How extensive are redwood root systems?

It has been shown that a single redwood can grow a root system up to 1,115 ft by root resprouting and other clonal reproductive mechanisms. However, the same interconnected clone may not necessarily be contiguous, so there may be trees that are genetically different interspersed among identical ones. More frequently though, multiple interconnected individuals (up to 20 moderate size trees–up to 20 inches diameter—or 6 to 8 mature redwoods) are found at a distance of 131 to 196 ft.

How extensive are redwood root systems?