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

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Undershrubs or dwarf shrubs e.g. thyme, sage, the many species of broom, species of Cistus (rock roses) and Phlomis. Undershrubs are not potential trees; they reproduce by seed. Most species are unpalatable to herbivores.

plant community

An assemblage of individuals of one or more species that influence one another and modify their environment (after Mueller-Dombois and Ellenberg, 1974).

plant-soil feedback

Can be negative e.g. when monocultures stimulate growth of soil borne pathogens and diseases; or positive e.g. when plants improve soil fertility in terms of organic matter content, water holding capacity and nutrient availability.


A purposeful course of action, comprising a long series of more-or-less related activities, which governments pursue to reach goals and objectives related to a problem or matter of concern and to produce certain results. A policy is not a single, discrete, unitary, disembodied phenomenon, but a series of decisions. It concerns what is actually done (or not done) as opposed to what is proposed or intended; policy implementation and enforcement complete the actual policy process. Essential constituent elements of a policy are its object, interested and/or involved actors, their goals, the resources and means available, the instruments used to achieve the goals set and the implementation mechanisms (Briassoulis 2005, 21-22).

positive feedback

The process by which a state variable (e.g. vegetation composition) modifies the environment in a way that is beneficial for itself. (From Kéfi 2008, Ph.D. Thesis, p.15.) If a system includes a feedback, a series of mechanisms that form a loop is observed. The feedback is positive when a change in a state variable leads to another change of the same sign, as a consequence of the loop (i.e. a variable increase leads to a further increase). In drylands, for example, it has been observed that vegetation can modify the environment in a way that is beneficial for itself.

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