Table 2 Critical appraisal criteria to assess studies in the full text stage

Study design

Experimental studies (includes also quasi-experimental studies)

Observational studies

Case studies (descriptive studies)

Sampling

 Large sample size relative to outcome measure and species in question (high confidence that replication is appropriate and representative)

 Sampling method suitable for the population of interest^a

 Randomisation accounting for spatial heterogeneity

Control and intervention areas matched based on their ecological characteristics

 Small to medium sample size relative to outcome measure and species in question (medium level of confidence that replication is appropriate and representative).

 Sampling method suitable for the population of interest^a

 Control and intervention areas comparable based on their ecological characteristics

Sampling method not suitable for collecting data on the population of interest^a

Accounting for heterogeneity and potential effect modifiers

Potential biologically important effect modifiers that could influence the study findings identified, and data collected on them. The context in which the study took place clear

Potential biologically important effect modifiers that could influence the study findings identified, and considered in relation to the results. The context in which the study took place clear even when there was no direct data

Effect modifiers not identified or considered. The context of the study is unclear

Data analysis methods

Methods appropriate^b

Methods appropriate^b

Methods not appropriate^b