Crop Production Regression Model - Understanding output

Hello (again, sorry for all these questions),

I ran the Crop Production Regression Model twice, using two different LULC map:

  • the 1st has 7 land-use classes and its resolution is 50mx50 (made in 2018 by the Japanese Space Agency)
  • the 2nd one has more than 20 land-use classes and its resolution is 300mx300m (made in 2015 by ESA).

The study area is the same. I’m focusing on rice production, and I use the InVEST sample data to produce the Landcover to Crop Table and the Fertilization rate table path. I know that the 1st LULC shows more rice fields than the 2nd one.

Notwithstanding, I don’t understand the result table (here attached, showing both results). The area (ha) is 8 time larger with the 1st map, and that’s ok. I have the following questions:

  • why the production observed of the 1st map is only 7 times larger than the second one
  • what is the difference between production observed and modeled
  • what is the unit of nutrients both observed and modeled (e.g. proteins)
  • why I have some “modeled” values that are negative

Thank you,
Marcoresult_table.csv (2.7 KB)

  • why the production observed of the 1st map is only 7 times larger than the second one

It’s hard to say for certain without taking a closer look at your inputs, but the very fact that there are big differences in your landcover codes being used would make me wonder. Are there differences in the areas being represented by each landcover code? Are there differences in how those landcover codes map to different crops?

  • what is the difference between production observed and modeled

Observed yields are taken from the Monfreda dataset. This is included in the InVEST sample data and is in the crop data folder provided as a model input. Modeled production is the actual modeled output based on your inputs, which is described here: http://releases.naturalcapitalproject.org/invest-userguide/latest/crop_production.html#id4

  • what is the unit of nutrients both observed and modeled (e.g. proteins)

There’s a description of the units in http://releases.naturalcapitalproject.org/invest-userguide/latest/crop_production.html#interpreting-results. Please let us know if you have any more specific questions!

  • why I have some “modeled” values that are negative

I’d suggest taking a look at your inputs and also the Monfreda dataset in your study area and making sure that everything looks like it makes sense.

Hope this helps, and feel free to ping us back with any further questions!
James

1 Like

Hi @jdouglass,

thank you for your answers. However I still have some doubts:

  • why the production observed of the 1st map is only 7 times larger than the second one

It’s hard to say for certain without taking a closer look at your inputs, but the very fact that there are big differences in your landcover codes being used would make me wonder. Are there differences in the areas being represented by each landcover code? Are there differences in how those landcover codes map to different crops?

There are no differences in the areas, however, each LULC map crops differently. In fact, the ESA’s one map 37 land use classes, why the Japanese Space Agency only 7

what is the unit of nutrients both observed and modeled (e.g. proteins)
There’s a description of the units in http://releases.naturalcapitalproject.org/invest-userguide/latest/crop_production.html#interpreting-results. Please let us know if you have any more specific questions!

So for example I would be able to tell the amount of proteins of a crop per pixel in metric tons per pixel per year?.

why I have some “modeled” values that are negative
I’d suggest taking a look at your inputs and also the Monfreda dataset in your study area and making sure that everything looks like it makes sense

**I mean, it seems to me that everything is fine. I just used LULC maps and tabular data that I derived from the Monfreda dataset. Maybe there’s something that I should check again? I attach the inputs that I used to run the regression model (using the LULC produced by ESA) crop_table_p.csv (27 Bytes) fert_rate.csv (99 Bytes) lulc.tif (152.4 KB) **

Thank you so much for your help.

Marco