Glossary of Terms Used in
Range Management and Ecology
This glossary is meant to provide students majoring in Plant Ecology and Range Management with some terms that are most encountered in literature. It was compiled using the following references:
· Cain, M.L., W.D. Bowman and S.D. Hacker. 2008. Ecology. Sinauer Associates, Inc.; 1st edition. 552 p.
· Kothmann, M.M. (Ed., Chair.). 1974. A Glossary of Terms Used in Range Management, 2nd Edition, published by the Society for Range Management
· Powter, C.B. (Compiler). 2002. Glossary of Reclamation and Remediation Terms Used in Alberta – 7th Edition, Alberta Environment, Science and Standards Branch, Edmonton, Alberta. Pub. No. T/655; Report No. SSB/LM/02-1. 88 pp.
A
Abiotic Factors: All non-living elements of the environment
Abundance: The total number of individuals of a species in an area, population, or community
Accessibility: The ease with which rangeland can be reached and grazed by animals
Accuracy: The closeness of a measured value to its true value
Actual Use: The consumption or destruction of forage on any area by livestock and/or wildlife
Adventitious Root: A root that arises from a stem, rather than from the primary root tissue
Aerial Root: Root growing above ground or water
Age Class: A descriptive term indicating the relative age of plants in a population
Alien Plant: A plant that did not originally occur in an area where it is now established, but which arrived directly or indirectly by human activity
Allelopathy: Interaction between two different species involving chemicals produced by one, which suppresses the growth or reproduction of the other
Alpha diversity: Species diversity at the local or community scale (Compare beta diversity, gamma diversity)
Animal-Unit (AU): One mature (454kg) cow or the equivalent based on average daily forage consumption of 12kg dry matter
Animal-Unit Conversion Factor: A numerical figure expressing the forage requirements of a particular kind or class of animal relative to the requirement for an animal-unit
Animal-Unit Month (AUM): The amount of feed or forage required by an animal-unit for one month
Annual Plant: A plant that completes its life cycle and dies in one year or less
Annual Range: Rangeland on which the principal forage plants are herbaceous annual species
Apomixis: Plant reproduction by seeds without fertilization, meiosis or production of gametes, so that the resulting seed is vegetatively produced
Arid: A term applied to regions or climates where lack of sufficient moisture severely limits growth and production of vegetation
Asexual Reproduction: Reproduction which does not involve the union of gametes
Autecology: A branch of ecology that deals with the relationship of individual organism and their environment
Autotroph: An organism that makes its own food from light energy (or chemical energy). Most of green plants are autotrophs. Autotrophs are the base of the food chain
Avoidance. A response of an organism to stressful environmental conditions that lessens their effect through some behavior or physiological activity that minimizes exposure to the stress (Compare tolerance)
B
Barren: Any area devoid of vegetation
Basal Area: The area of ground surface covered by the stem or stems of a range plant (See percent cover)
Beta diversity: The change in species number and composition, or turnover of species, as one moves from one community to another (Compare alpha diversity, gamma diversity)
Bias: A term which refers to how far the average statistic lies from the parameter it is estimating, that is, the error which arises when estimating a quantity. Errors from chance will cancel each other out in the long run, those from bias will not
Biennial: A plant that lives for two years, producing vegetative growth the first year and usually flowering and fruiting in the second year and then dying
Biodiversity: (= Biological diversity)
Biological Diversity: The variety and variability among living organisms and the ecological complexes in which they occur
Biomass: The sum total of living plants and animals above and below ground in an area at a given time
Biome: A major biotic unit consisting of plant and animal communities having similarities in form and environmental conditions
Biota: All the living species of plants and animals occurring within an area or region
Biotype: A group of individuals with the same genotype
Biotype: Distinct physiological races or strains within morphological species; a population of individuals with identical genetic constitution
Browse: That part of leaf and twig growth of shrubs, woody vines and trees available for animal consumption
Brush: A growth of shrubs or small trees usually undesirable for livestock or timber management. It may sometimes be of value for browse and for watershed protection
Brushland: An area covered primarily with brush
Bunch Grass: A grass having characteristic growth habit of bunch form
C
Canopy: The vertical projection downward of the aerial portion of shrubs and trees, usually expressed as percent of occupied ground
Carrying Capacity: The maximum stocking rate possible without inducing damage to vegetation or related resources. It may vary from year to year on the same area due to fluctuating rainfall and hence forage production
Class of Animal: Age and/or sex-group of a kind of animal
Class: Age and/or sex-group of a kind of livestock
Climate: The average weather conditions of a place over a period of years
Climax Species: A species that dominates a site under climax conditions
Climax: The highest ecological development of a plant community capable of perpetuation under the prevailing climatic and edaphic conditions
Clone: All asexually derived individuals produced from a single sexually produced individual
Common Use: The use of a range by more than one kind of grazing animal either at the same time or at different times within the same growing season
Community: A group of ecologically related populations of various species of organisms occurring in a particular place and time
Community: A group of one or more populations of plants and animals in a common spatial arrangement
Competition: The general struggle for existence within a trophic level in which the living organisms compete for a limited supply of the necessities of life
Complete Protection: The exclusion of all grazing mammals from an area, usually for an extended period of time
Composition: (See species composition)
Concentrate Feed: Grains or their products and other processed food materials that contain a high proportion of nutrients and are low in fiber and water
Condition Class: (See range condition class)
Conservation: The use and management of natural resources according to principles that assure their sustained, highest economic and/or social benefits without impairment of environmental quality
Consistency: Logical and numerical coherence
Continuous Grazing: The grazing of a specific unit by livestock throughout a year or for that part of the year during which grazing is feasible
Controlled Burning: (See prescribed burning)
Conversion Factor: See animal-unit conversion factor
Cool-Season Plant: A plant which generally makes the major portion of its growth during the winter and early spring (Compare warm-season plant)
Cover: The combined aerial parts of plants and litter
Critical Area: A severely eroded sediment producing area which requires special management to establish and maintain vegetation in order to stabilize soil conditions
Cropland Pasture: Cropland planted to grasses and/or legumes to provide grazing
Cured Forage: Standing, dried plant materials available for grazing
D
Decomposer: Heterotrophic organisms, chiefly the bacteria and fungi, that break down the bodies of animals or parts of dead plants and absorb some of the decomposition products releasing simpler compounds usable by producers
Decreaser: Plant species of the original or climax vegetation that will decrease in relative amount with continued overuse
Deferment: Delay of grazing on an area for an adequate period of time to provide for plant reproduction, establishment of new plants, or restoration of vigor of existing plants
Deferred Grazing: The use of deferment in grazing management of a management unit, but not in a systematic rotation including other units
Degree of Use: The proportion of current year's forage production that is consumed and/or destroyed by grazing animals
Density: The number of individuals per unit area
Desirable Plant Species: Species which contribute to the management objectives
Deteriorated Range: Range on which present vegetation and soil conditions represent a significant departure from natural potential
Disclimax Community: A type of climax community that is maintained by either continuous or intermittent disturbance to a severity that the natural climax vegetation is altered
Dispersal: The spreading of reproductive plant parts from one place or area to another
Disturbance Pattern: Spatial and temporal arrangement of of disturbance
Dominant: Plant species or a group of species, which by mean of their number, coverage or size, have considerable influence or control upon the conditions of existence of associated species
Dual Use: The use of range by two kinds of livestock during the same growing season
E
Ecological Integrity: Quality of a natural, unmanaged or managed ecosystem, in which the natural ecological processes are sustained, with genetic, species and ecosystem diversity assured for the future
Ecology: The study of the interrelationships of organisms with their environment
Ecosystem Diversity: The variety of ecosystems that occurs within a larger landscape, ranging from biome (the largest ecological unit) to microhabitat
Ecosystem: The complex of a living community and its physical environment, functioning as an ecological unit in nature
Ecotone: A transition area of vegetation between two communities, having characteristics of both kinds of neighboring vegetation as well as characteristics of its own
Ecotype: A locally adapted population of a species which has a distinctive limit of tolerance to environmental factors
Edaphic: Related to the soil
Edge Effect: The influence of one adjoining plant community upon the margin of another affecting the composition and density of the populations
Effective Precipitation: That portion of total precipitation available for plant growth. It does not include precipitation lost to deep percolation below the root zone or to surface runoff or to evaporation
Emergency Feeding: Supplying feed to range animals when available forage becomes insufficient due any reason
Enclosure: An area fenced to confine animals
Endangered Species: A species that is in danger of extinction throughout all or a significant portion of its range. A species is declared as endangered if the factors causing its vulnerability or decline continue to operate
Endemic: Prevalent in or restricted to a particular area, region, or country
Endemism: The occurrence of a species in a particular locality or region
Energy Flow: The transfer of captured energy by the primary producer through a food chain to different trophic levels
Environment: The sum of all external conditions that affect an organism or community to influence its development or existence
Equilibrium Theory: A theory stating that greater numbers of species are found on larger islands because the populations on smaller islands are more vulnerable to extinction
Erosion: Detachment and movement of soil or rock fragments by water, wind, ice, or gravity as a result of some human activities
Exclosure: An area fenced to exclude animals
Exotic: A species which is not native to the region in which it is found
Extinction: Disappearance of a taxonomic group of organisms from existence in all regions
F
Fauna: An assemblage of animals of a given area, usually arranged in systematic fashion
Feed: Harvested forage, grain or other processed food for livestock or game animals
Feral: A domesticated species that has adapted to existence in the wild state but remains distinct from other wild species
Fibrous Root System: A plant root system having a large number of small, finely divided, widely spreading roots, but no large taproots. Typified by grass root system
Flora: An assemblage of plants of a given area, usually arranged in systematic fashion
Foliage Cover: (See cover)
Foliage: The main organ of photosynthesis and transpiration in higher plants
Forage Production: The weight of forage that is produced within a designated period of time on a given area
Forage Reserve: Standing forage specifically maintained for future or emergency use
Forage Use Factor: (See use factor)
Forage: All browse and herbaceous material that are available to grazing animals
Forb: Any herbaceous plant other than those in the Poaceae, Cyperaceae and Juneaceae families
Frequency: A quantitative expression of the presence or absence of individuals of a species in a population. It is determined as the ratio between the number of sample units that contain an individual(s) of a species and the total number of sample units
Fresh Weight: The weight of plant materials at the time of harvest
Full Use: The maximum use of range forage that can be made under a given grazing management without causing range deterioration
G
Game Range: Range that is chiefly grazed by wildlife at seasonal or annual basis
Game Refuge: An area set aside as a refuge for game animals
Game: Wild birds, fish and other animals hunted for sport or for food
Gamma Diversity: Species diversity at the regional scale; the regional species pool (Compare beta diversity, alpha diversity)
Gene flow: The transfer of genes between different individuals e.g. pollen mediated gene transfer between sexually compatible plants. Also refers to the transfer of genes from one plant population to another through seed dispersal or the movement of regenerative plant parts or whole plants
Genetic Diversity: The variety of alleles and genotypes present in a population and this is reflected in morphological, physiological and behavioral differences between individuals and populations
Genetic Drift: A cumulative process involving the chance loss of some genes and the disproportionate replication of others over successive generations in a small population, so that the frequencies of genes in the population are altered. The process can lead to a population that differs genetically and in appearance from the original population
Genotype: The genetic constitution of an organism, as distinguished from its physical appearance
Grass: A member of the family Poaceae
Grassland: Land on which grasses dominate plant cover
Grasslike Plant: A plant of the Cyperaceae or Juncaceae families which vegetatively resembles a true grass of the Poaceae family
Graze: The process of consuming standing forage by livestock or wildlife
Grazing Capacity: (= carrying capacity)
Grazing Distribution: Dispersion of livestock grazing within a management unit or area
Grazing Management Plan: A program of action designed to secure the best use of the forage resources
Grazing Management: The manipulation of livestock grazing to accomplish a desired result
Grazing Period: The length of time that livestock are grazed on a specific area
Grazing Preference: Selection of certain plants over others by grazing animals
Grazing Pressure: The actual animal-to-forage ratio at a specific time
Grazing Survey: The systematic-collection of data pertaining to forage resources and other information pertinent to range management. May be either extensive or intensive grazing survey
Grazing System: Systematically recurring periods of grazing and deferment for two or more management units
Grazing Unit: An area of rangeland, public or private, which is grazed as an entity
Ground Cover: (See cover)
Growing Season: The portion of the year when temperature and moisture are usually most favorable for plant growth
Growth Form: The characteristic shape or appearance of a plant species
H
Habitat: The natural space (which includes food, water and shelter) suitable for the survival and reproduction of an organism
Half Shrub: A perennial plant with a woody base whose annually produced stems die each year
Halophyte: A plant that is adapted to salty soils
Heavy Grazing: A comparative term indicating that the stocking rate of a range unit is relatively greater than that of other units. Often incorrectly used to mean overuse
Hema Grazing System: An ancient traditional conservation program controlled by individuals or tribes to effectively utilize range resources and prevent mismanagement
Herb: Any flowering plant except those developing persistent woody stems above ground
Heterotrophy: A living organism that eats other living organisms to survive. Unlike plants, which are autotrophs, it cannot make its own food
Humus: The organic fraction of soil in which decomposition is so far advanced that its original form is not distinguishable
Hydrophyte: A plant that has high water requirements (Compare with mesophyte and xerophyte)
I
Ice-Cream Species: An exceptionally palatable species sought and grazed first by livestock and wildlife. Such species are usually over-utilized under proper grazing
Increaser: Plant species of the original vegetation that increases in relative amount, at least for a time, under overuse
Indicator Species: Species that indicates the presence of certain environmental conditions, seral stages or previous treatment
Indigenous: Originating and living or occurring naturally in an area or environment
Interseeding: Seeding into an established vegetation cover
Interspecific Plant Competition: Competition between one plant species and another
Intraspecific Plant Competition: Competition among individuals one plant species
Introduced Plant: (See introduced species)
Introduced Species: A species not a part of the original fauna or flora of an area
Invader: Plant species that were absent or present in very small amounts in undisturbed portions of the original vegetation of a specific range site and will invade following disturbance or continued overuse
Invasion: The migration of organisms from one area to another area and their establishment in the latter
Invasive Species: (=Invader)
Invasiveness: Ability of an organism, particularly an alien species to spread beyond its presently established site, and become established in new locations
K
Key Area: A portion of range which because of its location, grazing value, and/or use, serves as an indicative of management performance
Key Species: Forage species used as a basis for grazing management of a specific unit
Kind of Animal: An animal species or a group of species
L
Land Capability: The suitability of land for use without permanent damage
Landscape: All the natural features such as fields, hills, forests, water, etc., which distinguish one part of the earth's surface from another part. Usually that portion of land or territory which the eye can see in a single view, including all its natural characteristics
Life Form: Characteristic form or appearance of a species at maturity, e.g., tree, shrub, herb, etc
Light Grazing: A comparative term indicating that the stocking rate of one range unit is relatively less than that of other units. Often incorrectly used to mean under-use
Litter: Dead plant matter lying on the soil surface
Litter: The amount of previous year's plant growth left on the soil surface for nutrient recycling
Livestock Exclusion: Range that is closed to grazing by domestic livestock
Livestock Management: Application of technical principles and business methods to livestock production
Livestock Production: The weight, number of animals, etc., that a particular range produces
Livestock: Domestic animals usually include camels, cattle, sheep or goats
M
Maintenance Feeding: Supplying feed to range animals when available forage is too limited to meet their minimum daily requirement. Usually necessitated by overuse
Management Area: An area for which a single management plan is developed and applied
Management Plan: A program of action designed to reach a given set of objectives
Management Unit: A subdivision of a management area
Marginal Land: Land of questionable physical or economic capabilities for sustaining a specific use
Marsh: Flat, wet, treeless areas usually covered by standing water and supporting a native growth of grasses and grasslike plants
Mesophyte: A plant that has moderate water requirements (Compare hydrophyte, xerophyte)
Moderate Grazing: A comparative term indicating that the stocking rate of a range unit is comparable to the rates of other units. Often incorrectly used to mean proper use
Multiple Use: Harmonious use of range for more than one purpose; i.e., grazing of livestock, wildlife production, recreation, watershed and timber production. Not necessarily the combination of uses that will yield the highest economic return or greatest unit output
Mycorrhiza: The association of fungi with the roots of seed plants
Native Landscape: A landscape that contains assemblages of plants and plant communities that are indigenous to a particular region
N
Native Plant: (= native species)
Native Species: A species which is part of the original fauna or flora of an area
Net Primary Production: The net increase in plant biomass within a specified area and time interval, i.e., primary production less that used in metabolic processes
Non-selective Grazing: Utilization of forage by grazing animals in such a way that all forage species and plants are grazed to a comparable degree. It can generally be achieved by using a high stocking density for a short grazing period
Nonuse: Absence of grazing use on current year's forage production
Noxious Species: A plant species that is undesirable because it conflicts, restricts, or otherwise causes problems under the management objectives
Nutrient Cycling: The processes by which nutrients are continuously transferred from one organism to another in an ecosystem
Nutritive Value: Relative capacity of given forage to furnish nutrition for animals
O
Open Herding: Allowing a herd to spread naturally while grazing
Open Range: Rangeland which has not been fenced into management units
Opening Date: The date on which an established grazing season begins
Outcrop: The exposure of bedrock or strata projecting through the overlying cover of soil
Oven-Dry Weight: The weight of a substance after it has been dried in an oven at 105°C to equilibrium
Overgrazed Range: A range that has deteriorated and may still be deteriorating from its productive potential due to overgrazing
Overgrazing: Continued overuse creating a deteriorated range
Overstocking: Placing a number of animals on a given area that will result in overuse if continued to the end of the planned grazing period. Not to be confused with overgrazing because an area may be overstocked for a short period, but the animals may be removed before the area is overused. However, continued overstocking will lead to overgrazing
Overstory: The upper canopy of plants. Usually refers to trees, tall shrubs and vines
Overuse: Utilizing an excessive amount of the current year's growth which, if continued, will result in overgrazing and range deterioration
P
Palatability: The relish with which a particular species or plant part is consumed by an animal
Park: A land area reserved and managed to protect an outstanding landscape and to make it available for public enjoyment
Pasture: A grazing area enclosed and separated from other areas by fence
Percent Cover: The area covered by the combined aerial parts of plants and mulch expressed as a percent of the total area (Compare basal area)
Percent Use: Grazing use of current growth, usually expressed as a percent of weight removed
Perennial Plant: A plant that has a life cycle of three or more years, tending to flower and fruit repeatedly
Phenology: The study of periodic biological phenomenon such as flowering, seeding, etc., especially as related to climate
Phenotype: The observable appearance of an organism, as determined by environmental and genetic influences (Compare genotype)
Photo Interpretation: The art and science of identifying objects and conditions from photographs
Photogrametry: Measurements made from aerial photographs including area measurements, distance, direction, height or differences in elevation or slope and the processes of mapping
Photosensitization: A non-contagious disease resulting from the abnormal reaction of light-colored skin to sunlight after a photodynamic agent has been absorbed through the animal's system. Grazing certain kinds of vegetation or ingesting certain molds under specific conditions causes photosensitization
Phytotoxic: Toxic to plants
Pioneer Species: Plant species that initially invade a newly exposed surface
Pitting: Making shallow pits or basins of suitable capacity and distribution on range to reduce overland flow from rainfall and snowmelt
Plant Succession: (See succession)
Plant Succession: The process of vegetational development whereby an area becomes successively occupied by different plant communities of higher ecological order
Plant Vigor Index: An estimate of plant vigor based on measurement of one or a few attributes
Poisonous Plant: A plant containing or producing substances that causes sickness, death, or a deviation from normal state of health of animals
Population: A group of individuals of one species that are found in a distinct portion of the species range and that interbreed with some regularity and therefore have a common set of genetic characteristics
Precision: The closeness of repeated measurements of the same quantity
Predator: An animal that obtains its food primarily by killing and consuming other animals
Preference: (See grazing preference)
Preferred Species: Species that are preferred by animals and are grazed by first choice
Prescribed Burning: The use of fire as a management tool under specified conditions for burning a predetermined area
Presence-absence: Manner of completing a vegetation survey or analysis based on the presence or absence of a species instead of abundance-dominance
Primary Production
: The conversion of solar energy to chemical energy through the processes of photosynthesis. It is represented by the total quantity of organic material produced within a given period by vegetation
Primary Succession: This type of succession occurs when plants or animals colonize a previously deserted area, such as bare rocks, a sand dune, or recently glaciated ground. In these situations soil bacteria, insects, plants, and animals must come from nearby habitats
Producer: An organism that can use radiant energy to synthesize organic substances from inorganic materials
Proper Grazing: The act of continuously obtaining proper use
Proper Stocking: Placing a number of animals on a given area that will result in proper use at the end of the planned grazing period. Continued proper stocking will lead to proper grazing
Proper Use Factor: (See use factor)
Proper Use: A degree and time of use of current year's growth which, if continued, will either maintain or improve the range condition consistent with conservation of other natural resources. Syn., proper utilization
R
Rain Shadow: The region of diminished rainfall on the lee side of a mountain range, where the rainfall is noticeably less than on the windward side
Range Appraisal: The classification and valuation of rangeland from an economic or production standpoint
Range Condition Class: One of a series of arbitrary categories used to classify range condition and usually expressed as excellent, good, fair or poor
Range Condition Trend: The direction of change in range condition
Range Condition: The current productivity of a range relative to its potential productivity
Range Degeneration: The process whereby the same area becomes successively occupied by different plant communities of lower ecological order
Range Forage: Forage produced on range
Range Improvement: Any practice designed to improve range condition or facilitate more efficient utilization of the range
Range Inventory: An itemized list of resources of a management area such as range sites, range condition classes, range condition trends, range use, estimated proper stocking rates, physical developments and natural conditions such as water, barriers, etc
Range Management: A distinct discipline founded on ecological principles and dealing with the husbandry of rangelands and range resources
Range Readiness: The defined stage of plant growth at which grazing may begin under a specific management plan without permanent damage to vegetation or soil. Usually applied to seasonal range
Range Reseeding: Application of range seeding to an area previously seeded. Generally the result of failure of the previous range seeding
Range Retrogression: (See range degeneration)
Range Science: The organized body of knowledge upon which the practice of range management is based
Range Seeding: The process of establishing vegetation by the artificial dissemination of seed
Range Site. A distinctive kind of rangeland, which in the absence of abnormal disturbance and physical site deterioration, has the potential to support a native plant community typified by an association of species different from that of other sites. This differentiation is based upon significant differences in kind or proportion of species, or total productivity
Range Suitability: The adaptability of a range to grazing by livestock and/or game
Range Trend: (See range condition trend)
Range Type: (See vegetation type)
Range: Embraces rangelands and also many forest lands which support an understory of periodic cover of herbaceous or shrubby vegetation amenable to certain range management principles or practices
Rangeland Remote Sensing: The detection, identification and assessment of condition of objects on rangeland with a camera, or other imaging device, situated at an appreciable distance from the imaged subject
Rangeland: Land on which the native vegetation (climax or natural potential) is predominantly grasses, grass-like plants, forbs or shrubs suitable for grazing or browsing use. Includes lands revegetated naturally or artificially to provide a forage cover that is managed like native vegetation. Rangelands include natural grasslands, savannahs, shrublands, most deserts, tundra, alpine communities, coastal marshes and wet meadows
Rare Species: A species not widely distributed or not easily found within a given area. Rare species include but are not necessarily limited to endangered, threatened or vulnerable species
Reclamation Burning: Use of prescribed burning to reclaim brush areas
Reclamation: The process of reconverting disturbed land to its former or other productive uses
Reconnaissance: A general examination or survey of a region with reference to its main features, usually as a preliminary to a more detailed survey
Recreation Area: A land area reserved and managed for both developed and undeveloped recreation
Regression: (See range degeneration)
Rehabilitation: Implies that the land will be returned to a form and productivity in conformity with a prior land use plan, including a stable ecological state that does not contribute substantially to environmental deterioration and is consistent with surrounding aesthetic values
Relict: A remnant or fragment of a flora that remains from a former period when it was more widely distributed
Reproductive Effort: The quantity of energy and resources an organism devotes to reproduction
Reseeding: (See range reseeding)
Rest Period: A period of deferment included as part of a grazing system
Restoration: The re-creation of entire communities of organisms closely modeled on communities that occur naturally. It is closely linked to reclamation (Compare reclamation, rehabilitation)
Restricted Area: An area on which grazing tenure is limited
Revegetation: The reestablishment or improvement of vegetation through management practices or chemical or mechanical means.
Rhizome: A horizontal stem, usually underground but also occurring on soil surface, usually sending out roots and above-ground shoots from the nodes
Rodent Control: Measures taken to reduce or control the rodent population of a given area. This may apply to a specific species or rodents in general
Rotation Grazing: System of pasture utilization embracing short periods of heavy stocking followed by periods of rest for herbage recovery during the same season. Generally used on tame pasture or cropland pasture
Rouphage: Plant materials containing a low proportion of nutrients per unit of weight and usually bulky and coarse, high in fiber and low in total digestible nutrients. Roughage may be classed as either dry or green
Runoff: The total stream discharge of water, including both surface and subsurface flow, usually expressed in acre-feet of water yield
Rush: A member of the family Juncaceae
S
Sacrifice Area: A portion of the range, irrespective of site, that is intentionally overgrazed to obtain efficient overall use of the management area
Sacrifice Site: A range site which is intentionally overgrazed to obtain efficient overall use of the management area
Salting: Providing salt as a mineral supplement for animals
Sample: A part of a population taken to estimate a parameter of the whole population
Savannah: A grassland with scattered trees, whether as individuals or clumps; often a transitional type between true grassland and forest
Scrub: Vegetation dominated by short, stunted woody plants growing thickly together or intermingled with cacti
Seasonal Distribution: The progressive grazing in a sequence of moves from one part of a range to another as vegetation develops
Seasonal Grazing: Grazing restricted to a specific season. cf. grazing system, seasonal distribution, seasonal zone
Seasonal Use: Seasonal preference of certain plant species by animals
Seasonal Zone: An area of the, range which livestock and wildlife prefer at certain seasons
Secondary Compound: One of a wide variety of chemicals produced by plants and used in functions such as defense against herbivory, protection from harmful radiation, and soil nutrient cycling; secondary compounds are so-named because they are synthesized on side branches off of the primary metabolic pathways that produce the carbohydrates, amino acids, lipids, and other compounds common to all organisms
Secondary Production: Energy in an ecosystem that is derived from the consumption of organic compounds produced by other organisms (Compare primary production)
Secondary Range: Range which is lightly used or unused by livestock under minimal management and will ordinarily not be fully used until the primary range has been overused
Secondary Succession: Succession that involves the reestablishment of a community in which most, but not all, of the organisms have been destroyed. (Compare primary succession)
Sedge: A member of the family Cyperaceae
Selective Grazing: The grazing of certain plant species on the range to the exclusion of others
Semiarid: A term applied to regions or climates where moisture is normally greater than under and conditions, but still definitely limits, the production of vegetation
Sex Ratio: The ratio existing between the number of male and female animals within a given herd, band or population
Shannon Index: The index most commonly used to describe species diversity quantitatively
Short-Duration Grazing: Any grazing system of grazing management having a stocking density index >2
Shrub: A plant that has persistent, woody stems and a relatively low growth habit, and that generally produces several basal shoots instead of a single bole
Shrubland: Any land on which shrubs dominate the vegetation
Site: The place or seat of any specified thing.
Sod Grass: Stoloniferous or rhizomatous grass which forms a sod
Soil Condition Class: One of a series of arbitrary categories based principally on the amount of ground cover weighted by the degree of accelerated erosion used to identify soil stability
Soil: The unconsolidated mineral and organic material on the immediate surface of the earth that serves as a natural medium for the growth of land plants
Species Accumulation Curve: A graph that plots species richness as a function of the total number of individuals that have accumulated with each additional sample
Species Composition: The identity of the species present in a community
Species Diversity: A measure that combines both the number of species (species richness) in a community and their relative abundances compared with one another (species evenness)
Species Evenness: The relative abundances of species in a community compared with one another
Species Richness: The number of species in a community
Species–Area Relationship: The relationship between species richness and area sampled
Spot Grazing: Repeated grazing of small areas while adjacent areas are lightly grazed or unused
Stand: A group of plants growing together on a contiguous area
Standing Crop: The total amount of living plant material in above ground parts, per unit of space at a given time
Stochastic: Models, processes, or procedures that are based on elements of chance or probability
Stocking Density Index: The reciprocal of the fraction land available to the animals at any one time/land available to the animals for the entire grazable period
Stocking Density: The relationship between number of animals and area of land at any instant time. It may be expressed as animal-units per hectare, animal-units per section, or AUM/ha (see stocking rate, stocking pressure)
Stocking Plan: The number and kind of livestock assigned to one or more given management areas or units for a specified period
Stocking Pressure: The weight of forage which the operator has allowed per animal-unit for a relatively short grazing period of specified length. Expressed as wt. forage/A.U. (See grazing pressure, stocking rate, stocking density)
Stocking Rate: The area of land which the operator has allotted to each animal-unit for the entire grazable period of the year. May be expressed as a ratio in various forms such as AU/Section; ha/AU; or ha/AUM (Compare with stocking density, stocking pressure)
Stolon: A horizontal stem which grows along the surface of the soil and roots at the nodes
Stress: An abiotic factor that results in a decrease in the rate of an important physiological process, thereby lowering the potential for an organism’s survival, growth, or reproduction
Stubble: The basal portion of herbaceous plants remaining after the top portion has been harvested either artificially or by grazing animals
Succession: The gradual transformation of a biological community as new species come into an area and alter the environmental conditions. The process of succession may take hundreds or thousands of years and involves a number of intermediate communities, each called a seral community. The replacement of one seral community by another in most cases leads to the eventual formation of a climax community, a relatively stable community of plants or animals
Suitability: (1) The adaptability of an area to grazing by livestock or wildlife. (2) The adaptability of a particular plant or animal species to a given area (Compare suitable range)
Suitable Range: (1) Range accessible to livestock and which can be grazed on a sustained yield basis without damage to the resource. (2) The limits of adaptability of plant or animal species
Supplement: Nutritional additives (salt, protein, phosphorus, etc.) intended to remedy deficiencies of the range diet
Sustained Yield: The continuation of desired animal or forage production
Synecology: The branch of ecology that deals with the structure and development of entire ecological communities and the interrelationships of the plants and animals within them
T
Tame Pasture: Grazing lands, planted to primarily introduced or domesticated native forage species, that receive periodic renovation and/or cultural treatments such as tillage, fertilization, mowing, weed control, and irrigation
Taproot System: A plant root system dominated by a single large root, normally growing straight downward, from which most of the smaller roots spread out laterally (Compare fibrous root system)
Threatened Species: A species that is likely to become endangered if limiting factors are not reversed
Threshold: A theoretical concept defining the point where the total load of accumulated stress on the ecosystem exceeds the system’s ability to accommodate change and a fundamental shift occurs in the system
Tolerance: The ability to survive stressful environmental conditions
Total Annual Yield: The total annual production of all plant species of a plant community
Toxic Plant Species: A species of plant which may accumulate or produce a substance toxic to animals (See poisonous plant)
Trampling: Treading under foot; the damage to plants or soil brought about by movements or congestion of animals
Transect: A sampling system that involves the measurement or recording of data along a line. The line intercept method involves measurements of objects that occur beneath the line, while in other cases, small sampling plots are located along the line at specified distances
Tree: A woody perennial, usually single-stemmed plant that has a definite crown shape and reaches a mature height of at least 2.5 m. There is no clear-cut distinction between trees and shrubs
Trend: (See range condition trend)
U
Undergrazing: The act of continued underuse
Understocking: Placing a number of animals on a given area that will result in underuse at the end of the planned grazing period
Understory: Plants growing beneath the canopy of other plants. Usually refers to grasses, forbs, and low shrubs under a tree or brush canopy (Compare overstory)
Underuse: A degree of use less than desired
Undesirable Species: (1) Species that are not readily eaten by animals. (2) Species that conflict with or do not contribute to the management objectives
Unsuitable Range: An area which may have value for wildlife but has no value for, or should not be used by, livestock because of steep topography, barrenness, dense timber, lack of forage or unstable soils
Use Factor: An index to the grazing use that may be made of forage species, based on a system of range management that will maintain the economically important forage species, or achieve other management objectives such as maintenance of watersheds, recreation values, etc.
Use: (See utilization)
Utilization: The proportion of current year's forage production that is consumed or destroyed by grazing animals. May refer either to a single species or to the vegetation as a whole
V
Vegetation Type: A plant community with distinguishable characteristics (Compare range site)
Vegetation: Plants in general or the sum total of the plant life
Vegetative Reproduction: Production of new plants by any asexual method
Vegetative: Relating to nutritive value and growth functions of plant life in contrast to sexual reproductive functions. Should not be confused with vegetation
Vigor: (See plant vigor index)
W
Wadi: A valley or streambed in desert regions that remains dry except during the rainy season
Warm-Season Plant: A plant which makes most or all its growth during the spring, summer or fall and is usually dormant in winter
Water Development: Development of a new or improved source of water supply for livestock together with storage and delivery system
Watershed: A total area of land above a given point on a waterway that contributes runoff water to the flow at that point
Wildlife Refuge: A land area reserved and managed for the benefit of one, or more species of wildlife
Wildlife: Undomesticated vertebrate animals considered collectively, with the exception of fishes (See game)
Wolf Plant: A plant that, though of a species generally considered palatable, is not grazed by livestock
Woodland: A land area occupied by trees
X
Xerophytes: Plant adapted to arid or dry habitats and conditions
Y
Yearling: An animal approximately one year of age
Year-long Grazing: Continuous grazing for a calendar year
Year-long Range: Range that is, or can be, grazed yearlong
Yield: (See forage production, total annual yield)
Z
Zoning: A means by which governmental authority is used to promote the desired use of land under certain circumstances. This power traditionally resides in the state, and the power to regulate land uses by zoning is usually delegated to minor units of government, such as town, municipalities, and counties, through an enabling act that specifies powers granted and the conditions under which these are to be exercised