The Fred and Goose Cove study sites at Glacier Bay are only 4.2 km (2.7 miles) apart and the glacier exposed Goose Cove only about a decade earlier than Fred. The vegetation development at Goose Cove during the two decades after I established the plots (ca. 1990-2010) should be comparable to the most recent two decades of development at Fred (ca. 2000-2020). Precise comparisons require that I know how old the two sites are.Continue reading “Have photo – will date”
The second youngest of my 10 study sites at Glacier Bay is called Fred because there is a USGS benchmark there named Fred. Fred is dominated by alder. When the plots were established in 1988, there were no spruce and the average diameter of the cottonwood trees was 7 cm (2.8 inches). There were about five of these little cottonwood trees in each plot and 280 alder stems. There are 10 plots and we measured the diameter of all 2800+ stems.
The primary source I used to date Fred’s emergence from under the glacier was an aerial photo taken in 1948. The McBride remnant, a large extent of shrinking, stagnant ice, was 550 m away from the plots and I guessed that four years earlier the ice had probably covered the plots. I was probably off by a few years.Continue reading “Dating Fred”
Three decades ago I started monitoring vegetation change in Glacier Bay National Park where glaciers have been retreating and exposing new land to colonization by plants. Each of the 10 sites I study was exposed at a different date over the last 250 years and it’s important to know that date for each site. It seems even more important now that I have so much data from the sites.Continue reading “Dating retreat”