The purpose of monitoring is to determine the current condition of our resources and how they change over time. Monitoring differs from inventory in adding the dimension of time, and the general purpose of monitoring is to detect changes or trends in a resource. Detection of a change or trend may trigger a management action, or it may generate a new line of inquiry. Monitoring is often done by sampling the same sites over time, and these sites may be a subset of the sites sampled for the initial inventory.

Natural resource monitoring is conducted primarily for two purposes: (1) to detect significant changes in resource abundance, condition, population structure, or ecological processes; or (2) to evaluate the effects of human-induced impacts on population or community dynamics or ecological processes. Monitoring should have a specific purpose, and is a prerequisite for management action, which is triggered when values reach or exceed some pre-determined threshold value.

You can find out more about the Inventory and Monitoring Program at the national program website.