Move mouse cursor off image to see original March 2004 star trail photo. Position mouse cursor over image to see March 2007 daytime photo of same scene.
March 2004: The stars form arcs around Polaris, and passing planes leave faint dotted lines, during this 1-hour exposure. Tall saguaro cactuses frame the sky in this photo taken in the Arizona desert.
March 2007: Three years after taking the original star trail photo, I returned to the same spot, hoping to use the two towering saguaros in another star trail photo. Even though I was sure I was in the right place, I couldn't find the saguaros. Then I realized they had collapsed and died -- only their decaying ribs remained. What could cause the death of two apparently healthy saguaros in such a short time? Was it drought (the preceding two years had been very dry) ... or something else?
June 2007: Thanks to Sue Rutman, Plant Ecologist at Organ Pipe Cactus National Monument, for the following note:
Its hard to say what killed the saguaros in your 2004 photo. Drought is a likely culprit but so are other things. The saguaro on the right in the 2004 photo shows damage on the lower half of the stem. Both saguaros show constricted ribs, indicating some drought stress. And yet saguaros can survive and even flower for 2 years with no rain at all. We are not seeing widespread death of saguaros due to drought, but in 2005 there was a widespread failure of the saguaro bloom. Less than 10% of reproductive plants produced flowers, and those that did produce flowers had fewer than normal.
We can never be certain that these two saguaros died from drought stress, but it is a good possibility.
Star trail image:
Date: March 12, 2004
Time: 9:39pm to 10:39pm MST
Location: Organ Pipe Cactus National Monument, Arizona
Camera: Olympus OM-1 35mm SLR on fixed tripod
Film: Fuji Provia 100F slide
Focal length: 24 mm
Exposure time: 60 minutes
Scanner: Nikon Coolscan LS-2000
Date: March 17, 2007
Time: 4:42 p.m. MST
Camera: Kodak Z650 Zoom Digital