Pitfall of big databases

Now, more and more studies use big databases, such as the World Database on Protected Areas (WDPA) (https://www.protectedplanet.net/), which is now a predominant source of information on world protected areas (PAs) (1⇓⇓–4). In PNAS, Elsen et al. (5) report that mountain ranges in Africa and Asia had the lowest elevational protection, based on analyses of the WDPA database. We suspect that this may not be true. China is a mountainous country in Asia (Fig. 1 A ) (5); we analyzed the elevational protection by China's National Nature Reserves (CNNR) and found that higher elevation regions are under a higher proportion of coverage by CNNR (Fig. 1 B ). The area of CNNR differed obviously among elevational gradients (Kruskal–Wallis test: χ2 = 143.29, P < 0.01), with the proportion of coverage becoming … [↵][1]1To whom correspondence may be addressed. Email: hujh{at}cib.ac.cn or jiangzg{at}ioz.ac.cn. [1]: #xref-corresp-1-1