Community-level patterns of forest recovery
Wind disturbance has been studied for long enough now that long-term trends in recovery can be revealed. For example, Peterson’s dissertation study site, the old-growth Tionesta Scenic Area, was disturbed by a very large and powerful tornado in 1985; we periodically return to resample that site.
Unpublished data from that location shows that the 1985 tornado has shifted tree composition substantially: prior to the disturbance, the forest was dominated by eastern hemlock (Tsuga canadensis) and American beech (Fagus grandifolia), with smaller components of yellow birch (Betula alleghaniensis), red maple (Acer rubrum), and black cherry (Prunus serotina). The 1985 tornado hit a forest with a very sparse woody understory that, due to decades of heavy deer browsing, was mostly beech root suckers and understory striped maple (Acer pensylvanicum). A summer drought in 1988 caused heavy mortality to the regenerating hemlock seedlings, greatly reducing hemlock abundance in the wind damaged part of the Tionesta Scenic Area; hemlock abundance has not rebounded since and now it is very sparse in the wind damaged area. During the period 2000-2010, beech bark disease arrived in that part of northwestern Pennsylvania, and many adult beech were killed. Beech continues to be abundant in the regeneration of the wind damaged area, but its long-term viability is uncertain. Currently, the main part of the tornado swath at Tionesta is dominated by yellow and black birch, with red maple and beech as secondary species.
Currently we are monitoring regeneration of woody species at several sites in northern Georgia (within Chattahoochee National Forest), and in Great Smoky Mountains National Park.
Both of these areas were disturbed by tornadoes in April of 2011. Our main questions related to the regeneration are a) How does regeneration vary as a function of structural complexity?, and b) what is the impact of salvage logging (see below)? Due to limited time and personnel, we have thus far given little attention to dynamics of the herbaceous community, would most welcome new grad students or collaborators who might focus on the herbs.