How climatic conditions, site, and soil characteristics affect tree growth and critical loads of nitrogen for northeastern tree species
Gen. Tech. Rep. NRS-172. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 143 p.
Forest health is affected by multiple factors, including topography, climate, and soil characteristics, as well as pests, pathogens, competitive interactions, and anthropogenic deposition. Species within a stand may respond differently to site factors depending on their physiological requirements for growth, survival, and regeneration. We determined optimal ranges of topographic (elevation, aspect, slope gradient), climatic (average temperature for January, July, and May to September; annual and May to September precipitation), and soil (pH, percent clay, percent coarse sand, permeability, depth to bedrock) parameters for 23 tree species of the northeastern United States. We primarily used importance values (a measure of how dominant a species is in a given forest area under existing site conditions) from a published analysis of more than 100,000 U.S. Forest Service Forest Inventory and Analysis plots to set optimal ranges for the abiotic factors. The region included in this assessment is defined by level 2 ecoregions: mixed wood plains in the Eastern Temperate Forest Ecoregion; Atlantic highlands and mixed wood shield in the Northern Forest Ecoregion. In addition to summarizing ranges for abiotic modifying factors, we also determined the critical load of nitrogen—the deposition below which no harmful ecological effects occur—for each species. The information can be used in forest health assessments to determine whether species growth at a site is expected to be optimal or suboptimal, and can also be used to modify critical load ranges for each species based on site conditions.
Data for the species Quercus alba have been added to the graph at the top of page 138, as of January 23, 2018. This data was inadvertently omitted from the original; data for other species did not change.
Robin-Abbott, Molly J.; Pardo, Linda H. 2017. How climatic conditions, site, and soil characteristics affect tree growth and critical loads of nitrogen for northeastern tree species. Gen. Tech. Rep. NRS-172. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 143 p. https://doi.org/10.2737/NRS-GTR-172.