Fallen Trees to Soil

Winter is a wonderful time to assess the condition of a woodland.  While the trees are in a leafless condition, it’s easy to get a quick idea of tree density, species composition, trunk size and general condition.  Viewing a winter woodland reminds me of visiting a home stripped of furniture and fixtures.  The basic foundation is laid bare to be appreciated.  What we see during the winter is the infrastructure upon which the diversity of summer life will depend.

I think the best way to describe the Blue Jay Barrens woodland is to say that it is recovering.  1938 aerial photographs show the area to have been woodland then and it has remained in that condition since.  I doubt that this area avoided the deforestation that resulted from timber harvest to create charcoal for the Iron Furnace industry in the early 1800’s.  Since that initial clearcutting, I suspect that the area has remained woodland, so except for that small break, the influence of a closed canopy environment has been at work here for centuries.  Timber harvests have taken place during the past 150 years, but they have been selective cuts that left much of the canopy in place.  Each harvest took the best timber and left the remaining trees standing.  That long term strategy has left its mark.  Most of the large trees display damage or deformities that would have made them of low value during the last harvest.  Add to that the damage that occurred to tree roots from cattle grazing in the woods and you have a stand of trees that is in far from prime condition.  The woodland as a whole is slowly improving, but recovery is a long process that is still working through some ugly times.

Most of the woodland is located along a series of east-west oriented ridgetops.  The ridgetops are quite narrow and drop off steeply on each side.  This topography is probably what kept the area from being plowed for crop production.  Soil is extremely shallow to bedrock on these ridgetops, which would have also made them unsuitable as cropland.

Part of the woodland recovery process is the loss of trees that were weakened by past abuses.  A few trees have traditionally fallen each year.  This process creates pockets of light that allow younger trees to grow.  The result is a diversity of tree size within the woodland itself.  The 2012 derecho accelerated the process by simultaneously bringing down multiple trees in several different areas.

A common monument to a wind thrown tree is the mass of newly exposed roots.  Healthy trees can survive some awfully strong winds.  The problem is that so many trees suffer from multiple environmental factors.  This particular tree had several trunk deformities as the result damage inflicted early in the tree’s life.  Cattle in the woods would have stressed the tree through soil compaction and physical damage to the roots.  Shallow, droughty soil provided harsh growing conditions throughout the life of the tree.  When you add to that the stresses put on most trees by general air and rainfall quality factors, the result is a tree that is extremely vulnerable to a wide range of hazardous conditions.

The root masses can be quite impressive.  This one measures about seven feet from the ground to the top of the soil ball.  Broken roots project upward another couple of feet.  Typical of most of these trees, there are no particularly large lateral roots present.

As the tree fell, chunks of bedrock were scattered about.  The presence of a solid bedrock layer just below the soil surface prohibited the tree from developing any sort of tap root.  With such a tenuous hold on the earth, it’s surprising that the tree remained upright as long as it did.

The bottom of the root mass mirrors the solid rock layer that blocked all root penetration.

The smaller roots, responsible for drawing water and necessary elements from the soil, were restricted to an inches thick layer above the bedrock.  Annual drought stress would have come early to this tree.

In addition to changing the composition of the woodland overstory, fallen trees modify and diversify the woodland floor.  The root mass will eventually decompose through a series of roughly predictable stages.  During the first few years, soil particles will detach from the roots and drop down to form a mound.  Next, the smaller roots will begin to decompose.  This material, along with small rocks, will be deposited on top of the soil mound.  The larger roots and stump will be the last to decompose.  As this material breaks down, the large rocks will be released to take their place atop the soil mound.  Decades from now, an area of slightly deeper soil beneath a mound of loose rock will provide an interesting microhabitat for plants and animals.  It might also cause some people to wonder how that pile of rock came into existence.

Another habitat changer is the tree trunk itself.  Like the tree stump, the trunk will eventually decompose and disappear from sight.  What it will leave behind is a strip of slightly deeper soil with an organic matter content that will allow it to hold slightly more moisture than the surrounding area.  These soil conditions would most likely support a greater concentration of plant growth and produce a noticeable swath of plant life across the future woodland floor.

Prior to my arrival on the property, the fallen trees were regularly cut and used as firewood.  As a result, I have few old logs that have had time to completely disappear.  I do have many that have come a long way on their return journey to the soil.

Subtle differences in available moisture, soil depth, soil composition, sunlight exposure, temperature and other environmental factors create a diversity of micro habitats that allow for a diversity of plant and animal life in a given area.  Each tree that falls and processes back into the soil, increases that diversity and that matches well with my property management goals.

When I see a fallen tree, I often contemplate what that will mean to the health of the woodland environment 50 or 100 years from now, but I don’t forget the immediate changes that occur.  A downed tree, whether or not it has actually completed its journey to the ground, provides an instant source of food and shelter to animals and plants that could not have utilized that resource while in its vertical position. 

The woodland at Blue Jay Barrens is certainly an odd looking creation.  I won’t be around to see this woodland graduated from its recovering status to that of healthy, but I’m confident that it is moving in that direction.

Flood Damage - Plants

My greatest concern following a major flood event is the recovery of the streamside plant communities.  The plants must recover in order for the animals to recover.  Billions of small organisms were swept away with the leaf litter and topsoil.  Those that were left behind have lost the environment they need to survive.  Roots that once gathered nutrients from the decomposing leaves are left exposed to dry out and die.  It could be tough growing for some of the plants this spring.  The bare soil will dry out much more quickly and will heat rapidly when exposed to the sun.  Conditions will improve some when plants grow enough to shade the ground.  Soil creation can begin anew next autumn when falling leaves fill in the space between plants.

While some places lost their topsoil, others gained soil material.  Plants must now push their way up through a thick layer of sediment.

Both situations involve this stuff.  At one point these crumbs were all neatly stacked and arranged to form a cohesive block of soil.  In that condition they provided the structure needed for a healthy soil ecosystem.  Now they’re like shards of glass from a broken drinking glass; Recognizable pieces of what they once were, but no longer functional as a whole.  It will take a long time for these crumbs to be broken down and reformed into healthy soil.

In some cases, leaf litter was also redistributed.  Shallow water flows pushed leaves together to form tightly packed drifts several inches deep.  I moved some leaves aside to show the thickness of this pile and found a plant buried beneath.  Leaves packed at this density can form an effective mulch that blocks the upward movement of growing plants.

These Downy Rattlesnake Plantains were perched at the top of the bank at the high water line.  One still holds the stalk and seed capsules from last year’s flower.

Rhizomes that were just beginning to reach out into the surrounding soil, now have nowhere to go.

Plants farther from the stream were threatened by sheets of water flowing from the hillside.

Some areas closer to the channel hardly seem capable of supporting plants.  Had a logjam not developed directly upstream, there might not have been anything left here.

Just a few feet downstream of the logjam is the site of a single Large Flowered Trillium that has been growing here for about ten years.  It has bloomed several times during that period and flood water has flattened it about an equal number of times.  Hopefully it will be poking its way through in a few weeks.  I sometimes wonder if I should relocate plants growing in such precarious positions, but I figure there must be a reason for the plant to be growing on this site, instead of the many places I believe to be better suited. 

This Swamp Milkweed grows in the center of the creek channel where it’s anchored by one stout root in a crack between the rocks.  Most of its roots are exposed on the creek bed.  I figured it wouldn’t last long at all in this location.  Despite my opinion, the plant has flourished and flowered for the past several years.  It’s occasionally battered by flood water, but it bounces right back up and produces a beautiful floral display.  I’m hoping the rest of the plants along the creek follow its example.

Chicken House

A past land use can produce effects that last for decades. Up until the middle 1960’s a chicken house was maintained in the middle of this field. Here is an old foundation stone that supported one corner of the structure.

Despite the fact that the house and chickens have been gone for over 40 years, you can still see the area once enclosed by the chicken yard fence. Outside the former yard the Indian Grass abounds. Inside, a slow transition to native grassland is underway.

During the years of occupation by chickens, the soil was cleaned of vegetation and subjected to erosion and compaction. Compacted soil results in the complete breakdown of the soil ecosystem. When the chickens were removed, the soil was not conducive to growing plants and typical farmland annual weeds began to colonize the area.

Tall Fescue is now the most common grass here, but even that hearty grass doesn’t thrive here. There are a few stalks of Little Bluestem scattered around, gradually working a transition from exotic plants to natives. The change still has many years to go.

Battling invasive plants, such as this Teasel, will be the major management activity here. The native plants will eventually claim this area if the non-natives are kept out of the way. This particular area will probably be out of sync with the rest of the field, but given another 50 years, you probably won’t even suspect there had been any damage here.

No Grow Zone

I have enough mysteries needing solved at Blue Jay Barrens to keep me busy for a lifetime. This is a puzzling little patch of ground. For some reason, nothing will grow here. This 10 foot by 20 foot area has looked like this since I moved here.

There is some erosion occurring here, but nothing severe. The site hasn’t changed significantly during the past 25 years, so it’s not accelerated erosion that keeps plants from growing.

Roots grow across the area. These roots are from a nearby cedar. The roots come out of the surrounding soil at the level of this red colored soil layer. Maybe plant roots don’t penetrate this layer and are restricted to the topsoil layer in the adjacent areas. That may explain why the short prairie grasses dominate here.

A lot of rocks here. I’ve found pieces of limestone, sandstone, quartz and oddities that must have been seriously altered by the meteor strike.

Moving water does change the surface pattern occasionally. When saturated, the surface can be quite soft and when dry, quite hard. This site is near the area of one of the large family dump sites, but I don’t think the lack of plant life is a result of foreign chemicals contaminating the soil.

A close up view of the soils reveals something quite interesting. Sand. Could this be decomposed sandstone brought near the surface as the shattered rock layers rebounded from the meteor strike? Sand is certainly less prone to erosion than smaller soil particles and it can be quite inhospitable to seeds trying to germinate. The sand particles seem to be from quite varied origins. This site certainly warrants more detailed investigation. I’ll have to put it on my ever growing list of things to study.