Fig. 4.17

Key differences in the broad types of studies in landscape ecology; viz: true experiments, quasi experiments, natural experiments and observational studies; strength of inference increases from bottom to top (i.e. from observational studies to true experiments). The primary difference between strong versus weak quasi-experiments is whether interventions are exogenous or endogenous. Endogenous variables are those internal to an ecosystem such as natural regeneration of trees and other vegetation) rather than being assigned to them (i.e. exogenous or originating outside the ecosystem such as a pre-determined intervention involving planting of vegetation). (Redrawn from Remler and Van Ryzin 2014)