Northern Wisconsin forests: Pattern and process on a historical landscape

I characterize regional patterns in northern Wisconsin (USA) forests and disturbance regimes for the period prior to Euroamerican settlement (ca. 1850). This period offers an informative ecological baseline for both science and natural resources management because it represents conditions just prior to rapid and unprecedented land use change. Pre-Euroamerican forest patterns, heavy windthrow dynamics, and stand-replacing fire disturbance can be represented by the U.S. General Land Office's original Public Land Survey (PLS) records.; My work shows much more regional-scale variability than previous studies of historical northern Wisconsin vegetation. Whereas yellow birch ( Betula alleghaniensis) was previously thought to be only subdominant or co-dominant within northern Lakes States hemlock-northern hardwoods forests (primarily Tsuga canadensis, Acer saccharum, Betula alleghaniensis , and Tilia americana), my quantitative analysis reveals that this species prevailed on many of the glacial moraines. Maps also show broad areas dominated by white pine (Pinus strobus), and that jack pine (P. banksiana) had a more limited distribution than previously suggested.; Patterns of both heavy windthrow and stand-replacing fire were not random at any scale, and environment had a strong influence on this. The top-down control of climate exerted its influence on the distribution of both wind and fire disturbance, while bottom-up controls of forest type and physiography were respectively important. Topographic factors were not significant in explaining the distribution of wind or fire in this region where gradients are subtle. Together these factors worked to maintain complex historical forest patterns in northern Wisconsin. Heavy windthrow was the predominant disturbance dynamic structuring forests across the majority of the region, but fire was of strong sub-regional importance, largely on glacial sandy outwash and along the prairie-forest border. An uncommon positive feedback existed between wind and fire at a patch scale, where heavy windthrow increased the potential for fire disturbance on mesic sites. This was combined with a persistent negative feedback at the regional scale that made fire-prone areas less susceptible to windthrow.; My research paints a new view of ecological patterns and processes within northern Wisconsin's historical forests, and can be used as a baseline for current day forest management and ecological restoration.