Tools for spatially modeling ecosystem services: Publication trends, conceptual reflections and future challenges

We analyze scientific literature that report tools to spatially model ecosystem services (ES). In the 65 articles reviewed, the most used model starting in 2001 was SWAT and starting in 2009 the most commonly used was InVEST. Eighty percent of the scientific articles have been published from 2010 to 2015 suggesting that spatial modeling of ES is an emergent research field. Only 4 of the 9 tools encountered in our review are backed by papers, the others only offer grey literature. The spatial modeling of ES is mainly done in the U.S.A. and China, and the most frequently evaluated ES are related to hydrological services (water provision and quality treatment), climate regulation and soil formation. Most of the studies are done along hydrological basins, at different spatial scales and based upon different map resolution ranging from 20 to 900 m. With concern, we observe the lack of validation of the spatial models and the tools' lack of integrated validation modules. As long as the tools used to spatially model ecosystem services continue to be used as black boxes, the models they generate will suffer from a high degree of uncertainty and will not be reliable for decision making purposes. (C) 2017 Elsevier B.V. All rights reserved.