Calcium addition at the Hubbard Brook Experimental Forest increases sugar storage, antioxidant activity and cold tolerance
in native red spruce (Picea rubens)
Joshua M. Halman (1, 2), Paul G. Schaberg (3), Gary J. Hawley (1) and Christopher Eagar (4)
1. Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, VT 05405, USA / 2. Corresponding author () / 3. USDA Forest Service, Northern Research Station, 705 Spear Street, South Burlington, VT 05403, USA / 4. USDA Forest Service, Northern Research Station, 271 Mast Road, Durham, NH 03824, USA / Received August 23, 2007; accepted November 1, 2007; published online April 1, 2008
Summary
In fall (November 2005) and winter (February 2006), we collected current-year foliage of native red spruce (Picea rubens Sarg.) growing in a reference watershed and in a watershed treated in 1999 with wollastonite (CaSiO3, a slow-release calcium source) to simulate preindustrial soil calcium concentrations (Ca-addition watershed) at the Hubbard
Brook Experimental Forest (Thornton, NH). We analyzed nutrition, soluble sugar concentrations, ascorbate peroxidase (APX)
activity and cold tolerance, to evaluate the basis of recent (2003) differences between watersheds in red spruce foliar winter
injury. Foliar Ca and total sugar concentrations were significantly higher in trees in the Ca-addition watershed than in trees
in the reference watershed during both fall (P = 0.037 and 0.035, respectively) and winter (P = 0.055 and 0.036, respectively). The Ca-addition treatment significantly increased foliar fructose and glucose concentrations
in November (P = 0.013 and 0.007, respectively) and foliar sucrose concentrations in winter (P = 0.040). Foliar APX activity was similar in trees in both watersheds during fall (P = 0.28), but higher in trees in the Ca-addition watershed during winter (P = 0.063). Cold tolerance of foliage was significantly greater in trees in the Ca-addition watershed than in trees in the
reference watershed (P < 0.001). Our results suggest that low foliar sugar concentrations and APX activity, and reduced cold tolerance in trees
in the reference watershed contributed to their high vulnerability to winter injury in 2003. Because the reference watershed
reflects forest conditions in the region, the consequences of impaired physiological function caused by soil Ca depletion
may have widespread implications for forest health.
