A point in history that is considered to be representative of the natural conditions of an ecosystem. This point, which may be in the past or present, is chosen such that it is within the historic or natural range of variability for a particular area.

A pattern of regular or semi-regular occurrences or processes that characterizes and governs a natural system, as in precipitation regime, fire regime, disturbance regime, etc.

The outcome of an experiment conducted using the scientific method. This observed result is compared to the expected result according to the research hypothesis, and a conclusion is made about whether the results support or contradict the hypothesis.

1. The series of rational steps that leads to the proof (or disproof) of a scientific or research hypothesis. The steps are observation, which leads to the formulation of a hypothesis through abductive reasoning, followed by tests or experiments to determine the validity of the hypothesis (deductive reasoning). The observed result of the experiment is compared to the expected result, and a conclusion is made supporting or contradicting the hypothesis. 2. The scientific method is the process by which scientific facts are discovered, proven, or learned.

1. Live trees of merchantable species and sufficient size that they can be profitably harvested and sold. Timber is then milled and made into lumber and other wood products. 2. Forest land covered by trees of suitable size, kind, and quality to be of commercial value.

A branch of the U.S. Department of Agriculture responsible for managing the national forests of the United States. Popularly known as the "U.S. Forest Service.