Essay: Grouse Numbers--the Long-term Ecosystem View

In order to grasp the main important concepts in the fluctuations of any wildlife populations, including Ruffed Grouse, it is important to see them as part of the larger system in which they are embedded. It is also important to recognize the scale of time and space on which the system is changing. Without the larger view there is no hope of making rational decisions on the management of our wildlife species, or of, at the larger scale, our forests.

A good simple example which shows this is the recent boom/bust cycle of wintering Evening Grosbeaks, which largely disappeared in about the year 2000 from NC after being quite common before then. People wondered why? Old data, however, revealed that prior to 1960 the Grosbeaks were almost unheard of in NC and the probable cause of their “decline” was large scale recovery of their Canadian forest habitat, after logging/budworm issues, which allowed Grosbeaks to return to their old habit of staying up north in the winter.

So to understand the large scale factors involved in land changes, we must examine the one thing that is causing massive changes in ecosystems across the planet—people. The first wave of human habitation in the eastern US about 20,000 years ago was marked by massive large scale use of fire in a place where fire was previously almost nonexistent. The regular and extensive burning of the forests of the eastern US by Native Americans was well noted and wondered at by the European explorers of the 15^th century. There is no doubt that this practice caused very large and long-lasting changes to the land and ecosystems, and that the animals present either adapted or perished.

But the first American people had not developed metal tools and did not clear the forests or till the soil on a large scale, and it is unlikely that their burning depleted or harmed the soils which were on the order of feet in depth even in the uplands. The soil structure at that time was very good and productive, so that the flush of growth after burning was extremely fast and lush. Those conditions are likely to have favored grouse and other ground-dwelling omnivores, which also benefitted by the extinctions and population crashes of most major large predators at that time. So grouse populations either boomed immediately, or they adapted to the new conditions and increased markedly over time. Grouse populations before then were likely much lower, and restricted to high elevation and northern forests which are subject to seasonal extremes, favoring low herbaceous growth.

In a historical twist, the forested lands of Eastern North America were largely abandoned for about 250 years beginning in about 1525 when American Indian populations were decimated by bacterial and viral diseases which they were not ready for. Then the forests had a couple hundred years free of fire and the vegetation grew densely again at ground level, surely making it difficult for grouse and similar species, and reducing their populations accordingly.

In the more recent past, the biggest single change to our ecosystems in North Carolina was the absolute destruction of the soil in approximately 99.9% of our uplands. It is only necessary to take a small shovel into any forest and dig to find bare clay, rock, or sand within an inch of the surface. This was caused by the clearing of the forests and tilling of the then-rich soils to grow food crops by the European immigrants with metal tools and draft animals.

The time scale for soil formation is several hundred years. Now, even our most mature upland forests are at a very early stage of ecological succession, because there is almost no soil. With no soils left, burning our forests does several undesireable things: it slows soil formation by removing the organic material that is so vital, it directly burns and destroys the top layers of soil, and destroys small plants whose roots hold the soil back against erosion. It also favors fast-growing successional species which produce very little refractory(or slow-decomposing) organic matter and therefore have very little long-term benefit for the soil. Clearcutting produces similar undesireable effects by resetting succession to zero.

So even though there is some evidence that burning and clearcutting our forests can lead to temporary increases in grouse populations, these practices are extremely harmful to the longterm productivity of our forests, their ability to provide clean air and water, fertile soils, and support diversity of wildlife. I would go so far as to say the longterm survival of even Ruffed Grouse and most of our other ground-dwelling omnivorous species, is directly threatened by reductions in forest productivity, from short-sighted, short-term thinking that resets ecological succession to zero and keeps our soils from regenerating.

Only by allowing the soils to be re-established over the long-term can we truly ensure the productivity of our upland forests, and their ability to provide us with clean air, water, and abundant wildlife.