Changes in land cover and subsequent effects on Lower Fraser Basin ecosystems from 1827 to 1990

European settlement began in the Lower Fraser Basin (LFB) in western British Columbia in 1827 and has impacted the basin ecosystem in a number of ways, especially affecting the vegetation. Using previously published data, air photos, and other historical material for the area, estimates of land cover were made for the years prior to 1827 and for 1930 and 1990. The area of coniferous forest changed from 71% prior to 1827 to 50% in 1930 to 54% in 1990. However, prior to 1827, only 27% of the forest would have been immature (< 120 years old), while 40% would have been immature in 1930 and 73% of the forest was immature in 1990. The amount of wetland area decreased from 10% to 1% of the study area while urban and agricultural area increased to 26% of the study area by 1990. The changes in rend cover have had adverse effects on soil, water, and air quality: aquatic life; and plant and animal populations. Estimates of changes in net primary production and organic soil carbon suggest a decline over the past 170 years, although the latter rate of decrease has slowed since 1930. As human populations in the Lower Fraser Basin continue to increase, the quality of air, water, and soil will continue to decline unless measures are taken.