Calcium abundance in trees have been the subject of investigation in North Carolina, New Hampshire and Sweden, and decreasing Ca abundance is common in all locales. The data for the trees for Long Island suggest that a similar process may be occurring here. The tulip trees show an increase from 1915 to 1995. The record for the pitch pines is not as clear. From 1915 to 1975 there was an increase in Ca, but these trees may be undergoing a reduction in Ca since then.
Conclusion Ca abundances in tulip trees studied here appear to be increasing with time.
The trend for the pitch pines is not as clear. If acid rain is responsible for some of the increases in Ca, this has serious implications. Ca depletion would be inevitable according to trends observed in other areas. The removal of Ca and other base cations from the soil will encourage the mobilization of harmful elements such as Al into soil solution and then into trees.