ecosystem property/state occurring because an ecological threshold has been reached and because positive feedbacks, or nonlinear instabilities in the system cause changes to propagate in a CASCADE-like fashion that is potentially irreversible. Once such a critical transition has occurred, the ecosystem in question is not likely to spontaneously return to its previous state.


Development of a surface layer on soils ranging in thickness from a few millimetres to a few centimetres, which is more compact, hard and brittle when dry than the material immediately beneath it (see also compaction).


Commission of Sustainable Development


UNCCD Committee for Science and Technology

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