Different or dissimilar in structure, function, composition, quality, or origin.

Describes the solar energy-driven process by which water moves and is distributed on the earth's surface; includes as major components precipitation, evaporation, transpiration, infiltration, surface runoff, and groundwater flows.

An explanation for natural or other phenomena, developed using abductive reasoning following observation (the scientific method). The hypothesis is tested through the use of designed experiments, and shown to be either valid or invalid. If the original research hypothesis is deemed invalid, a new hypothesis must be developed, often based on further ovservation as well as the results from the previous experiment(s).

A scale comparing relative values with each other or a predetermined reference.

The process by which precipitation enters sub-surface layers of the soil; some is held as soil moisture recharge, some resurfaces as streamflow, and the remainder becomes part of groundwater flows (aquifers).

The activities, operations, or purposes that are employed in a particualr geographic area; the specific manner in which a parcel or tract of land is utilized. Land use is usually regulated by municipal governments through zoning ordinances, although some land uses are regulated by state or federal governments.

The first step in the scientific method, observation is the act of examining, inspecting, or scrutinizing natural or other phenomena in such a manner that leads to the use of abductive reasoning to explain them.

The actual outcome of a designed experiment using the scientific method. This outcome is compared to the expected outcome as described in the research hypothesis, and a conclusion is made that the experimental data either supports or contradicts the hypothesis.

Occurring regularly or semi-regularly in time, as a periodic tenancy, periodic rent, periodic portfolio review, etc.

Water that falls from the atmosphere to the earth's surface due to climatic factors, primarily in the forms of rain and snow.

Refers to the era prior to European settlement of North America, especially to the period before industrialization made it possible for these settlers to induce unprecedented ecosystem changes.

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.

See "Surface runoff".

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.

The characteristics of a site that influence growth of vegetation, including soil chemical and physical properties, climate, aspect, elevation, topography, and disturbance regime.

A contiguous group of trees that are similar enough in species composition, age class distribution, and site productivity or characteristics that it can be considered a single unit, regardless of size.

Surface runoff that is confined to a stream or river channel.

Water that flows over the earth's surface; precipitation that falls to the earth, is not infiltrated, evaporated, or transpired, and exceeds the capacity of the soil or the vegetation to absorb it.

Agricultural production that includes ecological and sustainability concerns in addition to economic and commodity values. Also known as "Alternative agriculture", this set of farming methods often includes organic farming, locally-based food production, biological pest control, and unique marketing strategies. This type of system is sustainable in the sense that the social, economic, and ecological benefits can last for extended periods of time without degradation of natural resources.

Generally, temperature decreases as elevation increases. For every 1,000 foot increase in elevation, temperature decreases three (3) degrees Fahrenheit, and vice versa. As latitude becomes more northward in the Northern Hemisphere and more southerly in the Southern Hemisphere, temperature decreases. The general rule is that temperature changes three (3) degrees Fahrenheit for every 300 mile change in latitude at an elevation of sea level. These temperature changes influence greatly the diversity and abundance of plant and animal species from place to place. However, other factors such as soil, topography, aspect, and precipitation are also extremely important in determining the types of plant and animal life that occur in any given area.

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.

The process by which water is released to the atmosphere by trees and other plants.

1. Area of land that drains all surface runoff to a common point. Large watersheds often contain numerous small watersheds; all land areas of the earth are within at least one watershed or sub-watershed.
2. The land area drained by a river and its tributaries.