DENDROCHRONOLOGICAL AND WOODY DEBRIS ASSESSMENT OF FOREST DEVELOPMENTAL PATTERNS ALONG A LACUSTRINE SAND DUNE CHRONOSEQUENCE

<p dir="ltr">The Grand Sable Dunes is a perched lacustrine dune system located within Pictured Rocks National Lakeshore, MI. Wind provides constant disturbance which has shaped the successional pathways of these dunes. The primary objective of this study was to identify the relationships between forest stand age, successional processes, and overall forest development by categorizing forest type and regeneration patterns, mapping the dendrochronological sequence, and quantifying coarse woody debris accumulation of the Grand Sable Dunes. I surveyed the understory, midstory, and overstory woody vegetation across 43 tenth hectare circular plots. Cores from the four largest trees were collected and coarse woody debris volume was measured within each plot. Results from statistical tests indicated that there is a clear chronosequence across the dunes that is supported by the apparent successional stage evidenced by forest type and coarse woody debris. There was a positive relationship between distance from shore (i.e., inverse row number) and midstory diversity, overstory diversity, stand age, and coarse woody debris accumulation with all variables increasing when moving south away from Lake Superior. Northern rows, those closest to Lake Superior, appeared to be at an early successional stage and dominated by jack pine (<i>Pinus banksiana</i>) and sand cherry (<i>Prunus pumila</i>), both species that occur in early dune succession. The southern rows were at a much more advanced successional stage with sugar maple (<i>Acer saccharum</i>) as the dominant overstory and understory species. The mid-dune rows were at a transitional stage with mature jack pine dying and hardwood species establishing. Stand age followed this suggested successional pathway with the oldest individuals occurring in the later successional southern rows and the youngest individuals in the northern rows. Overall, the Grand Sable Dunes appear to be following the traditional successional pathway and linear chronosequence across the dunes despite general debate over successional processes and the complexity reality of a chronosequence.</p>