Lake Large natural body of standing fresh water formed when water from precipitation, land runoff, or groundwater flow fills a depression in the earth created by (1) glaciation, (2) earth movement, (3) volcanic activity, or (4) a giant meteorite. See eutrophic lake, mesotrophic lake, oligotrophic lake.

land-use planning Process for deciding the best present and future use of each parcel of land in an area. See ecological land-use planning.

late successional plant species Mostly trees that can tolerate shade and form a fairly stable complex forest  community. Compare early successional plant species, midsuccessional plant species.

latitude Distance from the equator. Compare altitude.

law of conservation of matter In any physical or chemical change, matter is neither created nor destroyed but merely changed from one form to another; in physical and chemical changes, existing atoms are rearranged into different spatial patterns (physical changes) or different combinations (chemical changes).

law of tolerance Existence, abundance, and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within the range tolerated by the species. See threshold effect.

LD50 LD means lethal dose, 50 is the percent that dies at that dose. Other numbers can be used. Used in toxicology.

leaching Process in which various chemicals in upper layers of soil are dissolved and carried to lower layers and, in some cases, to groundwater.

life cycle cost Initial cost plus lifetime operating costs of an economic good. Compare full cost.

life expectancy Average number of years a newborn infant can be expected to live.

limiting factor Single factor that limits the growth, abundance, or distribution of the population of a species in an ecosystem. See limiting factor principle.

limiting factor principle Too much or too little of any abiotic factor can limit or prevent growth of a population of a species in an ecosystem, even if all other factors are at or near the optimum range of tolerance for the species. See range of tolerance.

linear growth Growth in which a quantity increases by some fixed amount during each unit of time. Compare exponential growth.

liquefied natural gas (LNG) Natural gas converted to liquid form by cooling to a very low temperature.

liquefied petroleum gas (LPG) Mixture of liquefied propane (C3H8) and butane (C4H10) gas removed from natural gas and used as a fuel.

Lithosphere Outer shell of the earth, composed of the crust and the rigid, outermost part of the mantle outside the asthenosphere; material found in earth's plates. See crust, mantle.

loams Soils containing a mixture of clay, sand, silt, and humus. Good for growing most crops.

logistic growth Pattern in which exponential population growth occurs when the population is small, and population growth decreases steadily with time as the population approaches the carrying capacity. See S-shaped curve. Compare J-shaped curve.

low-quality energy Energy that is dispersed and has little ability to do useful work. An example is low-temperature heat. Compare high-quality energy.

low-quality matter Matter that is dilute or dispersed or contains a low concentration of a useful resource. Compare high-quality matter.

low-throughput economy Economy based on working with nature by (1) recycling and reusing discarded matter, (2) preventing pollution, (3) conserving matter and energy resources by reducing unnecessary waste and use, (4) not degrading renewable resources, (5) building things that are easy to recycle, reuse, and repair, (6) not allowing population size to exceed the carrying capacity of the environment, and (7) preserving biodiversity. Also used low-waste cociety. See environmental worldview. Compare high-throughput economy, matter-recycling economy.