Posted: Mon Apr 03, 2017 10:01 am
by wisconsitom
Soil pH and CEC-cation exchange capacity-are two factors of extreme relevance to where a given plant species ends up not just living, but thriving. Botanists of the past sometimes thought the distribution of native species across the continent was a complete mystery,with no underlying factors. The great plantsman Fernald showed this to be nonsense: using tow quite opposite species, albeit both conifers, he used the soil requirements of jack pine and northern white cedar to show that these two occupied opposite ends of the soil pH spectrum. Without going into those particular details, it can be shown that soil pH and the presence or absence of good supplies of mineral nutrients like calcium and magnesium say as much about where plant species end up as anything else. In the case of jack pine, it thrives only in areas of very poor, sandy soil, with low pH and little CEC. Northern white cedar-a plant which most of you only know of as a hamburger-bun-shaped shrub outside somebody's foundation, is a vigorous grower in the forests of places like eastern Wisconsin, eastern UP of Michigan, NE Maine, and adjacent New Brunswick...and a handful of other locations, you will have never seen this tree in its actual habitat. It is a tree, with space between its branches, not a horribly dense, ungainly thing. Very beautiful trees, among the very best. But only doing well in areas where either dolomitic limestone is at or near the surface.......or where glaciation has dragged such materials back or forth into an area. These are the areas where this tree reaches its maximal growth. So it is related to glaciation, but not so simple as the initial subject of this thread.