In forest below Mann Library sugar maple, beech, hemlock, and basswood are common. The presence of numerous very large trees attests to the age of the stand, as do the large dead trees that are still standing or decaying on the forest floor. Trees of mixed ages typically coexist in very old forests, such as this one. The forested slopes south of Beebe also have younger trees and weedy vegetation. Whenever a large tree dies naturally or is cut, it leaves a sizable light-filled gap in a forest. Saplings, seedlings, and branches of adjacent trees then grow rapidly to fill in the canopy. The young trees below Toboggan Lodge are growing in the space where there once was a long toboggan run, extending from the hilltop near Olin Chemistry Research Lab, past Toboggan Lodge (hence the name), down to Beebe Lake. Look for black gum (Nyssa sylvatica) on the upper slopes at the east end of the lake, and New Jersey tea (Ceanothus americanus) at the base of the slope at the west end.
Because the long Fall Creek corridor attracts many birds from the outlying areas to Beebe Lake, the diversity of bird species is especially high.Bird watchers may want to check out Werly Island for meadow and water Birds. The woodland trail heading east from Sackett Bridge, on the north side of Fall Creek, is also a prime birding spot.
The glacial history of the area strongly affects the present landscape at Beebe Lake. During the most recent glaciation (about 10,000 years ago), the former Fall Creek Valley was filled with gravel. Since then, Fall Creek has cut a new channel, sometimes through bedrock, occasionally through the gravel deposit that filled the old channel. Above the lake at Sackett Bridge, and below the lake at Triphammer Falls, the creek is cutting through resistant layers of rock, while Beebe Lake and the slopes surrounding it sit in a very deep, erosible gravel deposit. The rushing water of Fall Creek slows when it reaches Beebe Lake, dropping its sediment load into the lake. The present landforms at Beebe reflect the natural filling and eroding processes of the creek. Sand and gravel bars (such as Werly Island) are created whn heavy gravel, the bulk of the material carried by the stream, is dropped in the slower-moving lake water. Finer sediments are carried farther into the lake. When floodwaters retreat, gravel bars, like deltas, remain at the inlet.