Forest Plantations Defy the Science and Ignore the Economics.
Bob Bancroft, MSc (President, Nature Nova Scotia)
Published in the Chronicle Herald 22 Aug 2020
The NS Department of Lands and Forestry and the forest industry are planning to replace more than 800,000 acres of fertile public forest land with even-aged, softwood plantations that are simplified, even-aged crop rotation systems largely devoid of nature. This feat will be accomplished at tremendous public and environmental expense. Ignoring long term economic and scientific realities, it flies in the face of history and will produce only short-term, private profits.
Clearcutting followed by even-aged softwood plantings of up to three species on former hardwood and mixed hardwood-softwood sites severely degrades these sites over a short period of time. The resulting ecological imbalance promotes pest infestations, disease, vulnerability to strong winds and stresses caused by hot, dry weather.
The only reason for using the plantation approach on public (Crown) lands is entirely economic. It amounts to quick and easy fibre extraction for short term, private profits with financing placed on the backs of taxpayers. Such a fast return is sanctioned only when economic goals remain a focus unfettered by ecological literacy. What makes that possible are public subsidies that include nursery production, planting, herbicides, thinning treatments and even road-building. Ecological expenses are ignored, while the legacy of severely impoverished sites persists for human generations and centuries.
The history of European forestry demonstrates that only management on an ecological foundation maintains the healthy, balanced conditions that can promote ample, continuous wood production along with the amenities that society and nature require to carry on in a healthy manner.
More than 200 years of science regarding forestry and forest evolution in central Europe offers some insights for North Americans. The 1700s saw rapid industrialization in Germany and looming timber shortages as a result of unregulated forest exploitation. They proposed plantations of fast-growing Scotch pine and Norway spruce as the answer. As a result the composition of German forests shifted from their pre-industrial state of two-thirds mixed hardwood species to two-thirds softwood species.
This approach used intensive nursery production, planting, weeding, clearcutting and heavy machinery. It necessitated frequent responses to pests, disease and other stresses including soil fatigue. By the 1800s, scientists were demanding a return to mixed (hardwood-softwood) forests and more healthy soils.
Given the problems that arose, in the 1880s some forest owners began improving soils and using more tree species. Those forests soon became less attractive for pests. Yield studies confirmed that this approach was more productive. Woodlands once again became more species-complex with older trees and hardwoods included as an essential component for health. The results were more like natural forests.
To paraphrase Minkler (1980), “forestry is not a form of long-term crop agriculture”. He added that the concept is doomed to fail by the workings of forest ecology.
Ecological stability in forest ecosystems
Balanced forest ecosystems have conditions that tend to maintain pest populations at naturally controlled levels. Pure spruce plantations create biological empty spaces to be filled up by pests, which result in huge financial losses spent on chemical controls. E.P. Odum (1953) and H.J. Lutz (1959) found that softwood plantations were vulnerable to infestations, compared to mixed (hardwood-softwood) stands. F.S. Baker (1950) stated that destructive epidemics occurred more readily in monocultures. R. Dubos (1972) found that oversimplified plantation ecosystems require the massive use of chemical fertilizers, pesticides and other synthetic products. Ecosystems lose their diversity, become less stable, and less likely to remain suitable for a variety of species, including mankind.
Two or three plantation rotations (crops of trees taken off the same site) were enough to reveal mismanagement and poor economic results. A return to ecologically-sound management was a slow, expensive process that placed a heavy burden on society.
Ecological integrity maintains productivity
One firmly established law of ecology relates to the environmental stability of natural ecosystems.
Diversity maintains stability against pests and physical disturbances. It also makes for long term perpetuity of productive capacity, the ability of nature to remain healthy and productive.
Simplicity provokes instability in forest ecosystems, resulting in the spread of pests, retrogressive changes of the environment, and the gradual deterioration of the site for wood production.
Softwoods are well adapted to ample precipitation and cooler summer temperatures. Shallow-rooted, they quickly take up water in the upper soil layers. Conifer soil litter under the trees has little water holding capacity and holds more heat than the rich debris under hardwood forests. For these reasons, softwoods suffer more readily from water deficiencies. Notable exceptions are southern pines, junipers with deep root systems and hemlocks, which take another approach to conserve water.
Hardwood species tolerate warmer temperatures and less rainfall. The presence of hardwoods results in the rapid spreading of fungi, insects and other animals as deeper, more productive soils form. Hardwoods inhabit the better soil sites and use three to six times more soil depth for their roots than softwoods. Hardwoods efficiently capture more nutrients with less soil losses due to leaching and seepage. Their deep roots act as mineral pumps, delivering to the surface what softwoods need in mixed hardwood/softwood forests.
The broad leaves of hardwood forests and their ground cover plants produce larger amounts of rich soil humus. These trees also live longer and are able to establish and grow in forest shade. Many are more resistant to native pests and other natural, destructive forces like floods, fires, wind and snow.
Softwood needles are acidic, lowering the pH (increasing the acidity) of soils and causing podsol or hardpan soil layer that inhibits root depth.
In contrast, hardwood leaves sweeten the soil, producing larger quantities of richer humus layers than is found in soils under softwood forests.
Nova Scotia has some of the poorest soils in Canada. Most forested areas have been subjected to repeated harvests for three hundred years or more. The province is challenged by continental North American acid rain and dry deposition, due to its location and prevailing winds from industrial areas.
The Maritime region traditionally had predominantly mixed (hardwood/softwood) forests composed of various combinations of many species. Yet white spruce, balsam fir and pines now abound over the present landscape, the result of recent land history.
Nature would gradually replace softwoods on exhausted farmlands with secondary plant species that include hardwoods. This is a healing forest that, with time, becomes a more productive and diverse forest with mixed ecotypes (assorted assemblages of species and age classes). Maintaining a succession of softwood plantations on a site is a “fight-nature” approach that degrades soils and wildlife habitats.
The ecological backbone of our mixed forests is the hardwoods that can only thrive on the better sites. These forests are able to maintain and improve their quality by physical means that include the annual shed of leaves to add to the humus layer, and by creating proper conditions for a variety of plant and animal life.
It’s been two years since the Lahey report was tabled, with ecological forestry its frontspiece. Massive clearcutting was to be curtailed.
Instead large clearcuts on public lands continue, disguised on paper with technical terminology, using bafflegab words like “variable retention”, “salvage cut”, and my favorite, “continuous cover low retention irregular shelterwood”.
The resulting treatments leave too little forest for wildlife to survive. They often fail to promote the regeneration of valuable tree species. But they perpetuate all the major deleterious clearcut effects, which include sun-exposed soils, dryness, increased temperatures with tree shade removed, hit-and-run rains in brooks, causing wildly fluctuating water levels in streams, and major nutrient losses in soils.
P.A. Twight and L.S. Minckler (1972) consider clear-cutting a “drastic practice and a menace to the future of northern hardwood forestry.” Clearcutting has only short-term benefits and is not justifiable as a general, long-term policy.
The public can easily sense that clearcutting healthy forests followed by repeated plantations are changes too abrupt for forest wildlife to survive, and result in soil depletion.
Policy makers and politicians need to understand that brutal harvesting methods, whatever they are labelled, have extremely detrimental consequences for the future productivity of forests, the land base, wildlife and people. Nature is dwindling quickly.
Let’s stop this stupidity.
Bob Bancroft, MSc
President, Nature Nova Scotia
Blomidon Naturalists Society : Cape Breton Naturalists Society : Eastern Shore Forest Watch : Friends of Nature : Friends of the Pugwash Estuary : Halifax Field Naturalists : Nova Scotia Bird Society : Nova Scotia Wild Flora Society : Tusket River Environmental Protection Association : Young Naturalists Club of Nova Scotia