(individual organisms). Inherent in this hierarchy are the interactions and 

 relationships between and within the various levels. However, these attributes are 

 often neglected when an assessment is made,- in part because of the gap between 

 accepted knowledge at the level of individual organisms and knowledge of their 

 relationships at the community or ecological subsystem level." A useful synthesis of 

 ecological theory that begins to bridge this gap is "An Ecosystem Paradigm for 

 Ecology."^ For most practical purposes, the spatial boundaries of ecosystems can be 

 defined by various levels of integration of physical properties, in a hierarchial 

 fashion. This approach to classifying and delineating ecosystem units is discussed in 

 Robert Bailey's chapter: this concept represents a cornerstone for the progress to 

 come in the 1980s. 



Within the framework of the ecosystem, the ecological concepts that can pro\ idea 

 starting or focal point for practical assessment design are numerous and diverse. 

 Four common approaches are: (I) habitat space; (2) ecological niche: (3) 

 evolutionary: and (4) functional.' The chapters that follow in this section 

 demonstrate several applications of these conceptual approaches, sometimes in 

 various combinations. 



The habitat space approach is defined as the analysis of species distributional 

 relationships to environmental (biotic and abiotic) factors. ^''^ The ecological niche 

 approach can be described as going beyond "where an organismic unit is found" to 

 "what the organismic unit does" in the context of the ecosystem.'- A combination of 

 these two approaches has been developed to ecologically characterize regional 

 landscapes in response to programm.atic needs of the new Federal Coal Management 

 Program.'^ Charles Cushwa's paper discusses several data base development efforts 

 that focus on the habitat space concept. 



The evolutionary approach is the identification of the adaptive strategies of the 

 various species of an ecosystem and the selective forces that account for these 

 strategies.''* Implicit in this approach is that for each set of environmental conditions 

 there is a bioenergetic benefit and cost to the various structural and functional 

 relationships a species can adopt.'-* Further, evolutionary selection tends to produce 

 (but not necessarily perfect) adaptation to complex and sometimes conflicting 

 environmental problems. 3- '' Jack Ward Thomas discusses in his paper a combina- 

 tion of the ecological niche and evolutionary approaches developed by the Forest 

 Service in eastern Oregon. 



The functional approach may be defined as the analysis of the properties of energy 

 and material exchange in ecosystems, and the study of the behavior of ecosystems 

 under stress or perturbation.' This is a broad description intended to include more 

 than energy budgets and systems modeling. 2''" The study and analysis of ecosystem 

 function was essentially born in the late sixties and the seventies; it should mature in 

 the coming decade. The development of coastal characterizations presented in James 

 Johnston's chapter introduces elements of the functional approach, blended with 

 aspects of the previous three concepts. 



Comprehensive ecosystem analysis must blend each conceptual approach, with 

 proper linkages, to obtain refinement and substantiation of an integrated theory. The 

 translation of this integrated theory into the applied w orld of ecological assessment is 

 a major challenge of the decade ahead. Certainly the design requirements (Figures 1 

 and 2) can provide guidance as to the proper amount of each conceptual approach 

 required for a specific assessment need. 



Most real world ecological assessment designs result in the layering of several 

 relatively independent ecological assessment processes, with little if any real 

 integration.- A structured approach to matching conceptual frameworks to 

 appropriate methods and problems solution, (e.g., the development of strategies for 

 ecological assessment) is lacking; indeed, it has been said to be nonexistent."' 

 Especially in the public arena, the decisionmaking procedure called "'successive 

 liniitecl comparisons.'" which tends to produce incremental policy change, ^^ fosters 

 the practice of iteratively defining and applying ecological assessments. Perhaps in 



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