Course:CONS200/2023/Riparian buffer zones restoration: Why is it important for conserving salmon habitats?

From UBC Wiki
Salmon, Image from Wikimedia Commons.

A riparian buffer zone is an area, usually highly vegetated, near a stream which provides sanctuary to many biotic communities, including Salmon. According to Young, “Riparian zones contribute critically to the ecological character of forest ecosystems by containing high levels of floral and faunal diversity creating unique microclimates, providing connectivity within increasingly fragmented landscapes, and serving as chemical, biological, and physical boundaries between streams and rivers and the watersheds they drain” [1]. As a keystone species, salmon support saltwater and freshwater ecosystems. According to Ecology and Society, salmon contribute to three of four ecosystem services[2]: provisioning, as a food source; cultural, lending to spiritual practices of indigenous peoples; and supporting, as vehicles for marine nutrients toward freshwater ecosystems. The first step in conservation efforts for these ecologically important zones is often assessment practices. This will help conservationists understand what must be done and which zones are in most need of conservation help. Additionally, the use of new screening technology will help scientists uncover “infecting agents” which pose threats to fish health and genotype technology can help to stop the illegal fishing trade and in turn the overfishing that many of these zones are experiencing [3]. The buffer zone is an essential part of the salmon's life cycle, with the loose gravel and sediment being essential habitat for salmon eggs. Due to anthropocentric activities like “logging and road building”[4], riparian zones have been degraded throughout the British Columbia.

Riparian Zones and Buffers

Riparian Buffer Zone. Image from Wikimedia Commons.

Riparian zones are the interfaces between waterways and adjacent lands. Riparian buffers, however, are a vegetated and undisrupted area between a waterway and a disruptive land use activity, such as a farm or an urban area[5].

Riparian Zone

As water flows downhill, it will establish preferential flow paths based on the path of least resistance, which ultimately results in the formation of channels for streams and rivers. As water drains across the lands surface, it interacts with many different land covers[5]. Riparian Zones encompass both the terrestrial and aquatic ecosystems near and surrounding water channels [6]. The zone is an area providing a natural sanctuary to many biotic communities, including Salmon and other riparian wildlife. Riparian zones contribute critically to a forest's ecosystems because of the presence of plant and animal communities diversifying a forest into multiple microclimates within stream based ecosystems. The exact boundary of a riparian area is often difficult to determine because it is a zone of transition between the water body and the upland vegetation [7]

A riparian zone can be quantified and categorized into main features depending on the topography, soil conditions, width of the natural flood plain area and natural vegetation zones.[8] The focus is primarily on immediate surroundings near streams and channel corridors that would have the most direct buffer effect on the many biotic creatures within stream ecosystems.

Buffer Zone

Buffer zones essentially serve as an indirect shelter against land use impacts while supporting ecosystem services within waterways, acting as a buffer between land and streams[5]. Found within a riparian zone, are the riparian buffers that are highly vegetated areas most proximate to water . Natural, vegetated riparian buffers provide key ecological functions, including bank stabilization, decreased erosion, flood buffering, sediment and nutrient filtration, shading and temperature moderation, and climate regulation[5]

Ecosystem Services

Socio-economic values and uses of riparian zones consist primarily of species richness and diversity, bank stabilization and flood control, nutrient-rich soil for agricultural activities, aesthetic benefits for residential properties, recreational opportunities, including birdwatching, hunting, biking, and hiking and water filtration for improved water quality. [5]

Damaging Agents

Dams

The construction and implementation of dams has large scale impacts for riparian zones. Dams cause blockages in the stream which forces the water to pool on the bank and flood the buffer zones. This will completely alter the buffer zones and transform them into aquatic zones. When dams are implemented into these fragile ecosystems, the riparian buffer zones can be affected both above and below the dams[9]. Above the dams, the entirety of these zone will be flooded in a completely state altering way and can result in a complete change in the type of vegetation and in turn fauna that grows and lives in these areas [9]. Additionally, erosion can occur both above and below dammed areas due to factors such as saturated river banks or significant changes in water flow velocity and quantity. Dams are built as a source of renewable energy created by hydropower. They are able to regulate the flow of water that they release and this constant alteration of flow in these rivers and streams can be extremely detrimental to the health of the ecosystems both in the main body of the river and in the riparian buffer zones [9].

Bank erosion
Bank Erosion, image from Wikimedia Commons.

Logging

Logging has had a large effect on riparian zones historically, and continues to have a large effect to this day. Historically log flumes were used to transport cut logs to a river to then be transported down difficult terrain to then bunch logs at river heads. These bunched logs would then be transported downstream in large rafts called timber rafts. These rafts would float downstream, causing damage to the river where ever jams would occur, causing flooding and stream bank damage[10].

Another damaging aspect of logging is the removal of trees and the implications that this absence of vegetation has on the area. Trees and smaller vegetation has a way of holding moisture and humidity in the area which is vitally important for riparian buffer zones. Without these trees and plants, these ecosystems will be far more xeric and less able to perform the ecosystem services that it would be able to in a more mesic environment. [11]

Modern logging has greatly improved its methods, reducing damage to riparian zones but its effects can still be seen in logged areas[12]. The removal of trees destabilizes soils which is further degraded by the impacts of heavy duty equipment impacting and altering the structural integrity of the soil. These effects are most shown in increased sediment load of logged streams, with much higher fine particle content being found in these streams along with more nutrients such as nitrogen and potassium [12].

Livestock

Livestock can have negative effects on riparian zones, with large animals such as cattle, sheep and pigs being land scape engineers. These animals when released in a riparian zone will weaken stream banks due to their weight, and will feed on important species that are only found in the riparian zone. Heavy livestock such as cattle can cause major destruction and erosion in these fragile riparian areas[13]. Additionally, soil compaction in these eroded and trampled areas make it much more difficult for important plants to grow. With an absence of such plants, riparian buffer zones are no longer able to hold important humidity levels or or act as habitats for animals, eventually causing a decrease in species diversity in both the flora and fauna[13].

Mining and Road construction

Resource extraction is an incredibly destructive process, with many of its effects being seen in riparian zones. Mining and road construction require large amounts of bedrock to be deposited, with this material often being deposited wherever is convenient. This leads to waste materials often being placed in riparian zones to stabilize their soils for heavy equipment. The fine sediment that is released also effects the stream beds down stream of deposited waste materials. It is not uncommon for mining and extraction projects to completely destroy riparian zones[14]. This is detrimental for multiple reasons one of them being that riparian areas are known as one of the most effective carbon sequestration ecosystems which means that it is of pivotal importance when put into consideration with the increase of greenhouse gasses in the atmosphere[14].

Infecting Agents

Most infecting agents, such as those that are considered runoff from pesticides and nutrients released onto crops, are not actually especially detrimental to the health of riparian buffer zones. These zones act as a filtration system between the runoff and the rivers or streams that they are buffering [15]. This, in addition to all the other reasons that riparian buffer zones are incredibly important, is pivotal when it comes to the health of the world’s near land aquatic ecosystems.

Conservation Methods

Methods of Restoration

The restoration of depleted or destroyed riparian buffer zones is one of the main concerns for many environmental protection groups, as they are responsible for much of the biodiversity in an ecosystem. Do to this there are many different methods of restoring riparian zones. The plantation of native species along transitional zones is a common way of protecting shore lines as the native species stabilize the soil and prevent erosion from destroying the bank. These plants also provide habitat for many different species, including insects, birds and small mammals.

Restoration Method, Image from Wikimedia Commons.

The reconstruction of man made channels has begun to become common place is certain areas, including the interior of British Columbia. [16] This restoration is often more intensive as it often requires the diversion of watershed to allow heavy equipment to restore the cannel to a more natural state.

Laws and Governance

Due to the inherent value of riparian zones, there are strict rules that govern the management and construction around these areas. The Riparian Areas Protection Act [17] was created in the late 90's to act as president for the protection of riparian zones. The Riparian Management Field Workbook [18] also sets guidelines on what practices must be followed in the management of said areas. These include survey guidelines[19], building guidelines[20], and guidelines for agriculture and livestock uses.[21][22][23][24]


Pacific Salmon Habitat and Lifecycle

Salmon Migration, Image from Wikimedia Commons.

In North America, 7 species of Pacific Salmon can be found. Chinook salmon (Oncorhynchus tshawyscha) are the biggest in average size at maturity, followed by Chum (Oncorhynchus keta), Coho (Oncorhynchus kisutch), Sockeye (Oncorhynchus nerka) and the smallest species, Pink salmon (Oncorhynchus gorbuscha). Pacific Salmon are anadromous fish that are recognized for their extensive migrations that can be thousands of kilometers long, which start in fresh water as fertilized eggs that are buried for several months in gravel by their mother [25]. The fertilized eggs hatch into alevin, which are nourished from a yolk sac [25]. The alevin live in the rocky substrate of the stream or lakebed until their yolk sac is consumed, where they emerge into a lake or stream, and are then termed salmon “fry” [25]. After some period in fresh water, which varies between days, months or years amongst species and populations, all species exemplify anadromy, which is a seaward migration to feed primarily in the ocean, grow to their final size, and then return to fresh water to reproduce [25][26]. Eventually, they will return to their natal stream to reproduce, before this lifecycle is repeated by their offspring.


Importance of Salmon to Ecosystems, Economy and Culture

Intrinsic Value

Grizzly bear with salmon, Image from https://commons.wikimedia.org/wiki/Main_Page

Keystone Species

Oxford Languages defines a keystone species as "a species on which other species in an ecosystem largely depend, such that if it were removed the ecosystem would change drastically." Salmon are a keystone species in both marine and fresh-water ecosystems. In fresh-water systems, large land predators like bears and wolves feed off salmon. Historically, salmon-rich ecosystems house bear populations of up to 20 times greater in density than those which are salmon-poor, with bears eating an average of 15 salmon per day at peak run[27]. On the lower end of the chain, invertebrates living in vegetation of riparian buffer zones sustain salmon during their time in slower-moving streams. As such, the management of riparian vegetation likely influences salmon's food supply, ultimately impacting the productivity of ecosystems more broadly[28].

Ecosystem Services

Salmon contribute largely to three of four ecosystem services: provisioning, as a food source; cultural, lending to spiritual practices of indigenous peoples; and supporting, as vehicles for marine nutrients toward freshwater ecosystems. They are also indicators of regulating services, though are not directly related[2]. Early studies of salmon's supporting service suggest a positive feedback loop forming: the uptake of salmon-derived marine nutrients by riparian vegetation, and the resulting riparian environment being ideal for salmon spawning[29]. Riparian zones contribute to regulating climate and temperature for streams, and salmon populations are indicative of the health of these zones. Many of the same habitat characteristics that support robust salmon populations, like intact riparian systems, also support regulating ecosystem services.[2]

Extrinsic Value

Economic Contributions

In salmon-rich places such as Coastal British Columbia, the direct economic impact of the species is sizable. A 2007 report by the BC Legislative Assembly's Special Committee on Sustainable Aquaculture exhibits the GDP contributions of salmon farming, wild commercial salmon fishing, and salmon sport fishing. Despite salmon farming being the main contributor to the provincial GDP (accounting for $134 million in 2005), the wild commercial salmon sector accounted for $67 million[30]. When evaluating the trend of the wild commercial salmon industry, it becomes apparent that the size of the industry declined, with total outputs decreasing by more than 30% between 1997 and 2005[30], a trend that is likely to continue without the reparation of salmon habitat, in part by protecting spawning streams from human activities through rich riparian buffer zones.

Cultural Significance

Salmon touch the lives of many as an iconic, native species that symbolizes many positive attributes, from fertility to perseverance[2]. From northern California to the Gulf of Alaska, salmon have been a principal focus of spiritual and cultural lives of Indigenous Nations[31]. Insight into a thriving salmon population could emerge from the significance placed on the species by First Nations. The 2022 Canadian Technical Report of Fisheries and Aquatic Sciences from the Department of Fisheries and Oceans explores the importance of riparian zone management for freshwater fish and fish habitat protection. In this report, section 6.2 of Considerations for Determining Riparian Management Measures is titled Indigenous Knowledge, and states that riparian management measures must develop in partnership with Indigenous peoples and communities that account for their interests and local governance structure over fisheries and natural resources[32].

Why Buffer Zones are Critical for Salmon habitats

Riparian habitats form as transitional habitat between an aquatic ecosystem and a terrestrial ecosystem[33]. These buffer zones between both ecosystems are very biodiverse, acting as an essential habitat for for many different species. Salmon use this buffer area as spawning ground for their eggs as it is acts a shelter repository for their eggs[34]. Without their spawning ground, the eggs of salmon are at a high risk of being predated on by terrestrial and aquatic species.

The ideal salmon spawning habitat is cold fast moving streams or rivers with a gravel bottom.[35] These conditions provide ideal spawning habitat for pacific salmon as females will bury their eggs 12-15cm in the gravel to protect them from predation and the current. Buffer zones provide this spawning habitat for salmon. During a salmon run, mature female salmon will deposit their eggs into the gravel bottom of the buffer zone in a riparian habitat, then proceed to die, completing their lifecycle[36]. The decomposition of the dead salmon release nutrients such as nitrogen and phosphorus into the ecosystem adjacent to the river[37].

These habitats while common, are extremely susceptible to degradation, and once degraded are unable to support salmon spawning.[38] With wide spread degradation of these habitats due to human economic activity, salmon populations have suffered greatly.

References

  1. ↑ Young, K. A. (2000). "Riparian zone management in the pacific northwest: Who's cutting what?". Environmental Management. 26: 131–144.
  2. ↑ 2.0 2.1 2.2 2.3 Bottom, D.L. (2009). "Reconnecting Social and Ecological Resilience in Salmon Ecosystems". Ecology and Society. 14.
  3. ↑ Bank, M. S.; Sonne, C.; Hansson, S.V.; Rillig, M. C. (2021). "Science-informed salmon conservation strategies". Science (American Association for the Advancement of Science). 374: 700.
  4. ↑ Crow, T. R.; Gustafson, E. J. (1997). "Ecosystem management: managing natural resources in time and space". Creating forestry for the 21st century: 215–228.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 Stokes, Gretchen; Smidt, Samuel. "Riparian Buffers and Land Cover Change". Encyclopedia of Inland Waters (Second Edition). 4: 440–449.
  6. ↑ Naiman, Robert; Decamps, Henri (1997). "The Ecology of Interfaces: Riparian Zones". Annual Review of Ecology and Systematics. 28: 621–658.
  7. ↑ Hillard, C; Reedyk, S (07/29/2020). "Riparian Area Management". Agriculture Canada. Retrieved 03/21/2023. Check date values in: |access-date=, |date= (help)
  8. ↑ Mander, Ü; Tournebize, J (2015). "Riparian Buffer Zones: Functions and Dimensioning". Reference Module in Earth Systems and Environmental Sciences.
  9. ↑ 9.0 9.1 9.2 Muhammad, Arif; Jie, Zheng; Wokadala, Charles; Songlin, Zhang; Zhongxun, Yuan; Zhangting, Chen; Dong, Zhi; Xinrui, He; Changxiao, Li (Summer 2021). "Assessing riparian zone changes under the influence of stress factors in higher-order streams and tributaries: Implications for the management of massive dams and reservoirs". Science of The Total Environment. 776 – via Elsevier.
  10. ↑ Sedell, J. R.; Leone, F. N.; Duval, W. S. 1991. Water transportation and storage of logs. In: Influences of forest and rangeland management on salmonid fishes and their habitats; Special Publication 19. [Place of publication unknown]: American Fisheries Society: 325-368.
  11. ↑ Oldén, Anna; Peura, Maiju; Sonja, Saine; Kotiaho, Janne S.; Halme, Panu (2019). "The effect of buffer strip width and selective logging on riparian forest microclimate". Forest Ecology and Management. 453 – via Elsevier. line feed character in |title= at position 74 (help)
  12. ↑ 12.0 12.1 Richardson, John S.; Béraud, Salomé (September 2014). "Effects of riparian forest harvest on streams: a meta-analysis". Journal of Applied Ecology. 51 – via British Ecological Society.
  13. ↑ 13.0 13.1 Roche, Leslie M. "A Review of Livestock Impacts on Riparian Ecosystems: Vegetative and Aquatic Consequences and Grazing Management". Prized Writing.
  14. ↑ 14.0 14.1 Qin, Yunbin; Chen, Zhihao; Ding, Bangjing; Li, Zhengkui (June 2020). "Impact of sand mining on the carbon sequestration and nitrogen removal ability of soil in the riparian area of Lijiang River, China". Elsevier.
  15. ↑ Aguiar, T.R., Bortolozo, F.R., Hansel, F.A. et al. Riparian buffer zones as pesticide filters of no-till crops. Environ Sci Pollut Res 22, [[1]] (2015). https://doi.org/10.1007/s11356-015-4281-5
  16. ↑ "Restore Penticton Creek".
  17. ↑ "Riparian Areas Protection Act".
  18. ↑ Riparian Management Field Workbook.
  19. ↑ [chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www2.gov.bc.ca/assets/gov/environment/plants-animals-and-ecosystems/fish-fish-habitat/riparian-areas-regulations/rar_assessment_methods.pdf "Riparian Areas Regulation Assessment Methods"] Check |url= value (help) (PDF).
  20. ↑ [chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/agriculture-and-seafood/agricultural-land-and-environment/strengthening-farming/local-government-bylaw-standards/riparian-setbacks/823400-1_agricultural_building_setbacks.pdf "AGRICULTURAL BUILDING SETBACKS FROM WATERCOURSES IN FARMING AREAS"] Check |url= value (help) (PDF).
  21. ↑ [chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/agriculture-and-seafood/agricultural-land-and-environment/water/riparian/649000-7_riparian_pasture_design.pdf "Riparian Pasture Design"] Check |url= value (help) (PDF).
  22. ↑ [chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/agriculture-and-seafood/agricultural-land-and-environment/water/riparian/648000-4_selecting_seasonal_feeding_areas.pdf "Selection of Regional Feeding Areas"] Check |url= value (help) (PDF).
  23. ↑ [chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/agriculture-and-seafood/agricultural-land-and-environment/water/riparian/648000-5_managing_seasonal_feeding_areas.pdf "Managing Seasonal Feeding Areas"] Check |url= value (help) (PDF).
  24. ↑ [chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www2.gov.bc.ca/assets/gov/farming-natural-resources-and-industry/agriculture-and-seafood/agricultural-land-and-environment/water/livestock-watering/590302-1_direct_access.pdf "WATERING LIVESTOCK DIRECTLY FROM WATERCOURSES"] Check |url= value (help) (PDF).
  25. ↑ 25.0 25.1 25.2 25.3 Cooke, S.J; Crossin, G.T; Hinch, S.G (2011). Encyclopedia of Fish Physiology: from Genome to Environment. San Diego: Academic Press.
  26. ↑ McDowall (03/2001). "Anadromy and homing: two life-history traits with adaptive synergies in salmonid fishes?". Fish and Fisheries. 2: 78–85. Check date values in: |date= (help)
  27. ↑ Reimchen, T. E. (2000). "Some ecological and evolutionary aspects of bear-salmon interactions in coastal British Columbia". Canadian Journal of Zoology. 78 (3): 448–457.
  28. ↑ Allan, J. D.; Wipfli, M. S.; Caouette, J. P.; Prussian, A. (2003). "Influence of streamside vegetation on inputs of terrestrial invertebrates to salmonoid food webs". Canadian Journal of Fisheries and Aquatic Sciences. 60: 309–320.
  29. ↑ Schindler, D. E.; Palen, W. J. (2003). "Pacific salmon and the ecology of coastal ecosystems". Frontiers in Ecology and the Environment. 1: 403–411.
  30. ↑ 30.0 30.1 MacKay, Stuart; Petersen, Fiona; Rey, Angela (May 2007). "Economic Impacts and Prospects of the Salmon Farming and Wild Salmon Industries in British Columbia". Special Committee on Sustainable Aquaculture – via Legislative Assembly of British Columbia.
  31. ↑ Matson, R. G.; Coupland, G. (1995). "The prehistory of the Northwest Coast". Academic Press, New York.
  32. ↑ Collison, Ben R.; Gormack, Aimee G. (2022). "Importance of riparian zone management for freshwater fish and fish habitat protection: analysis and resommentations". Canadian Technical Report of Fisheries and Aquatic Science.
  33. ↑ "Riparian Forest Buffers". U.S. DEPARTMENT OF AGRICULTURE. 2023-03-24.
  34. ↑ Levy, David A. (July, 1993). A Review of Habitat Capacity for Salmon Spawning and Rearing. gov.bc.ca. Check date values in: |year= (help)
  35. ↑ Levy, David A. (July, 1993). A Review of Habitat Capacity for Salmon Spawning and Rearing. BC Government. Check date values in: |year= (help)
  36. ↑ "The Salmon Life Cycle".
  37. ↑ Bartz, Krista (Aug, 2005). "Effects of Salmon-Borne Nutrients on Riparian Soils and Vegetation in Southwest Alaska". https://www.proquest.com/docview/733070724?accountid=14656&pq-origsite=summon&forcedol=true. Check date values in: |date= (help); External link in |journal= (help)
  38. ↑ Corpuz-Bosshart, Lou (Aug 5, 2021). "Up to 85 per cent of historical salmon habitat lost in Lower Fraser region".


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