EcoService Models Library (ESML)
Relationships potentially described as “ecological models” can vary widely in complexity, presentation and subject matter. Some are elaborate simulation tools with software, manuals and websites; others are simple equations not found beyond the pages of a journal article. Typically, an “ecological” model can draw from a single discipline (e.g., a predator-prey interaction in ecology) or many (e.g., including physical-chemical-biological, and potentially social-political-economic, elements).
The goal of ESML is to help users find models that are useful for estimating production of final ecosystem goods and services (FEGS). We define ecological production functions (EPFs) as quantitative expressions describing the production of final ecosystem goods or services.
EPFs are valuable for helping us better understand the relationship between environmental conditions and human well being. However, other ecological models (EMs) – which represent ecosystem processes yet may not estimate FEGS – may also be useful to that end. EMs that terminate in estimates of social benefits are termed ecological benefit functions; some EMs in ESML are ecological benefit functions (for a diagrammatic description of the categories of variables within these functions see also Using the ESML Variable Classification Hierarchy to categorize EM variables).
For purposes of ESML, an EM is defined as a quantitative relationship (i.e., a “function” or “model” having predictor [independent] and response [dependent] variables) that can help the process of estimating FEGS. Because a cascade of influences link human actions to ecological states and processes, it may be necessary to combine several EMs to develop an EPF that is suitable for a given situation. For this reason ESML includes many EMs that are not in themselves EPFs but are judged potentially useful for ecosystem service estimation. Moreover, the precise characteristics of a final ecosystem service vary over space and time, because a final service occurs only when a potential human beneficiary exists. For these reasons we use the term EPF to identify models that achieve the goal of estimating FEGS production, but we use the broader term EM to encompass all of the models in ESML.