The story of Coastal Douglas-fir forests: All about Gabriola Island

This installment is the second in a series of several articles seeking to explore the ways ecosystems  differ between the islands within the Coastal Douglas-fir (CDF) biogeoclimatic zone. Rob Brockley, President of the Gabriola Land and Trails Trust, explains the ways topography, soil conditions, and increasing development pressure have influenced and continue to shape the ways CDF forests and associated ecosystems function on Gabriola Island. 

Can you describe the CDF forests and associated habitats on Gabriola Island? How do they differ from other Gulf Islands?

Firstly, Gabriola is less topographically diverse than most other Gulf Islands, with its highest elevation being only 180 m. Much of the landscape is relatively flat or gently sloping, and there aren’t the extreme peaks and valleys, and associated vegetation changes, that are present on many of the other islands. According to sensitive ecosystem mapping, wetlands account for more than 15% of Gabriola’s land area, which is considerably more than any of the other Gulf Islands. This may be largely due to the flatter topography and underlying glaciomarine sediments. Many of these wetlands are seasonal and have fluctuating water tables. Wetland vegetation is consistent with the various ecosystems associated with the western redcedarーskunk cabbage site series. Tree cover is usually sparse due to wet soil conditions. Salmonberry and red elderberry are dominant shrubs, and common herbaceous species include rushes, sedges, lady fern, horsetail, and skunk cabbage.

According to Islands Trust data, less than 65% of Gabriola is forested, which is less than many other Gulf Islands. Only 13% of Gabriola’s land area is classified as mature forest. However, there is a considerable amount of 80 to 100-year-old forest on Gabriola, which, due to out of date mapping and limited  ground truthing accompanying past mapping efforts,  may be incorrectly classified as immature on sensitive ecosystem maps. Sadly, there is no true old growth forest on Gabriola, although there is a small amount of older, mature forest with old growth characteristics. Fortunately, many of these older forests are protected in parks or nature reserves.   

The predominant forested ecosystem on Gabriola is the zonal Douglas-firーsalal site series, occurring on moderately dry soils with poor to medium nutrient regimes across the island. Trees are mostly Coastal Douglas-fir with some western redcedar and small amounts of western hemlock (although these two species are slowly disappearing due to a changing climate). The understory is primarily salal and dull Oregon-grape. The drier Douglas-fir-shorepine-arbutus ecosystem is less prevalent, typically occurring where a thin veneer of coarse-textured soil overlies bedrock such as along  rocky coastlines and at the edges of herbaceous ecosystems where there is not enough soil to support a closed, canopy forest. 

Where forest canopies are more open, these mixed Douglas-fir-arbutus stands have been classified by the Islands Trust Conservancy (ITC) as ecologically sensitive Woodland habitat due both to their fragility (lack of soil moisture and exposure mean that once disturbed, these ecosystems are challenging to restore) and uniqueness within the CDF. Garry oak is sometimes present, usually on shoreline rocky outcrops and open meadows. The understory of these drier sites is dominated by drought-tolerant shrubs such as evergreen huckleberry and salal, and the herbaceous layer is typically sparse. Overall, Garry oak is less common on Gabriola than on most other southern Gulf islands, probably because we are nearing its northern range.

Ecosystems that are somewhat richer than the Douglas-fir-salal forests are represented by the Douglas-fir-grand fir-Oregon grape site series. This red-listed ecological community seems to be more common on Gabriola than on many other Gulf Islands. Douglas-fir and western redcedar are the dominant tree species, with smaller amounts of grand fir, western hemlock and bigleaf maple. Common understory species include Oregon-grape, salal, sword fern, and Oregon beaked moss. Conversely, Gabriola has lesser amounts of forested ecosystems associated with slightly dry to fresh soil moisture conditions and rich nutrient regimes (especially the western redcedar-grand fir-foamflower site series) than most other Gulf Islands. This may be due to the relative absence of streams, moisture-receiving sites, and deep soils. Where these sites do occur, tree species such as western redcedar, grand fir, bigleaf maple, and red alder are usually abundant and herbaceous species such as sword fern, vanilla leaf, and foamflower dominate the understory.   

Finally, sandstone bedrock occurs at, or near, the surface at many locations on Gabriola which provides for unique herbaceous ecosystems. Pockets of soil can support trees such as arbutus and shore pine, but thin soils and exposed bedrock are mainly covered with mosses, herbs, and grasses. These ecosystems are very fragile and recovery following disturbance to the moss layer is very slow. Several Snuneymuxw First Nation petroglyph sites occur on these mossy meadows at scattered locations on Gabriola. 

What have been the primary disturbances within Gabriola’s forests?  How have the  CDF forests and associated ecosystems on Gabriola changed over time?

There has been a long history of forest harvesting on the island, beginning in the early 1900’s. However, the effects of past logging are probably less apparent than on most other Gulf Islands, and there has been no large-scale harvesting since the 1990’s, shortly after Weldwood sold its extensive forestry holdings and moved off the island. Much of the past logging on Gabriola has been by selective harvesting, often targeting high value, single species such as western redcedar. Further, almost all post-harvesting and post-wildfire regeneration has occurred naturally. This is in contrast to other Gulf Islands, such as Galiano, that have experienced extensive clearcutting and monoculture replanting.  So, unlike many other Gulf Islands, there are virtually no industrial forest plantations on Gabriola. There are a small number of Private Managed Forest Land properties on Gabriola, but much of this land has been recently subdivided into residential lots or is in the process of being subdivided.

Despite these lower impacts from industrial forestry, being only a short ferry ride away from Nanaimo, the pressures of rural development on Gabriola, and the disturbance of natural habitat, has been higher on Gabriola than on many other islands in the Islands Trust Area. Only Mayne Island has a higher amount of human disturbance than Gabriola. Gabriola has the second highest population density of all the islands in the Trust Area (only slightly below Bowen Island). According to the Regional Conservation Plan (2018-2027) of the ITC, 27% of Gabriola’s ecosystems had been modified for human use (ITC, 2018). As Gabriolans well know, there has been even more disturbance of natural habitat on our island during the five years since that report was written.

The Islands Trust Council has cited research showing ecosystem health will likely decline at disturbance levels above 30%, so the serious threat of relentless development pressure to the health and sustainability of the Gabriola community and to the island’s sensitive ecosystems is very real (2019). There are currently more than 500 undeveloped properties on Gabriola, and future “build out” will inevitably result in even greater fragmentation of natural habitat. In addition to fragmentation of habitat, further development will put added pressure on groundwater resources, which will in turn affect CDF ecosystem health.

There have been no major forest fires on Gabriola for the past 80-100 years, and wildfire threat and fire restrictions are taken very seriously. However, as is the case with most other Gulf Islands, widespread fire suppression has resulted in the accumulation of unnaturally high fuel loads in many island forests. Fuel management activity has been minimal, so the threat of a future catastrophic wildfire is high. However, mitigating fire risk is a very complex issue. For example, prior to its protection, the 707 Community Park (once 707 acres in size, and more recently was expanded to over 1,100 acres) was essentially clear cut in the early 1990s. Instead of being replanted, it was left to naturally regenerate. While this has generally resulted in high biodiversity, it has meant that in some areas conifer trees have regrown at high density creating an increased fire risk. Had this been managed (i.e. through selective thinning) early in the regeneration cycle, fire risk would likely be relatively low today. Now that the forest is over 20 years old, however, the level of disturbance that might be caused by intervening would undoubtedly cause significant ecological damage. Further, the existing 707 Community Park management plan restricts active forest management. This is meant to allow forest succession to unfold naturally, but in practice may depress biodiversity and increase fire risk.

Similar to many other Gulf Islands, Gabriola has a high black-tailed deer population with no natural predators. This has resulted in heavy browsing and alteration of the native understory of island forests, and native plant gardens and restoration plantings must be protected with fencing. Fortunately, Gabriola does not have the added pressure of fallow deer populations that impacts some other Islands in the region.

Human disturbance of natural landscapes has resulted in the introduction of several invasive plant species on Gabriola. Common invasive species include Scotch broom, daphne, tansy ragwort, English ivy, and holly. Also, yellow flag iris and reed canary grass are becoming established in some of Gabriola’s wetlands. Gabriola Land and Trails Trust (GaLTT) volunteers are very involved in the removal of invasive species on the island, with different species being prioritized in different seasons.  Unfortunately, simply removing invasive species often results in other invasive species (e.g., periwinkle) becoming established. Restoration efforts have been most successful when invasive removal is accompanied by re-seeding and planting native species. For several years, GaLTT has worked closely with BC Parks and other community groups to restore a beautiful Garry oak meadow on Gabriola. It’s been heartening to observe the re-emergence of wildflowers, such as camas and spring gold, where previously only Scotch broom could be found.

Finally, a changing climate is rapidly changing the character of Gabriola’s CDF forests. Prolonged summer drought in recent years has caused significant mortality of western redcedar, grand fir, and western hemlock. This trend will likely result in the essential disappearance of these species from island forests in future decades. 

Are there changes needed to secure a more stable future for CDF habitats?

Only 12% of Gabriola’s land area is currently protected within Regional District parks, provincial parks, nature reserves, and conservation covenants. This is the fourth lowest rate of protection among the 13 major islands in the Trust Area, and far below the Islands Trust average of 20% protected land. Of the four most populated Trust Areas, Gabriola ranks dead last in the relative and absolute amounts of protected land. Compared to Gabriola’s 12% of protected land, each of Salt Spring, Bowen, and Pender islands have more than 20% of their land areas under some form of protection. Though we are slowly making progress—only 4% of Gabriola was protected when GaLTT was formed in 2004 – much more work is required.

In addition to the rapidly increasing costs of land acquisition common to many Gulf Islands, Gabriola is faced with some unique conservation challenges: Our island has the largest proportion of small properties (less than 0.5 ha) in the entire Trust Area and has the lowest percentage of parcels more than 20 ha. Approximately 10% of Gabriola’s land area (approximately 600 ha of provincially and federally managed lands) has been set aside for treaty settlement with the Snuneymuxw First Nation. These lands include some of the largest undisturbed parcels on the island and represent a large portion of the island’s unfragmented mature forest, wetlands, and high biodiversity ecosystems.

Approximately 17% of Gabriola’s land area is held within the Agricultural Land Reserve. This designation was applied based on high level mapping undertaken in the 1970s when the ALR was first established. Much of this land is forested and may be better suited for growing trees than growing crops. However, due to ALR restrictions, virtually none of the undisturbed, forested parcels are realistically available for protection by conservation covenant.

GaLTT works to formally protect CDF ecosystems on Gabriola and nearby islands through land acquisition and conservation covenants. GaLTT also recently launched a new Nature Stewards program to informally engage with private landholders to encourage voluntary restoration and retention of native habitat and to help people make more ecologically sensitive decisions on their private properties. About two-thirds of the land on Gabriola is privately owned, so the support and commitment of these landholders will be critical in retaining remaining natural ecosystems and in restoring ecosystems that have been previously disturbed. The goal of the Nature Stewards program is to raise community awareness about the importance of protecting threatened CDF ecosystems and to ask as many Gabriolans as possible to voluntarily agree to keep at least 30 percent of their properties as natural habitat.

Another urgently needed change is for the provincial government to grant the Islands Trust the jurisdictional authority to preserve and protect CDF ecosystems, including the ability to regulate forestry operations and tree cutting. For example, clearcutting of forests and logging of old-growth trees should not be allowed anywhere in the Trust Area. There are other proven models of sustainable forest harvesting systems in CDF forests that do not require large-scale removal of trees across the landscape. Finally, sensitive ecosystem mapping and terrestrial ecosystem mapping needs to be updated and improved on Gabriola, and presumably other Gulf Islands. 

What are your key recommendations for people living in and maintaining CDF forests? 

Firstly, I encourage all Gulf Islanders to get outside and experience the incredible beauty and diversity of our CDF ecosystems. GaLTT firmly believes public support for conservation is enhanced when people are given the opportunity to learn about, and experience, the natural world. That is one of the major reasons GaLTT advocates for, builds, and maintains an extensive public trail network on Gabriola, including signing trail license agreements with private landholders. A desire to connect Gabriolans with the natural world surrounding them is one of the main reasons GaLTT developed a Big Tree Registry, which documents and celebrates Gabriola’s largest specimens of all tree species native to the CDF. Community members are encouraged to nominate trees, either on their own properties or on public land. 

Secondly, we all need to become advocates for strengthened Islands Trust regulatory authority, especially in the areas affecting ecosystem preservation and protection. Without the necessary jurisdictional authority, the IT cannot effectively uphold its ‘preserve and protect’ mandate, which is viewed by many people as an overarching priority to safeguard the ecological integrity of the Trust Area. Landholders with the good fortune of living on larger properties with significant natural features like mature forests, woodlands, wetlands, and other valuable wildlife habitat areas might consider permanently protecting the land for future generations by placing a conservation covenant on the property.

It is also important to keep updated, ground truthed, and maintained ecosystem maps, as so many land-use decisions are made using these spatial data. Current mapping cannot be relied upon, especially to plan for protecting sensitive ecosystems, as it is often out of date,  too high-level, and has not been ground truthed. The data used to designate land into the ALR for example, is around 50 years old having been collected in the 1970s and is likely no longer an accurate representation of current ecological conditions.

Finally, I encourage all private landholders – those with large properties and those with small rural lots – to take voluntary actions to maintain or restore native habitat on their own properties. The collective actions of neighbours and neighbourhoods can have a huge positive impact on maintaining unfragmented natural ecosystems. 

About Rob Brockley

Rob Brockley worked for BC Ministry of Forests, Research Branch as a forest research scientist for 30 years. Originally from coastal BC, he moved back to the coast (Gabriola Island) from Vernon after retiring in 2010. He joined the board of the Gabriola Land and Trails Trust in 2012 and became board president in 2019. 

Additional reading and references

Islands Trust Conservancy. (2018). Islands Trust Conservancy: Regional conservation plan. https://islandstrust.bc.ca/document/itc-regional-conservation-plan-2018-2027-2/

Islands Trust Council. (2019). State of the Islands indicator project: Final report. https://islandstrust.bc.ca/wp-content/uploads/2020/05/TAS_2020-01-22_StateOfTheIsland_FinalReport-with-Survey.pdf

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