Data extraction & quality control
The final set of 28 studies contained 101 pairwise control (unburnt) and treatment (burnt) plots and 5311 observations, where one observation equates to a species being present in a burnt or unburnt plot (Appendix 2, Table S1 ). Some studies reported changes in tree and shrub communities but used plot sizes that are widely considered too small for accurate estimates of the species richness of these groups as the plots could only contain one or two mature individuals of these life forms. We thus did not include observations for calculating tree species richness when plots were less than 100 m2, or for shrub species richness when plots were less than 16 m2(see Mueller-Dombois et al., 2008). Most studies (n = 24; 85 %) provided their study site’s latitude and longitude but when these were not provided, they were obtained using the description of the study site location and the online toolhttps://www.latlong.net/. Not all studies provided data on species’ abundances (density or percentage cover), so we converted data into a presence/absence matrix for each burnt and unburnt site.
From each study, we extracted data on two fire metrics – time since fire (number of years between the most recent fire and sampling period), and fire type (prescribed or non-prescribed burns). We defined each site as protected if it was within the boundaries of a protected area (IUCN categories I to VI) as defined by the World Database on Protected Areas (WDPA) database (UNEP-WCMC & IUCN, 2020); this was achieved using thewdpar R package version 1.3.2 (Hanson, 2020).
Biomes were classified according to Olson et al. (2001) as i) Tropical and Subtropical Moist Broadleaf Forests (TSMBF; 5 papers & 1846 observations) ii) Tropical and Subtropical Dry Broadleaf Forests (TSDBF, 6 papers & 859 observations) iii) Tropical and Subtropical Coniferous Forests (TSCF, 1 paper & 31 observations), iv) Tropical and Subtropical Grasslands, Shrublands & Savannas (TSGSS, 13 papers and 2433 observations) and v) Flooded Grasslands and Savannas (FGS, 3 papers and 142 observations).