Critical Loads Publications & Products

The following documents, which contain critical loads background and calculation information, can be downloaded as PDFs.

Critical Load Calculation Methods

• Approaches for Estimating Critical Loads of N and S Deposition for Forest Ecosystems on U.S. Federal Lands
  This paper describes the basic mass balance approach for calculating critical loads, presents the various critical thresholds, and explains the assumptions inherent in the calculation and data selection procedure.

Critical Loads Calculations in Forest Service Class 1 Areas

• Protocol for Calculating Critical Loads of Nitrogen and Sulfur Deposition for Forest Ecosystems in Forest Service Class 1 Areas (draft)
• Data Availability for Forest Service Class 1 Areas (draft)
  A summary of data available for critical loads models of Forest Service class 1 areas.
• Ecosystem Descriptions for Forest Service Class 1 Areas (in progress)
  This document contains four tables summarizing climate, vegetation, and soil attributes associated with EcoMap Sections and Subsections.

Critical Loads Data Management

• Critical Loads Database – Data Management Protocol (draft)
  The Data Management Protocol contains instructions for preparing data for simple mass balance calculations of critical loads.
• Critical Loads Database Parameters
  A one page graphic of database parameters and structure.
• Instructions for Calculating Critical Loads
  This document discusses model input, intermediate calculations, background data and data for additional analysis.
• Data Required for Critical Loads Calculations
  This is a one page table indicating required and additional parameters for calculating critical loads.
• European Data Requirements
  This is a list of mandatory and optional parameters for calculating critical loads from the ICP Forests and ICP Waters manual.

Critical Loads in the United States

• Assessment of Effects of Acidic Deposition on a Forested Ecosystem in Great Smoky Mountains National Park using Critical Loads for Sulfur and Nitrogen. This report was prepared for the Tennessee Valley Authority and appears here with permission.
• Assessment of Nitrogen deposition effects and empirical critical loads of Nitrogen for ecoregions of the United States. This report synthesizes current research relating atmospheric nitrogen deposition to effects on terrestrial and aquatic ecosystems in the United States, and identifies empirical critical loads for atmospheric N deposition.
• Effects of nitrogen deposition and empirical nitrogen critical loads for ecoregions of the United States.
  This paper summarizes nitrogen deposition effects on ecosystems across the United States and provides critical loads data.
• Critical Loads of Acidity in the United States Database (Microsoft Access Database)
  A database of published critical loads of acidity in the United States.  If you use information from this database, please cite it appropriately.
• Critical Loads of Acidity Database Description and Parameters
  Information on database composition and structure.
• Critical Loads of Acidity Database Tables
  Summary data from Critical Loads of Acidity Citation, Site, an Critical Loads Tables.
• Susceptibility of Forests in the Northeastern U.S. to Nitrogen and Sulfur Deposition and Implications for Forest Health (7mb pdf)
  This report provides steady state mass balance calculations of critical load for
  S+N, critical load for nutrient N, and exceedance for forested sites in New England and New York, as well as a comparison of forest health parameters with exceedance.

Critical Loads Demonstration Plots

• Site Selection Criteria for Critical Loads Demonstration Plot
• Demonstration Plot Soil Sampling Protocol
• Demonstration Plot Design (jpg image)
  ICP Forests plot design from ICP Forest Manual.

Additional Related Products

• Excess Nitrogen in the U.S.Environment: Trends, Risks, and Solutions. (pdf)
  This article describes the major sources of excess nitrogen in the United States, the impacts of excess nitrogen, and potential mitigation options.
• Assessment of Forest Sensitivity to Nitrogen and Sulfur Deposition in New England and Eastern Canada
  Conference of New England Governors' and Eastern Canadian Premiers' Pilot Phase Report
• Protocol for Assessment and Mapping of Forest Sensitivity to Atmospheric S and N Deposition
  The New England Governors' and Eastern Canadian Premiers' Forest Sensitivity Mapping Group.
• Tree Chemistry Database General Technical Report (download PDF or Database)
  The GTR documents the development and use of a database of C, N, P, K, Ca, Mg, Mn, and Al concentrations in bole bark, bole wood, branches, twigs, and foliage.

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