On Random generated Plots

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Joined: Mon Jul 11, 2016 8:10 pm
Location: Mexico

On Random generated Plots

Post by hdelaconcha » Fri Nov 24, 2017 1:51 pm

In my previous project the city gave me the shape files with the boundary and it happened that the shapes fit perfectly the urban area with basically no rural or agricultural land so everything worked fine. Now I have another city that gave me their shape files but in some cases there is a lot of Ag land and even in one case a piece of a natural reserve (20% of the area of the district) is included in the area, I am not sure how to proceed, I think there are 2 options
1) Reduce the boundaries to the actual urban area, excluding as much as possible the rural areas and natural reserve so the valuation takes place only on urban trees or

2) include everything then increase the number of plots but those that are located in rural areas or reserves just discard them. Will this affect the statistics?

Any suggestion or comment will be welcome
Horacio de la Concha
Cuernavaca MEXICO
i-Tree Team
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Joined: Fri Dec 21, 2012 7:45 am

Re: On Random generated Plots

Post by Jason.Henning » Wed Nov 29, 2017 2:50 pm

This really depends on what you are trying to estimate the tree benefits for. If they want to know the benefits for the whole district including the areas of Agriculture and Preserve then you have to measure plots in those areas. If you only want to know the tree benefits for the urban area then you should only measure that area using a boundary that only represents the area you are interested in. I think that is what you are saying in your first option.
I wouldn't recommend you second option because you will end up with incorrect estimates. This is because the area of the entire polygon will be used in the expanding the plot estimates but you are only measuring plots in urban areas. So that calculations will actually assume that the Agriculture and Preserve lands are comparable in tree cover to the urban plots that you did measure. This is likely not the case.
You may also want to consider a stratified project but even in that case you will need an estimate of the hectares that are urban, agriculture, and preserve.
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