The Role of Calcium Supply In The Structure and Function of a Northern Hardwood Forest

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ABSTRACT PROPOSAL # : 9726837 INVESTIGATOR(S) : DRISCOLL INSTITUTION: SYRACUSE UNIVERSITY Long-term studies at the Hubbard Brook Experimental Forest in New Hampshire and elsewhere in eastern North America have shown the depletion of large quantities of calcium from base-poor soil by acid rain. Calcium is an important nutrient of forest ecosystems. The supply of calcium controls the acidity of soil and waters, and influences important characteristics of northern forests and streams. This research will investigate the role of calcium in the ecology of forests and streams. The supply of calcium to an experimental watershed at Hubbard Brook will be enhanced by the experimental addition of a highly-weatherable calcium-silicate mineral, wollastonite. The wollastonite will be applied by helicopter. The added wollastonite will dissolve in approximately seven years, replacing the calcium that has been depleted from the watershed over the last 50 years. The wollastonite has a distinct stable isotope signature that will enable the transport and fate of added calcium to be traced with high sensitivity. Changes in the chemical characteristics of soil and water, the activity of soil microbes, soil invertebrate communities, forest vegetation and stream biota will be determined. Continued monitoring will attempt to quantify the cause-effect relationship between the soil calcium content and the ecological characteristics of northern forests and streams over very long time scales (i.e. 50 yr).