Existing in several fragmented, relict populations, the largest of which numbered only around 120 mature trees in 2006, the dawn redwood is one of Asia’s rarest trees (1). Since its discovery the species has been protected, with initial measures focussing on protecting individual trees rather than whole populations. Although this prevented the species from direct threats, through agricultural encroachment and firewood collecting, the natural habitats surrounding dawn redwood trees have been severely degraded. In place of natural forests with a diversity of tree species, forests dominated by dawn redwood trees have arisen. This has had the adverse affect of providing ideal conditions for insect pest species to thrive, while the largest, oldest trees are more vulnerable to lightening strikes (8).
An additional threat to this species is pollution from coal burning households. The population in the Xiaohe Valley is now eight times larger than it was when the dawn redwood was first discovered, with the local community increasingly changing from burning firewood to coal. Those dawn redwood trees closest to such households shed their leaves earlier and also produce less fruit than those in more isolated locations (8). Furthermore, the dawn redwood appears to have a low genetic diversity as a direct result of its low population number (9) (10).