Lesson Plan Glossary

Absorption: The ability to take in or soak up water.

Acid: A water solution containing more hydrogen ions than hydroxide ions. Acids have a pH of less than 7. Acid solutions taste sour, like lemon juice and turn litmus paper red.

Adaptation: The process by which organisms change, physically or behaviorally, to increase their chances of survival.

Adze Hoe: A fire-fighting tool with a specialized head for chopping vegetation or digging trenches.

Alkali (base): A water solution containing more hydroxide ions than hydrogen ions. Bases or alkaline solutions have a pH greater than 7. They taste bitter and turn litmus paper blue.

Bark: The outer covering on a trunk or branches of a tree.

Biodiversity: Variety of animal and plant life on earth, generally counted by species.

Biome: A large land ecosystem such as a woodland, desert, or forest.

Biota: The living plant and animal life of a region.

Branch: The part that grows out from the main trunk of a tree or shrub.

Carbon: A widespread chemical element found in plant and animal tissue. Organic compounds of carbon form the physical basis of all living things.

Carbon Dioxide: A gas, composed of carbon and oxygen, present in air in small quantities. It is released into the air through respiration and the combustion of carbon containing materials. Carbon dioxide does not support combustion.

Chaparral: A vegetation type dominated by shrubs and small trees, especially evergreen species with small, thick leaves such as chamise.

Chlorophyll: The green substance in plants that used energy from the sun and carbon

dioxide to produce sugar and oxygen.

Climate: Weather of an area over an extended period of time.

Coastal Sage Scrub: A vegetation type characterized by plants that include sage, buckwheat, and lemonadeberry.

Combustion: Rapid reaction between oxygen and a fuel.

Condensation: The changing of water from its vapor state into a liquid.

Conifer: A tree, usually evergreen, that  produces cones as fruit. Cones contain the seeds.

Conduction: Moving heat from one fuel particle to the next.

Convection: The transfer of heat energy through a liquid or a gas. Warm matter rises, while cooler matter sinks. This motion sets up currents of moving matter. In wildland fires convection currents are often responsible for the pre-heating of higher shrub layers and tree canopies, thus causing the fire to move upward.

Coordinate: Any number or letter that defines the position of a point, line, or the like.

Critical Habitat: A geographical area occuppied by a threatened or endangered species that is essential for its survival.

Crown Fire: Fire that burns the tree tops, jumping from tree to tree. Usually results in the complete destruction of a forest.

Decay: The breakdown of organic matter through a bacterial process.

Defensible Space: An area where material capable of causing a fire to spread has been treated, cleared, reduced, or changed to act as a barrier between an advancing wildland fire and the loss to life, property, or resources. In practice, "defensible space" is defined as an area a minimum of 30 feet around a structure that is cleared of flammable brush or vegetation.

Dendrochronology: The study of tree rings.

Density: Mass of a substance per unit of volume.

Desert: A dry area that receives less than 10 inches of annual rainfall. Desert cover most of eastern San Diego County and range from below sea level to 5,800 feet in elevation.

Drought: A long period without rain.

Duff: The layer of decomposing organic materials lying below the litter layer of fallen twigs, needles, and leaves and immediately above the mineral soil.

Ecology: The study of the interactions of living organisms with each other and with their environment.

Ecosystem: A natural community of organisms interacting with one another and with their nonliving environment.

El Niño: The periodic warming of the central Pacific Ocean that causes chaotic weather changes worldwide: abnormally wet weather in dry climates and dry weather in typically wet locations. El Niño and La Niña result from the interaction between the surface of the ocean and the atmosphere in the tropical Pacific. Changes in the ocean affect the atmosphere and climate patterns around the globe. In turn, changes in the atmosphere affect ocean temperatures and currents.

Endangered: A species that has so few members left that it is in danger of becoming extinct.

Endemic: Found in a certain geographical area and no where else.

Erosion: The process of earth being worn away by flowing water, ice, or wind, especially

common and more dangerous after fires remove stabilizing vegetation.

Escape Route: A predetermined plan for exiting a house or building in the event of fire.

Evaporate: The process by which a liquid changes to a vapor.

Extinct: No longer existing.

Fire Adaptation: The evolution of special traits that gives a species the ability to survive fires (for example: serotinous cones, fire resistant bark).

Fire Behavior: The manner in which a fire reacts to the influences of fuel, weather, and topography.

Fire Ecology: A branch of ecology that studies the relationship of fire with living organisms and their environment.

Fire Dependence: A concept that applies to species of plants that rely on the effects of fire to make the environment more hospitable for their regeneration and growth.

Fire History: A concept that describes how often fires occur in a geographical area.

Fire Regime: Describes the patterns of fire occurrence, size, and severity in a given area or ecosystem.

Fire-Resistant Species:  Species with physical characteristics that give it a lower probability of being injured or killed by fire than a Fire-Sensitive species, which has a relatively high probability of being injured or killed by fire.

Fire Storm: Violent convection caused by a large continuous area of intense fire often characterized by destructively violent surface indrafts, near and beyond the perimeter, and sometimes by tornado-like whirls.

Fire Suppression: Method used to put out a fire once it has started.

Fire Swatter: A fire-fighting tool that looks like a giant candle snuffer on a long handle.

Fire Triangle: The sides of a triangle are used to represent the three factors (oxygen, heat, fuel)

necessary for combustion and flame production. Removal of any of the factors causes flame production to cease.

Flammable: Able to burn easily.

Flood: Unintended flow of water outside the banks of a river, stream, or lake. This typically

occurs when there is excess runoff.

(California) Floristic Province: A mediterranean climate region located on the Pacific Coast of North America with a distinctive flora that bears similarities to other regions experiencing a winter rainfall, summer drought climate like the Mediterranean Basin. With an area of 293,804 km² , it includes 70% of California and extends into southwestern Oregon, a small part of western Nevada and northern Baja California.

Fog: Condensed water vapor that forms a cloud close to the ground and limits visibility.

Fuel: Combustible material that releases energy when it burns.

Fuel Load: The amount of fuel present expressed quantitatively in terms of the amount of fuel per unit area.

Fresh Water Marsh: A low-lying area usually fed by a creek, stream or lake, 1-6 feet in depth, rich in minerals, and supporting low growing plants like grasses and sedges.

Grassland: A habitat found in interior valleys up to 4,000 feet. Many of these areas are presently dominated by non-native grasses.

Ground Fire: Fire that burns in the organic material below the litter layer, mostly by smoldering combustion. Fires in duff, peat, dead moss and lichens, and punky wood are typically ground fires.

Groundwater: Water under the ground, such as water in an aquifer or well.

Habitat: A natural area where plants and animals live and grow.

Hydrologic (water) Cycle: The hydrologic cycle (or water cycle) refers to the path water takes as it moves throughout the Earth’s systems—ocean, atmosphere, surface water, and ground water. It is a never-ending cycle.

Ignite: To set on fire.

Lagoon: An area of shallow water separated from the sea by low banks. The coastal lagoons are a mixture or salt water and fresh water.

Landform: A distinctive geogrpahical area defined by elevation, slope, orientation, stratification, rock exposure, and soil type. Landforms by name include mounds, hills, cliffs, caves, valleys, beaches, slat marshes, lagoons, lakes, watersheds.

La Niña: The periodic cooling of the central Pacific Ocean that causes chaotic weather changes worldwide: abnormally dry weather in dry climates and wetter weather in typically wet locations. El Niño and La Niña result from the interaction between the surface of the ocean and the atmosphere in the tropical Pacific. Changes in the ocean affect the atmosphere and climate patterns around the globe. In turn, changes in the atmosphere affect ocean temperatures and currents.

Leaf: A part of a plant that grows from a node on a stem, usually a thin, flat blade on a stalk.

Marsh: Any area of low lying wetlands, such as a bog or swamp.

McLeod Tool: A fire-fighting tool that is a combination rake and hoe, used for digging and clearing.

Mediterranean Climate: Mild climate, located in a temperate latitude, moderated by proximity to sea, characterized by warm to hot, dry summers and mild, wet winters.

Mixed Conifer Forest: A habitat found in the mountain ranges of San Diego County at elevations above 4,500 feet. It consists of dense growths of pine, cedar, and firs to more open forests with pines and oak trees.

Montane (mountain) Meadow: A habitat that occurs as scattered areas within the mixed conifer forest where the soil is too moist for trees to grow.

Nitrogen: A chemical element found in the air. It does not support combustion. It is part of amino acids and proteins that are found in all living organisms.

Non-point Source Pollution: The source of waste is spread out, at a number of points, rather than a specific, easily identifiable pollution point.

Nutrient: Substance that provides the raw materials and energy to keep an organism alive.

Oak Woodland: A habitat found in the inland foothills and canyons between 1,500 and 4,500 feet elevation. It consists of oaks trees with grasses and wildflowers and patches of chaparral shrubs.       


Oxygen: A chemical element found in air, soil, and water. It supports combustion. Plants produce oxygen by the process of photosynthesis.

Percolate: The passage of a liquid to through porous material such as soil.

pH: A scale that measures acidity/alkalinity of a liquid, 0-7 is decreasing acidity, 7 is neutral, and 7-14 is increasing alkalinity.

Phosphorous: A chemical element found in nature, usually combined with oxygen. It is an essential nutrient of plants and animals.

Photosynthesis: In green plants the synthesis of plant food from carbon dioxide and water in the presence of sun.

Pith: The central core of stems and tree trunks that stores food and water.

Potassium: A chemical element essential for muscles and nerves. It is found in soil minerals and in fertilizers.

Precipitation: Condensed water that is heavy enough to fall to the Earth’s surface in the form of rain, snow, sleet, hail, or fog.

Pulaski Tool: A fire-fighting tool that is a combination axe and hoe for digging and chopping.

Radiation: Transfer of heat through space by rays, such as from the sun or a flame. Radiation and convection   most of the preheating of fuels surrounding a fire, allowing the fire to spread.   

Rain Shadow: Local mountains act as barriers to storms; moisture is released on the ocean side while the far side remains dry—deserts in the eastern part of San Diego County.

Relief Map: A three dimensional map that depicts the topography of the earth’s surface.

Resin: A gum-like substance that oozes from cracks and cuts in trees and bushes.

Respiration: Process by which living organisms combine oxygen with food to produce energy. Carbon dioxide is a by-product.

Riparian: A streamside habitat found at the bottom of canyons and valleys throughout the County. It is characterized by deciduous trees that require a close source of abundant water.

Runoff: Excess surface water that drains into a watershed.

Salt Water Marsh:

Santa Ana Wind:


Species: Organisms of the same kind that are capable of breeding with other members of the group, but not outside of the group.

Stem: The main stalk of a shrub that bears leaves.

Surface Fire: Fire that burns in litter and other live and dead fuels at or near the ground, mostly by

flaming combustion.

Surface Water: Water found in oceans, lakes, streams, and wetlands.

Threatened: A species that is still abundant in its natural range, but which may become endangered in the foreseeable future.

Topographic Map: A two dimensional map that uses a series of curved, connecting lines (contours) to depict elevation.

Topography: The surface features of area, such as lakes, mountains, canyons.

Trunk: The main woody stem of a tree.

Vapor: The gaseous form of a substance that is usually solid or liquid at ordinary temperatures.

Vernal Pool: A shallow, seasonal body of water that occurs in depression in grassland and woodland areas. These pools fill with water in winter and dry up during summer.

Watershed: A drainage basin into which water, sediments, and dissolved minerals drain from the land into a common body of water—like a stream, lake, or the ocean.

Water Table: The distance water lies under the ground. This can range from a few feet to hundreds of feet below the surface.

Weather: Conditions affecting the atmosphere and a particular time and place.

Weathering: The process by which rocks when exposed to rain, wind, and ice wear away.

Wildland Fire: Any non-structure fire, other than prescribed fire, that occurs in wildland.

Wildland Urban Interface: The line, area, or zone where structures and other building development meet or

intermingle with undeveloped wildland or vegetative fuel.

Xylem: The tissue in tree trunks that carries water and nutrients to the stems and leaves. It is between the bark and pith.