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- Inventory Monitoring PageParameter Values that summarize properties of the population are known as parameters. Commonly expressed parameters are the population mean () and the population variance (2). Each population has a…
- Inventory Monitoring PageKey Areas Key areas are sampling sites deliberately selected, based mainly on professional judgement, in rangeland inventory or monitoring programs to be representative of the entire management unit…
- Inventory Monitoring PageKey Species Rangeland inventory or monitoring programs usually concentrate on sampling only a few important species or species groups that serve as indicators of status and/or trend for the entire…
- Inventory Monitoring PageLeaf Area Index Leaf area index is the total area of all leaves of plants relative to the ground surface, within a give area. It is slightly different than a simple measure of canopy cover because…
- Inventory Monitoring PageLine Intercept Method The line intercept method was developed by Canfield in the 1940's to estimate cover in the grasslands of southwestern USA and has been widely adopted in rangeland inventory and…
- Inventory Monitoring PageLine Sampling to Determine Cover Another common approach to determine cover involves extending a line (usually a tape) across the site and recording the proportion intercepting plant material. In…
- Inventory Monitoring PageRangeland Inventory, Monitoring, and Evaluation: Management Applications Introduction | General Principles | Sampling Concepts | Vegetation AttributesRangeland Evaluation | Management Applications…
- Inventory Monitoring PageMatching Forage Supply and Animal Demand A straightforward approach to determine the number of animals the management unit can support over a period of time is to divide the total forage biomass (ie…
- Inventory Monitoring PageSample Mean The sample mean () is the average of a set of values that are sampled from a population. Because vegetation attributes usually exhibit a normal distribution, a greater proportion of the…
- Inventory Monitoring Page
10 Mean Area
Mean Area Mean area, or the average space available to each plant, is another way to consider density. Mean area is the mathematical reciprocal of density, and is the basis of the various distance… - Inventory Monitoring PageNested Quadrats Nested quadrats are a special sample unit that includes a series of different sized quadrats all placed at the same location. They are usually positioned so that all have a common…
- Inventory Monitoring PageNormal Distribution Normal distributions are sampling distributions generated when an attribute possessing a continuous, and typically unbounded, range of outcomes is recorded from a series of…
- Inventory Monitoring PageRangeland Inventory, Monitoring, and Evaluation: Chapter Outline Susan Muir (New Mexico State University) and Mitchel P. McClaran (University of Arizona) 16 September 1997 (Draft for Review)…
- Inventory Monitoring PageRangeland Inventory, Monitoring, and Evaluation Susan Muir (New Mexico State University) Mitchel P. McClaran (University of Arizona) 16 September 1997 (Draft for Review) Introduction | General…
- Inventory Monitoring PageDesired Plant Community The desired plant community is selected as the one species composition that is most compatible with management objectives for a site. This decision depends on the relative…
- Inventory Monitoring PagePlant Dimensions Many different attributes describing plant dimensions can be used to determine plant biomass. Measurements on plant height, plant basal area, twig length and diameter, trunk…
- Inventory Monitoring PagePlotless Sampling to Determine Cover Cover estimated by plotless methods has the advantage of integrating large areas within a single sampling point. Early range assessments relied on the ocular…
- Inventory Monitoring PageArrangement of Points Observations based on single points, such as the step point method, tend to take less time to record and give a more precise estimate of cover than do the same number of points…
- Inventory Monitoring PagePoint Frame Method The point frame method, based on point sampling to determine cover, was first suggested as an instrument to measure cover by Levy and Madden in the early 1930's. It consists of a…
- Inventory Monitoring PagePoint Sampling to Determine Cover Point sampling is one of the most common approaches to estimate cover of a site, since being conceived by New Zealand pasture scientists, Levy and Madden, in the…
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21 Point Size
Point Size An underlying assumption in point sampling to determine cover is that the sample unit is theoretically reduced to an infinitely small, dimensionless point. In practice, however, most… - Inventory Monitoring PageStep Point Method The step point method, an approach based on point sampling to determine cover, was developed by Evans and Love in the 1950's. To implement this procedure, the observer uses a mark…
- Inventory Monitoring PagePoint Transect Method The point transect method is a technique based on point sampling to determine cover. To follow this method, point readings are taken at either systematic or random locations…
- Inventory Monitoring PagePoisson Distribution Poisson distributions are special sampling distributions generated when discrete individuals are counted from a series of sample units. Sample units should be independent and…
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25 Population
Population The population is the set of all individuals possessing the particular attribute we wish to describe. Therefore, the limits to the population are decided by the objectives of the sampling… - Inventory Monitoring PageMethods to Determine Density Two general approaches can be adopted to determine density. With the first approach, density is directly determined by counting plants within a defined sample unit,…
- Inventory Monitoring PageData Recording and Calculations to Determine Frequency The field sheet to record frequency usually includes a species list and a tally is made for every quadrat where the species is recorded. Only a…
- Inventory Monitoring PageVariable Plot Method The variable plot method to determine cover was originally developed by European foresters, before being introduced to the USA by Cooper in the late 1950's as a technique for…
- Inventory Monitoring PageWandering Quarter Method The wandering quarter method was developed by Catana in the 1950's as a plotless technique to estimate density. Adapted from the point-center quarter method, the wandering…
- Inventory Monitoring PageSample Units for Counting Individual Plants to Determine Density Counting individual plants to determine density typically involve sampling procedures using a sample unit with defined boundaries (…
- Inventory Monitoring PageRooted or Canopy Dimensions The ground rule for determining the frequency of herbaceous species is conventionally based on the presence of the base of the plant in the sample unit (i.e., rooted…
- Inventory Monitoring PageDistance Methods Distance methods to determine density that involve plotless sampling regimes are based on determining the mean area associated with each plant by measuring the spacing between them…
- Inventory Monitoring PageSampling Distributions Sampling distributions describe general patterns in the spread and frequency of the values in the sample data. The type of sampling distribution generated during sampling…
- Inventory Monitoring PageDouble Sampling Method The double sampling method is designed to determine biomass by sampling in quadrats. Depending on the objectives of the study, the double sampling method can be used to…
- Inventory Monitoring PageDry-Weight Rank Method The dry-weight rank method is specifically designed to determine species composition by providing a measure of the relative contribution of various species to the total…
- Inventory Monitoring PageUse of Equipment Poorly functioning equipment can jeopardize sample accuracy and sample precision. All measuring equipment, such as scales used to weigh samples for herbage biomass, should be…
- Inventory Monitoring PageRangeland Evaluation Introduction | General Principles | Sampling Concepts | Vegetation Attributes Rangeland Evaluation | Management Applications | Chapter Outline Rangeland evaluation is the…
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38 Forage
Forage Forage is biomass that is potential food for livestock and wildlife, including herbaceous and woody sources. Only plants that are available and palatable to grazing animals are classified as… - Inventory Monitoring Page
39 Frequency
Frequency Frequency is the vegetation attribute that describes the probability of finding a species within a particular area. The probability is based on the occurrence of that species in a series… - Inventory Monitoring PageSpecific Guidelines on Sample Size for Frequency Sample size is a critical decision in determining frequency, because it is a key way to influence the precision of the collected data. Larger sample…
- Inventory Monitoring PageMethods to Determine Frequency There is only one general approach to determining frequency and it is based on identifying key species in each quadrat. It does not require that individuals are…
- Inventory Monitoring PageRangeland Inventory, Monitoring, and Evaluation: General Principles Introduction | General Principles | Sampling Concepts | Vegetation AttributesRangeland Evaluation | Management Applications |…
- Inventory Monitoring PageGraphing Techniques Sampling precision is improved by increasing sample size because data describing the vegetation attribute is collected for a greater proportion of the population. At some point,…
- Inventory Monitoring PageGrazed Class Method The grazed class method has been widely used by land management agencies to determine utilization of key species. This method uses data that is collected along pace transects…
- Inventory Monitoring PageGrazed Plant Method The grazed plant method was developed by Roach in southern Arizona during the early 1950's to determine utilization. This method involves initially developing a regression…
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46 Ground Cover
Ground Cover Ground cover describes the proportion of the soil surface covered by some type of protective material, which usually includes litter, gravel, rocks, microphytic crusts, in addition to… - Inventory Monitoring PageSpecies Groups Considering each individual species at the site, even to determine species composition, is often a time consuming and inefficient approach to collect data, especially for attributes…
- Inventory Monitoring PageCurrent Year's Growth Current year's growth is the above-ground biomass produced during the previous 12 months. In environments with distinctive seasons, such as the monsoonal influence in the…
- Inventory Monitoring PageHeight-Weight Method Assessment of utilization by height-weight methods closely follows the approaches of indirect sampling to determine biomass. This technique involves initially establishing a…
- Inventory Monitoring PageHow Often to Sample Data need only be collected on a single occasion for an inventory program, to document rangeland resources and to evaluate their current status. In contrast, monitoring must be…