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I've created 2km buffers around 108 points and clipped habitat maps to these buffers, as per instructions given. I now need to calculate the area of each polygon of each habitat type within each buffer and I've very lost on how to do this.

When I clipped the habitat map to the buffers the attribute table produced gave the area of each individual polygon (all >2000 of them) but there's no field in the table to say which buffer the polygons belong to and I cannot think of a way to add a field like this in.

I've tried summary statistics to get the area but this gives total area from all buffers when I need the areas for the habitats within each buffer.

My supervisor told me to add an additional field to each layer file and the ‘calculate geometry’ function to calculate the area for each habitat type within each buffer. However, I can't add the names of the habitats as fields to the table as the names are too long. When I shortened the names and tried this, it calculated an area for all the habitats, not just the habitat in the field heading.

The other suggestion was to use the Tabulate Areas function of the Spatial Analyst extension in Arcview to calculate the area of each buffer occupied by the habitats it overlapped with - however, I don't have this extension so I can't do this.

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    Your problem description isn't clear enough for me to understand what you have and what you need. Since you need to understand these things to solve the problem, I suggest you break the problem down further, explaining exactly what the tables you have look like, and showing what your goal is. Or you can go back to your supervisor, who can look over your shoulder. – Vince Jul 27 '16 at 13:27
  • Sorry about that. My goal is to get the areas of the polygons within each individual buffer (so I could say x buffer has 12ha of grassland and 65ha of woodland, for example)- but I can only get the total area of all polygons within all buffers. I was told this is an "easy" step, but I've no idea how to do it. Unfortunately my supervisor is away and not available, so I resort to stack exchange. – rakuenvi Jul 27 '16 at 13:41
  • You could always calculate the geometry(area) of each habitat polygon, with a site ID value and a habitat value, and drop it into excel and a pivot table would give you a table that summarizes the habitat area of each buffer area. As far as adding the buffer ID value, you could do a spatial join prior to habitat clipping to match the buffer to the corresponding point. – TDavis Jul 27 '16 at 13:56
  • Thanks TDavis. I did that pivot table in excel, but I don't see how that gives the habitat area of each buffer? It's a table with 3 columns - ID, area, habitat type. The ID is for each individual polygon and there's nothing that ties that polygon ID to a particular buffer. I also did the spatial join (joined buffers to habitat map) and then clipped, but the attribute table produced is the same as the one I got without joining the data... – rakuenvi Jul 27 '16 at 14:30
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    Please edit the question in response to requests for clarification. It's not fair to the volunteers who would help you to need to scan comments for critical information. – Vince Jul 27 '16 at 15:01
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If you had an advanced license, you could simply use the Tabulate Intersection tool.

Without it:

1) Buffer the points. Do not select the option to dissolve the buffers; otherwise, they won't retain the identifying attributes of the original points.

2) Instead of using the Clip tool, you need to use the Intersect tool. The output of this tool retains all the fields from both inputs. In this case, intersect the buffers and the habitat; the output features will have all the same fields as the buffers and the habitat. It even handles situations in which buffers may overlap by duplicating the records from the habitat data, as needed.

3) Dissolve the result of the intersection based on whatever unique identifying field(s) you have for both the points and the habitats. So, in the "dissolve fields" box, you would select something like "Point_Name" and "Habitat_Type".

4) To the output of the dissolve, add a new field to store the area and calculate its geometry.

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