sampling principles
DESCRIPTION
Statistical SamplingTRANSCRIPT
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Field BasedBiomass Estimation
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Literature
Cooperative Extension ServiceU.S. Department of Agriculture
Jeffrey E. Herrick
Justin W. Van Zee
Kris M. Havstad
Laura M. Burkett
Walter G. Whitford
Caryl L. Elzinga
Daniel W. Salzer
John W.Willoughby
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Sampling PrinciplesIntroduction to sampling
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Sampling
The process of selecting a part of something with the intent of showing the quality, style, or nature of the whole
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Why Sample?
To learn about population or area of interest
Difficult to accurately census
To make inferences about population
To generalize with confidence
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Populations and Samples
Population: Complete set of Individuals or entire area that you want to describe, or make inferences about The set of variables in the sampling universe
Consists of ALL sampling units
Sample: Subset of the population Subset of sampling units
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Sampling units
Choice of sampling unit depends on objectives for sampling What do you want to know? Why?
Types Points
Transects
Quadrats or plots
Individuals Whole plant
Plant parts
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Plant BiomassIntroduction to measuring Biomass on Rangelands
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Plant Biomass Terminology
Phytomass
Production
BiomassYield
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Browse
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Double Sampling Methods
- Double_Sampling.xlsxDouble_Sampling.xlsx
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Indirect MethodsCapacitance Meter
Electronic capacitance is related to biomass because capacitance is directly affected by height and density of forage in a plot. Electronic capacitance must be converted to biomass with a double sampling procedure like that outlined above. In the regression equation the capacitance becomes the estimated value.
Rising Plate Meter
The rising plate meter is also a double sampling technique were some of the plots must be clipped to calibrate the meter. The height must be converted to biomass with a double sampling procedure like that outlined above. In the regression equation the height becomes the estimated value.)
Spectral reflectance
Spectroreflectance curves are measured with a spectrophotometer and then related to biomass.
Cover, height, and density estimates have also been used to estimate biomass and have been found reliable in some vegetation types.