Risk: Summary Statistics

The Summary Statistics form is used to summarize FLP or FSL point data by a Grouping layer which is another shapefile. The shapefile can represent anything of interest, such as forest stands, threatened or endangered species habitat, wildland-urban interfaces (WUIs), or a combination of factors. The form has the ability to intersect the FLP or FSL point data (Two separate layers) or use data that have already been intersected (Single intersected layer). What is output is an Excel workbook.

Input layer(s):

Two separate layers can be used to intersect the FLP or FSL Layer with a shapefile that defines the summary group, Grouping Layer.
If the summary group is already part of the shapefile attributes, a Single intersected layer can be used.
The Grouping Attribute is the attribute that the summary statistics will be based on.

What is being summarized?

When a FLP is summarized the workbook contains three tabs: CFL Statistics, Expected and Conditional.
- The CFL statistics summarize conditional flame length.
- The Expected worksheet contains the average value for burn probability (PBurn) and probabilistic FILs for each unit and the overall landscape.
- The Conditional worksheet the average value for burn probability, each FIL, and the conditional flame length for each unit and the overall landscape.

Excel worksheets for CFL,expected and conditional outputs from a 6-category FLP averaged by ownership.

When a Fire Size List (FSL) is summarized the workbook contains one tab (Fire Size Statistics) with summary statistics by grouping.

Excel worksheets for fire size averaged by management allocation.

When Selected attributes are selected the workbook contains tabs for each with the minimum, maximum, total, and average value of the attribute of interest. This form is useful for summarizing not only burn probability and conditional flame length like with the FLP option but other values that are attributed within the FLP shapefile, like NVC (see Net Value Change for more information about NVC) values.
- This option can be used for any point data files, it does not need to be an FLP.

Excel worksheets for CFL, cNVC and eNVC calculated for lynx habitat averaged by proposed treatment type.

These data can be used to create scatter plots and curves to represent risk. Scatter plots and risk curves can be used to show the relative risk of different subunits (polygons) within a landscape.

Example of wildfire risk scatter plots (A) and curves (B) from a 20-category FLP averaged by forest type.

Exercise 31—Averaging FLP outputs by land management allocations

Depending on the size of the landscape, and resolution of the run , the output FLP can contain millions of points. The Summary Statistics form in ArcFuels10 can be used to summarize both the expected and conditional probabilities in each FIL, overall burn probabilities and the conditional flame length, using another polygon shapefile to define the groups. This is helpful for understanding averages by land management allocation, forest type, species habitat, etc. In this exercise a LP - 6 Bin English (FLP6_s300_FLP converted in Exercise 25) will be averaged by land management allocation.

Click the Risk button on the ArcFuels10 toolbar, then select Averages from the drop-down list.

Fill out the Summary Statistics form following the figure below.

Click the Calculate Summary Statistics button.A progress meter will open.
The Excel workbook will open when the averages are calculated.
Click the Close button to close the form.

Go to the Excel workbook.

Go to the Conditional worksheet.
- Plotting the likelihood (PBurn) and intensity (CFL) shows the relative exposure among different land management allocations. Those points that fall in the upper right-hand corner have a higher liklihood of burning at higher intensities than those in the lower left-hand corner.
When you are done, close the Excel workbook.

Scatter plot of wildfire risk by land management allocation. Private land has the lowest wildfire risk in the smaller sub area analyzed.

Exercise 32—Summarizing Net Value Change (NVC) for lynx habitat by management allocations

In this exercise the cNVC for lynx habitat (calculated in Exercise 28) will be summarized by land ownership .

Click the Risk button on the ArcFuels10 toolbar, then select Averages from the drop-down list.

Fill out the Summary Statistics form following the figure below.

Click the Calculate Summary Statistics button.The Excel workbook will open when the averages are calculated.
Click the Close button to close the form.

Go to the Excel workbook.

Look at the averages in the cNVC_Lynx spreadsheet, Notice with this option the minimum, maximum, total and average values are summarized.
When you are done, close the Excel workbook.

Exercise 33—Summarizing fire size by forest type

Fire size will be summarized by forest type within a sub area of the Mt. Emily landscape. This exercise will use the FSL_SubArea300 which was converted in Exercise 27.

Click the Risk button on the ArcFuels10 toolbar, then select Averages from the drop-down list.

Fill out the Summary Statistics form following the figure below.

Click the Calculate Summary Statistics button.The Excel workbook will open when the averages are calculated.
Click the Close button to close the form.

Go to the Excel workbook.

Look at the averages in the Fire Size Statistics spreadsheet, notice the Engleman spruce-subalpine fir forests have the largest mean fire size and subalpine fir the smallest.
When you are done, close the Excel workbook.

Average fire size by forest types within a sub area of the Mt. Emily landscape.

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