|White Mountain National Forest - lessons in landscape|
I walked into a wilderness last week. The hike in was an adventure as we had to ford a swollen and icy cold Sabbaday Brook three times before the trail reached the boundary of the wilderness. Stepping past the sign for the Sandwich Range Wilderness, you would be hard-pressed to notice any difference between the woodland either side of the (fenceless) boundary.
We were walking in the White Mountain National Forest in New Hampshire. This small state seems an endless forest landscape (over 60% woodland coverage, second highest in America) with the 800,000 acres of the federally-owned National Forest taking up about 6% of the state. Just under 100 years ago, the land which makes up the National Forest was a clear-felled mess, looking more like a post-apocalyptic landscape and laying bare the glaciated upland and valleys of granite and quartz. Soil erosion from water and wind was catastrophic. Dismay at this despoliation led to the Weeks Act in 1911 and the public purchase of much of the land in the White Mountain area. Today, the mixed forests of hardwoods and conifers look for all the world to have been there forever and, in once sense, they have been since the woodland you see today arose through natural regeneration from the seed bank present in the soil.
The White Mountain National Forest is a working woodland in many ways, its signage strapline proclaiming "a land of many uses". A primary aim is of course for timber products, but as importantly it is wildlife habitat, a source of clean water and wild foods, and a recreational resource of immense value in the scenic lakes and ponds, waterfalls and rocky gorges, the many miles of hiking and backpacking trails, back country shelters, and cross country ski trails. We chose to visit in autumn when the renowned fall colours of the hardwood leaves are a magnet to leaf peepers. The deep reds of the red maples mingle with the red/yellow medley of the sugar maples, pin cherries and mountain ash, the leathery red of the hobblebush, and the yellows of the striped maple, witch hazel, birch, beech, aspen and basswood. Set these against the evergreen foliage of hemlock, fir and spruce and you have mosaics of colour that distinctly characterise the natural mixtures of tree and shrub species that this forest contains.
Why, with so much activity going on, does the forest look so untouched such that when you do enter one of the five wilderness areas inside the National Forest, there is a seamless transition? First, we should recognise that there is no productive activity in the wilderness areas, and only hiking and some backcountry camping is allowed. This is true for all wilderness areas designated within the National Wilderness Preservation System, first set up in America in 1964. Sandwich Range Wilderness (25,000 acres) was designated in 1984 and it is one of five internal core areas of self-willed and totally wild land that make up a sixth of the White Mountain National Forest.
Perhaps the answer lies in the management approach of the National Forest Service. They manage the non-wilderness areas for a wide range of objectives, as described above, but the primary concern is that of forest health, which is maintained through ensuring a diverse and multi-layered woodland of varying age (75% of the trees are over 80 years old, and only 5% have been growing for less than 20 years). They firmly believe that forestry is an art, as well as a science, and this shows in the design aesthetic of their management approach, which unsurprisingly draws its inspiration from natural systems.
A key observation from nature is disturbance and survival. Small disturbances - such as the odd, dead tree falling, a tree hit by lightning, insect outbreaks, or a few trees toppled by high winds - are part of the natural cycle and create new openings in the forest canopy. These openings allow sunlight and rain to reach plants on the forest floor below, allowing younger trees to grow up and existing trees to grow stronger. Larger events - such as forest fires and massive blowdowns - create larger openings and more dramatic changes, but they happen less frequently. When they do, the forest responds quickly. Berry bushes are the first to take advantage of the increased sunlight. Soon tree and shrub seeds falling from adjacent trees, or lying dormant in the ground, sprout and grow. Before long the earth is covered in new growth. In this way, the forest is continually changing as trees age and die or as openings form from disturbance where succession begins anew. Thus the healthy forest maintains a multi-age, multi-layer community.
Forest management in the National Forest is based on an understanding of these varying patterns of natural disturbance and their outcomes. Methods of tree harvest thus mimic increasing levels of natural disturbance and each method has a particular aim and outcome. Design is a key component in their use.
Single tree selection maintains the diversity of the forest by taking out individual trees of all ages and sizes. Little additional sunlight reaches the forest floor with this method because so few trees are removed. This favours regeneration of shade-tolerant species, particularly the conifers and sugar maple. Because the canopy remains largely intact, this method is often used near trails, recreation areas and other visually sensitive areas.
Shelterwood cutting takes a 2 step approach to regenerating new stands of trees. Lower quality trees are thinned out through an area, leaving the good quality trees to provide shelter and seeds for new growth. Regeneration is off to a fast start as young seedlings of shade-tolerant trees thrive in the partial shade of older trees, and there is vigorous growth among the seed trees that remain after the initial cut. Once the seedlings are well established, the seed trees are harvested some 15-20 years later. This practice provides a soft visual transition from cut to uncut forests.
Small group selection is used to create a multilayered composition of different aged trees across a forest landscape that includes many species. This method initiates nature by harvesting small groups of 10-20 trees – usually in areas of less than an acre – to allow a limited amount of sunlight to reach the forest floor and stimulate the growth of shade tolerant species that are in smaller numbers in the mature woodland. Over time, a patchwork effect is created by groups of trees of various ages - a true forest mosaic.
Clearcuts of 10-30 acres mimic a major natural disturbance, and are designed to leave only scattered clumps of standing trees, including those that bears feed from, contain nesting cavities, or provide perches for hawks and owls that like to hunt in new growth. Where clearcuts are visible from roads or trails, the shape and edges are designed to appear as natural as possible. A clearcut is a fresh start: it encourages regeneration of different species compared with small group selection, such as the pioneer species pin cherry or white birch, and the sun loving species such as aspen. None of these trees need planting in these clearcut areas because forestland in the White Mountain National Forest will naturally spring back to life, producing up to 20,000 seedlings per acre.
When I crossed into the Sandwich Range Wilderness, I realized that here was a remarkable example in practice of a fuzzy transition between the different intensities or zones of land use that characterize Permaculture Design. The managed woodland represented Zone 4 land use and the wilderness represented Zone 5, an area in which productive land use is eschewed. As I learnt more about the management in the National Forest, I came across created meadows of one to six acres, where the open nature of the land is maintained longterm through cutting or fire. The edge between these two habitats of forest and field is especially diverse. In the meadow, spring brings lush growth that is invaluable for wildlife impoverished after a long winter, late summer brings an abundance of wild berries – a favourite of black bear – and seed eating birds seek out these places during their fall migration. But you could just as easily imagine humans living in these fields in the forest (some were historically abandoned farm fields). And again there is a parallel with other land use zones in Permaculture Design and their inter-relationship.
Wilderness and wild land is a challenging concept for people living in Britain. Its value will only become recognized when it is set within the context of broader land use. The zonal approach to land use in Permaculture Design sets this context in a simple, functional way and should make it easier to understand. Sometimes, though, a walk in a landscape like the White Mountain National Forest just makes everything become so clear.
Mark Fisher, 27th October 2005
You can read more about the management methods in the White Mountain National Forest by downloading the educational material produced for their Forest Discovery Trail - see https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5262270.pdf