Presentation on theme: "In Transition Residential, Industrial and In Transition Agriculture Urban and Agricultural Encroachment onto Fraser Lowland Wetlands Urban and Agricultural."— Presentation transcript:
In Transition Residential, Industrial and In Transition Agriculture Urban and Agricultural Encroachment onto Fraser Lowland Wetlands Urban and Agricultural Encroachment onto Fraser Lowland Wetlands Abstract: The Canadian Wildlife Service published a technical report entitled "Wetlands of the Fraser Lowland, 1989: An Inventory" which included maps and descriptions of wetlands in the settled area between Vancouver and Chilliwack, British Columbia. With funding from the Georgia Basin Ecosystem Initiative, these maps were subsequently converted into a current GIS environment, missing wetlands were added, corrections were made, the polygons were georeferenced to a finer-scale basemap, and then were compared to 1999 orthophotos to assess change. Wetlands that were part of the Fraser River Estuary Management Program were not included in the assessment. A total of 320 wetlands, as well as 10 partly outside of the FREMP inventory were assessed for changes between 1989 and The purpose was to identify the number and total area of wetlands that have been affected by urban and agricultural encroachment over this ten year period. Results indicate that one in five wetlands had been affected by encroachment and to varying degrees. Half experienced a loss of under 5% of their original size, while over one quarter experienced a 5-15% loss. About 41% of the lost wetland area was to agricultural development, the remainder to various urban developments or was in transition to some type of future land use. Most of the agricultural development was for cranberry and berry crop production. Despite an increased societal recognition in that period of the importance of wetland ecosystems, they continue to be developed. Although a number of the wetlands experienced only small losses, this continual, incremental loss is occurring on what already are mere fragments of the wetlands that were in the area prior to European settlement. Isolated decisions, involving many land use types and many separate planning processes, affecting seemingly trivial amounts of wetland are, in fact, cumulative and unsustainable. Instead, planning must take an ecosystem-based approach that places a priority on protecting the region’s wetlands. Golf Course Commercial Before After Discussion: Despite an increased societal recognition of the importance of wetland ecosystems, this study has shown that wetlands are still being used for urban and agricultural expansion. One in five wetlands assessed in this study experienced some degree of encroachment. The majority of the loss was due to agricultural uses, golf courses, land fill expansion and other urban development, or were in transition to some future use. Although the encroachment was typically a small percent of the original wetland size, this continual, incremental loss is occurring on what already are mere fragments of the wetlands that were in the area prior to European settlement. One study examining the change in land cover in this region found freshwater wetlands declined 85% between the period of first European contact (1827) and present day (1990). Figure 4 and Table 2 shows the approximate land cover for the Lower Fraser Basin as it was prior to 1827 (Boyle and others 1997). Figure 5 shows the Fraser River floodplain as it was mapped by land surveyors between 1859 and 1890 (North and Teversham 1984). Sumas Lake was a prominent feature at the time but was completely drained by This resulted in the conversion to agricultural use of approximately 3,600 hectares of lake bed and 8,000 hectares of surrounding marshland and sloughs (Moore 1990). Another study used the land surveyor maps described above to determine the changes in wetlands that were considered to be fish habitat between the 1800s and present day for three river reaches: the north arm of the Fraser River near Sea Island, the Queens Reach of the Fraser River near Port Mann, and the lower Harrison River. Marsh transplant sites that were established as compensation for development elsewhere were factored in. Comparison of all wetland types was not possible since some types were simply not identified by the land surveyors at the time. Nonetheless, results showed that there was a reduction in wetlands in the three river reaches of 96%, 82%, and 75% respectively. Much of this loss can be attributed to the dyking, draining and conversion of seasonally-flooded natural-grass prairies to agricultural and urban uses (Kistritz and others 1996). Information on the loss of wetlands that has occurred in recent years, placed in the historical context of all that was lost since European settlement, illustrates that existing land use planning in the Fraser Lowland is failing to protect wetlands. Isolated decisions, involving many land use types and many separate planning processes, affecting seemingly trivial amounts of wetland are, in fact, cumulative and unsustainable. Instead, planning must take an ecosystem-based approach that places a priority on protecting the region’s wetlands. Method: The Canadian Wildlife Service published a technical report entitled “Wetlands of the Fraser Lowland, 1989: An Inventory” (Ward and others 1992) which involved air photo interpretation, site visits and data processing into a digital Geographic Information System. The minimum wetland size for inclusion in the inventory was one-half hectare. Adjacent wetland polygons with identical characteristics were grouped into the same wetland unit. Some 398 wetlands were identified in the settled area between Vancouver and Chilliwack, British Columbia. Subsequently, in the late 1990s, with funding from the Georgia Basin Ecosystem Initiative, some missed wetlands were added, some corrected, the original maps were converted to a more current GIS environment, and then georeferenced to a finer-scale basemap. Because of these modifications, the area of each wetland was re-calculated. The total number of wetlands in the inventory increased to 432. These maps were then compared to 1999 orthophotos to identify locations and total area affected by urban and agricultural encroachment between 1989 and Air photos from the original inventory were referred to in order to verify genuine change. Importantly, 102 wetlands within the Fraser River Estuary Management Program (FREMP) area were not included in this assessment. Since FREMP is currently updating its habitat maps at a much finer scale (1:2,500) it was decided that these 102 wetlands would not be included in this study of encroachment. There were 10 wetlands that were partly in the FREMP area and only the portion outside of FREMP was assessed in this study. As a result of removing the FREMP wetlands, this study is primarily assessing freshwater wetlands only; all of the brackish marshes, estuarine marshes, and mudflats in the original wetland inventory were excluded. Results: Of the 320 wetlands assessed in this study, as well as the 10 located partly outside of the FREMP area, about one in five (22%) experienced some degree of encroachment from urban or agricultural development between 1989 and In this time there was one wetland of 14 ha created on what was seasonally flooded farmland, one increased slightly from enhancement work, and another small portion of a wetland that had been cleared of vegetation (counted as a loss) was later the subject of restoration work. It remains to be seen whether these projects are able to attain full wetland functioning but they cannot negate the irrevocable loss of 965 ha of original wetland area. The degree of encroachment on individual wetlands varied. Figure 1 shows wetlands grouped into five categories based on the percentage of the original wetland size that was lost. Of those wetlands affected, half experienced a loss of under 5% of their original size, while over a quarter experienced a 5-15% loss. The type of the encroachment is shown in Figure 2. Importantly, from a planning perspective, no one type of encroachment is responsible for the wetland loss. Approximately 41% of the lost wetland area was due to agricultural development, 25% to golf courses, 16% to land fill expansion, and the remainder to other urban development or was in transition to some type of future land use. Table 1 further demonstrates that the degree of impact on individual wetlands varies. For example, golf courses accounted for 244 ha that were lost, but actually affected 4 individual wetlands. Similarly, over 150 ha went into the expansion of a single landfill in the southern edge of Burns Bog. In contrast, transportation accounted for 6 ha that were lost which actually affected 14 wetlands. Since agriculture accounted for the highest proportion of encroachment, it is interesting to note the type of farm operations that were developed on the wetlands. The highest portion (over 314 ha) was for the expansion of cranberry and other berry crop production, primarily in the Pitt Meadows area. Other significant agricultural uses were forage and grain crops, and for turf/sod production. Figure 3 shows the location of the affected wetlands. The majority of the area affected by urban or agricultural encroachment was in the Fraser Valley Regional District. Authors: Kathleen Moore ) and Katrina Roger Canadian Wildlife Service, RR1, 5421 Robertson Road, Delta British Columbia, V4K 3N2 Acknowledgements: Many thanks to Peggy Ward, Cyril Chan, Betty Ling and Pam Whitehead for their kind assistance Table 1. This table shows the data used to calculate the proportion of the lost wetland area to each type of encroachment, as shown in figure 2. It also indicates the number of wetlands that were affected by each type of encroachment, further illustrating that the degree of impact on individual wetlands varies. Total wetlands affected by encroachment = 71 * Note: some wetlands were affected by more than one type of land use GIS Unit Pacific Wildlife Research Centre Canadian Wildlife Service March 28, 2003 wetlands water forest Table 2. From Boyle and others 1997 Figure 4. From Boyle and others 1997 * Total Figure to to 1999 References: Boyle, C.A., L. Lavkulich, H. Schreier, E. Kiss Changes in land cover and subsequent effects on Lower Fraser Basin ecosystems from 1827 to Environmental Management. 21: Ward, P., K. Moore, R. Kistritz Wetlands of the Fraser Lowland, 1989: An Inventory. Technical Report Series No Canadian Wildlife Service, Environment Canada. 216 pp. North, M.E.A. and J.M. Teversham The vegetation of the floodplains of the Lower Fraser, Serpentine, and Nicomekl Rivers, 1859 to Syesis. 17: Moore, K.E Urbanization in the Lower Fraser Valley, Technical Report Series No Canadian Wildlife Service, Environment Canada. 12 pp. Kistritz, R.U., K.J. Scott, C.D. Levings Changes in fish habitat in the Lower Fraser River analyzed by two wetland classification systems. Pages in C.D. Levings and D.J.H. Nishimura (eds.), Created and restored sedge marshes in the Lower Fraser River and estuary: an evaluation of their functioning as fish habitat. Canadian Technical Report of Fisheries and Aquatic Sciences Science Branch, Department of Fisheries and Oceans Orthophotos: McElhanney Consulting Services, Vancouver, 1999 Airphotos: BCC534#041, BCC534#049, BCC534#092, BCC539#077, BCC539#148, Province of British Columbia, September (Note: Linework based on fieldwork conducted in 1989). Figure 1. Wetlands affected by encroachment, grouped into 5 categories based on the percentage of the original wetland size that was lost. Figure 2. Type of encroachment, expressed as a proportion of the 965 hectares of lost wetland area. Figure 3. Total wetland area lost In each Regional District, in hectares.