Measuring Moisture Content in Living Chaparral: A Field User's Manual. Countryman, C. M. & Dean, W. A. Volume PSW-036 of USDA Forest Service General Technical Report, United States Department of Agriculture.
This manual standardizes procedures for determining the moisture content of living chaparral for use in a proposed statewide system of monitoring living fuel moisture. The manual includes a comprehensive examination of fuel moisture variations in California chaparral, and describes techniques for sampling these variations. Equipment needed to sample and determine living fuel moisture is discussed. Detailed procedures for collecting living fuel samples and processing the samples for moisture content are provided. [Excerpt: Procedures] Of the several methods available for determining the moisture con- tent of wildland fuels, drying the fuels in a conventional laboratory drying oven appears to be best for monitoring living chaparral moisture levels and trends. Determining moisture content by oven drying has long been a standard technique in science and industry, and equipment designed for the purpose is readily available. The method is very simple: freshly collected samples of foliage and twigs are weighed, dried in an oven for a specified period at a temperature slightly above the boiling point of water, then weighed again. The moisture content of the fuel sample can then be calculated, based on the weight measurements obtained before and after oven drying. Since the drying process does not require monitoring, the cost in technician hours for the moisture determination process is low. Safety problems are few-the process is not any more hazardous than using a domestic oven for cooking food. [] [...] [::Moisture Content] The moisture content of the samples is obtained from the equation: [::] Percent moisture = (Sample weight loss) / (Sample dry weight) x 100 [] Remember that moisture content for living chaparral fuels is expressed as a percentage of dry weight. Solution of the equation requires the following steps (an example is shown on the sample record form, fig. 4): [::1.] Record the empty container weights in column C, on the moisture determination record form. If the container weight is not marked on the container, secure it from the container weight record. [::2.] Subtract the empty container weight, column C, from the gross weight dry, column B, to obtain the dry weight of the sample. Record this dry weight in column D on the record form. [::3.] To determine the sample weight loss, subtract the gross weight dry, column B, from the gross weight wet, column A. Record the weight loss in column E on the record form. [::4.] Divide the weight loss, column E, of each sample by its dry weight, column D. Carry this calculation to three decimal places. [::5.] Multiply the quotient obtained in step 4 by 100 by moving the decimal point two places to the right. The result is the moisture content of the sample in percent, and this value is to be recorded under percent moisture, column F, of the record form. [::6.] If any samples have a dry weight in excess of 50 grams or an indicated moisture greater than 275 percent, it is possible that they are too compact or moist to dry completely in 15 hours. Open such samples and dry them an additional 6 hours in the oven. Repeat steps 5 through 7 of the drying procedures, then recalculate the moisture content. [] [...]
@book{countrymanMeasuringMoistureContent1979,
title = {Measuring Moisture Content in Living Chaparral: A Field User's Manual},
author = {Countryman, Clive M. and Dean, William A.},
date = {1979},
volume = {PSW-036},
publisher = {{United States Department of Agriculture}},
location = {{Berkeley, California}},
url = {http://www.fs.fed.us/psw/publications/documents/psw_gtr036/},
abstract = {This manual standardizes procedures for determining the moisture content of living chaparral for use in a proposed statewide system of monitoring living fuel moisture. The manual includes a comprehensive examination of fuel moisture variations in California chaparral, and describes techniques for sampling these variations. Equipment needed to sample and determine living fuel moisture is discussed. Detailed procedures for collecting living fuel samples and processing the samples for moisture content are provided.

[Excerpt: Procedures] Of the several methods available for determining the moisture con- tent of wildland fuels, drying the fuels in a conventional laboratory drying oven appears to be best for monitoring living chaparral moisture levels and trends. Determining moisture content by oven drying has long been a standard technique in science and industry, and equipment designed for the purpose is readily available. The method is very simple: freshly collected samples of foliage and twigs are weighed, dried in an oven for a specified period at a temperature slightly above the boiling point of water, then weighed again. The moisture content of the fuel sample can then be calculated, based on the weight measurements obtained before and after oven drying. Since the drying process does not require monitoring, the cost in technician hours for the moisture determination process is low. Safety problems are few-the process is not any more hazardous than using a domestic oven for cooking food. [] [...]

[::Moisture Content] The moisture content of the samples is obtained from the equation:

[::] Percent moisture = (Sample weight loss) / (Sample dry weight) x 100

[] Remember that moisture content for living chaparral fuels is expressed as a percentage of dry weight. Solution of the equation requires the following steps (an example is shown on the sample record form, fig. 4): [::1.] Record the empty container weights in column C, on the moisture determination record form. If the container weight is not marked on the container, secure it from the container weight record. [::2.] Subtract the empty container weight, column C, from the gross weight dry, column B, to obtain the dry weight of the sample. Record this dry weight in column D on the record form. [::3.] To determine the sample weight loss, subtract the gross weight dry, column B, from the gross weight wet, column A. Record the weight loss in column E on the record form. [::4.] Divide the weight loss, column E, of each sample by its dry weight, column D. Carry this calculation to three decimal places. [::5.] Multiply the quotient obtained in step 4 by 100 by moving the decimal point two places to the right. The result is the moisture content of the sample in percent, and this value is to be recorded under percent moisture, column F, of the record form. [::6.] If any samples have a dry weight in excess of 50 grams or an indicated moisture greater than 275 percent, it is possible that they are too compact or moist to dry completely in 15 hours. Open such samples and dry them an additional 6 hours in the oven. Repeat steps 5 through 7 of the drying procedures, then recalculate the moisture content.

[] [...]},
keywords = {*imported-from-citeulike-INRMM,~INRMM-MiD:c-14148965,field-measurements,live-fuel-moisture-content,shrubs,standard,vegetation},
pagetotal = {28},
series = {{{USDA Forest Service General Technical Report}}}
}