Background
The Appalachian Trail (A.T.) rare plant monitoring program originates from a series of natural heritage inventories that were conducted within each of the 14 states through which the A.T. passes. These inventories, conducted from 1989 to 2001, documented rare, threatened and endangered (RTE) species and rare or exemplary natural communities within the A.T. corridor. Documentation of RTE vertebrates varied from state to state, and only a few heritage inventories include non-vascular plants and invertebrates.

The state natural heritage inventories documented approximately 1,750 occurrences of rare, threatened or endangered species and nearly 300 rare or exemplary natural communities.

Objectives
In accordance with the National Park Service's mission statement (1916), the Appalachian National Scenic Trail Park Office (ATPO or A.T. Park Office) and its managing partners are obligated to "preserve unimpaired [the park's] natural and cultural resources and values [...] for the enjoyment, education, and inspiration of this and future generations."

This obligation translates first and foremost into a responsibility that the A.T. Park Office, the Appalachian Trail Conservancy (ATC) and all its maintaining clubs, and other managing partners do no harm to the Trail's natural heritage. The ATPO and ATC's natural heritage monitoring program is a first step towards fulfilling this obligation. By tracking the status of rare plant or community occurrences, the A.T. managing partners can ensure that A.T. related activities and management decisions are not adversely affecting these natural resources.

Methods
A new rare plant monitoring protocol was developed in 2008 following completion of a thorough program review. The new "written" protocol includes sections on Quality Assurance / Quality Control (QA/QC), volunteer training, data collection and analysis.

The program focuses monitoring efforts on plant species that are globally defined as critically imperiled (1), imperiled (2) or vulnerable (3) on a global (G) or sub-national (S) basis. These definitions, by NatureServe are universally recognized and offers managers and monitors a way to prioritize efforts. In some cases, selection of occurrences for monitoring may be based in part on location, degree of threat, or species life history traits related to monitoring success, but whatever the decision, reasons for inclusion or exclusion of sites and occurrences must be documented. Rare plant monitoring typically employs some combination of 1) monitoring the distribution or spatial extent of rare plant populations; 2) monitoring the size, condition and/or vigor of rare plant populations; 3) intensive demographic monitoring of specific populations to document and predict population trends, and this program is no exception.