Scientists examine why the 300-foot trees plummet to forest floor.
Yosemite N.P, Calif.- Two trees fell in the forest, and no one was there to hear them-but from the looks of things, there must have been quite a racket.
"If you look at the damage to the area around where [the trees] fell, you see that everything in their path was affected," said Deb Schweizer, a ranger at Yosemite. "It is a very impressive sight. It must have been something to see for the squirrels and birds. Just imagine what it must have sounded like."
The two trees, each standing nearly 300 feet tall and as much as 1,000 years old, plummeted in early spring in the Mariposa Grove area along Yosemite's southern border. The fallen trees were cross-sectioned but otherwise left alone on either side of a public trail.
Park scientists think that the root or soil system of the first tree failed, causing it to fall, and that tree brought the other one down with it.
"The first tree had a stream going through its system -- which is bad for sequoias," said Schweizer. "We're still looking into whether that water was diverted from something that we did," such as constructing a nearby trail 50 years ago, "or whether it was a natural meandering of the stream that eventually brought the tree down."
Another theory is that heavy foot traffic around the bases of the trees contributed to their fall by damaging root systems. To be safe, the park fences off its oldest sequoias.
"There are some stresses to the grove," said Schweizer, "but we feel pretty happy about the health and regeneration of the sequoias. They are doing pretty well."
Park officials did not find many sequoia saplings prior to the 1970s, but starting a prescribed fire program has proved beneficial; fire helps giant sequoias to regenerate. "We're seeing those saplings now," said Schweizer. "They may have skipped a generation, but we're seeing a lot of those saplings coming back up now."
Fallen sequoias are rare at Yosemite, according to park statistics. The most recent was in 1998, after a 30-year hiatus. Probably because of that rarity, visitors to Yosemite have been asking plenty of questions.
"It's been a huge story here," said Schweizer. "People are really interested in the trees. They want to know about why they fell and how often. They're fascinated. It is just a great opportunity for us to teach them about how special these trees are."
