Since the introduction of the "ecosystem engineer" concept in 1994, it has been used to describe all manner of organisms. Jones et al.’s original designation describes species that significantly modify, create, or destroy habitat via physical changes in the environment, dividing organisms into two categories: autogenic or allogenic. Autogenic engineers use their own physical structures while allogenic engineers use external abiotic or biotic materials to modify their environment. Because every organism plays a role in an ecosystem, such broad use brings into question the application of this term, as warned by Wright and Jones (2004). Our goal was to understand use of "ecosystem engineers" over the last 20 years and determine if it has maintained its utility as an ecological concept given its ambiguity. To address our goal, we reviewed the literature from 1994 to 2016, using the keyword "ecosystem engineer*" following accepted methods of PRISMA for structured reviews. A search in Web of Science, Google Scholar, and Ecology Abstracts yielded 2,208 unique records.
We found the term’s use increased over time, particularly within the last 12 years, describing a plethora of organisms. Many papers used the term exclusively as a keyword or confused it with trophic interactions or keystone species. Of the 2,208 papers, only 53% focused on describing ecosystem engineering processes or consequences. The proportion was reduced to 43% after excluding articles without empirical data with 22% focused on plants and 70% on animals. The remaining 8% focused on both plants and animals, or bacteria as ecosystem engineers. All plants were categorized to autogenic engineers while animals were identified as autogenic (23%) or allogenic (77%). Despite warnings, ecosystem engineering has become a token buzzword applied to nearly any biotic effect to promote a species’ relevance in an ecological community. Moving forward, we argue the term be restricted to allogenic ecosystem engineers. We suggest that the category of "autogenic engineer" devalues the utility of ecosystem engineering because autogenic engineering is adequately described by niche construction, facilitation, etc. We anticipate that this application will remove confusion and ensure the utility of ecosystem engineering as an ecological concept.