A laboratory study of weather effects on the drying rate of jack pine litter

1979 ◽  
Vol 9 (2) ◽  
pp. 267-275 ◽  
Author(s):  
C. E. Van Wagner
Keyword(s):  
Jack Pine ◽  
Absolute Temperature ◽  
Drying Rate ◽  
Fuel Moisture ◽  
Weather Index ◽  
Fire Weather Index ◽  
Free Moisture ◽  
External Conditions ◽  
Drying Rates ◽  
Two Stages

This paper describes the variation in the drying rate of jack pine (Pinusbanksiana Lamb.) litter with external conditions. Temperature, relative humidity (RH), and wind were varied separately. Drying runs were carried out in a cabinet with controlled temperature and humidity and also in the open laboratory. Most runs followed the exponential pattern, and the drying rates were measured in terms of the slope of the semilog graph of free moisture content versus time. The logarithm of this slope was found to be inversely proportional to the reciprocal of absolute temperature. The drying rate varied with 100 – RH at high RH but increased only slightly below 60% RH owing to the limiting effect of the wax and resin content on the rate of internal diffusion. Drying in wind proceeded in two stages, the first faster than the second. Wind was important at low speeds, and the drying rate increased but little above 2 km/h. These principles were used in the design of the drying equations of the Fine Fuel Moisture Code of the Canadian Forest Fire Weather Index.

Prediction of forest-floor moisture content under diverse jack pine canopy conditions

1989 ◽  
Vol 19 (11) ◽  
pp. 1483-1487 ◽  
Author(s):  
Z. Chrosciewicz
Keyword(s):  
Forest Floor ◽  
Mineral Soil ◽  
Jack Pine ◽  
Fuel Moisture ◽  
Weather Index ◽  
Fire Weather Index ◽  
Moisture Contents ◽  
Straight Line ◽  
Best Fitting ◽  
Pure Surface

Moisture contents of organic forest-floor materials were studied by strata in a semimature jack pine (Pinusbanksiana Lamb.) stand in relation to their within-stand locations and changes in both duff moisture code and fine fuel moisture code, the two weather-based components of the Canadian Forest Fire Weather Index System. The resulting best-fitting curvilinear regressions (Y = aebX) of the duff moisture code showed distinctive patterns of variation so that both the surface and subsurface forest-floor strata were consistently more moist in stand openings than under stand canopy. An initial moisture inversion between the surface and subsurface forest-floor materials manifested itself near the start of the regressions wherever live Schreber's moss (Pleuroziumschreberi (Brit.) Mitt.) and litter were the combined surface materials; otherwise, pure surface litter was consistently drier than the subsurface materials. Combinations of all these materials down to mineral soil showed intermediate moisture contents both in stand openings and under stand canopy. In contrast, the best-fitting regressions of the fine fuel moisture code just for surface forest-floor strata were of the straight line (Y = a + bX) category and had generally lower r2 values than those for the corresponding curvilinear regressions (Y = aebX) of the duff moisture code.

Predicting fuel moisture in jack pine slash: a test of two systems

1984 ◽  
Vol 14 (1) ◽  
pp. 68-76 ◽  
Author(s):  
Albert J. Simard ◽  
James E. Eenigenburg ◽  
Richard W. Blank
Keyword(s):  
Predictive Accuracy ◽  
Jack Pine ◽  
Rating System ◽  
Fire Weather ◽  
Regression Equations ◽  
Fuel Moisture ◽  
Wood Moisture ◽  
Weather Index ◽  
Fire Weather Index ◽  
Moisture Profiles

Observed jack pine (Pinusbanksiana Lamb.) slash moisture was compared with U.S. National Fire-Danger Rating System (NFDRS) and Canadian Fire Weather Index (FWI) predictions. The NFDRS models underestimated wood and foliage moisture; the FWI models overestimated wood moisture but were accurate for foliage moisture. Differences in predictive accuracy between the two sets of regression equations were not significant. The NFDRS equations were somewhat more data dependent, however, and their residuals tended to be biased. Significant differences in moisture profiles were noted among three fuel size classes, between fuels with and without bark, and between litter and needles. Differences between fuels on the ground and above the ground were not significant. The results should be applicable to most fuels influenced by moist climates.

Fire weather index system components for large fires in the Canadian boreal forest

2004 ◽  
Vol 13 (4) ◽  
pp. 391 ◽  
Author(s):  
B. D. Amiro ◽  
K. A. Logan ◽  
B. M. Wotton ◽  
M. D. Flannigan ◽  
J. B. Todd ◽  
...  
Keyword(s):  
Weather Conditions ◽  
Fire Season ◽  
Fire Weather ◽  
Fuel Moisture ◽  
Weather Index ◽  
Fire Weather Index ◽  
System Parameters ◽  
System Components ◽  
Large Fires ◽  
Canadian Boreal Forest

Canadian Fire Weather Index (FWI) System components and head fire intensities were calculated for fires greater than 2 km2 in size for the boreal and taiga ecozones of Canada from 1959 to 1999. The highest noon-hour values were analysed that occurred during the first 21 days of each of 9333 fires. Depending on ecozone, the means of the FWI System parameters ranged from: fine fuel moisture code (FFMC), 90 to 92 (82 to 96 for individual fires); duff moisture code (DMC), 38 to 78 (10 to 140 for individual fires); drought code (DC), 210 to 372 (50 to 600 for individual fires); and fire weather index, 20 to 33 (5 to 60 for individual fires). Fine fuel moisture code decreased, DMC had a mid-season peak, and DC increased through the fire season. Mean head fire intensities ranged from 10 to 28 MW m−1 in the boreal spruce fuel type, showing that most large fires exhibit crown fire behaviour. Intensities of individual fires can exceed 60 MW m−1. Most FWI System parameters did not show trends over the 41-year period because of large inter-annual variability. A changing climate is expected to create future weather conditions more conducive to fire throughout much of Canada but clear changes have not yet occurred.

An index for tracking sheltered forest floor moisture within the Canadian Forest Fire Weather Index System

2005 ◽  
Vol 14 (2) ◽  
pp. 169 ◽  
Author(s):  
B. M. Wotton ◽  
B. J. Stocks ◽  
D. L. Martell
Keyword(s):  
Moisture Content ◽  
Forest Fire ◽  
Forest Floor ◽  
Jack Pine ◽  
Fire Weather ◽  
Moisture Index ◽  
Northern Ontario ◽  
Weather Index ◽  
Fire Weather Index ◽  
Overstory Trees

The Duff Moisture Code (DMC) component of the Canadian Forest Fire Weather Index (FWI) System is used by fire management agencies across Canada as an indicator of the susceptibility of the forest floor to lightning fire ignition. However, this model was developed for the moisture content of the forest floor away from the sheltering influences of overstory trees, an area where lightning strikes usually ignite the forest floor. Through destructive sampling of the forest floor in a mature jack pine stand in northern Ontario over several summers, the moisture content of the forest floor in sheltered areas close to the boles of dominant overstory trees was found to be significantly lower than in other less heavily sheltered areas of the stand. Observations from a network of in-stand rain gauges revealed that rainfall penetration through the canopy (throughfall) was correlated with both open rainfall amount and the duration of a storm. Observed throughfall amounts were used to develop a throughfall relationship for extremely sheltered locations (within ~0.5 m of the boles) in a mature jack pine stand. This throughfall model was used, along with differences in forest floor drying rate, to develop a new duff moisture index for strongly sheltered areas of the forest floor. Calculated values of this new moisture model, which has the same daily weather observation requirements as the FWI System’s DMC model, were found to match observed moisture contents quite well.

Relationships between the moisture content of fine woody fuels in lodgepole pine slash and the Fine Fuel Moisture Code of the Canadian Forest Fire Weather Index System

1988 ◽  
Vol 18 (1) ◽  
pp. 128-131 ◽  
Author(s):  
R. Trowbridge ◽  
M. C. Feller
Keyword(s):  
Moisture Content ◽  
Forest Fire ◽  
Index System ◽  
Lodgepole Pine ◽  
Fire Season ◽  
Fire Weather ◽  
Fuel Moisture ◽  
Weather Index ◽  
Fire Weather Index ◽  
Moisture Contents

Unsuccessful attempts to ignite slash resulting from the mechanical knocking down of lodgepole pine in west central British Columbia led to a short-term investigation of the relationship between the Fine Fuel Moisture Code of the Canadian Forest Fire Weather Index System and the moisture content of various fine fuel components <1 cm in diameter. Of the types of fuel sampled, the moisture contents of B.C. Forest Service fuel moisture sticks and aged slash were similar to, and well correlated (r = 0.79 and 0.81, respectively) with, the equivalent moisture content calculated from the Fine Fuel Moisture Code. The Fine Fuel Moisture Code was not designed to relate to the moisture content of uncured fuels. Thus, the moisture contents of fresh living slash (material from knocked down trees still attached to living roots) and of fresh dead slash (material unattached to living trees that had not yet experienced a complete fire season in which to fully cure) were poorly correlated with moisture content (r = 0.16 and 0.42, respectively). The moisture content of the progressively curing, needle-bearing fresh dead slash was relatively high at the beginning of the fire season, but became similar to the moisture content during the first half of July. This suggests that the Fine Fuel Moisture Code can also be used to predict the moisture content of such fine slash after these fuels have cured for approximately 3 months during the snow-free period.

scholarly journals Atmospheric and Fuel Moisture Characteristics Associated with Lightning-Attributed Fires

2012 ◽  
Vol 51 (11) ◽  
pp. 2025-2037 ◽  
Author(s):  
Andrew J. Dowdy ◽  
Graham A. Mills
Keyword(s):  
Fuel Moisture ◽  
Atmospheric Conditions ◽  
Lightning Stroke ◽  
Weather Index ◽  
Fire Weather Index ◽  
Southeastern Australia ◽  
Seasonal And Diurnal Variations ◽  
Weather Parameters ◽  
Comparison Of The Results ◽  
The Relationship

AbstractA systematic examination is presented of the relationship between lightning occurrence and fires attributed to lightning ignitions. Lightning occurrence data are matched to a database of fires attributed to lightning ignition over southeastern Australia and are compared with atmospheric and fuel characteristics at the time of the lightning occurrence. Factors influencing the chance of fire per lightning stroke are examined, including the influence of fuel moisture and weather parameters, as well as seasonal and diurnal variations. The fuel moisture parameters of the Canadian Fire Weather Index System are found to be useful in indicating whether a fire will occur, given the occurrence of lightning. The occurrence of “dry lightning” (i.e., lightning that occurs without significant rainfall) is found to have a large influence on the chance of fire per lightning stroke. Through comparison of the results presented here with the results of studies from other parts of the world, a considerable degree of universality is shown to exist in the characteristics of lightning fires and the atmospheric conditions associated with them, suggesting the potential for these results to be applied more widely than just in the area of the study.

scholarly journals Stand-specific litter moisture content calibrations for the Canadian Fine Fuel Moisture Code

2007 ◽  
Vol 16 (4) ◽  
pp. 463 ◽  
Author(s):  
B. Mike Wotton ◽  
Jennifer L. Beverly
Keyword(s):  
Moisture Content ◽  
Significant Influence ◽  
Forest Type ◽  
Stand Density ◽  
Fuel Moisture ◽  
Large Dataset ◽  
Weather Index ◽  
Fire Weather Index ◽  
Surface Conditions ◽  
The Relationship

A large dataset of litter moisture measurements collected at several sites across Canada by the Canadian Forest Service over the period from 1939 to 1961 is analysed. The stands in which sampling was carried out were described by three main variables: forest type (pine, spruce, Douglas fir, mixedwood and deciduous), season (spring, summer and fall), and stand density (light, moderate and dense). All three variables were found to have a significant influence on the relationship between the Canadian Forest Fire Weather Index System’s Fine Fuel Moisture Code (FFMC) and surface litter moisture. Moisture in the upper duff layer was also found to have a significant influence on the relationship between FFMC and litter moisture content, with a wetter duff layer leading to moister surface conditions than would be indicated by the FFMC value. A model for litter moisture is developed, which provides a method of adjusting the standard FFMC value for the influences of forest type, stand density, season and duff moisture content.

Prediction of forest-floor moisture content on jack pine cutovers

1989 ◽  
Vol 19 (2) ◽  
pp. 239-243 ◽  
Author(s):  
Z. Chrosciewicz
Keyword(s):  
Moisture Content ◽  
Forest Floor ◽  
Mineral Soil ◽  
Jack Pine ◽  
Fuel Moisture ◽  
Fire Weather Index ◽  
Clear Cut ◽  
Moisture Contents ◽  
Best Fitting ◽  
Curvilinear Regression

Moisture contents of organic forest-floor materials were studied by strata on a clear-cut jack pine (Pinusbanksiana Lamb.) site in relation to slash distribution and changes in both duff moisture code and fine fuel moisture code, the two weather-based components of the Canadian Forest Fire Weather Index System. The best-fitting curvilinear regression (Y = a + b/X) of the duff moisture code showed distinctive patterns of variation, so that both the surface and subsurface forest-floor strata were consistently moister under slash cover than in slash openings, and for each of these two slash conditions, the subsurface forest-floor strata were consistently moister than the surface strata. Combinations of these materials down to mineral soil showed intermediate moisture contents both in slash openings and under slash cover. The straight line regression (Y = a + bX) of the fine fuel moisture code was the best-fitting moisture content relationship for the surface forest-floor materials, but only in slash openings; under slash cover, the curvilinear regression (Y = a + b/X) of the duff moisture code was more suitable. The coefficients of correlation, r, as derived from these varied regressions, were all very highly significant at P < 0.001.

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