Reconciliation of Review Comments on:
Calculating physical characteristics of wildland fuels in the Fuel
Characteristic Classification System (FCCS)
Cynthia L. Riccardi, David V. Sandberg, Susan J. Prichard, Roger D. Ottmar
June 15, 2006
Reviewers
Matt Dickinson – USDA Forest Service, Northeastern Research Station
Mark Finney – USDA Forest Service, Rocky Mountain Research Station
Mike Hilbruner – USDA Forest Serv. Vegetation Management and Protection Research
Ruddy Mell – National Institute of Standards Technology
Elizabeth Reinhardt – USDA Forest Service, Rocky Mountain Research Station
Scott Stephens – University of California Berkeley
Jan W. van Wagtendonk – USGS Ecological Research Center
David Weise – USDA Forest Service, Pacific Southwest Research Station
Matt Dickinson
Page 2, line 5. Change “to” to “for”?
Accepted.
Extrinsic and intrinsic properties vs fuel bed and fuel particle properties. My preference
is to use what is already in the USFS fuels and fire behavior literature. Extrinsic and
intrinsic seem nebulous in reference to fuel properties. Won’t fuel bed and fuel particle
properties work for FCCS?
During the revision process, I’ve tried to illustrate the fact that there is confusion, as you
point out, in terminology. I’ve rewritten the introduction and the discussion sections to
discuss these inconsistencies.
Page 6, line 3. Not sure what the sentence that begins on this line means.
Hopefully this is clear in the revision.
Page 7, line 11. What is flammability? Is heat content low heat or high heat of
combustion?
Flammability is neither low nor high heat content but rather based on primary and
secondary plant compounds (i.e. terpenes, fats, etc.).
Reconciliation of FCCS Calculator Paper -- 1
Page 8, line 17. This definition of optimum packing ratio doesn’t make sense to me.
Hopefully this is clear in the revision.
Page 8, line 23. What do you mean by “general form”?
General form refers to the concept of an equation of a line (y = mx + b) so regardless of
the numbers, the equation is the same. This holds true for certain calculations in FCCS.
In other words, regardless of the stratum, category or subcategory, and numbers, the
equation used throughout is the same.
Page 10, line 23. I’m lost by the definition of optimum particle spacing. More
background is needed.
Accepted.
Page 12, equation 5b. What is crown shape? It must have a mathematical definition
since it has a numeric value.
Listed in Table 3.
In all the equations involving summations or averages of fuel properties, no weightings
were applied (I am a confused here, the added subscripting will help). This is in contrast
to Rothermel who weights by surface area to volume ratio and loading. Why this or
another weighting procedure is not followed needs to be discussed in manuscript 3 and
not only in manuscript 4.
If I interpret your comment correctly, the FCCS calculates and sums values for
components hence weighting is not required.
Page 17, line 9, Not sure what the sentence that begins on this line means.
Addressed in revision.
Mark Finney
The manuscript is intended to provide a description of the calculations of synthetic fuel
values used in fire potential calculations. This paper contains much overlap with the
introductory manuscripts (Riccardi et al. and Ottmar et al. The manuscript is not in
publishable form at present but could easily be combined with the two other overview
papers to cover the introductory material, leaving the calculations and tables to be
included as appendices in a GTR. Most of the calculations themselves are very standard
– (how to convert weight from density, etc.) and don’t need a full exposition in the text.
Those that are unique can only be appreciated in the context of the usage for the derived
value – and should therefore be imbedded in the Potentials paper. In fact, without the
Reconciliation of FCCS Calculator Paper -- 2
Fire Potentials, this paper is quite unnecessary, since it only describes ways that the data
are mathematically transformed for use in fire potential calculations.
Pages 1-7 mostly same as 2 other papers.
All manuscripts have been revised considerably, and the additional material should
clarify and differentiate between the individual manuscripts. Specifically, the
manuscripts by Riccardi et al. are now more clearly distinctive. Some duplication of
material between manuscripts is unavoidable, because each manuscript needs to stand on
its own.
I have some specific comments that may be useful in revision:
Metric units for publication
Metric units are included in the revised manuscript, and will be included in the next
version of the FCCS.
Equations – symbology could be more conventional. Better communication if common
Greek symbols were used (e.g. σ for SV, δ for Depth) and subscripts denoted by index
rather than name (e.g di)
These changes were made.
Page 3 line 22, yes, inventory labor intensive – but FCCS not an alternative as statement
implies – just requires more intensive inventory to populate it with values that can’t be
used or justified for fire behavior/effects modeling. And, logically, if real data aren’t
used, then are you suggesting that FCCS fuelbeds are just “models” that are
recommended to be used for areas not measured? (just like fuel models?)
FCCS fuelbeds are not fuel models because fire behavior fuel models are “…a complete
set of inputs for the mathematical spread model.” (Rothermel 1972, p. 35) Although,
FCCS fuelbeds can be used to create a customized fire behavior fuel model, that was not
the original, nor the only, objective of FCCS fuelbeds.
Page 4 line 3. The statement “FCCS was developed to provide greater quantitative
detail on fuel properties that resource managers need for planning and analysis” is
puzzling – how does FCCS actually provide details? It appears that it actually requires
details from the user that are not yet (and may never be) used in fire behavior or effects
models.
FCCS provides a set of outputs (details) based on a set of inputs. As noted above, they
are not intended as a substitute for fuel models, but as a more complete description of
fuelbeds that includes six strata, with each stratum containing several descriptors.
Reconciliation of FCCS Calculator Paper -- 3
Page 5, line 22. There is no justification for why the mode is being claimed as
representative of a fuel bed property. It seems arbitrary and perhaps suspicious because
standard fuel inventory methods produce means and often some metric of dispersion from
which confidence limits could be calculated. I assume that the photoseries data all have
this kind of data.
Additional justification for using the mode was included in the revision. Analogous to its
statistical meaning, it is intended as a central value of fuelbed properties. The Photo
Series have lots of data, although typically there are insufficient data to fairly represent
variability such that accurate means and variance can be calculated in a strict statistical
sense.
The Discussion section should be edited to remove adjectives that give the impression of
advertisement rather than provide description (robust, dynamic, valuable). Page 17 line
4 is totally unsupported – there is no technical justification offered in this manuscript (or
any of the others) that the FCCS provides long-term and large-spatial capabilities for
fuels or fire. This sounds like an sales pitch. Also, I don’t see the point in describing
possible future enhancements to the system (page 17, line 6-11).
Some of this wording was modified for clarity. It seems reasonable to briefly describe
enhancements to the system, just as future research issues are addressed in most scientific
articles.
Mike Hilbruner
Overall, I found inadequate explanation of some new concepts and citation of some
existing ones in this paper. I sense that the rationale and underlying structure is sound,
but would appreciate a somewhat more in depth treatment on some topics. These are
noted in the draft and I will cite a couple of examples here.
I found the discussion on the flammability parameter incomplete. I was uncertain
whether this is a binary, yes/no value and how it is used in the system. I am familiar with
heat content and mineral damping coefficient as ways to express the presence of
accelerants and slowing the combustion reaction. I don’t see how this flammability
parameter differs from these concepts or their implementation (ref page 7).
There is mention of fuel area index for “very fine (flash)” fuels (page 9) but I do not find
a definition nor, in my experience, is there a commonly accepted precise one in use.
I found the notation with regard to fuel loading either inconsistent or confusing, I’m not
sure which. Wo, in my experience, refers to a gross loading but I don’t see this point
made when the term is introduced (page 9, I believe). Then further on in the paper, the
term W is used – should it be Wo in each instance?
Additional detail and clarification of concepts and terms were included in the revision.
Reconciliation of FCCS Calculator Paper -- 4
There is mention that an optimum packing ratio is calculated for each stratum except
ground fuels but I did not see why ground fuels are excluded (page 10).
Ground fuels are excluded because we assume that ground fuels burn only in smoldering
stages. The concept of a βop is irrelevant, because there is no way to establish an
optimum packing with current information.
The bulk volume parameter is introduced as a flammable portion of the fuel stratum,
seemingly a volume interpretation of available fuel. This is defined using terms like
“accelerant foliage”. Is the assumption that 100 percent of these fuels combust during
the flaming front passage? Is post-frontal combustion included? Neither? More
discussion would help me. A physical definition of accelerant would help.
The definition of accelerant was expanded for greater clarity and specificity.
I also felt that more extensive use of subscripts to clarify the application or use of a
particular parameter in equations and text where practicable would be helpful. Some
equations include the subscript “stratum” for example but many other do not. The
subscript notation could be more uniformly applied to aid the reader in understand
whether an equation refers to a stratum, category, or other grouping without having to
refer to the text.
All of the terminology was carefully checked to ensure completeness and consistency.
I have some additional comments and questions in my annotated draft paper. I like the
overall organization and subject matter of the paper but I believe it needs to focus a bit
more on explanation and in general become a bit more robust.
Ruddy Mell
Many quantities are introduced without giving the reader a sense of why they are needed
or what they will be used for.
Additional justification was provided where appropriate.
The methods used when summing over subtypes needs to be fully explained for every sum.
For example, in some cases the components of the sum are weighted by percent cover (a
quantity which also needs to be fully explained) but this weighting does always seem to
be used (or is it?).
The weighting is indicated where appropriate and not indicated when not used.
A consistent use of variable denotations would facilitate the reading.
All of the terminology was carefully checked to ensure completeness, consistency, and
appropriate definitions.
Reconciliation of FCCS Calculator Paper -- 5
p4 line 4-9: (reviewer comment: It would be very helpful, and give additional credibility
to this effort, if examples were given of how improved fuel property information will
actually help resource managers. Without such a discussion the reader is left wondering
how such information is relevant beyond FCCS itself. This is especially true given that
the fire potentials are essentially a reworking of the Rothermel approach .
This rationale was beefed up considerably in the revision.
p4 line 19-20: (reviewer comment: It seems that the use of National Fuelbeds could be
removed without loss of clarity).
The terminology was changed to “FCCS Fuelbeds.”
p5 line 3: (reviewer comment: see comment starting at or near page 3 line 18 of
characterization paper)
p5 line 13-14: (reviewer comment: what calculations are referred to here?)
?
p6 line 17-18: (reviewer comment: How is relative cover measured or determined? Is
there a reference?)
Relative cover is the proportion of its coverage compared to that of all components
(species). This is a standard measure in forestry and ecology.
p7 line 3-6: (reviewer comment: This is confusing, at least to me, what calculations are
you referring to here? Are these calculations of fuel properties? What is meant by
cumulative? For example you can’t simply add densities up to get a cumulative value.
Could you give a simple example?
This section was clarified in the revision.
p7 line 22-23: (reviewer comment: The units need to also be on Table 3; metric units are
needed too; references are for quantities in Table 3)
These points are clarified in the revision. Metric units are included in the revised
manuscript, and will be included in the next version of the FCCS.
p8 line 2-3: (reviewer comment: See comment on Table 4)
p8 line 5-6: (reviewer comment: Definition of and reference for crown shape factor is
needed)
Reconciliation of FCCS Calculator Paper -- 6
Crown shape has been addressed a fair amount in the literature on physiognomy and
morphology of tree crowns. It is hopefully described adequately in the revision.
p8 line 7-9: (reviewer comment: Bulk density on Table 3 is given has computed from the
particle density and the packing ratio with no reference given for bulk density. Is Ottmar
et al 2004 used for bulk density and the packing ratio then derived or …?).
Yes, the first is correct and this has been clarified in the revision.
p8 line 18-19: (reviewer comment: so does this mean that the characteristic diameter of
a some vegetation is used to derive the surface-to-volume ratio?
p9 line 6: added “particle” after “fuel”
p9 line 10-11: after “favorable” added “(from the point of view of maximum fire
intensity)”.
p9 line 18: added “particle” after “fuel”
p10 line 5-6: (reviewer comment: equation 2 below is not a percentage but a fraction)
Minor revisions were made where appropriate.
p10 line 20- p11 line 3: (reviewer comment: The method used to compute the
summations over categories, stratums, etc. needs to be written out explicitly. And, since
there is more than one way to compute a packing ratio for a volume that contains more
than one kind of vegetation. For example, is the canopy stratum value computed by
summing Wo, PDF and Depth individually over the sub-, mid- and over- stories, and then
computing (W/PDF)/Depth? This, to me, seems to not be the right way to do it but is
implied in the above discussion.
The fuel load is calculated individually for the categories and subcategories in a stratum
and summed to produce the total for the stratum. Foliage particle density ρf is calculated
for each species, and then weighted by the species relative cover to produce a weighted
ρf. Depth is calculated for the stratum using the components of the stratum. Depth is not
a summation. This approach seems reasonable and appropriate.
p11 line 13-14: (reviewer comment: Font used for ‘bulk volume’ needs to be consistent
with Eq. 3)
Addressed in revision.
p12 line 5-10: (reviewer comment: Either a full explicit derivation of Eqs. (3, 3a) is
needed or a reference to a peer reviewed work containing such a derivation. As it stands
now the reader has no idea whether these equations are derived from experiments, some
dimensional analysis, or the result of or motivation for some modeling work. Some
Reconciliation of FCCS Calculator Paper -- 7
discussion is also needed as to why these quantities are important. How will they be
used? Only in the calculation of fire potentials or do they have other uses?)
Additional detail was provided for this section.
p13 line 4-6: (reviewer comment: this doesn’t make sense, the sum of what, the number
of trees, snags and ladder fuels; the sum of mass, …?)
p13 line 6-7: (reviewer comment: what is meant by tree layer? Over-, mid-, or under
story?
p13 line 10: (reviewer comment: how is percent cover determined? Is this the same as
relative cover?)
p13 line 12: (reviewer comment: where do the Crown shape values in Table 3 come
from?
p14 line 13: (reviewer comment: Is there any other work that can be referenced for this
assumption?) ,
p15 line 21: assumed to be (or is there a reference?):
p16 line 9-10: assumed to be (or is there a reference?):
Revision were made to address minor issues where appropriate.
p16 line 19-20: (reviewer comment: where do 8 and 4 come from? What’s the rationale
or is there a reference?),
Taken from geometry – volume equations. 8 is used for variations on half-paraboloids,
and 4 used for half-cylinders and half-ellipsoids.
p16 line 20-21: (reviewer comment: how is BD computed?).
BD was inferred by litter type as discussed in the text and in Table 4.
p32 line 2-3: Table 3: (reviewer comment: References are needed, units are needed
(including metric))
This revision was made. Metric units are included in the revised manuscript, and will be
included in the next version of the FCCS.
p34 line 4: Table 4: (reviewer comment: References are needed, units are needed in
metric)
This revision was made.
Reconciliation of FCCS Calculator Paper -- 8
p34 line 4: Table 4, last column: he wrote “is lb acre-1 in-1 a commonly used unit?”
p35 line? he wrote “what is lb ft-1?”.
Yes, for forest or rangeland or grassland organic matter values.
p41 line 4-5: (reviewer comment: references are needed).
Accepted.
Elizabeth Reinhardt
I think this has the potential to be a really valuable manuscript. But it needs a lot more
specific detail.
If the manuscripts are printed as chapters in a larger paper, the introduction could be
deleted, as the material was presented in the previous two manuscripts.
Throughout this ms. my comments will emphasize beefing up the technical content.
Citations are essential to support values used in computations or assignments. The
technical content has to be laid out in detail even though this will require much longer
tables. I believe organization would be clearer if the ms. proceeded by strata, rather than
inferred, calculated..etc. Maybe the tables could also be organized by strata.
Canopy bulk density, a required input for FARSITE, BEHAVE and NEXUS, is not
included as a computed variable, although the FCCS is purported to supply the values
needed to predict fire behavior and effects.
The technical content, level of detail, and citations were improved considerably in the
revision. Please see Table 9 which now includes much of the information requested by
the reviewer.
The method for computing W (Wo at other parts of the ms.) seems backwards to me.
Crown bulk density varies greatly by tree crown class, i.e. whether the tree is dominant,
codominant or suppressed, and has not been directly measured in the field. However, a
number of studies have measured foliage and branch biomass directly in the field, and
these values relate well to tree diameter and height, by species. So why not compute W in
a more straightforward way from species, diameter, height and trees per acre, and then
calculate canopy bulk density by dividing by canopy volume?
Indeed this is a complicated issue and for this release we decided against your suggestion
mainly because there are more tree species that have not been measured for foliage and
branch biomass than have been measured. However, we will definitely consider this
issue for future versions.
Reconciliation of FCCS Calculator Paper -- 9
Pg 5, last paragraph. Again, please reconsider the term “mode” and the decision to use
English units.
Additional justification for using the mode was included in the revision. Analogous to its
statistical meaning, it is intended as a central value of fuelbed properties.
Pg 7. Would “assigned values” be clearer than “inferred variables”? I’m still
struggling with vocabulary, and the use of the terms “variable”, “inferred variable”,
“type designation” (line 6), “types” (line 12), “calculated fuel characteristics” (pg 8,
line 5), “fuel type” (pg 10, line 4) are some of the terms that could be tightened up. The
word “type” is esp. difficult for me, and again, I wonder if “component” could
substititue for type as well as category and subcategory. Maybe this ms. needs a glossary.
Even though I did not produce a glossary, I paid particular attention to nomenclature
during the revision process.
Pg 8, line 2. Assumption that fuel particles are cylinders is poor for grasses, herbaceous,
canopy and shrub fuels.
This is clearly a limiting assumption, and we have tried to qualify its shortcomings in the
revision.
Pg 9, line 4. Define very fine fuels. SV > than some value?
This is included in the revision.
Pg 10. What is the source for the optimum particle spacing?
This is included in the revision.
Pg 11, line 20. “Canopy stratum loading is the sum of all trees, snags and ladder fuels.”
Please clarify whether this means foliage only, foliage and fine branchwood, all above
ground biomass, or what.
This is included in the revision.
Pg 12, line 4-9. Bulk density of crowns is said to be an inferred variable as in table 3,
but no values are reported in table 3. Citations are needed.
No values are given because it is calculated using the formula and values listed in Table
3.
What is the bulk density of Class 1 snags? What is the source of this data?
Reconciliation of FCCS Calculator Paper -- 10
No values are given because it is calculated using the formula and values listed in Table
3.
Eq 7a, Pg 13, line 11 Shouldn’t this say density rather than relative cover?
No.
Page 14, line 12. Document what values are used for PDW and the source of the data.
Cited in text.
Page 15, line 4 Stems per acre should read piles per acre.
Page 16, line 12. Suggest rewording “Mathematical modeling of fire behavior and
effects requires knowledge of physical properties and characteristics of wildland fuels.”
Thank you.
Page 16, line 17. Again, the word classify confuses me.
This is addressed in greater detail in the revision.
Page 16, line 18. “A valuable set of physical fuel characteristics” I agree that this
would indeed be very valuable, but it is not sufficiently presented either here or in the
software. We need to see the details, including the assigned values and the sources of
data.
This is addressed in greater detail in the revision.
Tables 1 and 2 seem redundant.
Table 1 outlines the fuelbed classification.
Table 2 details the input variables.
Table 3. add another column for data source, and one for units. (possibly leave out min
and max).
References are now included in the text, as requested.
Why are tables 4 and 6 missing so many values? For ex. In table 4 woody fuels have no
values for density or heat content. And in table 6 many eq’ns are missing.
In both cases, “missing” values are exceptions and are discussed in the text.
Table 4. How can FAI be assigned as a constant for ladder fuels? Should vary with
abundance.
Reconciliation of FCCS Calculator Paper -- 11
Thank you. This is a good suggestion and will be considered for future versions.
Table 4. Columns seem poorly aligned.
This was revised.
Table 4. Add another column for data source or citation.
References are now in the text.
Table 7, add references.
References are now in the text.
Scott Stephens
In general I found this manuscript to be well written. One general comment is the use of
the term fuel loading throughout this and other manuscripts. I would recommend using
fuel loading to describe the quantity of biomass that has the potential to burn. The
addition of ing to the end of this word is not justified. You are simply interested in the
fuel loads, not the fuel loading.
When appropriate “ing” has been removed from the word “loading”.
The manuscript mostly introduces readers to the variables used by the FCCS system.
Page 2, line 7. You have ‘FCCS uses measured or averaged physical properties...’ What
does ‘measured or averaged’ mean here? It is not clear.
This is addressed with greater clarity in the revision.
The introduction is somewhat similar to that presented in previous manuscripts. I believe
it may be best to combine this manuscript with ‘National system to characterize physical
properties of wildland fuels’ as both of these works are generally presenting information
on a similar topic. Combining them would also allow the creation of longer discussion
sections (this manuscript has a 1 page discussion) that would be needed for publication
in a journal.
Combining the manuscripts was not done, but the introduction and discussion sections in
each manuscript have been revised to better frame the material discussed in the
manuscripts.
Page 4, line 18. Same issue given in Page 2, line 7 above.
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This is addressed with greater clarity in the revision.
FCCS must be able to work with both English and metric units. English units alone are
not enough, especially if you would like to get this published in a scientific journal.
Metric units are included in the revised manuscript, and will be included in the next
version of the FCCS.
The computer interface of the FCCS system is well done and is user friendly. The help
functions are well done and very useful to the user.
Thank you.
The user needs to have access to the references used to create the fuel properties in this
system (such as the inferred variables and other information related to fuelbeds). This is
a critical issue. If data are from a peer-reviewed paper, great. If data are from an
internal white paper or from expert opinion, the user needs to know this.
Indeed it is a critical issue and we are currently working on supporting the references
within FCCS. In addition, we are considering publishing the references as an electronic
appendix.
It is not clear how overstory, midstory, shrubs, and seedlings are used in fire behavior
simulations. It seems that there could be an issue when calculating crown fire potential
and surface fire behavior bases on which fuelbed that you are analyzing. I believe shrubs
and trees are treated differently by the model but they essentially occupy the same
physical space on real landscapes. This should be addressed in a revision.
These specifics have been addressed in the other manuscripts dealing with FCCS
potentials.
You have quite a list of variables that depict a fuelbed. It would be very important for
you to specify which variables are critical for a particular application. I could see a
manager wanting to use your system and they would tell their summer crews to go out
and measure all of these variables. This would not be an efficient use of their time and
some direction from you on this topic would be very useful.
This is a good point, and greater specificity has been added with respect to the relevance
of variables for different applications.
p.2 line 7: circled and put a question mark on ‘measured or averaged’.
p.4 line 10 & 11: circled and wrote ‘6’ next to ‘six horizontal fuelbed’.
p.4 line 12: underlined ‘canopy, shrubs, non-woody vegetation, woody, litter-lichenmoss, and ground fuels’.
Reconciliation of FCCS Calculator Paper -- 13
p.4 line 13: circled ‘16’.
p.4 line 18: circled and put a question mark on ‘measured or averaged’.
p.5 line 6 & 7: circled ‘the best available published data and, where necessary,
unpublished information’.
p.5 line 13: circled ‘fuelbeds by seven qualitative criteria’.
p.5 line 19 & 20: circled ‘reported values include the mode, minimum, and maximum’.
Minor comments were addressed where appropriate in the revision.
p.5 line 22: circled ‘the modal values are used’ and wrote ‘can you provide a metric
version too? You really need to’.
Metric units are included in the revised manuscript, and will be included in the next
version of the FCCS.
p.6 line 8: crossed out ‘ing’ from the word ‘loading’.
p.6 line 16: underlined ‘default values for fuel properties’.
p.6 line 17: underlined ‘inferred variables’.
p.7 line 2: circled ‘inferred variables are internal sets of data that augment the fuelbed
data’.
p.7 line 7 & 8: circled ‘The inferred’ and ‘are static and cannot be modified’.
p.7 line 17: circled ‘Flammability is mostly’ and asked ‘tested in lab?’
p.8 lines 9 & 10: crossed out ‘ing’ on all occurrences of the word ‘loading’.
p.8 line 11: circled the acronym ‘FAI’.
p.9 line 2: underlined ‘fuel surface area for all size classes of fuels’.
p.9 line 3: circled ‘FCCS Fire Potentials’.
p.9 line 9: crossed out ‘ing’ in the word ‘loading’.
p.9 line 15 & 16: circled and wrote ‘yes’ next to ‘Each fuel environment has an optimum
packing ration in which fuels are ideally configured for maximum fire intensity’.
Reconciliation of FCCS Calculator Paper -- 14
p.10 line 11: wrote ‘not clear as to how this equation was developed’.
p.10 line 20: wrote ‘not clear where this came from’.
p.11 line 11: underlined entire equation.
p.11 lines 17 – 21: crossed out ‘ing’ in all occurrences of ‘loading’.
p.12 line 4: wrote ‘you are going to include units for a peer review?’
p.12 line 13 & 14: underlined entire sentence starting on line 13.
p.12 line 16 & 17: crossed out ‘ing’ in all occurrences of ‘loading’.
p.13 line 8, 16, 19, 20, & 22: crossed out ‘ing’ in ‘loading’.
p.13 line 18: circled ‘Vines-liana’.
p.14 lines 3 – 9, and line 20: crossed out ‘ing’ in all occurrences of ‘loading’.
p.14 line 5: wrote ‘why? others too’.
Minor comments were addressed where appropriate in the revision.
p.15 line 5 and 6: circled ‘8’ and ‘4’ and wrote ‘? need to explain this’.
Taken from geometry – volume equations. 8 is used for variations on half-paraboloids
and 4 used for half-cylinders and half-ellipsoids.
p.15 lines 7, 8, 16, 19, 20, 21: crossed out ‘ing’ in all occurrences of ‘loading’.
p.15 line 16: circled ‘Duff’ and wrote ‘including litter?’.
p.16 line 1: wrote ‘missed something?’ next to equation.
p.16 line 3: circled ‘(ines)’.
p.16 line 6 and 8: crossed out ‘ing’ in all occurrences of ‘loading’.
p.16 line 11: wrote ‘very short discussion section’.
p.16 line 12 – 20: wrote ‘in intro, not needed here again’.
p.17 line 7 & 8: circled ‘of the inferred variables used in’ and ‘calculations’.
Reconciliation of FCCS Calculator Paper -- 15
p.23: next to bottom row second column it says ‘Duff, squirrel middens, and basal
accumulation’. Next to that he wrote ‘no litter?’.
p.30 line 4: crossed out ‘ing’ in all occurrences of ‘loading’.
p.31 line 3: crossed out ‘ing’ in all occurrences of ‘loading’.
Minor comments were addressed where appropriate in the revision.
Jan van Wagtendonk
General Comments
This is a generally well written paper explaining the methods used to calculate fuel
characteristics. There may be a problem getting it published in the peer-reviewed
scientific literature, however; since there is no new science being reported. I do think it
would be appropriate as a general technical report. Perhaps it could be combined with
paper #3.
My primary concern has to do with the manner in which the information is presented.
The paper presents the inferred and calculated characteristics but does not do so in an
easily followed manner. We are told how the various fuel characteristics were calculated
but not the rationale for those calculations. For example, it would have been useful to
have include a discussion on the fuel area index, the concept behind the idea, and what it
means from a fuels point of view. Similarly, more information on the calculation of crown
bulk density needs to be included. I never did figure out if my assumptions about its
calculation were correct.
Thank you for the suggestion of reordering the manuscript. Although the same general
organization was retained, additional information was provided to improve the clarity of
presentation and logic of technical relationships.
It seems to me that a better way to present this information would be to organize it
around the tables. I would first briefly discuss the input (measured) variables (Table 2)
and then delve into the inferred variables (Tables 3 and 4). Following that should be a
more thorough variable by variable discussion of the all of calculated variables.
The authors did not avail themselves of much of the published literature on fuel
characteristics. Nor did they cite the sources for many of the characteristics they did use.
Some of the published articles are referenced in the three publications that I have
enclosed.
The scientific literature has been augmented considerably to improve the overall context
for the current work, and demonstrate the advances provided in this new system. The
Reconciliation of FCCS Calculator Paper -- 16
tables do help to organize the material in a logical order, and the revised material in the
tables and elsewhere is now more complete and better referenced.
Specific Comments:
Page 4, line 10. A sentence describing the three “historical” layers and a citation would
be useful here.
Addressed in the revision.
Page 4, line 14. I would not capitalize “National” – there could be the connotation that
the system is Nationally approved (e.g., NFDRS).
The word national was used in the context of “affecting a (or the) nation as a whole;
nationwide in scope, involvement, representation, etc.” (Webster’s New World
Dictionary 3rd ed. 1991). However, the terminology has been changed to “FCCS
Fuelbeds.”
Page 5, line 3. They are available for some parts of the country. For example, I derived
mean diameter, surface-to-volume ratio, specific gravity, ash content, and heat content
for woody particles of 19 conifers occurring in the Sierra Nevada.
Indeed they are available for some parts. I derived them for hardwood forest of Central
Appalachia.
Page 5, line 4. Remove “artistically.” There could be a negative or positive connotation
inferred from its use.
Addressed in the revision.
Page 5, line 23. Metric units should also be reported.
Metric units are included in the revised manuscript, and will be included in the next
version of the FCCS.
Page 6, line 8. What’s that “W” doing in there?
It represents loading.
Page 7, line 11. “Flammability” needs to be defined. Your use of the term appears to be
restricted to the presence of combustible volatiles. There are other definitions.
Clarified in the revision.
Page 7, line 23. What about other published sources? Brown (1972), Beaufait et al.
(1975), Sackett (1980), Ryan and Pickford (1978)?
Reconciliation of FCCS Calculator Paper -- 17
Although these particular references were not added, many others were added to augment
the scientific context of the manuscript.
Page 8, line 1. Add “are” between “rotten” and “unknown.” These values are known
for many species, however. I came up with a specific gravity for rotten wood of 0.36.
The default particle densities need to have units (lb ft-3?).
Addressed in the revision.
Page 8, line 23. Add an “l” to “fuebed.”
Done.
Page 10, line 23. There needs to be a citation for the optimum depths reported here.
Included in the revision.
Page 11, line 7. Isn’t duff part of the ground fuel stratum?
Yes.
Page 11, line 20. I am still confused about the method to calculate canopy bulk density.
Let me know if I am following you correctly (measured variables in italics, inferred in
bold and italics, and calculated in bold):
Crown Bulk Density is equivalent to LAI?
LAI = FAI / π (I never could figure out this one!)
FAI = ( Wo x SV ) / PDF
Wo = (Adjusted crown volume x Bulk density) / 2,000
Adjusted crown volume = Volume (relative cover/100) x crown shape)
Volume = (Percent cover/100) x 43,560 x (Height - Height to live
crown)
Bulk density = PDF x β
β = (Wo / PDF) / Depth
Depth = (Height and Height to live crown)
Whether I assumed right or wrong, I think the logic for such a calculation should be
more explicit.
FCCS does not have a canopy bulk density. FCCS has crown bulk density that is
calculated and discussed in the section on inferred variables (Table 3).
Page 12, line 9. Bulk density is calculated.
Page 14, line 9. “Lightered” is too colloquial to use – pitchy will do.
Reconciliation of FCCS Calculator Paper -- 18
Page 15, line 20. There are published values for bulk density.
Page 16, line 3. Remove the “es” from “ines.”
Minor comments were addressed where appropriate in the revision.
Page 23, Table 1. There continues to be the problem of defining short trees as part of the
canopy in situations where there is a shrub stratum. In that case, the trees are really
contributing to fire behavior similar to shrubs.
This issue is handled in different ways by different investigators, in different
publications, and in different software applications. It should not necessarily be a
concern if handled and quantified in a consistent manner.
Page 24, Table 2. Why is it assumed that the shrub layer does not have live and dead
woody material? The moisture content of the dead woody material, especially if percent
live is low.
This differentiation is challenging to accurately quantify in the field, and although shrubs
clearly contribute to certain types of fire behavior, it is difficult to justify a specific
quantitative proportion of live and dead.
Page 25, Table 2. Remove “Lightered”, define “Perched”, add “herbaceous” to
“Grass.”
Addressed in revision.
Page 27, Table 3. What are the sources of these values? Are packing ratios for other
types of fuels inferred?
References are cited in the text.
Page 27, Table 3. Isn’t bulk density a calculated variable.
Yes, in some cases.
Page 28, Table 4. What’s that in-1 unit doing in the bulk density column?
?
Page 28, Table 4. What are the sources of these values? Why are Jackpots, piles and
windrows considered to be rotten?
This is a general assumption that seems reasonable for most cases.
Reconciliation of FCCS Calculator Paper -- 19
Page 28, Table 4. What happened to stumps?
Stumps are not applicable to this table.
Page 29, Table 4. What are the sources for the 6,000 BTU lb-1 values for lichens and
mosses?
This value is derived from field data collected by R.D. Ottmar.
Page 30, Table 5. There isn’t much in this table that could not be discussed in the text.
Good point, although I felt that the clarity of presentation in a table was better than words
in the text.
Page 31, Table 6. I thought these were all calculated values, but some seem to be missing
(crown bulk density), and others are obviously input values (percent cover, height to live
crown, height, depth) or inferred values (density). What is live foliar moisture doing
here?
The derivation of all values has been clarified in the revision.
Page 31, Table 6. Why did you not include the stratum/category-specific equations for
loading?
They are not appropriate in this table.
Page 32, Table 7. What are the sources of these values?
References are now cited in the text.
Page 32. Table 7. The level of detail in this table far exceeds that in 3,4, and 6, which are
of much greater interest to the reader. This information could almost make a good
research note.
Thank you for the comment. On the whole, I hope that the balance of information will be
useful documentation for readers.
David Weise
p1 line 7: General comments – more detail needed about what is in the system and
southern fuels work seems to have been completely ignored. See
http://www.srs.fs.usda.gov/pubs/1074 for many of the titles related to southern fuels.
Addressed in the revision.
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p3 line 11: added “as examples” after the first “models”.
p3 line 12: Before sentence starting with “Finally” he added “Hough and Albini (1978)
developed a dynamic fuel model specific to the palmetto-gallberry fuel type of the
southeastern Atlantic Coastal Plain and Cohen (1986) developed 2 fuel models for
chaparral. Hough and Albini. 1978. Predicting fire behavior I palmetto-gallberry fuel
complexes. Res. Pap. SE-174. 44 p. Cohen, J.D. 1986. Estimating Fire Behavior with
FIRECAST: user's manual. Forest Service. 1986; General Technical Report (PSW90):11 pages.
The Hough and Albini reference has been added. Thank you.
p5 line 2: after “content” he added “Consider using Davis, K.P. 1959. Forest Fire
Control and Use, McGraw-Hill as a reference for this. Includes 2 chapter written by
George Byram on forest fuels and forest fire behavior.”
The Davis reference has been added. Thank you.
p6 line 6: after “(ft)” he added “Should be metric for a journal – the software should be
able to output in any system of units”.
Metric units are included in the revised manuscript, and will be included in the next
version of the FCCS.
p7 line 14: after end of sentence he added “Where did these vales come from? Why do
shrubs have same values? If this manuscript ends up as a station publication, then
including all of the references for the data should be possible.”
References were added where appropriate.
p8 line 11: after “FAI” he wrote “Has FAI been previously defined? Is FAI actual
surface area or projected surface area?”
It is surface area per unit ground area.
p10 line 23: after “0.11 ft” he wrote “How were these values of optimum particle
spacing determined?”.
Additional rationale is included in the revision.
p12 line 2: wrote “How were crown shape values determined?”.
Additional detail is included in the revision.
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