Glossary

TERM CATEGORY DEFINITION
Aerial photograph Computer mapping Photographs of the ground from an elevated position.
Air quality Air quality The condition of the air in the surrounding environment; often measured as the Air Pollution Index (API) or the Pollutant Standard Index (PSI).
Anthropogenic disturbances Nearshore zones Disturbance to the environment caused by humans.
Atmospheric deposition Air quality Atmospheric deposition occurs when pollutants are transferred from the air to the Earth’s surface.
Atmospheric pollutants Air quality Chemicals, particulate matter or biological materials that cause harm or discomfort to humans or other living organisms, or damage to the natural environment.
Benthic invertebrates (benthos) Invasive species Relating to the bottom of a sea or lake, and to the organisms that live there.
Biodiversity Invasive species Used to describe all the species living in a particular area.
Biomaterial Invasive species Any substance, natural or man-made, that comprises whole or part of a living structure or biomedical device that performs, augments, or replaces a natural function.
Continental crust Geology The layer of igneous, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves.
Cultural eutrophication Water quality The process that speeds up eutrophication and is the result of human activity.
Defensible space Home protection The area around the home that is noncombustible.
Drip torch Living with fire An ignition tool that drips a mixture of flaming diesel and gasoline onto the ground.
Ecosystem Invasive species An ecological community together with its environment, functioning as a unit.
Electromagnetic spectrum Computer mapping The range of all possible frequencies of electromagnetic radiation.
Eutrophication Water quality An increase in the concentration of chemical nutrients in an ecosystem to an extent that increases the primary productivity of the ecosystem.
Fault Geology A planar fracture or discontinuity in a volume of rock across which there has been significant displacement. Large faults within the Earth’s crust result from the action of tectonic forces. Energy release associated with rapid movement on active faults is the cause of most earthquakes.
Fire return interval Living with fire The number of years between two successive natural fire events at a specific site or an area of a specified size.
Fire severity Living with fire The effect of fire on plants. It is dependent on intensity and duration of the burn; an intense fire may not necessarily be severe. For trees, severity is often measured as percentage of basal area removed.
Forage fish Invasive species Related to the critical part fish play as the prey base for a large variety of other organisms.
Fuel load Living with fire The amount of available and potentially combustible material, usually expressed as tons/acre or kilogram/hectare.
Geographic Information System (GIS) Computer mapping A system that allows us to view, understand, question, interpret and visualize data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts.
Glaciation Geology The process of glacier growth and establishment.
Historic photograph Rephotographic survey A photograph taken at some point in the past.
Impervious landcover Water quality Any land use alteration which causes water to flow over a surface instead of soaking into the ground.
Invasive species, non-native Invasive species A species that is non-native (or alien) to the ecosystem under consideration and whose introduction causes, or is likely to cause, economic or environmental harm or harm to human health.
Ladder fuels Home protection Fuels, such as branches, shrubs or an understory layer of trees, which allow a fire to spread from the ground to the canopy.
Lean, clean and green Home protection Helping prevent home fires by ensuring that the area around the home does not have much fuel, has little accumulated dead litter and is alive and irrigated during the burning season.
Mechanical biomass treatment Living with fire The process of physically removing small trees or organic fuels.
Near-shore zone Nearshore zones Can be defined differently for each lake, however for Lake Tahoe, the nearshore is defined as starting at a water depth of one meter and extending offshore for 100 meters or to a water depth of 30 meters, whichever offshore distance is greater. (One meter equals 3.28 feet.)
Pelagic zone Nearshore zones The open body of water in a lake.
Periphyton Nearshore zones Sessile organisms, such as algae, that live attached to surfaces projecting from the bottom of freshwater aquatic environments.
Prescribed burn Living with fire A fire ignited under known conditions of fuel, weather and topography to achieve specific objectives.
Remote sensing Computer mapping The gathering and recording of information about the Earth’s surface by methods that do not involve actual contact with the surface.
Rephotographic survey Rephotographic survey An attempt by a documentary photographer/scholar to understand changes in the landscape by making a contemporary photograph at the same spot as a historical one and comparing the two images.
Satellite image Computer mapping A photograph or image taken of the Earth from an artificial satellite.
Secchi disc Water quality Black and white circular device used to measure water transparency.
Slash pile Living with fire Collection of large woody and herbaceous debris from tree removal. Generally, slash piles are intended to be burned during safe conditions, when the fire will not spread.
Stream Environment Zone (SEZ) Upland watershed management Consists of a stream and its drainage, as well as marshes and meadows.
Uplifting Geology A geological process most often caused by plate tectonics which increases elevation.
Urban encroachment Upland watershed management Expansion of urban areas.
Volcano Geology A volcano is an opening or rupture in a planet’s surface or crust, which allows hot magma, ash and gases to escape from below the surface.
Water quality Water quality The characteristics of water in relation to guideline values of what is suitable for human consumption, safety of human contact and for the health of ecosystems.
Water repellency Living with fire Resistance to soil wetting that can be increased by intense fires.
Watershed Water quality The area of land that water flows across or through on its way to a common stream, river or lake. Watersheds can be very large or small.
Whole-tree removal Living with fire The cutting down and removal of entire trees to reduce tree density or fuel loads in an area.
Wildfire Living with fire Any uncontrolled fire, natural or caused by humans, that occurs in the countryside or a wilderness area.
Wildland-urban interface Home protection Zone where structures and other human developments meet, or intermingle with, undeveloped wildlands.