Global databases of topsoil nitrogen and phosphorus contents and N:P ratio in urban greenspaces and natural ecosystems.

We compiled two global databases of topsoil N, P, and N:P ratio (0-20 cm depth) in urban greenspaces by conducting a literature survey through ISI Web of Science (http://isiknowledge.com), Google Scholar (https://scholar.google.com) and China National Knowledge Infrastructure (http://www.cnki.net), as well as in natural ecosystems based on seven published datasets. Overall, our databases of urban greenspaces and natural ecosystems included 373 measurements of topsoil N content from 220 cities, 139 measurements of topsoil P content from 91 cities, and 119 measurements of topsoil N:P ratio from 75 cities, as well as 345 measurements of topsoil N content from 263 sites, 185 measurements of topsoil P content from 147 sites, and 149 measurements of topsoil N:P ratio from 115 sites, respectively.