Bamboo

Post here questions, comments, and suggestions about the general i-Tree project. To avoid duplication, please be sure to check the i-Tree website and the FAQs before posting. Relevant topics include background, purpose, requirements, hardware, installation, training and events.

Moderators: i-Tree Support, i-Tree Team

twright
Posts: 7
Joined: Tue Jun 08, 2010 3:19 pm

Bamboo

Post by twright » Wed Jun 09, 2010 8:11 am

I had a slight inquiry. I tried to read through the Streets manual and did not find a listing for bamboo. What is the typical protocol for inventorying bamboo if it is growing on a selected street segment? Or did I miss that section entirely? For some reason I seem to remember either a discussion or a talk at a conference on bamboo in Streets but it could be sleep deprivation.

Thank you!
Jerry
Posts: 100
Joined: Wed Nov 28, 2007 8:11 pm

Neat question

Post by Jerry » Wed Jun 09, 2010 9:04 am

It seems to me that there are actually two questions here:
  • How are clumps defined and recorded?
  • Do specific values exist in the software for bamboo?
The first is the only one I want to address here.

I have found the following procedure to work for me in the field: 1) define a clump as more than one stem originating from the same root system, where the stems are below the threshhold diameter (e.g., 2") being used for the project, and then 2) count or estimate the number of stems, estimate the average diameter, and record the result as one tree. So, if I have 20 stems averaging 2", I record one 40" DBH tree, since

20 x 2π = 40π

I expect there may be some error (say, in stored carbon) involved with this method--though I have not seen anything on that--but any other field procedure has proved impractical.
Last edited by Jerry on Thu Jun 10, 2010 10:55 am, edited 1 time in total.
twright
Posts: 7
Joined: Tue Jun 08, 2010 3:19 pm

Post by twright » Thu Jun 10, 2010 10:26 am

Jerry,

Thank you for the insight. I had thought this would be the best manner to inventory shrubs or other woody vegetation with many stems. I am concerned as well as to the amount of error that you can introduce by expanding these smaller stems into a larger, overall, tree.

My question is more slated to your second dedution: Are specific values for bamboo contained within Streets? I have not come across this situation, yet, but I have seen bamboo on street segments that were not randomly selected. If bamboo were inventoried, how would you define that species later? Broadleaf Evergreen Small/Medium/Large?

Thank you for the quick response!
Jerry
Posts: 100
Joined: Wed Nov 28, 2007 8:11 pm

Post by Jerry » Thu Jun 10, 2010 10:54 am

Glad that was helpful. For the second question, though, we will have to wait for the i-Tree Team to respond--though I did look quickly through the Streets species list and did not find bamboo.
smaco
i-Tree Team
Posts: 66
Joined: Wed Dec 06, 2006 1:40 pm

Post by smaco » Thu Jun 10, 2010 4:32 pm

I am surprised that this hasn’t come up sooner! Thanks for the question and thanks for your input, Jerry.

With regards to the second question, I think, without a doubt, that bamboo should be excluded from the benefit calculations. Bamboo is a grass and its form and functions do not match any of the tree species that are the basis for modeling tree benefits. That is not to say that there aren’t benefits associated with bamboo, it’s just that the model can’t account for them.

I do agree, however, that there are many reasons that you would want to inventory the bamboo. For purposes specific to a Streets analysis, I would suggest keeping the bamboo as part of the inventory but indicate that they are “non-tree” records--just like you would for stumps, available planting spaces, etc. This way, you will see their abundance, but they will not be part of the benefit calculations.
a member of the i-Tree Team
Jerry
Posts: 100
Joined: Wed Nov 28, 2007 8:11 pm

Post by Jerry » Sun Jun 13, 2010 12:24 pm

Thanks, Scott--that's kind of what I thought. And it sounds like a reasonable position.

This question did make me snoop around a bit, and I was surprised to see that some bamboos are well positioned for carbon sequestration. Look at this, for example:
Bamboo has several advantages over tree species in terms of sustainability and carbon fixing capacity. Available studies conclude that bamboo biomass and carbon production may be 7-30% higher compared to the fast growing wood species. For instance tropical Bambusa bambos has been measured at a total above ground biomass 287 t/ha with a mean annual production of around 47.8 t/ha/yr, almost twice that of the Eucalyptus clones. Interestingly, the total biomass of mature Bambusa at 6 years is in fact higher than that of teak at 40 years: 149 t C/ha versus only 126 t C/ha for teak. Sub-tropical moso bamboo (Phyllostachys pubescens) reaches above ground biomass of 137.9 t/ha and is generally harvested at 5-8 years intervals. Every 5 years it would produce at least 86 t/ha biomass and sequester 43 t/ C/ha, almost twice as much as a teak plantation under the same conditions. This includes total biomass as well as products.
Kind of intriguing...
twright
Posts: 7
Joined: Tue Jun 08, 2010 3:19 pm

Post by twright » Mon Jun 14, 2010 1:34 pm

Scott,

Thank you for the clarifiation and suggestion. I will pass the word along to some associates for their use in Streets. I had given the idea some thought over the weekend and did not know, since bamboo is a monocot, if Streets would be able to accurately calculate benefits.

Jerry,

Intriguing is correct. I would not have guessed bamboo could outperform woody vegetation in carbon fixing. Learn something new everyday.

Thank you all once again for your help and for the information.
KatieRoseOutside
Posts: 1
Joined: Tue Nov 29, 2011 10:57 am

Other Non-Included Trees

Post by KatieRoseOutside » Tue Nov 29, 2011 11:22 am

When working with iTree for the southern region I am running into problems with i-Tree not listing certain species such as Acer barbatum/floridanum or Quercus laevis. Is there a way to import these trees, or should I be picking a close approximation?

Thanks!
azelaya
i-Tree Team
Posts: 348
Joined: Fri Jun 27, 2008 10:50 am

Adding species in Streets

Post by azelaya » Tue Nov 29, 2011 12:55 pm

Streets allows users to make up new species codes for trees not available in the regional climate zone lists. You will then need to assign a species value for any new tree created by accessing Input - Species from the Streets menu.

The following text is from Pg36 of the Streets manual which describes how to define a new species. Refer directly to the manual for more instructions such as adding non-tree items like stumps or available planting spaces.

Species MatchingYour inventory will most likely include species codes that were not included in the Streets default list. In this case, the first window you will see after uploading your data is the Define Species window. (This window can also be accessed under Input > Species.) Unmatched species codes will be marked with a red exclamation point. To match each marked species:

1 Click inside the row and enter the appropriate common and scientific names.

2 In the fourth column, Assigned Sp. Value, you must select the most closely matched species from the lists below. Click within the empty Assigned Sp. Value box to highlight it. Then, from the lists at the bottom of the window, select the most closely related species from either the common or scientific name drop-down menus. Take into consideration mature size, tree type, form, and family and genus relationships. Where direct matching is difficult, you can opt to select from the tree types (e.g., Broadleaf Deciduous Large, Conifer Evergreen Small).

3 If you conducted a sample inventory that included treeless street segments, ignore any species code you used to identify these segments (e.g., NOTREE). Simply leave these as unmatched.
A member of the i-Tree Team
dellings
i-Tree Team
Posts: 25
Joined: Thu Aug 21, 2008 2:12 pm

Post by dellings » Mon Dec 12, 2011 5:10 pm

Jerry wrote:I have found the following procedure to work for me in the field: 1) define a clump as more than one stem originating from the same root system, where the stems are below the threshhold diameter (e.g., 2") being used for the project, and then 2) count or estimate the number of stems, estimate the average diameter, and record the result as one tree. So, if I have 20 stems averaging 2", I record one 40" DBH tree, since

20 x 2π = 40π
FYI, this method is very inaccurate. The correct method to use is to do the following:

1. Measure the DBH of each stem.
2. Square the DBH of each stem.
3. Sum the squares of all the stems.
4. Take the square root of the sum and use it as the DBH.

IE: Given a tree with 3 stems that measure 10, 18, and 14 the combined DBH value is:

sqrt(10^2 + 18^2 + 14^2) = 24.9

This equation properly combines the cross sectional area of each stem and produces a DBH value that corresponds to a single stem with the cross sectional area equal to the sum of all the stems. The great thing about this equation is that it's simple enough to be done with an inexpensive calculator.

If tree benefits were only dependent on DBH alone, the above calculation would be sufficient. Unfortunately, this is not the case. Benefits also depend on the average height of the tree itself. i-Tree Streets, assumes a normal height tree for the given DBH and does not include height measurements. The above method will thus result in a slight overestimate of the tree's benefits. If more accurate results are required, i-Tree Eco should be used.

As Scott hinted, estimating the benefits of bamboo is difficult. Bamboo not only has multiple stems, but it also grows exceptionally tall quickly. If we modified the above formula to find the DBH of a tree whose cross sectional area was the same as that of a single bamboo stem (remember bamboo is hallow), we could model the bamboo in terms of the another species. However, as pointed out above, height is a major factor in determining the benefits of a tree. The height of an equivalent tree would most likely be smaller than that of the actual bamboo so this method would underestimate the value of the bamboo.
Jerry
Posts: 100
Joined: Wed Nov 28, 2007 8:11 pm

Post by Jerry » Tue Dec 13, 2011 12:13 pm

Thanks for commenting on that error and spelling out the correct approach. Old posts never die, I guess...

As I said earlier, I have long found this an intriguing question. My method was aimed for a specific situation:
more than one stem originating from the same root system, where the stems are below the threshold diameter (e.g., 2") being used for the project
and it carried a specific caveat:
I expect there may be some error (say, in stored carbon) involved with this method--though I have not seen anything on that--but any other field procedure has proved impractical.
There is no question that the method you describe is more accurate: for the sizes I was discussing. say 1" or 1.5" stems, the simple mean overestimates aggregate diameter by a factor of about 3. The question is whether that gain in measurement accuracy transfers into an actual gain in the estimation of environmental benefit that justifies the added time and instrument needed in a production context.

Diameter is used in both Streets and Eco, in my understanding, to gain by regression two numbers: 1) leaf area and biomass, and 2) stored carbon.

1) In the work context I was addressing, I have not been able to determine how badly the actual leaf area and biomass are under or overestimated by simply taking the mean diameter, since I have not found research on those quantities for such small diameters, though it may well exist somewhere. Nowak's widely cited 1996 article is based on trees between about 4 and 13 in DBH, so it would be an extrapolation with unknown validity to apply it here. Clearly, the actual leaf biomass and surface area could vary not only by species but also by other factors such as stem count per unit area.

2) In terms of stored carbon, I see huge problems using diameter in any case because a) most of the carbon of such stump sprouts is demonstrably underground, and b) such small stems typically have little if any heartwood so presumably the carbon density is relatively low. It seems unlikely to me that ten 1" stems have the same above-ground carbon storage as a single tree with a 3.2" diameter, and on the other hand likely that the stump may well have hugely more underground C stored than that 3.2" tree.

For all these reasons, I prefer to use the quick and easy method I described in a production context--though obviously not in a research context--convinced that there will be a huge and perhaps indeterminate error margin associated with any number because so many unknowns are involved.
Jerry
Posts: 100
Joined: Wed Nov 28, 2007 8:11 pm

Post by Jerry » Tue Dec 13, 2011 7:05 pm

Jerry wrote:Thanks for commenting on that error and spelling out the correct approach. Old posts never die, I guess...

As I said earlier, I have long found this an intriguing question. My method was aimed for a specific situation:
more than one stem originating from the same root system, where the stems are below the threshold diameter (e.g., 2") being used for the project
and it carried a specific caveat:
I expect there may be some error (say, in stored carbon) involved with this method--though I have not seen anything on that--but any other field procedure has proved impractical.
There is no question that the method you describe is a more accurate way to calculate the functional diameter: for the sizes I was discussing. say 1" or 1.5" stems, the simple mean overestimates aggregate diameter by a factor of about 3. The question is whether that gain in measurement accuracy transfers into an actual gain in the estimation of environmental benefit that justifies the added time and instrument needed in a production context.

Diameter is used in both Streets and Eco, in my understanding, to gain by regression two numbers: 1) leaf area and biomass, and 2) stored carbon.

1) In the work context I was addressing, I have not been able to determine how badly the actual leaf area and biomass are under or overestimated by simply taking the mean diameter, since I have not found research on those quantities for such small diameters, though it may well exist somewhere. Nowak's widely cited 1996 article is based on trees between about 4 and 13 in DBH, so it would be an extrapolation with unknown validity to apply it here. Clearly, the actual leaf biomass and surface area could vary not only by species but also by other factors such as stem count per unit area.

2) In terms of stored carbon, I see huge problems using diameter in any case because a) most of the carbon of such stump sprouts is demonstrably underground, and b) such small stems typically have little if any heartwood so presumably the carbon density is relatively low. It seems unlikely to me that ten 1" stems have the same above-ground carbon storage as a single tree with a 3.2" diameter, and on the other hand likely that the stump may well have hugely more underground C stored than that 3.2" tree.

For all these reasons, I prefer to use the quick and easy method I described in a production context--though obviously not in a research context--convinced that there will be a huge and perhaps indeterminate error margin associated with any number because so many unknowns are involved.
ccrhodes
Posts: 8
Joined: Thu Jan 24, 2008 11:25 am

Post by ccrhodes » Mon Jan 09, 2012 4:09 pm

dellings wrote:
Jerry wrote:I have found the following procedure to work for me in the field: 1) define a clump as more than one stem originating from the same root system, where the stems are below the threshhold diameter (e.g., 2") being used for the project, and then 2) count or estimate the number of stems, estimate the average diameter, and record the result as one tree. So, if I have 20 stems averaging 2", I record one 40" DBH tree, since

20 x 2π = 40π
FYI, this method is very inaccurate. The correct method to use is to do the following:

1. Measure the DBH of each stem.
2. Square the DBH of each stem.
3. Sum the squares of all the stems.
4. Take the square root of the sum and use it as the DBH.

IE: Given a tree with 3 stems that measure 10, 18, and 14 the combined DBH value is:

sqrt(10^2 + 18^2 + 14^2) = 24.9

This equation properly combines the cross sectional area of each stem and produces a DBH value that corresponds to a single stem with the cross sectional area equal to the sum of all the stems. The great thing about this equation is that it's simple enough to be done with an inexpensive calculator.

If tree benefits were only dependent on DBH alone, the above calculation would be sufficient. Unfortunately, this is not the case. Benefits also depend on the average height of the tree itself. i-Tree Streets, assumes a normal height tree for the given DBH and does not include height measurements. The above method will thus result in a slight overestimate of the tree's benefits. If more accurate results are required, i-Tree Eco should be used.
.
What is this calculation? Asking because it had been suggested to us to use QMD to calculate a dbh for tree having more than six stems in i-eco...but that gives you an inaccurate (too small) number (dividing the sum of the squares by the total number of stems before taking the square root)...this makes much more sense.
dellings
i-Tree Team
Posts: 25
Joined: Thu Aug 21, 2008 2:12 pm

Post by dellings » Tue Jan 17, 2012 1:55 pm

ccrhodes wrote:What is this calculation? Asking because it had been suggested to us to use QMD to calculate a dbh for tree having more than six stems in i-eco...but that gives you an inaccurate (too small) number (dividing the sum of the squares by the total number of stems before taking the square root)...this makes much more sense.
As stated above, this calculation calculates the DBH of a tree whose cross sectional area is the same as that of all the stems. The derivation of this formula is as follows:

Code: Select all

First a few definitions:
DBH = D = the diameter of a tree/stem
R = the radius of the tree
A = the cross sectional area of a tree

Now some basic formulas:
D = 2 * R
A = PI * R^2
R = D / 2

Given:
D1 = Diameter of 1st stem
D2 = Diameter of 2nd stem

A1 = PI * R1^2   By definition of Area
A2 = PI * R2^2   By definition of Area

A0 = A1 + A2                                             By definition of of Combined Area
PI * R0^2 = (PI * R1^2) + (PI * R2^2)                    By definition of Area
PI * R0^2 = PI * (R1^2 + R2^2)                           By distributive property of multiplication
R0^2 = R1^2 + R2^2                                       By definition of equals (division by PI)
(D0 / 2)^2 = (D1 / 2)^2 + (D2 / 2)^2                     By definition of radius
D0^2 / 2^2 = D1^2 / 2^2 + D2^2 / 2^2                     By Power of a Quotient property of exponents
D0^2/4 = D1^2/4 + D2^2/4                                 By definition of exponents
4 * (D0^2/4) = 4 * (D1^2/4 + D1^2/4)                     By definition of equals
D0^2 = D1^2 + D2^2                                       By distributive property of multiplication
sqrt(D0^2) = sqrt(D1^2 + D2^2)                           By definition of equal
D0 = sqrt(D1^2 + D2^2)                                   By definition of square root
The resulting formula is the one I've provided above. What this tells us is that the diameter D0 of a tree, whose cross sectional area is equal to that of all the stems, is equal to the square root of the sum of the diameters of the stems squared. However, this formula only takes into account the cross sectional area.

Tree benefits aren't solely dependent on area, they are more closely tied to volume than area. The standard equation for volume is: V = PI * R^2 * H, where H is the height. In other words V = A * H If the height of all the stems is relatively the same, this will produce a very accurate DBH estimate. If the heights differ, there will be some error in this approach. The suggested method to reduce this error is to use the average height of the stems for total tree height. This however only applies to i-Tree Eco, i-Tree Streets assumes the resulting tree is of average height for the given DBH. i-Tree Streets will therefore always overestimate the benefits of a tree using this method.

A more accurate method for calculating the overall height is to use the following formula:

Code: Select all

H0 = (D1^2 * H1 + D2^2 * H2) / (D1^2 + D2^2)
If H1 is equal to H2 then the exponential portion of this formula cancels out and you're left with H0 being the same as H1 and H2. I won't go into the derivation of this formula, but it is based upon the standard volume formula and the simplified DBH formula given above.

Using these two formulas together should provide very accurate estimates for your trees.
ccrhodes
Posts: 8
Joined: Thu Jan 24, 2008 11:25 am

re calculations

Post by ccrhodes » Tue Jan 24, 2012 4:00 pm

Thank you very much!!
Post Reply