Appendix S2
SUPPLEMENTARY METHODS
Testing the potential spurious correlation between ecoregion size and historical habitat loss
We adopted Brett’s (2004) procedure of bootstrapping with replacement to test if the observed
correlation between ecoregion size and historical habitat loss might be spurious. As the two
variables are not independent (x/y versus y correlations), relationships observed by considering
the correlation coefficient may be actually spurious. We generated 10000 sets of x (number of
human-altered habitat pixels) and y (total number of pixels in an ecoregion) equal to the number
of observations in the dataset by sampling the dataset with replacement and computed 10000
new x/y values (historical habitat loss metric). X and y values that resulted in historical habitat
loss values > 1 were discarded and replaced by resampling values from the dataset. The
randomized bootstrapped values of the Spearman rank-order correlation statistic (ρ) were
arranged in ascending order to generate the percentile bootstrapped confidence intervals (95%
CI: -0.41, -0.28). The result of the simulation showed that a negative correlation could be
obtained owing to chance. The negative correlation (ρ =- 0.22) observed from our data could
therefore be considered spurious, or may indicate a very weak positive relationship between
ecoregion size and historical habitat loss.
SUPPLEMENTARY RESULTS
Ecoregions with a high relative need for conservation assessments
One hundred sixty-eight ecoregions had > 40th percentile values of plant species richness,
historical habitat loss, and future human population growth, covering a total area of 17,003,000
km2. Most of these ecoregions were tropical and subtropical moist broadleaf forests (71: 42 %),
followed by tropical and subtropical dry broadleaf forests (19: 11 %). In terms of coverage,
tropical and subtropical dry broadleaf forests were highest (37% of all ecoregions in the biome),
followed up the tropical and subtropical moist broadleaf forests (35%). Most of the 178
ecoregions were found in the Neotropical (62: 37 %) and Indo-Malayan (29: 17 %) realms.
For the 60th percentile threshold, the number of ecoregions was reduced to 44 and
covered a total area of 5,182,000 km2. Like the ecoregions designated by the 40th percentile
threshold, most were tropical and subtropical moist broadleaf forests (17: 39 %), followed by
tropical and subtropical dry broadleaf forests (6: 14 %). In terms of coverage, the tropical and
subtropical dry broadleaf forests biome was again the most well-covered (12% of all ecoregions
in the biome), followed by the tropical and subtropical grasslands, savannas, and shrublands
(9%), and tropical and subtropical moist broadleaf forests (8%).The number of ecoregions from
the Neotropical (19: 43 %) and Indo-Malayan (10: 20 %) tops this group. There were only two
important ecoregions when we set the threshold at the 80th percentile.