Yes, well north of the glacier line, however in a pronounced topographic rainshadow effected area which resulted in an early retreat of glaciation. So, having cleared that up i've got no idea if the Worms here are indigenous or introduced. They have made themselves right at home in any case.
applestar wrote >> I'm thinking a ring of trench just beyond the root zone
Weaver and Bruner in writing of Hubbard Squash state, in: https://www.soilandhealth.org/01aglibrar ... 37toc.html
" A radial spread of 13 to 19 feet is attained. Five to seven main roots, with numerous branches 2 to 8 feet long and all again rebranched, form the groundwork which supports a remarkably branched root network that completely ramifies the surface foot of soil. Nodal roots, already 4 to 5 feet long and also superficial but extremely well rebranched, increase the absorbing area. Thus nearly 1,000 cubic feet of soil give of its supplies of water and nutrients to the support of a single plant. "
Makes us wonder where to put that ring trench doesn't it.
Thanks for your reply applestar.