Assessment of sugar maple health and associated soil conditions in the Adirondack Region of New York

This project provides a regional assessment of sugar maple health and associated soil conditions in the Adirondack Region of New York, where sugar maple are a major component of the forest. The focus of the study is to develop an improved understanding of relationships among watershed characteristics, soil chemistry, and acidic deposition effects on sugar maple trees and other tree species that grow in association with sugar maple, which are one of the most highly valued tree species in the northeast.  Project results are therefore important for the management of sugar maple in the Adirondack region where acidic deposition has lowered the nutritional status of soils by depleting calcium, a key nutrient for trees.

Purpose and Objective

The purpose of this research is to identify the linkages between chemical and biological effects of acidic deposition in Adirondack forests where highly-valued sugar maple trees are common.  This research builds upon U. S. Forest Service research conducted in Pennsylvania, where detailed analysis of damaged sugar maple stands indicated that sugar maple health was strongly tied to the availability of calcium and magnesium in the soil.

Study plots were were selected to include sugar maple trees, and were located in the watersheds of streams sampled in the original Western Adirondack Stream Survey (WASS).  This work, in conjunction with other USGS research in the Adirondack region, is part of an integrated ecosystem assessment of soil, stream water, and forest condition that is being applied to the Adirondack region as a whole. 

The primary objective of this study is to determine the extent to which soil base status (measured by base saturation, exchangeable Ca and Mg, and Ca:Al molar ratio) is associated with the health of sugar maple (measured by sugar maple abundance, growth history, regeneration, basal area, and canopy condition).  This project is also providing soils data for model-based assessments of stream water chemistry and investigations of soil effects on understory plants and physiological processes of sugar maple.

Key Findings

Effects of soil acidification linked to acidic atmospheric deposition were found to have negative effects on the canopy health, basal area increment, and regeneration of sugar maple trees across the Adirondack region where widespread depletion of soil Ca from acidic deposition has been documented. Sugar maple is a dominant canopy species in the Adirondack ecoregion, and it has a high demand for Ca. Trees in this region growing on soils with low exchangeable Ca and base saturation, which receive relatively high levels of atmospheric sulfur and nitrogen deposition, exhibited a near absence of sugar maple seedling regeneration and lower crown vigor compared with study plots with relatively high exchangeable Ca and base saturation and lower levels of acidic deposition. Basal area increment averaged over the 20th century was correlated with acid−base chemistry of the Oa, A, and upper B soil horizons. A lack of Adirondack sugar maple regeneration, reduced canopy condition, and possibly decreased basal area growth over recent decades are associated with low concentrations of nutrient base cations in this region that has undergone soil Ca depletion from acidic deposition.

Follow up research was conducted on these sites to assess relationships between understory vegetation and soils and to determine what how the composition of the understory may have been changed by effects of atmospheric deposition of nitrogen and sulfur deposition on these soils.  Results showed a relationship between understory plant communities and a soil-chemical gradient that suggested that soil acidification can reduce diversity and alter the composition of these communities in northern hardwood forests exposed to acidic deposition.