Rangeland Ecology & Management
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- Inventory Monitoring PageExample to Calculate Carrying Capacity by Matching Forage Supply and Animal Demand Problem A 4,000 ha ranch in the black grama (Bouteloua eriopoda) semi-desert ranges of south-eastern Arizona…
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102 Angle of Points
Angle of Points With most techniques involving point sampling to estimate cover, points are placed vertically to the ground. However, some studies indicate that points inclined at about a 45° angle… - Inventory Monitoring PagePoint-Centered Quarter Method The point-centered quarter method was developed by Cottam and Curtis in the 1950's as a plotless technique to estimate density. It assumes that the key species follow a…
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104 allocation
Allocation of Sample Units - Sampling Designs Decisions relating to the arrangement of sample units within the site have a large influence on sample precision, sample efficiency, and statistical… - Inventory Monitoring PageWeight-Estimate Method The weight-estimate method is designed to determine biomass from sampling in quadrats. Depending on the objectives of the study, the weight-estimate method can be used to…
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106 Comparison Areas
Comparison Areas Comparison areas, also known as reference areas or benchmark areas, are additional sampling locations established in rangeland inventory or monitoring programs to isolate the… - Inventory Monitoring Page
107 Sample Variance
Sample Variance The sample variance (s2) is a measure of dispersal that reflects the spread of data around the sample mean. The sample variance is calculated as This equation indicates that the… - Inventory Monitoring PageRangeland Inventory, Monitoring, and Evaluation: Vegetation Attributes Introduction | General Principles | Sampling Concepts | Vegetation AttributesRangeland Evaluation | Management Applications |…
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109 Sample Unit Size
Sample Unit Size The optimum sample unit size for rangeland sampling depends on the attribute being described, the size of plants present, and the scale of spatial patterns within the vegetation.… - Inventory Monitoring PageSpecific Guidelines on Sample Unit Size for Biomass The size of sample units is a critical decision in estimating biomass in order to obtain precise data without spending too much time sampling. If…
- Inventory Monitoring PageSpecific Guidelines on Sample Unit Size for Density The size of sample units is a critical decision in determining density, so that we can get precise data without spending too much time counting.…
- Inventory Monitoring PageSpecific Guidelines on Sample Unit Size for Frequency Size of sample units is a key decision made in frequency sampling because it has an overwhelming influence on frequency values, as well as…
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113 Utilization
Utilization Utilization refers to the amount of plant material that has been removed by animals during the grazing period. It can be based on either individual plants, key species, or an assessment… - Inventory Monitoring PageMethods to Determine Utilization Many methods have been developed to estimate utilization, but few have proven suitable for all situations. Depending on the objectives of the inventory or monitoring…
- Inventory Monitoring PageUtilization Zones Creating maps that describe utilization zones within the management unit is an important step in many rangeland inventory or monitoring programs to provide valuable background…
- Inventory Monitoring PageSpecific Guidelines on Sample Unit Shape for Frequency The effect of the shape of sample units on precision and boundary decisions is highly pertinent to frequency sampling, but quadrats of almost…
- Inventory Monitoring PageAnimal Unit Equivalents Animal unit equivalents (AUE) have been developed to standardize grazing demand among different herbivore species. An AUE expresses the quantitative forage demand of a…
- Inventory Monitoring PageAnimal Unit Months Animal unit months (AUM) is commonly adopted in rangeland situations as the unit used to express carrying capacity. AUM is a measure of forage supply within the management unit,…
- Inventory Monitoring PageSample Unit Shape Sample units used to sample vegetation attributes are generally circular, square or rectangular in shape. In a monitoring program, it is essential to use sample units of the same…
- Inventory Monitoring PageSpecific Guidelines on Sample Unit Shape for Density The smaller sample units used to determine the density of herbaceous species are conventionally square or slightly rectangular shaped quadrats.…
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121 Stocking Rate
Stocking Rate Stocking rate expresses the actual number of animals on a management unit throughout the time period of grazing. Therefore, stocking rates are the management interface that relate… - Inventory Monitoring PageStratified Sampling Stratified sampling involves dividing the site into sections that are more homogenous than the entire area. Boundaries of the sections should be based on factors that are readily…
- Inventory Monitoring PageSystematic Sampling In a systematic sampling design, sample units are selected according to a predetermined methodical pattern, which ensures that each unit of the sample represents an equal portion…
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124 Time of Sampling
Time of Sampling Season to season fluctuations in vegetation attributes represent the key consideration when deciding what time of year to conduct rangeland inventory or monitoring programs. To… - Inventory Monitoring Page
125 Transects
Transects Transects are specially shaped sample units having a length dimension that greatly exceeds the width, so that it extends in a continuous manner across the vegetation. Transects are the… - Inventory Monitoring PageSpecific Guidelines on Sample Unit Shape for Biomass The shape of sample units is a critical decision in determining biomass in order to obtain accurate and precise estimates of biomass. The smaller…
- Inventory Monitoring PageSpecific Guidelines on Sample Size for Density Sample size is a critical decision for determining density, because it is a key way to influence the precision of the collected data. Larger sample…
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128 Standard Error
Standard Error The standard error () is a measure of the variability among the sample means () of repeated samples taken from the same population. The standard error is a measure of precision, and… - Inventory Monitoring Page
129 Standing Crop
Standing Crop Standing crop is the total above-ground plant biomass on the site at a particular point in time. Standing crop includes current year's production together with that produced in… - Inventory Monitoring PageStatistical Techniques Sample size (n) can be determined using a statistical approach that considers the variability of the population and our requirements for precision. The formula to determine…
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131 Statistics
Statistics Values which summarize properties of the sample are known as statistics. Commonly expressed statistics are the sample mean () and the sample variance (s2). In sampling, we use statistics… - Inventory Monitoring Page
132 Site Selection
Site Selection Selection of sites for sampling is a critical consideration when designing rangeland inventory or monitoring schedules. Documentation of site locations, either on maps or with clear… - Inventory Monitoring PageInfluence of Spatial Patterns Spatial patterns exhibited by the species we want to sample have an important influence on the suitability of certain methods to determine density, and the sampling…
- Inventory Monitoring PageSpecies Data from Other Attributes A description of species composition can be obtained when procedures are followed to determine other attributes, such as biomass, cover, or density, provided the…
- Inventory Monitoring PageSpecific Guidelines on Sample Size for Biomass Sample size is a critical decision in determining biomass because it is a key way to influence the precision of the collected data. Larger sample sizes…
- Inventory Monitoring PageRangeland Inventory, Monitoring, and Evaluation: Sampling Concepts Introduction | General Principles | Sampling Concepts | Vegetation AttributesRangeland Evaluation | Management Applications |…
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137 Sampling Date
Sampling Date Due to the constraints of time and labor, it is unusual to conduct biomass sampling at a site more frequently than once a year. However, total standing crop fluctuates during the year… - Inventory Monitoring PageSampling Terminology and Theory Much of the terminology and concepts related to sampling is derived from the theory of statistical inference. People often become uncomfortable with statistical…
- Inventory Monitoring PageSelected Sampling Selected sampling involves active selection of members of the population that are considered to be most representative of the objectives outlined in the inventory or monitoring…
- Inventory Monitoring PageSelection of Attributes Rangeland inventory and monitoring programs have usually focused on describing vegetation attributes, although soil characteristics are assuming greater importance in recent…
- Inventory Monitoring PageSeparation of Dead and Live Material The actual components of above-ground biomass that are considered during sampling depend upon the biomass property to sample. Biomass categories that may be…
- Inventory Monitoring PageSite Conservation Rating Site conservation ratings assess the capacity of the current vegetation community to protect against the decline in productive potential of a range site. Evaluations are…
- Inventory Monitoring PageAccuracy and Bias The accuracy of a sample reflects how closely the sample mean () represents the true population mean (). Sample accuracy is jeopardized by systematic factors associated with the…
- Inventory Monitoring PageSpecies Composition Species composition refers to the contribution of each plant species to the vegetation. Botanical composition is another term used to describe species composition. Species…
- Inventory Monitoring PageConfidence Interval The confidence interval gives a range centered around the sample mean () and it indicates how closely we believe our sample mean is representing the population mean (). A large…
- Inventory Monitoring PageCounting Individual Plants Counting plants within clearly defined sample units is one of the earliest techniques used to determine density rangeland vegetation. Counting individuals is usually…
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147 Cover
Cover Cover is the vertical projection of plant material onto the ground when viewed from above. It is usually expressed as a percentage value. For example, 18% cover indicates a birds-eye-view… - Inventory Monitoring PageMethods to Determine Cover Much effort and imagination have been devoted to developing methods to estimate cover, reflecting its long tradition as an important attribute for rangeland inventory or…
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149 Critical Areas
Critical Areas Critical areas are sampling locations deliberately chosen in rangeland inventory or monitoring programs because of unique values or special concerns such as riparian zones, restricted… - Inventory Monitoring PageData Recording and Calculations when Counting Individual Plants to Determine Density Only a simple field sheet format is required when following the approach of counting individual plants to…