The Changing Nature of Garry Oak Ecosystems
By Eve Ruth
Keywords: Indigenous Stewardship, Restoration, Urbanization, Climate change, Garry Oak Ecosystems
Acknowledgment
Much of my understanding of Garry Oak ecosystems has come from having the privilege of participating in meadow restoration on the territory of the Lekwungen and WSANEC peoples, where I am an uninvited guest. I have been very fortunate to learn from knowledge holders, community members and ecologists on this territory.
Summary
The Garry Oak Ecosystems we see on Southeastern Vancouver Island today are a product of the complex interactions between climatic changes, Indigenous Stewardship, settler colonialism, and urbanization. They are profoundly anthropogenic and are deeply valued by both the Coast Salish People, who are their original stewards, and the many other people who live near them today. Despite this, less than 5% of their original extent remains due to urbanization, invasive species, and conifer encroachment. Efforts to support their recovery include revitalization of Indigenous stewardship, community restoration, and land conservation. The future is uncertain for these ecosystems. Climate change promises to bring warmer, drier conditions that will expand the range of potential growing conditions, but urban fragmentation, topographic barriers and the sheer speed of change prevents most species from taking advantage of this. Assisted migration is a possibility that needs further research. Invasive species will likely naturalize, bringing about novel assemblages. Stewardship, restoration, and conservation will continue and likely allow culturally important species and spaces to persist into the future, though the extent of this impact is impossible to predict at this time.
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Ecological Geneaology
The beginnings of what we now know as Garry oak ecosystems or camas meadows began in Southwestern British Columbia sometime after the last glaciation about 12,000 years ago (Beckwith, 2004; Marsico, 2008; McCune et al., 2013). The species that make up these ecosystems likely arrived from nearby glacial refuges and unglaciated areas further south (Marsico, 2008). Sometime after these ecosystems began to assemble, Indigenous People began to manage them to improve the production of important foods and medicines (Beckwith, 2004). It is unclear when exactly this began, but oral history and palaeoecological evidence indicate that Indigenous Stewardship of savannahs in this area goes back thousands of years (Beckwith, 2004; McCune et al., 2013). The principal species cultivated within these meadows was Camas (Beckwith, 2004; Penn, 2006). Comprising two local species, Camassia quamash and Camassia leichtlinii, camas is a perennial herb with a starchy bulb and blue flowers in the Asparagaceae family. Camas bulbs were one of the main sources of starch for the Straits Salish people and were baked in large pit cooks to break down the inulin they contained (Beckwith, 2004; Penn, 2006). Camas was also an important part of the economy and was traded up and down the coast between Nations (Beckwith, 2004; Penn, 2006). Camas was cultivated through burning, weeding, and sowing (Beckwith 2001; Penn 2006). This created a biodiverse open meadow landscape made up of forbs and some grasses with very few Garry oaks, Quercus garryana, and arbutus trees Arbutus menziesii scattered across the landscape (Beckwith, 2004; Gedalof et al., 2006). This open meadow landscape persisted even as the climate became cooler and wetter during the Little Ice Age; these changing climate conditions should have enabled rapid conifer canopy cover, but it is clear from the palaeoecological record this was prevented in large part by prescribed burns and other traditional management techniques (Beckwith, 2004; McCune, 2013; Pellatt & Gedalof, 2014).
Major changes in Camas meadows began at the end of the 18th century when epidemics of diseases from Europe began to decimate indigenous populations (Beckwith, 2004; Gedalof et al., 2006). This decreased Coast Salish capacity for camas cultivation, and it is during this period that conifer encroachment begins in Garry Oak ecosystems (Pellatt et al., 2015). In 1843, Fort Victoria was established by the Hudson’s Bay Company in what is now known today as downtown Victoria (Beckwith, 2004). The site was selected in large part due to the open park-like nature of the Garry Oak ecosystems surrounding the area, which Europeans found very attractive (Penn, 2006). Enabled by the concept of terra nullius, “belonging to no one,” and misleading treaties, Europeans began colonizing the land around Fort Victoria (Beckwith, 2004; Penn, 2006; Pellatt & Gedalof, 2014). Much of the nearby meadows were immediately converted to agriculture via plough or livestock grazing (Beckwith, 2004; Pellatt et al., 2015). At the same time, settlers began to prevent forcibly the prescribed burns that maintained the open meadows because they found them alarming (Beckwith, 2004; Pellat et al., 2015). This further enabled conifer encroachment. Settlers brought many plants with them, which quickly spread once introduced and by 1876, English daisies Bellis perennis, gorse Ulex europaeus and Scotch broom Cytisus scoparius had become naturalized (Beckwith, 2004). The Indian Act and the reserve system further limited Indigenous people's ability to steward the land as they had done for thousands of years by restricting movement off the reserve and regulating what could be grown on the reserve (Penn, 2006). Residential schools also impeded the transfer of knowledge on stewardship practices between generations. As Fort Victoria became a city, urbanization spread throughout southwestern British Columbia, destroying and fragmenting the vast majority of the Garry Oak ecosystems (Fuchs, 2001).
Major changes in Camas meadows began at the end of the 18th century when epidemics of diseases from Europe began to decimate indigenous populations (Beckwith, 2004; Gedalof et al., 2006). This decreased Coast Salish capacity for camas cultivation, and it is during this period that conifer encroachment begins in Garry Oak ecosystems (Pellatt et al., 2015). In 1843, Fort Victoria was established by the Hudson’s Bay Company in what is now known today as downtown Victoria (Beckwith, 2004). The site was selected in large part due to the open park-like nature of the Garry Oak ecosystems surrounding the area, which Europeans found very attractive (Penn, 2006). Enabled by the concept of terra nullius, “belonging to no one,” and misleading treaties, Europeans began colonizing the land around Fort Victoria (Beckwith, 2004; Penn, 2006; Pellatt & Gedalof, 2014). Much of the nearby meadows were immediately converted to agriculture via plough or livestock grazing (Beckwith, 2004; Pellatt et al., 2015). At the same time, settlers began to prevent forcibly the prescribed burns that maintained the open meadows because they found them alarming (Beckwith, 2004; Pellat et al., 2015). This further enabled conifer encroachment. Settlers brought many plants with them, which quickly spread once introduced and by 1876, English daisies Bellis perennis, gorse Ulex europaeus and Scotch broom Cytisus scoparius had become naturalized (Beckwith, 2004). The Indian Act and the reserve system further limited Indigenous people's ability to steward the land as they had done for thousands of years by restricting movement off the reserve and regulating what could be grown on the reserve (Penn, 2006). Residential schools also impeded the transfer of knowledge on stewardship practices between generations. As Fort Victoria became a city, urbanization spread throughout southwestern British Columbia, destroying and fragmenting the vast majority of the Garry Oak ecosystems (Fuchs, 2001).
Present Tense
Today, Garry Oak ecosystems are among the most endangered in all of Canada, occupying less than five percent of their original range (Gedalof, 2006, Penn 2006). Fire suppression, fragmentation, urbanization, and invasion of exotic species have all taken their toll and continue to threaten these ecosystems (GOERT, 2002; Beckwith, 2004). Remnant patches are most abundant in rocky sites where the soil was too shallow ever to be ploughed (GOERT, 2002). The shallow soil in these sites also prevents the encroachment of shrubs and conifers (Fuchs, 2001). A report in 2001 identified 61 plant taxa, 18 invertebrates, 2 reptiles, 9 birds and 3 mammals within Garry Oak ecosystems as being at risk (Fuchs, 2001). Invasive exotic species like Scotch broom Cytisus scoparius, English ivy Hedera helix, daphne Daphne laureola and various agronomic grasses dominate many remnant meadow sites, suppressing the growth of nearby native species (Pellatt & Gedalof, 2015). Native Blacktail deer Odocoileus hemionus columbianus populations have increased well outside of their historical population levels in many areas and, due to their preferential browsing of native species, are decimating wildflower populations (Fuchs, 2001).
To counteract the high rate of degradation and destruction of this ecosystem, restoration efforts are springing up all around the region. Community groups, Indigenous knowledge holders, ecologists and conservation organizations are all working to preserve this valued ecosystem. Since 2000, Lekwungen Knowledge holder Cheryl Bryce from the Songhees Nation has been working to return traditional management practices like prescribed burns and camas harvesting to the land while also working to remove the invasive species that are encroaching (Penn, 2006). In 1999, The Nature Conservancy of Canada acquired the Cowichan Garry Oak preserve, which, at 33 hectares, is now considered to be one of the largest relatively intact sections of the Garry Oak meadow habitat (NCC, 2024). Within the Gulf Islands National Park Reserve, Parks Canada is working to restore Garry Oak ecosystems on several islands through the exclusion of deer browsing and the removal of invasive species (GINPR, 2023). |
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Future Trajectories
Garry Oak ecosystems are adapted to warm, dry conditions, and as such, Climate Change has some hoping for a sudden expansion of suitable Garry Oak habitats equal to and beyond the largest extent that existed about 8000 years ago under the warmer, drier climate (GOERT, 2002). The reality is, unfortunately, more complicated than this.
Climate change does indeed have the potential to expand GOE growing conditions in British Columbia (Bodtker et al., 2009; Loarie et al., 2009). However, the sheer speed at which our climate is changing makes it unlikely that GOE species will be able to migrate north fast enough to take advantage of this (Bodtker et al., 2009). One estimate suggests that the current climate of these ecosystems will move north at a rate of 0.59 Km per year over the next hundred years, faster than most species can keep up (Loarie et al., 2009). Urban fragmentation, along with natural topographical barriers, also stand in the way of northward migration, meaning that seeds may never reach the habitat they could thrive in without human intervention (Bodtker et al., 2009; Loarie et al., 2009). Some scientists are working to overcome this barrier through assisted migration, which is the intentional movement of species beyond their historical range, typically northward, to areas that are or are expected to become more suitable for them under climate change (Lunt et al., 2013). Concerns around assisted migration creating invasive species rather than preserving biodiversity mean that it must be approached very cautiously. There is a very real potential that assisted migration could support the survival of Garry oaks and associated species and assist in revegetating areas that lose heat-intolerant native species; however, there is not enough data to provide predictions on how successful this could be. A study on Garry Oak meadow-associated butterflies suggests supporting adaptation to climate change is not as simple as moving species farther north (Pelini et al., 2009) Even if some GOE species are successful in moving northward, they will move as individuals, not as entire ecosystems (Baker, 2018). This will bring about new species assemblages, creating novel ecosystems that will likely be a combination of Garry Oak meadow species, northern plant communities and the invasive species that will inevitably spread with them. Within their current range, invasive species will continue to be a threat, and extreme climate conditions will only increase (Loarie et al., 2009). Conservation and restoration efforts will no doubt have an impact, though it is too early to predict how large these might be. It is easy to imagine that the highly valued spaces, parks, backyards, protected areas, and cultural sites where effective restoration is carried out regularly will likely continue to support some version of the Garry Oak ecosystem we know today. Some heavily managed spaces might evolve into what we consider to be a designed ecosystem functioning only with human input (Higgs, 2017). Perhaps restoration efforts will give some species enough time to adapt to changing conditions. The future of these ecosystems is uncertain, but this is not the first time they have undergone massive change. Human stewardship and relationships to the land have fostered biodiversity for thousands of years and have enabled culturally important species to survive climatic change in the past (Beckwith, 2004; McCune, 2013; Pellatt & Gedalof, 2014). Perhaps the revitalization of Indigenous stewardship practices alongside current conservation efforts will enable this ecosystem or at least some version of it to persist into the future. |
References
Barlow, C. M., Pellatt, M. G., & Kohfeld, K. E. (2021). Garry oak ecosystem stand history in Southwest British Columbia, Canada: Implications of environmental change and indigenous land use for ecological restoration and population recovery. Biodiversity and Conservation, 30(6), 1655–1672. https://doi.org/10.1007/s10531-021-02162-2
Beckwith, B. R. (2004). The queen root of this clime: Ethnoecological investigations of blue camas (Camassia leichtlinii (Baker) Wats., C. quamash (Pursh) Greene ; Liliaceae) and its landscapes on southern Vancouver Island, British Columbia. http://hdl.handle.net/1828/632
Bodtker, K., Pellatt, M., & Cannon, A. (2009). A bioclimatic model to assess the impact of climate change on ecosystems at risk and inform land management decisions: Report for the Climate Change Impacts and Adaptation Directorate, CCAF Project A718. Parks Canada Report.
Fuchs, Marilyn A. 2001. Towards a Recovery Strategy for Garry Oak and Associated Ecosystems in Canada: Ecological Assessment and Literature Review. Technical Report GBEI/EC-00-030. Environment Canada, Canadian Wildlife Service, Pacific and Yukon Region..
Gedalof, Z., Pellatt, M., & Smith, D. (2006). From prairie to forest: Three centuries of environmental change at Rocky Point, Vancouver Island, BC. Northwest Science, 80, 34–46.
GOERT. 2002. Recovery Strategy for Garry Oak and Associated Ecosystems and their Associated Species at Risk in Canada, 2001-2006. Garry Oak Ecosystem Recovery Team
Higgs, E. (2003). Nature by Design: People, Natural Process, and Ecological Restoration. MIT Press.
Higgs, E. (2017), Novel and designed ecosystems. Restoration Ecology, 25: 8-13. https://doi-org.ezproxy.library.uvic.ca/10.1111/rec.12410
Huebert, C. A. (2009). THE ECOLOGICAL AND CONSERVATION GENETICS OF GARRY OAK (Quercus garryana Dougl. Ex Hook).
Loarie, S., Duffy, P., Hamilton, H. et al. The velocity of climate change. Nature 462, 1052–1055 (2009). https://doi-org.ezproxy.library.uvic.ca/10.1038/nature08649
Marsico, T. (2008). Post -glacial migration, limitations to poleward range expansion, and growth responses to future climates of plants in the Garry oak ecosystem—ProQuest. https://www.proquest.com/openview/adadfefd3f14612b8da1b3b5fc097a8d/1?pq-origsite=gscholar&cbl=18750
McCune, J. L., Pellatt, M. G., & Vellend, M. (2013). Multidisciplinary synthesis of long-term human–ecosystem interactions: A perspective from the Garry oak ecosystem of British Columbia. Biological Conservation, 166, 293–300. https://doi.org/10.1016/j.biocon.2013.08.004
Pellatt, M. G., & Gedalof, Z. (2014). Environmental change in Garry oak (Quercus garryana) ecosystems: The evolution of an eco-cultural landscape. Biodiversity and Conservation, 23(8), 2053–2067. https://doi.org/10.1007/s10531-014-0703-9
Pellatt, M. G., McCoy, M. M., & Mathewes, R. W. (2015). Paleoecology and fire history of Garry oak ecosystems in Canada: Implications for conservation and environmental management. Biodiversity and Conservation, 24(7), 1621–1639. https://doi.org/10.1007/s10531-015-0880-1
Beckwith, B. R. (2004). The queen root of this clime: Ethnoecological investigations of blue camas (Camassia leichtlinii (Baker) Wats., C. quamash (Pursh) Greene ; Liliaceae) and its landscapes on southern Vancouver Island, British Columbia. http://hdl.handle.net/1828/632
Bodtker, K., Pellatt, M., & Cannon, A. (2009). A bioclimatic model to assess the impact of climate change on ecosystems at risk and inform land management decisions: Report for the Climate Change Impacts and Adaptation Directorate, CCAF Project A718. Parks Canada Report.
Fuchs, Marilyn A. 2001. Towards a Recovery Strategy for Garry Oak and Associated Ecosystems in Canada: Ecological Assessment and Literature Review. Technical Report GBEI/EC-00-030. Environment Canada, Canadian Wildlife Service, Pacific and Yukon Region..
Gedalof, Z., Pellatt, M., & Smith, D. (2006). From prairie to forest: Three centuries of environmental change at Rocky Point, Vancouver Island, BC. Northwest Science, 80, 34–46.
GOERT. 2002. Recovery Strategy for Garry Oak and Associated Ecosystems and their Associated Species at Risk in Canada, 2001-2006. Garry Oak Ecosystem Recovery Team
Higgs, E. (2003). Nature by Design: People, Natural Process, and Ecological Restoration. MIT Press.
Higgs, E. (2017), Novel and designed ecosystems. Restoration Ecology, 25: 8-13. https://doi-org.ezproxy.library.uvic.ca/10.1111/rec.12410
Huebert, C. A. (2009). THE ECOLOGICAL AND CONSERVATION GENETICS OF GARRY OAK (Quercus garryana Dougl. Ex Hook).
Loarie, S., Duffy, P., Hamilton, H. et al. The velocity of climate change. Nature 462, 1052–1055 (2009). https://doi-org.ezproxy.library.uvic.ca/10.1038/nature08649
Marsico, T. (2008). Post -glacial migration, limitations to poleward range expansion, and growth responses to future climates of plants in the Garry oak ecosystem—ProQuest. https://www.proquest.com/openview/adadfefd3f14612b8da1b3b5fc097a8d/1?pq-origsite=gscholar&cbl=18750
McCune, J. L., Pellatt, M. G., & Vellend, M. (2013). Multidisciplinary synthesis of long-term human–ecosystem interactions: A perspective from the Garry oak ecosystem of British Columbia. Biological Conservation, 166, 293–300. https://doi.org/10.1016/j.biocon.2013.08.004
Pellatt, M. G., & Gedalof, Z. (2014). Environmental change in Garry oak (Quercus garryana) ecosystems: The evolution of an eco-cultural landscape. Biodiversity and Conservation, 23(8), 2053–2067. https://doi.org/10.1007/s10531-014-0703-9
Pellatt, M. G., McCoy, M. M., & Mathewes, R. W. (2015). Paleoecology and fire history of Garry oak ecosystems in Canada: Implications for conservation and environmental management. Biodiversity and Conservation, 24(7), 1621–1639. https://doi.org/10.1007/s10531-015-0880-1