Ok, I found the scale setting for objects on the right.  Ends up no matter what I set that terrain size to when created, it was always about 1093 yds^2.  At least I now how to size them better now.

...but not out of the woods yet. 

So this is a picture of a 64x64yd terrain...and a 15 ft tree.  Also, and ecosystem of fields and trees.

I applied an EcoSystem to the terrain, and it created over half million objects and sized them as if I was far off?  Is there a setting or something that tells it that I want to apply an ecosystem which is proportional to the size of the terrain?