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Jamie Simpson

Many of us in Nova Scotia depend on the clean drinking water that healthy forests provide. Forests provide this service naturally and freely. But when forests are abused, so too are drinking water supplies. New York City recognized the connection between healthy forests and drinking water: the city is spending some $1.5 billon to protect 80,000 acres of forest land to safe-guard its drinking water. This may seem like a lot of money, but it’s a good deal compared to the $8 billon the city would have to spend to build a water filtration plant to accomplish the same services that a healthy forest provides.

Why are healthy forests and water so intricately connected? Water can be called the ‘lifeblood’ of the forest: clean, fresh, water is an essential ingredient of our native Acadian Forest. All life in the forest needs water to drink. By weight, trees are roughly one-half water, and a hectare of Nova Scotia forest can contain over 60 tonnes of water in the trees alone.

Water in the forest does much more than quench the thirst of lofty red spruce trees. Water provides rich habitat – a close look at a forest stream or pond reveals abundant life, from plants and mosses to salamanders, frogs, turtles, fish and countless insects. Forest ecologists report that some 90% of all wildlife relies on the habitat found in or next to forest waterways.

Trees provide shade that helps keep streams cool. Trout and salmon, for example, suffer when water temperatures rise. Tree roots prevent erosion, keeping sediment from clogging stream beds and smothering fish eggs. Dead trees that fall into streams create ideal pools and shaded hiding spots for fish.

Importantly for drinking water supplies, forests act as giant filters and sponges, removing pollutants and sediments from water, and soaking up and storing vast amounts of water, slowly but faithfully releasing clean water into waterways and underground water reserves.

People who own forest land can help ensure healthy forests, healthy water systems and sustained drinking water supplies.   (1) Let nature take its course. With time, degraded forest and aquatic ecosystems naturally recover. (2) Restore forest cover to the banks of water ways, especially on farmland. All waterways should have at least 30 metres (100 feet) of forest along their edges. (3) Don’t clearcut. Without forest cover, water can move too quickly through the forest, causing erosion, nutrient loss and drought.

Jamie Simpson

A few years ago I found myself tramping over a 400 acre woodlot in Cape Breton, hired by a family to provide advice on what to do with their forestland. None of the dozen or so family members wanted large-scale cutting, but beyond that opinions ranged from ‘just let it be’ to ‘but we have to do something’. Oh, and what about fire risk with all the dying spruce? I quickly realized my role was part forester, part mediator. The family’s key question was what to do with the patches of mature white spruce growing on old pasture land. As with almost all of eastern Nova Scotia, the white spruce were in various stages of decline due to the bark beetle.

As it happened, the family’s woodland provided an interesting case-study in forest ecology, particularly in forest succession. To set the stage a little, about half the property was covered with mature hardwood forest typical for the site: mostly sugar maple, beech and yellow birch. The other half had been farmland, let go to forest at various times over the past half century or so, and had grown back with mostly white spruce mixed with bits of red maple, fir and white birch. Some patches of white spruce had been clearcut 15 years ago, some patches were still reasonably vigorous, and some were well along the path to falling apart.

The patches of falling down white spruce told a rather interesting story of rapid forest succession in action. Pretty darn exciting, I know. As shown in the accompanying photos, seedlings of sugar maple, yellow birch, white ash and beech were well established wherever enough trees had died to allow partial light to reach the ground. Some of the young hardwood were already reaching over my head. These old-field white spruce stands were well along a transition to shade-tolerant mixed hardwood stands.

As I walked along I thought about why the sugar maple and yellow birch seedlings in these areas were growing so well. Anyone who plants hardwood knows that they can be tricky to establish. One plus was the moderate microclimate that the dead and dying spruce provided: not too sunny, not too shaded, not too hot, not too dry. The other plus, I surmised, was that the tangled mess of fallen spruce provided a physical barrier to browsing deer. Interested in this theory, I searched the scientific literature and, sure enough, found a study confirming that a mess of tree tops and branches left on the ground after harvesting helps protect seedlings from hungry deer.

So, what did I tell the family? In my report I explained that white spruce was not the natural forest cover for their land; while the bark beetle is hastening its decline, white spruce wasn’t destined to survive much longer on their land anyway. I suggested that they could indeed do some limited harvesting of some of the still-living white spruce to provide logs for their building projects, and that they had lots of potential to harvest firewood from the hardwood stands. Where the white spruce was already too far gone, I told them no need to worry, because the dead and dying spruce were nurturing the next forest – don’t lift a finger, and enjoy watching a new mixed hardwood forest grow, a forest much better suited to their property. In time, they may consider doing some pre-commercial thinning to help encourage tree species that would be common in old forests, such as sugar maple and yellow birch.

Some might suggest that the property should be “sanitized” by clearcutting to address the bark beetle problem. While such cutting might help to temporarily reduce the local population of bark beetles, it would not do much to stem the bark beetle infestation on a regional scale. The cause of the bark beetle outbreak is the un-natural abundance of mature white spruce across eastern Nova Scotia; the bark beetle problem won’t be solved until these white spruce forests evolve into new, more diverse forests that are less vulnerable to bark beetle.

As for fire danger, I explained that heavy tree-cutting would actually increase fire risk for their forest by putting a large amount of tinder-sized branches close to the ground, without any shade to keep things moist. As well, the fine branches of the dead and dying spruce (the material that adds to the fire danger) fall to the ground gradually, and are quickly decomposed, thereby avoiding a large build-up of dry branches close to the ground. As the young hardwood trees grow, they provide additional shade, thereby keeping temperatures down and moisture levels up, warding off fire hazard.

The areas on the property where white spruce had been clearcut some 15 years previously also told an interesting story. A few scattered young hardwood trees had grown in the clearcut, but were in rough shape. They were heavily branched due to lack of shade and stunted by repeated animal browsing.

With my report in hand, the family and I walked parts of the woodlot so they could see for themselves my key findings. Fortunately, all members of the family felt that their concerns and wishes for the property were respected: there was no need for drastic measures to reduce fire hazard or to renew the forest, but there were also ample opportunities for limited harvesting to meet their lumber and firewood requirements. A few years from now, I look forward to walking this family’s property again to see how their forest, and their understanding of their forest, evolves.

by Caitlyn Chappell and Jamie Simpson

[click here to read the whole article]

We reviewed and synthesized information sources that examine yield, regeneration, stand composition, costs, revenue and employment generated by clearcutting and partial cutting systems in the Acadian and other forest types in north-eastern North America with the aim of informing an analysis of the potential impacts of reducing the prevalence of clearcutting in Nova Scotia.

Of the seventeen sources reviewed, four sources involved sugar maple dominated hardwood stands (Metzger and Tubbs 1978; Niese and Strong 1992; Robinson 1997; Stevenson 1996). Two other sources examined northern conifer dominated mixed-woods (Frank and Blum 1987; Sendak et al. 2003). One source examined each of the following forest types: black spruce-balsam fir stands (Liu et al. 2007), hemlock dominated softwoods (Pannozzo and O’Brien 2001), red spruce dominated softwoods (Stewart et al. 2009), mixedwoods (Conservation Council of New Brunswick 2000), red spruce and balsam fir dominated mixed-woods (Pothier and Prévost 2008), beech dominated hardwoods (Leak and Wilson 1958) and red maple and beech dominated hardwoods (Leak 2003). Two sources examined forests that cover multiple forest types, including hardwoods, softwoods and mixed-woods (Erdle and Ward 2008; Pannozzo and O’Brien 2001), while another two sources did not describe in detail a particular forest type (Lansky 2002; Salonius 2007).

Each of the six sources that examine growth and yield indicate that over the longer term (30-150 years), selection cutting, including single tree, group and strip cutting methods, generates growth and yield similar to or greater than the growth and yield obtained from clearcutting (Conservation Council of New Brunswick 2000; Erdle and Ward 2008; Niese and Strong 1992; Pannozzo and O’Brien 2001; Sendak et al. 2003; Stevenson et al. 1996). Yield and growth obtained from selection cutting was 2% to 74% higher than growth and yield obtained from clearcutting on similar sites.

Each of the three sources that compare regeneration after group and/or single tree selection cutting and clearcutting, including the only study conducted in Nova Scotia, indicate that selection cutting treatments (1) favour the regeneration of shade-tolerant species over shade-intolerant species, and (2) promote better regeneration of shade-tolerant species than clearcutting treatments (Frank and Blum 1978; Metzger and Tubbs 1971; Stewart et al. 2009). Two of the studies found total stocking after group and/or single tree selection cutting to be 50% and 10% higher than after clearcutting (Metzger and Tubbs 1971; Stewart et al. 2009) and the other study found total stocking to be equal after partial cutting and clearcutting (98-99%) (Frank and Blum 1978). Only one of the five studies examining regeneration found total stocking to be lower following single tree selection than following large scale clearcutting (Leak and Wilson 1958); this study was conducted in old-growth forest conditions, which are unlike most of Nova Scotia’s forests (Mosseler et al. 2003).

The three sources that compare stand compositions 15 to 43 years after clearcutting and partial harvest treatments (group and/or single tree selection) show that selection cutting methods can result in a greater prevalence of shade-tolerant tree species than clearcutting (Conservation Council of New Brunswick 2000; Leak and Wilson 1958; Sendak et al. 2003). One source found that the presence of red spruce and other preferred crop species had increased during the eight years following single tree and group selection harvests (Stewart et al. 2009). As well, one study (Leak 2003) showed that 1/5 ha (1/2 acre) patch cutting increases the abundance of yellow and white birch compared to the original stand.

The five information sources that examine employment indicate that employment per unit volume of wood harvested is approximately equal or higher under partial cutting systems than clearcutting, ranging between 3% less and 370% more employment per unit volume (Erdle and Ward 2008; Lansky 2002; Pannozzo and O’Brien 2001; Stevenson et al. 1996).

The four information sources that examine harvesting profitability indicate that partial cutting can be profitable (Liu et al. 2007; Niese and Strong 1992; Robinson 1997; Salonius 2007). One of these four sources indicates that single tree selection harvesting may yield 11.5% higher mean profits per cubic metre compared to the clearcut treatment ($58.40/m3 and $52.39/m3) (Liu et al. 2007). Another study indicates that relative to an uncut stand, the net present value (NPV) of single tree selection cut treatments ($496) are on average higher than the NPV of clearcutting ($-401) (Niese and Strong 1992). Stevenson et al. (1996) also indicate partial cutting can generate 100% or 190% more revenue per unit area than clearcutting, depending on the site being cut.

Based on results of this information synthesis, we suggest that forestry in Nova Scotia on sites similar to those studied could be profitable and provide increased employment and yield if Nova Scotia were to transition away from clearcutting as the dominate harvest method. Increasing the use of partial harvesting methods, particularly single tree and group selection harvesting methods, could also increase the regeneration of shade tolerant, late-succession species that characterize mature Acadian Forests.

We recognize that single tree and group selection harvesting may not be silviculturally appropriate for all sites in Nova Scotia, thus the results presented here should not be construed to apply equally to all sites. We suggest that these results apply to those sites that are silvicultually appropriate for partial cutting systems, as well as some sites with potential for restoration to silviculturally appropriate, and more valuable, Acadian Forest assemblages.

The possible increase in harvest costs associated with a shift to partial cutting systems could be partially off-set by (1) redirecting a portion of current silviculture spending from practices associated with clearcutting to practices that promote partial cutting, and (2) adding new silviculture funding specifically for partial cutting treatments on private lands.

If our calculations and the assumptions of Erdle and Ward (2008) and the New Brunswick Federation of Woodlot Owners are correct, then reducing clearcutting across Nova Scotia by 50% while maintaining a provincial harvest level at Nova Scotia’s 10-year average annual harvest volume would increase the overall cost of harvesting by $4.06 to $5.07 per m3 on private lands and $3.68 to $4.60 per m3 on public lands (14.4% to 18.1% and 12.8% to 16.0% of the current estimated average cost per volume of wood harvested, respectively) due to the lower harvesting efficiency of selection cutting methods. We estimate that $1.87 and $8.65 per m3 are currently spent by the NS government on clearcutting-associated silviculture practices on private and public lands in Nova Scotia, respectively, which indicates an opportunity to offset potential increased costs of single tree and group selection harvesting through re-direction of silviculture spending, especially on Crown land. Other sources indicate that single tree selection harvesting could cost two to three times as much as clearcutting (Niese and Strong 2002, K. Thomas, personal communication, April 6th, 2010), and as a result, re-directing silviculture spending may not be sufficient to cover the increased costs of this harvesting method.

Over the longer term (>25 years), the potential increased harvesting costs of single tree and group selection harvesting might also be offset by an increased timber yield per unit of land, and an increased per-unit-value of harvested wood, especially of hardwood, as the timber quality and species composition of stands improves.