Imagine hiking the same 5-mile, 4,158-foot elevation gain trail 1,170 times — that adds up to 11,700 miles and 4,864,860 feet of elevation gained. That would be a big enough accolade, but Arizona hiker David Bertelsen also identified and recorded the condition every plant he saw on the Finger Rock Trail in the Catalina Mountains over a 24-year period.
With over 111,000 observations, scientists are drawn to Bertelsen's observations, which provide precise data and insight into how global warming and drought have affected the Sonoran desert over the last quarter-century. His detailed conclusions can provide climate-change researchers with historical data they can't get anywhere else.
Some of Bertelsen's salient observations include:
— On the last mile, Bertelsen has seen about 60 plant species, about one-tenth of the trail's total, "move up the mountain" by 400 to 1,000 feet, he said.
— Since 2002, he's seen 71 dead mature saguaros — more than in the previous 18 years.
— More than 50 Arizona white oaks, 42 mature ponderosa pines and 15 alligator junipers died in that period, he says — a scene similar to die-offs attributed to drought throughout the West.
— He's noticed major population declines in bird, mammal, reptile and amphibian species.
— In 1990, he started seeing 19 non-native grass species including buffelgrass invade the trail in patches; some scientists say global warming has made it easier for buffelgrass to thrive here. Since 2002, he has watched buffelgrass shoot four feet high and move uphill from 3,300 feet to 4,500 to 5,000 feet up.
— Perhaps most significantly, in recent years Bertelsen has seen more than a dozen wildflower varieties bloom for the first time on the trail's last mile. High-elevation blooming — and blooms earlier in the year, both here and elsewhere — are believed by many scientists to be a symptom of human-caused global warming.
Not bad at all for an amateur naturalist. Did we mention that he just turned 65? Bertelsen lost a year of research in 2005 to a broken leg and arm after an accident and triple bypass surgery, but luckily for scientists he vows to continue collecting data "as long as I'm able." — Ted Alvarez