Environmental stimuli

The theme of this article is the relationship of trees to their environment, or it might be better termed "Human misunderstanding of environment". The cause of most of the tree problems investigated over the past ten years or more could be categorized by some environmental stimulus such as landscape development, re-routing drainage systems, land clearing followed by backfilling, salting roads, etc. We do these things (stimuli) on the assumption that Mother Nature is obliged to cooperate with and give her blessing to our efforts. In my biological training, I was left with the realization that: "The environment will determine whether any new innovation is successful or not". With trees you don't get a lot of complaining or grumbling about stresses - only symptoms.

Twenty or more years ago, red pines were planted in vast numbers in northwestern and central western counties to make windbreaks, establish woodlots, yard trees, etc. converting abandoned fields into forests. In many places it has been a successful venture. In western Roseau, Kittson and Marshall Counties, the soils consist of a foot and one-half of sandy loam above a hardpan clay layer. For a few years the trees did quite well (our assumption), but after reaching 12-15 feet in height, they are now displaying symptoms of severe stress, ie: crown die back and winter injury. Now they are trying to hang on through periods of water-logged or water-starved soils.

In addition to these stimuli, winters that seem to be too cold, too long or too windy cause conifer needles to dry out, a phenomenon that we call winter burn. The constant water loss through the needles cannot be matched by water uptake into the roots. Most evergreens growing on offsite conditions show symptoms of winter desiccation this spring. In fact they did last year, too. In fact they seem to do so every spring. We keep justifying the notion that it was the winter's fault; too cold, too windy, too much snow, sometimes not enough snow, etc. I keep saying, "If things once get back to normal we'll be ok!" The trouble is that it's been so long since things (stimuli) have been normal that I've lost the meaning of the term. Is it normal to have an inch and a half of rain, thunder and lightning during the third week of November? Is it normal having to rely on compass triangulation to locate the woodpile you built the previous fall so you can find it in February?

Back to the issue of planting red pine in our story. Trees that need to develop deep root systems are not going to do well on soils characterized having a hardpan clay layer at eighteen inches. Examination of the growth rings of the red pine in question show good growth during the first ten to twelve years with very slow growth during the next seven years. Growth has nearly stagnated during the last five years. The pines probably grew well at first when lateral roots were growing through the porous layers but are now struggling to grow into the clay.

The point in this environmental story is that there are many areas where tree stresses are not observed and the trees appear to be taking in stride all the slings and arrows that Mother Nature is throwing at them. Planting or transplanting trees native to that locality and within their normal climatic zone in which they are adapted to should be a primary consideration. Forestry is just like and other human endeavor; we learn best by doing.