While humans no longer threaten giant sequoia with their saws, the trees are not free from our influence. Fire suppression practices in the forests of the Sierras have changed the natural environment. Without low intensity understory fires that seem to have been frequent in giant sequoia stands, a more dense understory has developed on many sites. The area shown here has developed a dense understory of white fir (Abies concolor), a species that is not resistant to fire. These understory trees alter water and nutrient cycles in the forest system, and also funtion as fire ladders, allowing otherwise small fires to spread into the crowns of mature giant sequoias, destroying the stand. While it may have been the original intent to protect the remaining bigtree groves, many hypothesize that fire suppression practices pose threats to the future continuance of the giant sequoia.