Scots pine in the restoration equation: Does it have a place? By Tim Mathers

Introduction

Scots pine is an interesting, if not enigmatic species, with a long and storied history in southern Ontario (LandOwner Resource Centre, 2005). Once favoured among foresters, nurserymen and Christmas tree growers, the last 25 to 30 years have seen the popularity of Scots pine decline significantly. In the Christmas tree industry, Scots pine is being replaced by a number of more desirable species; as a reforestation species, it has almost completely disappeared from use; and, in urban settings, it has been declared an invasive, exotic species (Havinga, 2000).

The intent of this article is to briefly:

1. Make a case for the re-examination of Scots pine in the so-called restoration equation;

2. Relate my own experience with this species; and

3.Provide some general recommendations as to how Scots pine, and other such species, might be used in the future.

Context

Scots pine (Pinus sylvestris), also known as Scotch pine, is the most widely distributed pine in the world. It grows naturally from the Atlantic coast in the British Isles to the Pacific Ocean in Siberia, and from the Arctic Circle in Scandinavia to the areas surrounding the Mediterranean Sea (Critchfield, et al., 1966).

Given this vast geographic range, Scots pine has adapted to a wide range of soils, landforms, elevations and climatic regimes. As a result of this exposure, Scots pine exhibits tremendous genetic variability and therefore, considerable physiological diversity (Ruby et al., 1976 and Wright, 1963). In fact, it is precisely this variation that has resulted in Scots pine being the most widely planted, non-native pine species in North America (Skilling, 1990 and Noecker, 1988). And while much of its use over the last 75 to 80 years has focused on large-scale plantings for timber and Christmas tree production, Scots pine has also been used extensively for windbreaks and erosion control on sandy, hilly areas once used for agriculture. In southern Ontario, many of these areas are associated with county and agreement forests on morainic deposits and sand plains lain down during the last glaciations (LandOwner Resource Centre, 2005).

The Problem

Given Scots pine’s extensive use, why has it fallen into such disfavour?

Practically, there are several reasons for Scots pine’s demise, including:

1. Susceptibility to a wide range of insect and disease pests, including alternate host status for a number of damaging insects and diseases (see Skilling, 1990);

2. Low commercial forestry value and therefore, few market opportunities;

3. Changes in Christmas tree market preferences away from Scots pine; and

4. Non-native species status with potentially invasive tendencies (Havinga, 2000).

While these factors are limitations to the continued widespread use of Scots pine, perhaps the most influential of these factors in recent times is the prevailing notion that most, if not all,  “conservation plantings” should be done with native plants. Indeed, has the fervour resulted in a battle against all things non-native, but more importantly, it has, in my opinion, often overlooked the functionality of many non-native species. In fact, as has been pointed out by some authorities, native plants are not always the short-term answer to the restoration of degraded or disturbed landscapes. In certain situations, including many contemporary climate change scenarios, it has been demonstrated that non-native species may well be a more appropriate, intermediate choice in the restoration and functionality of these landscapes (Ewel et al, 2004). This was the case in the middle of the last century when Scots pine was one of the preferred species to be planted on degraded sites, mainly because it could survive where many native plant species could not. Ironically, despite the poor condition of many remnant Scots pine plantings, they continue to contribute significant environmental benefit to those landscapes where they have become naturalized. 


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For the most part, Scots pine has ended up on a disproportionately large number of inappropriate sites. On many of these sites, poor performance has led to even poorer management, or no management at all. In this regard, Scots pine is not alone. In fact, I would argue that one of the primary reasons that many artificially regenerated species, including native ones like sugar maple and red oak, do not perform as well as expected, is because inadequate attention is paid to site selection, seed source selection and matching the right species (or variety) to the right site. Regrettably, when these conditions are pervasive enough, species like Scots pine develop a reputation as a poor and difficult performer, which in turn is used as justification for its disuse. Add to this impression that it is also an exotic invasive, and one has a complete underselling of the species’ utility on any project, including ones where it can indeed contribute some significant environmental benefits.  

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A Solution

Nevertheless, I believe that Scots pine still possesses considerable utility, and that this utility may paradoxically lie with the current trend toward ecosystem-based management. A very good example of this trend is the emerging field of forest restoration, where management is geared toward a more integrative and functional approach. For example, recent research has shown that many older conifer plantations in southern Ontario (including Scots pine) can be manipulated to restore the native, mixed hardwood forest found throughout pre-settlement times (Parker et al., 2008; McPherson et. al., 2002; and, LRC, 1997). It has been found that these plantations have not only met the objectives of initial establishment (e.g., erosion control, watershed protection, etc.), but that over time, they have also improved soil and micro-climatic conditions to allow for the natural and artificial re-establishment of native plant communities.

The interesting thing with this type of approach is that it provides an opportunity to use and manage species like Scots pine in a way that is both innovative and sustainable. In fact, many restoration projects are typified by their focus on:

- environmental benefits like vegetation community conversions or successions, creation of wildlife habitat, control of erosion and landscape degradation;

- long time frames before tangible results are realized;

- low expectations for short-term commercial profits; and

- usually involve poor site conditions, characterized by soil compaction, low fertility and pollution.

It would appear that Scots pine has a considerable role to play in achieving the objectives of such projects.

An Example

A case in point is my own property where Scots pine has been used successfully in converting an abandoned and very marginal agricultural field to an emerging stand of mixed hardwood species. This field was sloping, droughty, erodible and infertile – exactly the kind of land upon which many older Scots pine plantations throughout southern Ontario have been established (von Althen, 1974). Fortunately, the field was also adjacent to an existing, mature hardwood stand. Therefore, my objective was to use Scots pine as a nurse crop and the adjacent hardwood stand as a seed source to assist this field in reverting to its former hardwood cover.

Initially, several varieties of 2+0 Scots pine seedlings were planted on 2 m x 2 m spacing for Christmas tree production. The idea was to establish a tree cover, and perhaps, make enough money to pay for some of the out-of-pockets costs that would be incurred in implementing the reversion. Trees were then tended for 5 to 6 years, at which time selective harvesting began. Harvesting continued annually, for another 5 years, after which the remaining trees were too large to be sold for Christmas trees. However, because the stand was selectively thinned and not liquidated, there was a constant canopy cover on the field to provide weed control, microclimate amelioration and a supply of organic matter for the invading hardwood regeneration. After almost 12 years, the abandoned agricultural field is well on its way to a vigorous, mixed species stand of native hardwoods. Included in this stand is some remnant Scots pine. And while these individuals will eventually be shaded out because of their growth habit, form and pest resistance, they were favoured during thinning operations. As a result, many of these individuals are tall, straight trees that may, at some point in the future, provide revenues from pulpwood or chips.

The real point to be made here however, is that without Scots pine, the reversion of this abandoned agricultural field back to native hardwoods would have, at the very least, taken much longer than it did; more probably, it would not have taken place in my lifetime.

Therefore, the lesson to be learned from this example is that, with a little patience and planning, Scots pine can indeed be used successfully in the restoration equation. However, in doing so, the following recommendations are made.

Recommendations

1. Develop a clear idea of your project’s objectives, giving full consideration to what is possible in light of one’s budget (time and money), manpower, individual capabilities, site conditions, species availability and cost-sharing programs (municipal, provincial and federal);

2. Undertake a detailed site inspection (of soil/site conditions, local weather and climate, insect and disease conditions and adjacent land uses) in order to match the right species (and variety) to your site. Such an analysis will help you to determine whether your objectives are realistic; and,

3. Use source-identified, locally adapted planting stock and learn about the genetic variation and physical diversity of every species you use. This will allow you to use whatever species you choose to the fullest advantage and also give these species a place in the restoration equation.

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References

Critchfield, W., et al., 1966. Geographic Distribution of the Pines of the World. USDA Forest Service. Misc Publ 991. Washington, DC

Ewel, J., et al., 2004. A Place for Alien Species in Ecosystem Restoration. Frontiers in Ecology and Environment 21(7):354-360

Geomatics Int’l Inc, 1995. Management Options for Old Field Sites in Southern Ontario. Tech Report TR-009. SCSS, OMNR. Brockville, ON

Havinga, D., 2000. Sustaining Biodiversity: A Strategic Plan for Managing Invasive Plants in Southern Ontario. City of Toronto Parks & Rec. Toronto, ON

LandOwner Resource Centre, 2005. Scots Pine in Ontario. Ontario Ministry of Natural Resources. Manotick, ON

LandOwner Resource Centre, 1997. Managing Regeneration in Conifer Plantations to Restore a Mixed, Hardwood Forest. LRC Report 25. OMNR. Manotick, ON

McPherson, T., et al., 2002. Amelioration of Degraded Soils under Red Pine Plantations on the Oak Ridges Moraine, Ontario. Canadian Journal Soil Science 82: 375-388

Noecker, N., 1988. Scotch Pine Varieties, Characteristics and Performance. Christmas Trees 16(2):34-41

Parker, W., et al., 2008. Restoring Southern Ontario Forests by Managing Succession in Conifer Plantations. Forestry Chronicle 84(1): 83-94

Ruby, J., et al., 1976. A Revised Classification of Geographic Varieties of Scots Pine. Silvae Genetica 25(5-6): 169-175

Skilling, D., 1990. Scotch Pine. Pp 489-496. In “Silvics of North America: Vol 1 – Conifers”. USDA-FS Agriculture Handbook 654. Washington, DC

Von Althen, F. 1974. Successful Establishment of Sugar Maple in a Scots Pine Plantation. Can For Serv Info Report O-X-208. Sault Ste. Marie, ON 

Wright, J., et al., 1963. Geographic Variation in Scotch Pine. Silvae Genetica 12(1); 1-25 

Wright, J., et al., 1966. Performance of Scotch Pine Varieties in the North Central Region. Silvae Genetica 15(4): 101-110    

Photo Credit

¹ Gil Wojciech, Polish Forest Research Institute, Bugwood.org

This article was featured in a past edition of the S&W Report, the newsletter of the Ontario Woodlot Association. 

© Ontario Woodlot Association, 2011

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