NDR Output: Conceptual Understanding

Science, Research & Data
2

Hi @atershy,

Thanks for your great questions about InVEST’s NDR model outputs.

  1. Please do bear in mind that unless you have compared, calibrated, and validated the quantitative results against empirical data from your study area, we strongly discourage placing high confidence in the absolute values of the NDR model outputs and instead only recommend interpreting results as relative across space (comparing pixels values to one another). This will give you an understanding of where export, retention, etc. is higher and lower across the landscape. This is explained in the InVEST User Guide, here.
    That disclaimer aside, to get at the potential supply of nitrogen retention services provided by vegetation, use the “modified_load_n” raster result MINUS “n_export.tif”. That will give you annual nitrogen retention on each pixel in kg.

  2. ‘Modified load’ will be higher than ‘load’ for any pixel that has a higher nutrient runoff proxy (potential) than the average runoff proxy of all the pixels in the raster. This is explained in the User Guide’s section on Nutrient Loads.

I hope you find his information useful. Please let us know if you have more questions or would like further clarification.

-Jesse

2 Likes