Researchers at Princeton University recently found that striped maple trees can switch from male to female or female to male from year to year. A tree may be male one year and female the next, and the study also found that female trees are more likely to die. As a result, male trees usually outnumbered female trees by more than three to one, and since only female trees can make seeds, changes in these numbers of males and females could result in reduced populations.
Princeton University is a member of NYSERNet. Read more about the study here: https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=298683&WT.mc_id=USNSF_1