I have utilized an invest model to calculate carbon storage and provided input for four carbon pools in units of Mg/hac. However, I am uncertain about the units of the output and suspect it may be in Mg per pixel. As my land use pixel size was 30m, I am unsure whether I should convert the output to Mg per square meter or if there are other methods to obtain accurate results. Can you provide guidance on the input and output units of the carbon pools? Additionally, it would be helpful if you could advise me on the most appropriate approach to obtain accurate results given the circumstances. Thank you.
Welcome to the forum @Shaz -
As the User Guide notes, the output values are indeed given in tons (Mg) per pixel. It is not required that you convert the output to other units (like Mg/square meter), but of course you can if that’s appropriate for your analysis. I know it’s a bit confusing that we input tons/ha and get out tons/pixel, this has been a point of discussion for future model enhancement. That said, this topic has been discussed before on this forum, so you can use the Search function to see more details.
~ Stacie
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I converted Mg/hac to Mg per pixel for the input since my Land use map was in a 30 m pixel format. Is this a valid approach? To calculate carbon stock on a national scale, can InVEST be used to analyze carbon at a large scale? Alternatively, is there a list already estimated carbon stock in different countries?
@Shaz The model requires that the inputs be given in tons/hectare, as noted in the User Guide Data Needs section. The code translates tons/hectare to tons/pixel, so you will get incorrect results if you enter carbon pool values that are already tons/pixel.
The Carbon model has been used at many scales, from local to global. Since this model is so simple, it doesn’t require a lot of computational resources, but still, it will take longer and use more resources if your inputs are very high resolution and/or cover large areas.
~ Stacie
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can you please share any national scale results of carbon stock using inVEST
first I used tons per hac but total carbon stock was around 18 billion MgC ? how can I validate my results ? can you guide me in this regard ?
Personally, I haven’t done a national analysis that includes carbon, but one place to look is the InVEST Publications Database, which lists the publications that we are aware of that make use of InVEST models, including the specific model(s) used and location of the study.
Since the carbon model is so simple, the biophysical results are entirely dependent upon the values you provide in the carbon pool table. For validation, you could see if the country you’re working in has national data on carbon stocks. These might be found on a government data/geodata portal, or in a national REDD document, if one has been prepared. REDD documents can be particularly helpful, and they might provide carbon information for different land use/land cover types. You could also compare with one or more of the global carbon stock maps that others have created, which you can find with a web search.
~ Stacie
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