DOI: 10.6073/pasta/a287c4efa691179e3f74d60d1935d6ac
title: Differential impacts of calcium and aluminum treatments on foliar and sapwood nutrition and metabolism of sugar maple trees growing at the west edge of WS6 of the Hubbard Brook Experimental Forest from 1997-2009.

description: Plot levels Ca and Al additions study at WS6 BACKGROUD: To better evaluate the interaction of Ca depletion and Al mobilization on a northern hardwood forest, the Nutrient Perturbation (NuPert) study was initiated in 1995, west of the biogeochemical reference watershed (W6) at the HBEF (43.95411°N, 71.74779°W). The study area is on a south-facing slope, with an elevational range of 700–760 m, and most soils are classified as either Aquic Haplorthods or Aquic Haplumbredts (Halman et al. 22015 and references therein). Twelve sugar maple (Acer saccharum Marshall) dominated plots (45 m × 45 m) were randomly assigned to one of three treatments (Ca addition, Al addition, or control (no addition)), yielding four replicates of each treatment in the study. In addition to sugar maple, American beech (Fagus grandifolia Ehrh.) and yellow birch (Betula alleghaniensis Britt.) are co-occurring tree species in these plots, whereas hobblebush (Viburnum lantanoides Michx.) and striped maple (Acer pensylvanicum L.) dominate the understory. Treatments began in 1995 with annual CaCl2 (2.5 g·m−2) and AlCl3 (0.9 g·m−2) applications occurring each fall or spring during leafless periods. The use of CaCl2 was halted in 1999 in favor of a one-time application (38 g·m−2) of wollastonite (CaSiO3, a slow-release form of Ca). Thereafter, AlCl3 additions occurred in alternate years in fall or spring. Foliage was collected from sunlit branches in the upper to mid canopy dominant sugar maple trees. Five trees per plot of each group were selected for sampling in August 2008. There was an ice storm in 1998 at this site which might have interfered with this study findings. In 2009, tiny sapwood plugs were also collected. All the analyses were carried out using the procedures described under section A (Ca-supplementation study). SUMMARY: Acid deposition induced losses of calcium (Ca) from northeastern forests have had negative effects on forest health for decades, including the mobilization of potentially phytotoxic aluminum (Al) from soils. To evaluate the impact of changes in Ca and Al availability on sugar maple foliar and sapwood nutrition and metabolism at the Hubbard Brook Experimental Forest (Thornton, New Hampshire) in control and amended with Ca or Al plots beginning in 1995. Observations were taken from 1997-2009 at various intervals. Plots were mainly composed of sugar maple. The Ca:Al sensitivity of sugar maple contributed to divergent growth patterns that influenced stand productivity and composition. Given that acidic inputs are expected to continue, the growth dynamics associated with Al treatment may have direct relevance to future conditions in native forests. Study site The HBEF has long been documented as a site exposed to acidic inputs and subsequent Ca depletion (Bormann and Likens 1979; Likens et al. 1998). (Unpublished data) Likens GE, Driscoll CT, Buso DC, Siccama TG, Johnson CE, Lovett GM, Fahey TJ, Reiners WA, Ryan DF, Martin CW, Bailey SW (1998) The biogeochemistry of calcium at Hubbard Brook. Biogeochemistry 41:89–173 Bormann FH and Likens, GE (1979) Pattern and Process in a forested ecosystem. Springer-Verlag NY Inc. 253 pp