National Park Service

Northeast Temperate Network (NETN)

atmospheric deposition and stress


Healthy soil is an important component of the forest ecosystem. It is a strong foundation for trees and plants to grow on, a habitat for numerous insects, fungi, and algae, and a lab where old organic matter is recycled back into the ecosystem.

Trees depend on soil for; stability, nutrients, and water. Most nutrient cycling takes place in the top two feet of soil where supplies of air, water and food allow microorganisms to thrive. These include bacteria, fungi and algae. These microorganisms work in conjunction with insects and burrowing animals to break down dead or dying plant and animal life. In the process they release carbon dioxide into the air and nutrients into the soil.

Healthy soil is a living body made up of inorganic material, decaying organic matter, water, air and billions of organisms. Some organisms form partnerships with tree roots helping them to extract nutrients from the soil. Others are important in breaking down organic matter and cycling nutrients, making them available to the next generation of plants and animals.

Importance & Issues

NETN tech takes a soil sample The NETN will focus on ratios of carbon to nitrogen (C:N) and calcium to aluminum (Ca:Al) in forest soils. The impacts of atmospheric nitrogen deposition are measured through changes in C:N ratios in the soil. Ca:A; ratios are reliable indicators of the ecological impacts of acidic deposition.

Our overall goal is to monitor status and trends in the structure, function and condition of NETN forested ecosystems in order to inform management decisions affecting those systems. To do so, NETN will interpret and report the ecological integrity of NETN forested systems from monitoring data. The “ecological integrity” of an ecosystem is a measure of the structure, composition, and function of an ecosystem as compared to pristine or benchmark ecosystems operating within the bounds of natural or historic disturbance regimes (Karr and Dudley 1981, DeLeo and Levin 1997, Czech 2004). Ecological integrity can be assessed by comparing key elements or attributes of an ecosystem to a reference area or to historical measurements or modeling efforts. In this way, NETN hopes to provide reliable data to inform management decisions relevant to NETN forested systems, including NPS land management and forest harvest plans, exotic species control, deer population management, NPS internal development, and national pollution control legislation

Monitoring Objective

Determine the status and trend in soil Ca:Al and C:N ratios to assess the extent of base cation depletion, increased aluminum availability and/or nitrogen saturation impacting NETN forest soils.


Three metrics directly relate to soil condition. Forest floor condition is a qualitative assessment of both trampling impacts and exotic earthworm invasion upon the forest floor. Two useful indicators of soil chemistry are measured in both surface and deeper soil layers. The carbon to nitrogen ratio of the soil is an important indicator of nitrogen saturation, a problem caused by anthropogenic atmospheric deposition which can lead to watershed pollution and forest decline. Likewise, the calcium to aluminum ratio of the soil is a critical indicator of acidic deposition impacts.


Last Updated: December 30, 2016 Contact Webmaster