Assessing the ecological effects of habitat change: moving beyond productive capacity

Productive capacity can be defined as the “ecological effect” end of a habitat change ® ecological effect
cause–effect pathway. Determining whether and how a habitat manipulation, either inadvertently or deliberately, will affect productive capacity is the key analytical step of habitat management. We describe a process to ensure that this step is conducted in a manner that is rigorous and relevant. The process has four components: (1) determination of management objectives, (2) identification of indicators, (3) analysis of cause–effect pathways linking habitat changes to ecological effects, and (4) determination of strategies to effect desirable habitat change. The core of the process is the third step, in which we propose the use of hypotheses-of-effect, a network of cause–effect linkages leading from habitat change to ecological effects,
to ensure rigorous assessment of possible effects. We illustrate the process using examples of timber management effects on migratory brook trout (Salvelinus fontinalis) and urbanization effects on littoral warm water communities. We argue that this process, in addition to providing a rigorous means of assessing the evidence relevant to a particular issue, also provides an effective tool for examining uncertainty. We advocate the adoption of this process by management agencies as a method for adaptive habitat management.