Barbara (PhD Animal behaviour, MSc Occupational Psychologist) is a senior consultant with more than 20 year experience in environmental conservation and decision-making support. at local, national and international levels. She has been involved in CEE for more than 10 years and promotes evidence synthesis in French-speaking countries. She has been managing the CEEDER programme since 2022.


In the dynamic landscape of evidence synthesis for environmental management, publication of Systematic Maps is becoming more popular than Systematic Reviews. This might be expected as the former provide an initial assessment of what evidence exists, ‘constructs’ the evidence base in a broad area of concern (i.e. organic agriculture), indicate opportunities for further synthesis (e.g. Systematic Reviews) where substantial evidence exists, and highlight opportunities for primary research where there are evidence gaps. However, a question emerges in my mind concerning preferences of decision-makers (DM) for systematic maps compared to literature reviews and systematic reviews. Several members of the CEE community have reported interactions with policymakers and decision-makers who often ask to know “what evidence is there”, “what has been done”, or “what do we know about…” that could support preferences for systematic maps.

Systematic maps offer advantages to decision-makers compared to the other forms of synthesis. First, they include a broader search for bibliography, transparent screening process, and a structured presentation of results. The risk of bias in the search strategy is also often reduced. My concern is that the provisional synthesis and mapping of what evidence exists may inadvertently maintain a “business-as-usual” use of scientific evidence to inform decision-making. Could the appeal of systematic maps lie only in their relative novelty and rigour but still allow decisions that would ignore quantitative evidence synthesis, risk of bias and validity of conclusions?

Second, the broad scope of systematic maps can also be inspiring to decision-makers when they need to identify a possible course of action. Decision-makers may feel able to make several decisions for research, management and policy out of a systematic map. Yet, systematic map do not inform about the relative effectiveness of such actions, contrary to many systematic reviews. Moreover, a systematic map can make vote-counting easier to perform, which can lead to biased decisions (vote-counting happens when priority is given to results obtained by the majority of publications, notwithstanding possible differences in their individual reliability in conduct and reporting).

Finally, some systematic reviews may include meta-analysis, address the risk of bias, and provide conclusions and recommendations that are assessing the current available evidence. This may challenge current practice and investment in resources and may even require change from status quo. Some decision-makers may thus feel such systematic reviews narrow down the range of possible decision-making, constrains negotiation or management actions. This has been reported by those who oppose evidence-based medicine. Is this why systematic maps would be preferred in environmental management?