486 Glossary organization, from molecules to genes, to populations, to species, to ecosystems and the entire biosphere It is a multidimensional concept difficult to measure, and in practice most focus is on diversity at the species level Biodiversity assessment The identification and classification of species, habitats, and communities within a given area or region; can be done to evaluate whether management is necessary to conserve biological diversity Biodiversity hotspot See HOTSPOT Biodiversity offset A measures intended to compensate for adverse biodiversity impacts, with the goal of no net loss and preferably a net gain of biodiversity of species composition, habitat structure, and ecosystem function Biodiversity restoration See RESTORATION Bioelectricity An electric current generated by living tissue Electricity produced by burning biomass Bioenergetics The flow and transformation of energy within organisms, or between organisms and their environment Bioenergy A form of energy that can be extracted from biomass, including biodiesel from fats and oils, bioethanol from sugars, starches, and lignocellulosic material, and bioelectricity and bioheat from the combustion of lignocellulosic material Bioethanol Alcohol made from sugar (e.g., sugarcane), starch (e.g., corn grain), or cellulosic materials (e.g., cornstalks, wheat straw, prairie grasses, and trees) for use as a biofuel; sugar and starches are converted to ethanol through fermentation, while cellulosic material is converted via enzymatic hydrolysis or synthesis gas fermentation Biofuel Any of a variety of fuels in some way derived from biomass, including firewood, methane, or liquid transportation fuels obtained from plants or other biological materials Biofuel land-use change The conversion of forest land and pasture to cropland for the purpose of growing plants for biofuel The anticipated reduction in GHG emissions resulting from the substitution of biofuel for traditional fossil fuels is thus offset by release of carbon from biomass and soils, and there are a variety of other impacts such as loss of biodiversity and overexploitation of water resources, as well as market effects such as higher food prices (and possible food scarcity) due to reduction in the amount of land devoted to food crops Biogeochemical processes The various chemical, physical, geological, and biological processes that collectively govern the composition of the biosphere Biogeochemistry The scientific study of biotic controls on the chemistry of the environment and geochemical controls on the structure and function of ecosystems Biogeographic realm One of the largest divisions of the historic and evolutionary patterns of terrestrial plants and animals In such an area, plants and animals evolved in the isolation created by barriers such as oceans, mountain ranges, or deserts It can be a single continent, or it can span continents Biogeographic region A large region with characteristic assemblages of natural communities and species, distinct from other regions See BIOGEOGRAPHIC REALM Biogeography The study of the geographic variation of nature, including variation in any biological characteristics (e.g., body size, population density, or species richness) on a global scale Historical biogeography studies this variation over time Bioheat A fuel or heating system based on or employing a biological source Specifically, a fuel composed of conventional heating oil blended with a percentage of biodiesel (typically 2–20%) Biological assay See BIOASSAY Biological carbon pump See CARBON PUMP Biological control The use of naturally occurring or introduced natural enemies (e.g., predators and parasitoids) to control agricultural pests, as opposed to non-natural controls such as insecticide sprays Biological diversity See BIODIVERSITY Biological energetics See BIOENERGETICS Biological integration The fact of life functions being organized in distinct, self-regulating units (cells, tissues, organs, organisms, populations, communities, and ecosystems) Biological soil crust The combination of non-vascular and non-seed-forming plants that commonly occur on the soil surface of many arid and semiarid ecosystems May consist of mosses, lichens, liverworts, green algae, and cyanobacteria Bioluminescence The production of light by living organisms; e.g., fireflies, anglerfish Biomass The combined mass or weight of all the members of a given population or stock at a given time, or, on the average, over a certain time period The mass of biological material remaining after the removal of water from it by oven-drying at 70–100 1C; often expressed as mass per area of ground surface A collective term for all organic substances that can be used as energy sources, including wood, straw, agricultural and industrial plant residues, municipal organic wastes, and crops grown specifically for fuel Applies to relatively recent (non-geologic) fuel sources, excluding fossil fuels Biomass pyramid A graphic representation of the biomass relationships of a community, in which the total amount of biomass at each successive trophic level is proportional to the width of the pyramid at the appropriate height Biome A major terrestrial ecological community and landscape type, characterized by more or less uniform physiognomy of its potential natural vegetation and with characteristic fauna and flora, such as the tropical rainforest, the warm deserts, or the temperate grasslands Biomimetic An artificial compound, device, or structure that mimics or was inspired by nature Imitating or modeled after nature or a natural process Having to with or employing biomimetics (see next) Biomimetics The study of natural structures, processes, and systems as a model for human technology Also known as biomimicry Bionomic equilibrium In a biological common property resource, an equilibrium between resource production rate and exploitation rate, characterized by the dissipation of economic rents Bionomics The mode of life of a species Biophilia The innate tendency of humanity to focus on life and lifelike processes and to have an affinity for the natural world, said to have evolved over millennia and to be part of human inheritance