Quantifying Uncertainty in Ecosystem Studies

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### Uncertainty between trees with different diametric classes

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### Re: Uncertainty between trees with different diametric classes

**amburana****New member**Offline

- Registered: 10/06/2015
- Posts: 1

Hello everyone!!

Maybe someone can give me a clue!!

I am working in order to obtain the biomass and uncertainty of a forest inventory in Peru. The plots has not the same area for the bigger trees (dbh>= 30) and the smallest (dbh <30cm). Actually I create my function to obtain the biomass and uncertainty. But now I would like to sum both values the big and small trees. but I am not sure its going to be ok, to sum just as a simple way. I imagine I must weight the values, in order to do not make an statistical error. That any one can give and avise how i must weight de values, could i do it by basal area or number of trees by plot? I would appreciate it any comment!!

Best regards

**Ruth Yanai****New member**Offline

- Registered: 2/19/2015
- Posts: 9

If you calculate the biomass and uncertainty per unit area (you divide by the area measured), then you should be able to sum the two classes. Am I missing something?