Twisted science in Yellowstone
I would like to applaud High Country News for publishing and Frederic H. Wagner for writing the May 30, 1994, article about "natural regulation" policy in Yellowstone National Park. I have worked in and around the park off and on from 1969 to 1985 and continue to visit it periodically. As a soil mapper, I observe and make judgments about disturbances to the natural landscape because they relate to soil development.
In the northern range of Yellowstone Park, I saw unusual vegetation patterns compared to surrounding areas of the region. Aspen stands in the park were nearly all old age, contained no young or medium age classes and few if any sprouts. This is not uncommon for a species normally associated with early stages of succession. Don Despain, the Park Service botanist, explained the absence of young trees in the early 1970s as due to the absence of natural disturbance from fire, which would rejuvenate the aspen. But it seemed odd that many areas outside the park had young stands often on the margins of conifer forests. It was also impossible to find an aspen tree in the park which had white bark below the browse line. The elk and possibly bison would chew the bark leaving black scars on the trunk. An aspen blown over by the wind would lose all leaves and bark within days.
After the 1988 fires aspen trees sprouted profusely and it appeared that fire was an essential ingredient to restore the aspen stands. In 1992 and 1993 I went through the park to find that the sprouts were not getting more than a few feet tall. That is as much growth as some aspen make in one year and it had been four years since the fire. I assume the sprouts had been browsed by the elk and deer and possibly bison. I wonder how natural this is.
La Grande, Oregon