Creating vegetation cover survey

DavidMagnusson

I´m collection forest floor vegetation data and thought I might be able to use Survey123 for this. I haven´t worked with it before, but been going through some tutorials and starting to get a hang of it, but I don´t know if what I need is possible?

I´m going to collect species richness (note all species within an area, 2x2m) as well as their cover in a smaller area (1x1m). Thus I´d like to create a survey that:

1. Allows me to choose multiple species from a list (this I know how to do)

2. For each species I choose, have the option to also add it´s cover (like a slide 0-100, or integer if that´s easier)

Hope someone have any great ideas 🙂

David

TylerGraham2

David,

There is a big caveat about the select multiple to be aware of.  The select multiple creates and stores an array of the selected choices' codes [choice_1, choice_2, choice_3, etc] and they are stored in order of selection.  If you are doing any sort of calculation or trying to parse the array in Survey123 to anything but a repeat table you are going to run into issues. This is because if someone selects plant choices 1,2,3,4 in that order you get an array [1,2,3,4] where if someone selects the plants in the order 4,2,1,3 you get an array of [4,2,1,3]. Survey123 lacks a for loop for calculations, so even though the same plants were selected you have to account for the variations in the orders they could be selected.  Best practice is to break the array up and pass individual selections to a different field.  

Since you're looking to get individual species percent coverage of a plot, you want to pass individual selections from a select multiple into their own repeat record. For the begin repeat question go to the repeat_count column and use the count-selected(${question") formula where "question" is your select multiple question.  This will dynamically count the number of selected values and create a repeat field for each one. Order of selection doesn't matter. It also has the benefit of preventing someone from creating a bunch of extra repeat records (e.g. examining the same plant species 2+ times in one plot) and messing up your analysis.

Then you can pass each selected plant code into a species field in the repeat table by using the calculation column and the formula selected-at(${question}, position(..)-1).  Again, "question" is the select multiple question name. We are creating a poor man's for loop here.  Selected-at() starts counting at 0 in the array and position(..) starts the count at 1, so position(..)-1 aligns it with the starting count of 0 for selected-at().  

If you want the name instead of the code returned from the select multiple, look at the jr:choice formula.  

Formulas—ArcGIS Survey123 | Documentation

Return the index of a repeat record 

Here's how you can use Range to create a slider. I included an example of a range 0-100 for percentage with a 5 step increase.

https://doc.arcgis.com/en/survey123/desktop/create-surveys/range.htm

Since you don't want more than 100% of your plot to be covered in plants, in the main part of your form add a field that sums up the total of percentages entered and use a constraint to create an error if it is more than 100%.  

I've attached a simple xlsform that has all this functioning that you can look at and see how it works and play with it from there.  

Form 8.xlsx