Tuesday, September 23, 2008

Blow Down Natural History Part 2

Any visitor to a New England or Adirondack forest will note the pock-marked surface of the forest floor. The boils and depressions of the forest floor are grave markers where the past giants of the eastern forests once stood. Trees die of old age in the forest. They reach a point in their life where wood rots from within, insects and parasites rob the tree of energy, and even the stress of maintaining tissues on a giant tree decreases their vigor. Many trees fall on their own, but more often than not, they receive a nudge from occasional winds.

The winds of July 15, 1995 were anything but occasional. The blow delivered to the forest toppled healthy trees along with the diseased trees. The canopy of leaves acted like a sailboat spinnaker capturing the wind and bending to inflate. Yes, some trunks buckled, stretched and snapped. Roots cracked from the strain and where the wood held tough, the roots were pried from the sandy Adirondack soils. The legacy of the great blow was recorded in tree trunks laying in an easterly direction, shallow root profiles erected 90ยบ from the horizon, and divots left where the roots once lay. Smaller sub canopy trees still stand and smaller saplings still dotted the forest floor.

Although the woods must have looked like a war zone, they remained healthy over the coming weeks, months and years after the mighty blow down. Leaves slowly died and fell to the forest floor. The greenness of the leaves represents the tree tissue of the highest nutrient content. Leaves are loaded with nitrogen rich photosynthetic pigments and proteins. Foliage also contains essential elemental nutrition of calcium, phosphorus, and magnesium. The leaves softly buffer the forest floor and protect it from excessive dryness and intense sunlight. The salamanders, wood beetles, bacteria, and fungi all profit from the added protection as the woodlands suddenly were more exposed to life outside of the forest. As the leaves decompose, the nutrients are quickly capture by bacteria and fungi and transferred to forms utilized by the saplings. The forest babes grow quickly with the added sunlight and flush of life supporting nutrients.

Wood takes longer to decay. Wood beetles assist by tunneling under the bark and through the wood. This activity introduces bacteria and fungal spores to the tree’s interior and channels oxygen rich air in to support the decomposition. Armed with the right stuff in terms of enzymes and metabolic machinery, the fungi dismantle the hardened lignin and cellulose of the tree. Wood Decomposition takes time. Over several years, the bark loosens, the wood softens and splits and fungal threads infiltrate deeper into the wood. The tree cadaver becomes a sponge and water is slowly wicked from the soil upward and held in place by the pits, cells, and capillary fractures in the wood. Wood is not the most nutrient rich tissue, but it does add vital elements of calcium and potassium to the soil as it decomposes. By now, the tender saplings have grown into vigorous adolescents and shade the trunk. New organisms colonize the exposed surface of the bark. Moss and fern spores, land and germinate on this optimal bed of wet organic matter. The fragile filaments of moss branch, take root, and begin their assault on the new territory. Without surprise, red-backed salamanders have found the understory beneath the tree trunk as an ideal place to find invertebrate food and to mate, lay eggs, and bring forth young. New tree life springs forth from the mossy surface. Hemlock and yellow birch have a crazy itch to grow only atop mossy logs, tree stumps, and rocks with thin moist soil. This unique behavior ultimately produces hemlocks and birches with stilted roots in the woodland.

Every bit of the dead tree provides life and new opportunities in the Adirondack woodland. The empty divot where the roots once laid creates an interesting microhabitat of shade and moisture. Herbaceous wildflowers and ferns may utilize the more protected facets of the wind throw. The newly excavated underground caverns provide dens for weasels, fox, and skunk. Black bears may use larger excavations for winter dens. Owls seek winter refuge in the hollows of tree snags from the giants that snapped leaving a partial trunk in place.

So, what if the state/NYS DEC elected to harvest wood from the 1995 blow down? What impact would the harvest have on the land? Clear cut practices have a definite detrimental impact on the future recovery of the forest. Clearing wood from the blow down is far from clear-cutting, but some of the land would be negatively affected. First, machinery used to drag, load, and process the wood will rake and aerate some soil. Tire ruts and truck paths will compact the soil in other areas. Both disturbances will negatively impact the soil flora and fauna. Higher aeration leads to more rapid decomposition and drying of the soil. Mycorrhizal fungi that worked diligently with the forest die, retreat, or hide as spores. Rapid decomposition floods the environment with nutrients faster than the remaining seeds and saplings can use. Some of the more soluble elements such as nitrogen and phosphorus may leach from the soil throughout the watershed. Without the mycorrhizal fungi and the elemental nutrition, a new forest will recover more slowly and less vigorously. Without a quick recovery of juvenile trees, the slash and remaining wood dry and fail to support the microcosm of invertebrates, moss, salamanders, and young birch/hemlock seedlings. Without a rapid recovery, the ecological impact is felt in local streams that choke with increased erosion and mineral enriched waters.

Over the period of hundreds and thousands of years, the impact of a single wood harvest would be negligible. The most destructive force in the Adirondacks during the past 25,000 years hasn’t been wood harvests. Glaciers after all scoured all terrestrial life from the Adirondacks. The greatest threat from blow down harvest is a recession of ecological recovery. If timber harvests were allowed very time a blow down occurs, then the great AMerican forest may loose species diversity, and its rugged aesthetic appeal. Harvesting wood without ecological thinking will diminish the natural process of recovery that our state constitution guarantees for the Adirondack wilderness.

Our camping excursion to Spruce Island in Lake Lila on September 17, 2008 placed Tom and I near the heart of the 1995 blow down. The island is about 400 meters in length and no more than 100 meters at its widest point. For the most part, the island contains vegetation representative of the surrounding forest. Red spruce and balsam fir dominated the narrow north end of the island with paper birch, white pine, and hemlock on the wider southern end. It is within the later area that the impact of the 1995 blow down was observed. Former trees with heights of 75 meters lay in an easterly direction with root mass upturned and facing westward. The trunks were in various stages of decay. The bark was intact on most of trees from the blow down, although it was loosened and could easily be broken or lifted from the trunk. Shards of paper birch from the blow down provide the ignition matrix for our evening fires.

It was easily to distinguish trees from the 1995 blow down from older falls. The island was full of decaying logs where moss had colonized the trunk surface and rain and wind had deteriorated exposed root masses. The older trunks laid at angles much different from those that fell in 1995. The island has numerous craters, divots, and pock-marks of various stages of weathering. Much of the forest floor looked as if artillery explosives had once battered the island. The abundance of fallen trunks and overhanging limbs made island exploration a gymnastic adventure. Magnificent white pine trunks were still solid enough to permit the combined mass of Pasquarello and Broyles. Our greatest fear from trekking across blow down timber was the potential to impale our body part from half broken limbs.

We were impressed with the destructive power of blow down winds. Not only had massive trees with thousands of pounds of biomass tumbled, but incredible root systems with hundreds of pounds of soil had been uplifted like the light end of a school yard teeter-totter. Any rock with roots wrapped around it had also been uplifted and reoriented. Some of the craters were nearly a meter deep although most were significantly less than 0.5 meters. Adirondack soils, after all, are sandy and thin.

The blow down trees created light gaps in the forest and several species of tree took advantage of the sudden increase in sunlight. Several root masses provided a suitable site for new paper birch seedlings to colonize and grow. Straight vigorous paper birch saplings burst forth from the vertically oriented root masses. Red maple had colonized another light gap, and fire cherry was quick to invade two other sites. The presence of fire cherry is interesting on Spruce Island. No other large fire cherries occurred here and there was no indication that it existed on the island before the blow down. These plants were most likely new recruits from the surrounding forest. Their seeds probably traveled by blue jay, hermit thrush, or grosbeak from the surrounding Lake Lila forest. After passage through the avian intestinal pathway, the seeds of this pioneer species landed in these new light gaps with intent to grow.

Fallen trees from the 1995 blow down were evident elsewhere in the Lake Lila Wilderness. In all but a few locations, the damage was well-hidden within the forest. Three-hundred year old yellow birch still stood tall in upland areas, and wind-shaped white pine lined the lake. On the north end of Lake Lila, two campsites (#4 & 5), free exploration of the surrounding woods was limited by large fallen trees and tangles of dead branches. ALthough I didn't observe these campsites before the 95 event, I can imagine that the effective area of these camp sites had significantly decreased. A small pennisula just south of camp sites 4 & 5 bore the most glaring woodland scar. Here a large notch had been carved out of the pine forest. The site was impenetrable with downed logs. Nevertheless, recovery was evident here as well as seedlings and saplings had begun their assault on the freshly contested terrain. Nature wields the pain or destruction and the cures of ecological recovery in the Adirondacks.

1 comment:

Tom said...

Hi Steve,

Your post is a great illustration of the fact that the one constant in nature is change. This, in turn, helps make the case that a pragmatic view of nature is essential in developing effective policies to protect nature in our global industrial economy.