Tom's Blog

Saturday, February 5, 2011

The tree database has been completed!

In 2007 we started creating a database of all the trees at Pleasant Valley Conservancy that were larger than 10 inches in diameter. Each tree received a permanent numbered marker and its species and GPS coordinates were measured. We started in the White Oak Savanna (Unit 12A) and then moved systematically across the preserve. First along the south-facing slope, then the ridge-top savannas, and finally the north-facing woods (where most of the trees are). This was primarily a winter job. Heisley started this and when she moved on Amanda continued it. Just last week she finished. Over 4000 trees! The database, a large Excel file, has been brought in to ArcGIS, and is now ready for some major analyses.

I've been using the data as it became available, and last year I used the data to calculate crowncover for the savanna areas. But the full database has lots more uses. I'll show some more results in a later post, but here (photo above) I want to show what the whole database looks like.

Unfortunately, the resolution useful for a web site is fairly low, making the image pretty poor. (Double click on the image to bring it up a bit larger in its own window.) What the photo shows is the location of every tree in the database.

The second image, below, is a little better. What it shows is the location of the large trees; every tree larger than 30 inches in diameter. Each species has its own color, and I hope the resolution is enough so that the names are visible. Also, the number to the right of each species name in the box is the number of specimens of that species present at Pleasant Valley Conservancy. There are 29 white oaks and 28 bur oaks.

I'd be happy to send a high-resolution image to anyone interested. (ArcGIS creates 600 dpi TIFFs.)


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