Thoughts on Digging a Hole for the Outhouse

With winter behind, northern residents turn to their spring chores, which sometimes include digging a new hole for the outhouse, or clearing and tilling land for a garden. These tasks usually will bring the poor soul with the shovel into painful contact with a basic observation of plant life in the north: there's a heck of a lot of roots down there!

Why should northern plants invest more heavily in roots than their more southerly counterparts? They certainly are not needed for water intake; in fact, plants in wet sites seem to have the most roots. The roots are not needed to support the modest plant that grows above ground and rarely encounters more than a gentle breeze. The remaining major function of roots, uptake of mineral nutrients, seems the most likely cause for the extensive root systems of many northern plants.

As with other organisms, prudent behavior by plants leads to success in natural selection. In this case, prudent behavior implies investment of resources where they will contribute the most to growth.

Long summer days and summer's warmth permit northern plants to capture solar energy and convert it to sugar efficiently. For the plant to grow, this sugar must be combined with nutrients taken from the soil to produce the molecules that make up the plant.

Northern soils are slow to warm, with frozen ground persisting through much or even all of the summer. Partly for this reason the dead remains of earlier generations of plants are slow to decompose and release the nutrients back into the soil. Consequently, northern soils are characterized by a large accumulation of dead organic matter, and a shortage of available nutrients. Plants respond to this shortage by investing their resources in extensive root systems to maximize their access to the low concentration of nutrients. Most of the roots are found near the surface in the organic layer of the soil, where temperatures are warmest and nutrients are released by decay.

So there is a reason for the large number of roots that obstruct the shovel. But that doesn't make the hole any easier to dig.