DISTRIBUTION OF CA/MG IN THE SERPENTINE SOIL OF THE GREENBELT IN STATEN ISLAND, NEW YORK

Serpentine soils are known for their unfavorable physical properties to plants such as their lack of thickness and susceptibility to erosion. The chemical properties of serpentine soils are also known to inhibit the growth of most plants. The low biological productivity of serpentine soils has been attributed to the unfavorable ratio of Ca to Mg available in the soil. As a result, there has been a decline in the amount of native species in Staten Island Greenbelt and an increase in exotic species. In this study, the Ca/Mg ratio as determined by a soil fertility test is used to differentiate serpentine from non-serpentine soils in the Staten Island Greenbelt. In serpentine soils, this ratio is usually lower than 1.0 while most other soils shows a ratio greater than 1.0. Study sites that were determined to be non serpentine included the Brielle Ave slopes and ridges which have a Ca/Mg of 1.63 and 3.33 respectively and the Deere Park sites which has Ca/Mg between 1.67 and 3.00. Study sites that were determined to be serpentinitic included the Heyerdahl Hill site with Ca/Mg ranging between 0.38 and 0.87. Also the Bloodroot Valley site with a Ca/Mg of 0.23 and the Old Mill Road site with had a Ca/Mg of 0.21 and 0.51. Sites determined to have serpentine soils also had high Mg and Cr levels and low Ca/Mg values. The amounts of Ni and Cr decreased with depth to bedrock at all the sites. The low levels of available calcium limited the growth of serpentine-intolerant species. Serpentine endemic species such as andropogon scoparius (Little Bluestem) were found to be tolerant of low calcium levels and they occurred in natural serpentine soils within the Staten Island greenbelt.