A 5,000-Year Fire History in the Strait of Georgia Lowlands, British Columbia, Canada

Improved knowledge of long-term fire regimes and climate-fire-human relationships are important for effective management of forested ecosystems. In this study, we use two, high-resolution sedimentary-charcoal records to provide new, mid to late Holocene fire histories for the driest forests in south coastal British Columbia, Canada: Somenos Lake in the Moist Maritime Coastal Douglas Fir (CDFmm) forests on southeastern Vancouver Island and Chadsey Lake in the Dry Maritime Coastal Western Hemlock (CWHdm) forests in the central Fraser Valley. Peak fire frequency at Somenos Lake in southeast Vancouver Island was highest prior to 3,500 cal yr BP at 9.5 fires per 1,000 years (at ~4,500 cal yr BP), with a mean fire return interval of 188 years (122–259) and 24 fire peaks for the 4,855 year record. Peak fire frequency at Chadsey Lake in the Fraser Valley of the Lower Mainland of BC was highest (5.9) at 2,736 cal yr BP but fairly uniform from ~4,300 to 2,500 cal yr BP. The mean fire return interval at Chadsey Lake was 214 years (150–285) with 15 fire peaks for the ~4,258 year record. The fire history for Chadsey Lake appears to be strongly tied to broad regional climate patterns for the region whereas the variability in the Somenos Lake fire record displays a more complex pattern likely the result of the interplay between climatic and anthropogenic factors. Our results show how different age models using long- vs. short-term temporal scales of analysis can affect fire history interpretation and highlight the importance of considering spatial variability when interpreting mechanisms driving fire activity in this region

Extent of microplastics in Pacific Sand Lance burying habitat in the Salish Sea

Extent of microplastics in Pacific Sand Lance burying habitat in the Salish Sea Willem Peters MRM candidate Simon Fraser University, Dr. Cliff Robinson Department of Fisheries and Oceans, Dr. Karen Kohfeld Simon Fraser University, Dr. Marlow Pellatt Parks Canada, Dr. Doug Bertram Environment and Climate Change Canada School of Resource and Environmental Management, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6 CANADA, [email protected] The ingestion of microplastics by forage fish and their subsequent accumulation and transfer up the coastal food web is a growing concern to scientists, government, fisheries, and the health sector. One key forage species in the Salish Sea, the Pacific sand lance (Ammodytes personatus), buries in low silt, medium coarse sand patches from chart datum to 100 m depth. In the southern Salish Sea near Sidney, several of these burying habitats are located in the vicinity of sewage discharge pipes and may be subject to microplastic accumulation. This research assesses the level of microplastic accumulation in Pacific sand lance burying habitats in the Salish Sea. Seafloor sediment samples were collected in Spring-Fall 2017, using a Van Veen grab sampler. Samples were collected at different distances from shore and effluent discharge pipes, and from a variety of depths and tidal currents. Microplastic concentrations were determined from the sediment samples in the laboratory using standard methods, while controlling for contamination. The main results indicate a significant correlation between suitable Pacific sand lance burying habitat and higher microplastic concentrations. We also found a strong imbalance of microplastic type and colour, with blue fibres making up the majority of microplastics found. The relationship between microplastics and Pacific sand lance habitat suitability is not intuitive in that higher concentrations of microplastics were found in sediments that suggest higher current rates, where settling dynamics would suggest that fewer particles would settle. Possible explanations include evacuation of microplastics from sand lance when buried, the proximity of suitable habitat to effluent discharge, or other as yet unexplored factors. Overall, the presence of microplastics in the burying habitats and stomachs of Pacific sand lance (as noted in other research) indicates more research is required to understand the implication to higher trophic level species that feed upon Pacific sand lance, such as chinook and coho salmon, various groundfish, fish-eating alcids, and marine mammals such as the humpback whale. Ultimately, strategies to reduce microplastics entering the Salish Sea will need to be implemented

Quantification of Blue Carbon in Salt Marshes of the Pacific Coast of Canada

Tidal salt marshes are known to accumulate “blue carbon” at high rates relative to their surface area, which render these systems among the Earth’s most efficient carbon (C) sinks. However, the potential for tidal salt marshes to mitigate global warming remains poorly constrained because of the lack of representative sampling of tidal marshes from around the globe, inadequate areal extent estimations, and inappropriate dating methods for accurately estimating C accumulation rates. Here we provide the first estimates of organic C storage and accumulation rates in salt marshes along the Pacific coast of Canada, within the United Nations Educational, Scientific and Cultural Organization (UNESCO) Clayoquot Sound Biosphere Reserve and Pacific Rim National Park Reserve, a region currently underrepresented in global compilations. Within the context of other sites from the Pacific coast of North America, these young Clayoquot Sound marshes have relatively low C stocks but are accumulating C at rates that are higher than the global average with pronounced differences between high and low marsh habitats. The average C stock calculated during the past 30 years is 54 5MgC ha-1 (mean standard error), which accounts for 81% of the C accumulated to the base of the marsh peat layer (67 9MgC ha-1/. The total C stock is just under one-third of previous global estimates of salt marsh C stocks, likely due to the shallow depth and young age of the marsh. In contrast, the average C accumulation rate (CAR) (184 50 gCm-2 yr-1 to the base of the peat layer) is higher than both CARs from salt marshes along the Pacific coast (112 12 gCm-2 yr-1/ and global estimates (91 7 gCm-2 yr-1/. This difference was even more pronounced when we considered individual marsh zones: CARs were significantly greater in high marsh (303 45 gCm-2 yr-1/ compared to the low marsh sediments (63 6 gCm-2 yr-1/, an observation unique to Clayoquot Sound among NE Pacific coast marsh studies. We attribute low CARs in the low marsh zones to shallow rooting vegetation, reduced terrestrial sediment inputs, negative relative sea level rise in the region, and enhanced erosional processes. Per hectare, CARs in Clayoquot Sound marsh soils are approximately 2–7 times greater than C uptake rates based on net ecosystem productivity in Canadian boreal forests, which highlights their potential importance as C reservoirs and the need to consider their C accumulation capacity as a climate mitigation co-benefit when conserving for other salt marsh ecosystem services

Quantification of blue carbon in salt marshes of the Pacific coast of Canada

Tidal salt marshes are known to accumulate "blue carbon " at high rates relative to their surface area, which render these systems among the Earth's most efficient carbon (C) sinks. However, the potential for tidal salt marshes to mitigate global warming remains poorly constrained because of the lack of representative sampling of tidal marshes from around the globe, inadequate areal extent estimations, and inappropriate dating methods for accurately estimating C accumulation rates. Here we provide the first estimates of organic C storage and accumulation rates in salt marshes along the Pacific coast of Canada, within the United Nations Educational, Scientific and Cultural Organization (UNESCO) Clayoquot Sound Biosphere Reserve and Pacific Rim National Park Reserve, a region currently underrepresented in global compilations. Within the context of other sites from the Pacific coast of North America, these young Clayoquot Sound marshes have relatively low C stocks but are accumulating C at rates that are higher than the global average with pronounced differences between high and low marsh habitats. The average C stock calculated during the past 30 years is 54 +/- 5 Mg C ha(-1) (mean +/- standard error), which accounts for 81 % of the C accumulated to the base of the marsh peat layer (67 +/- 9 Mg C ha(-1)). The total C stock is just under one-third of previous global estimates of salt marsh C stocks, likely due to the shallow depth and young age of the marsh. In contrast, the average C accumulation rate (CAR) (184 +/- 50 g C m(-2) yr(-1) to the base of the peat layer) is higher than both CARs from salt marshes along the Pacific coast (112 +/- 12 g C m(-2) yr(-1)) and global estimates (91 +/- 7 g C m(-2) yr(-1)). This difference was even more pronounced when we considered individual marsh zones: CARs were significantly greater in high marsh (303 +/- 45 g C m(-2) yr(-1)) compared to the low marsh sediments (63 +/- 6 g C m(-2) yr(-1)), an observation unique to Clayoquot Sound among NE Pacific coast marsh studies. We attribute low CARs in the low marsh zones to shallow-rooting vegetation, reduced terrestrial sediment inputs, negative relative sea level rise in the region, and enhanced erosional processes. Per hectare, CARs in Clayoquot Sound marsh soils are approximately 2-7 times greater than C uptake rates based on net ecosystem productivity in Canadian boreal forests, which highlights their potential importance as C reservoirs and the need to consider their C accumulation capacity as a climate mitigation co-benefit when conserving for other salt marsh ecosystem services

Paleoecological Investigation of Vegetation, Climate and Fire History in, and Adjacent to, Kootenay National Park, Southeastern British Columbia, Canada

Paleoecological investigation of two montane lakes in the Kootenay region of southeast British Columbia, Canada, reveal changes in vegetation in response to climate and fire throughout the Holocene. Pollen, charcoal, and lake sediment carbon accumulation rate analyses show seven distinct zones at Marion Lake, presently in the subalpine Engelmann Spruce-Subalpine Fir (ESSF) biogeoclimatic (BEC) zone of Kootenay Valley, British Columbia. Comparison of these records to nearby Dog Lake of Kootenay National Park of Canada in the Montane Spruce (MS) BEC zone of Kootenay Valley, British Columbia reveals unique responses of ecosystems in topographically complex regions. The two most dramatic shifts in vegetation at Marion Lake occur firstly in the early Holocene/late Pleistocene in ML Zone 3 (11,010–10,180 cal. yr. B.P.) possibly reflecting Younger Dryas Chronozone cooling followed by early Holocene xerothermic warming noted by the increased presence of the dry adapted conifer, Douglas-fir (Pseudotsuga menziesii) and increasing fire frequency. The second most prominent change occurred at the transition from ML Zone 5 through 6a (∼2,500 cal. yr. B.P.). This zone transitions from a warmer to a cooler/wetter climate as indicated by the increase in western hemlock (Tsuga heterophylla) and subsequent drop in fire frequency. The overall cooling trend and reduction in fire frequency appears to have occurred ∼700 years later than at Dog Lake (∼43 km to the south and 80 m lower in elevation), resulting in a closed montane spruce forest, whereas Marion Lake developed into a subalpine ecosystem. The temporal and ecological differences between the two study sites likely reflects the particular climate threshold needed to move these ecosystems from developed forests to subalpine conditions, as well as local site climate and fire conditions. These paleoecological records indicate future warming may result in the MS transitioning into an Interior Douglas Fir (IDF) dominated landscape, while the ESSF may become more forested, similar to the modern MS, or develop into a grassland-like landscape dependent on fire frequency. These results indicate that climate and disturbance over a regional area can dictate very different localized vegetative states. Local management implications of these dynamic landscapes will need to understand how ecosystems respond to climate and disturbance at the local or ecosystem/habitat scale