Here are two photos of Whitewall Mountain taken from Zeacliff that line up pretty even if not in perfect focus. I took the black and white photo in July 1982 and the color photo below on 9/22/07, so they're about 25 years apart. Like the Mt. Madison photos I posted last month that were 44 years apart, you could say the vegetation has not made significant advances over these relatively short periods of time, but there's an incremental increase in density, or a "thickening", of vegetation, e.g. measurable lateral growth on existing stems and branches in both sites.
Whitewall and the area around it to the north was burned in a massive forest fire in the late 1800s and again in the early 1900s. There is a lack of specific information of the extent of damage from the two fires but we know that the trees and soil were totally consumed in the area of this photo. In the 1920s a report in Appalachia lists 13 major slides on this side of the mountain. Regenerative growth did not get established until the early 40's. Like the south face of Mt. Madison, there are some environmental and ecological pluses and minuses for plant life on these steep, upland slopes where the soil is marginal. On Mt. Madison's south face there's a lot of sun, but little moisture. On Whitewall's west face there's an enormous amount of wind that funnels through the notch but a lot of moisture. At any rate, one would expect growth to be relatively slow on these sites compared, for instance, with plant growth down on the floor of Zealand Notch next to Whitewall Brook.
I've started measuring individual trees on a number of sites including their stem diameters, height, and the length of primary branches as part of a study to see what differentials in growth there are at higher and lower altitudes and in different soil regimes; near the tree line, on old slide sites, and in older growth in densely forested areas.