Hey everyone,
I am a forestry student and my graduation project focuses on carbon storage and sequestration potential across the Iroquois watershed in northwestern New Brunswick (Canada). My study area is a forest massif so I have many strata and consequently, LULC classes.
Is there a limit to the number of LULC classes that can be entered in the Excel file to make the model work? For example, a maximum of 100 lucode or no limit?
Thank you in advance for your help.
Hi @Laurie -
The software team may know of some sort of technical limit, but I have successfully run several of our models on LULC rasters that have hundreds of land cover classes, and it seems like it should be able to handle at least an order of magnitude more than that (although if you’re using that many classes, I feel bad for you having to populate that carbon pool table!!!)
~ Stacie
Thank you for the answer. I admit that some forest strata should be grouped together. For now, I have 311 strata for my current LULC (2020), not counting the LULC classes associated with the 2050 projection.
For the development of future land use scenarios, what would you recommend to use to help us generate them? Do you know Geoplanneur?
Thank you.
HI @Laurie -
I can’t say I’ve ever used a tool for generating scenarios, although many people do. We’re often gathering stakeholder input and using it to alter baseline LULC maps, and/or alter the model values that are applied to each LULC class, using a very manual GIS process.
InVEST does include a simple Scenario Generator, which you might look into. And I’d enjoy hearing from others who have used different tools for creating scenarios.
~ Stacie
I can’t really speak to the scenario generation question, but I can speak to the LULC class limit:
There really isn’t a limit to the number of LULC classes that the model can handle, and the 311 classes that you mention should work in the model very well.
I think if you provided a lot of distinct classes (probably somewhere around a few million), you might start to see the model becoming impractically slow. The limiting factor there is mostly the amount of RAM available on your computer, but there’s so much memory shipping on consumer hardware these days that it really shouldn’t be an issue even if you had that many classes.
I have had success using the InVEST Helper Tool, Scenario Generator: Proximity Based, but it really depends on the types of scenarios you are looking to create. It’s helpful when expanding or contracting existing LULC types along or furthest from their edges by X hectares or X%, such as when creating reforestation, deforestation, or agricultural or urban expansion scenarios. You can check out the User Guide section on this tool here.
-Jesse
Hi Stacie, jdouglass and Jesse,
Thank you for your answers and comments.
I am currently defining all my values for the four main carbon reservoirs per current LULC class (2020) and equivalent values for my future forest management scenarios (2050). I will try to run the model without grouping my LULC classes. However, I will still have to group them together to facilitate the understanding of the decision-makers/managers and the reading of the maps.
To establish my scenarios, I will vary several forestry targets/objectives (% in protected areas, % in old forests, % in planting) based on the current policy of the province, a target of woody material production, land conversion and ecosystem management. I think I will explore several ways to generate my scenarios (combination of several tools, including forest planning).
Thank’s !
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