Evaluation Sourcebook (.pdf) - School of Natural Resources and ...

ECOLOGICALOBJECTIVESIntroductionSo what are the measurable or manageable elements of ecosystems that together contributeto overall health, integrity or biodiversity?Many practitioners consider ecosystems in terms of biotic (all living things) and abiotic(all nonliving things) parts. Levels of biotic or biological components include:• individual organisms• populations (made up of many individuals)• species (made up of many populations)• communities or habitats (made up of many species)• landscapes (made up of many communities)Elements of the physical or abiotic environment include:• water• air• rocks and mineralsAlternatively, because the biological and physical components are really very tightly linked,others consider ecosystems in terms of three primary attributes:• composition – the identity and variety of elements (e.g., number and type of speciesin a community)• structure – the physical organization or pattern of these elements (e.g., proximity ofhabitat fragments in the landscape) and• function – the ecological and evolutionary processes linking these elements (e.g.,nutrient cycling).In this Sourcebook ecological topics combine the focal biotic and abiotic and features ofecosystems with the linking concepts of composition, structure and function.ECOLOGICAL PROGRESS: COMPARED TO WHAT?To assess progress you need to know how “here and now” compares to some other benchmark orreference. This will give you an idea of whether you are moving toward your ecological objectives.Some useful comparisons for assessing progress toward ecological objectives include:• A “pristine” or low impact site such as a designated wilderness area or unused area• Different degrees of disturbance (e.g. moderately vs. severely polluted, no-till vs.conventional agriculture, or low vs. high intensity fire)• Different kinds of disturbance or resource use (e.g. agriculture vs. development)• Different management or restoration approaches (e.g. herbicide vs. herbicide + fire vs. fireonly vs. a no treatment control)• Before vs. after restoration or management activities• Before vs. after uncontrolled or catastrophic event (drought, flood, fire). This can informyou about how resilient a system is – how well it rebounds from disturbance.• Today vs. last year or vs. 50 years ago, depending on the time scale you expect theecosystem attribute to changeEcosystem • The Management range of natural Initiative variability22