As scientists striving to communicate results objectively, reflection is warranted regarding potential disconnects between results and rhetorical devices used to communicate those results. The field of invasion biology may be modern ecology’s worst offender when it comes to reliance on value-laden terminology. The word “invasive” itself conjures images of a battlefield. While several narrative reviews have lamented this problem, to our knowledge no quantitative syntheses have yet investigated it. Using a meta-analytic framework, we quantified relationships between a study’s communicated impact (word usage) and ecological impacts of non-native species (effect sizes). We hypothesized that (1) word use patterns would be explained by certain study characteristics; and (2) increased use of value-laden terminology would be associated with more negative invader impacts, with potential study system-specific relationships between effect sizes and word usage.
To test our hypotheses, we updated a recent meta-analysis of invader impacts on aquatic systems. Our updated dataset included 202 scientific articles and 1,003 effect sizes. (1) We used NMDS ordination to describe overall patterns in word usage from the full text of articles and used PERMANOVA and random forest analyses to determine predictors of word usage. (2) We also modeled system-specific relationships between effect size and word usage.
Results/Conclusions
(1) We found invader trophic level and publication year to be the most important predictors of word usage patterns. Studies focused on invasive vertebrates (predators or omnivores), filter-feeders, and plants all differed in word usage patterns. Over time, the use of value-laden words (“invasive,” “alien,” “aggressive”) has increased, while older papers tended to use more neutral words (“dominant,” “health,” “colonize”). Other significant predictors included citation rate, experimental design type, and journal type, but notably not effect size. (2) Relationships between effect size and word usage did differ by trophic level of the focal invader.
To our knowledge, our study is the first to quantitatively address the question of whether rhetorical choices vary systematically based on study characteristics, including study findings. We found quantitative support for previous suggestions that the field of invasion biology has become increasingly reliant on value-laden terminology. Our work also suggests that word use patterns vary among scientific subfields. Although many have called for neutral word choices when communicating research, invasion biologists do continue to rely on at least some value-laden patterns of language use.