Trees have been around for more than 370 million years, and today there are about 80 thousand species of them, occupying 3.5 billion hectares worldwide, including 250 million ha of commercial plantations. While forests can provide tremendous environmental, social, and economic benefits to nations, they also affect the hydrologic cycle in different ways. As the demand for water grows and local precipitation patterns change due to global warming, plantation forestry has encountered an increasing number of water-related conflicts worldwide. This document provides a country-by-country summary of the current state of knowledge on the relationship between forest management and water resources. Based on available research publications, the Editor-in-Chief of this document contacted local scientists from countries where the impact of forest management on water resources is an issue, inviting them to submit a chapter.