Understanding Output - Linkage Mapper & Pinchpoint

[C Seidel]

Hi Folks -- This is my first use of Linkage Mapper (within ArcPro) and also jumped into Pinchpoint Mapper.  I'm wanting to make sure I'm interpreting the results correctly.  Please see the attached PDF (contains 3 maps).

The interpretation I'm most unsure of is Pinchpoint.  The bands of yellow (most severe Pinchpoints) seem too wide.  The PDF includes screenshots of the respective model parameters.

Is there an additional step or two that I should do to help accentuate where exactly the pinchpoint is?

Lastly, what is represented by the 2 attribute fields populated when Pinchpoint runs?  I'm referring to the attributes [Effective_Resistance] and [cwd_to_Eff_Resist_Ratio] in the polyline file Least Cost Paths (LCPs).  Are the higher values more severe Pinchpoints than the lower values?

Thanks for your time and insights.

Best,

-Chris (she/her)

[John Gallo]

Hi Chris,

Thank you for the very professional layout with the screengrabs and parameters!

I can infer that your resistance surface is lower on average per distance unit than most.  THis is causing the default truncation of 200,000 to be meaningless.  I see your highest value on your landscape is 110,000.  Try a truncation of 50,000 or so and see how that looks for you.  Should answer your most pressing questions.  To get that parameter just right, you can work with your species or conservation experts to determine the minimum width of a linkage, find your most narrow one, and see what the value is that associates with that chosen width.

Good luck!

JOhn

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John A. Gallo, Ph.D.

Project Director

LinkageMapper.org

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Senior Conservation Scientist

Conservation Biology Institute

[C Seidel]

Please forgive me if this gets posted twice.....

Hi John -- Thanks for the prompt feedback and suggestions.  Forgive me but your simple sounding suggestions leave me perplexed as to how to find my way around the barn.

So, should/must I re-run the initial Linkage Mapper routine using 50,000 as the "Truncated Cost-weighted distance threshold"  --> then move on and run Pinchpoint Mapper with 50,000 as the "CWD cutoff distance (cost-weighted corridor width)" ?  OR can I skip re-running both LM and PinchPoint and just opt to use the "Clip Corridors to Cutoff Width" found the "utilities" sub-folder of the LM toolbox

-- hmmmmm, but if just using the Utilities tool then am I truncating the Normalized Least Cost Corridor Distance Raster --> then re-run PinchPoint OR just apply the Utility Clip Corridor to my present PinchPoint results?

Thanks for clarifying,

-Chris

[John Gallo]

On Tuesday, July 30, 2024 at 1:58:39 PM UTC-7 sei...@mvcommission.org wrote:

Please forgive me if this gets posted twice.....

Hi John -- Thanks for the prompt feedback and suggestions.  Forgive me but your simple sounding suggestions leave me perplexed as to how to find my way around the barn.

So, should/must I re-run the initial Linkage Mapper routine using 50,000 as the "Truncated Cost-weighted distance threshold"  --> then move on and run Pinchpoint Mapper with 50,000 as the "CWD cutoff distance (cost-weighted corridor width)" ? 

Yes, that is the one!!