Factors Influencing Tree Growth In A Bottomland Hardwood Along The Green River In Kentucky

In bottomland hardwood forests, large fluctuations in moisture availability can lead to stress from both flooded and drought conditions. These forests can have a complex species composition with different water use and drought strategies. The bottomlands in which these species co-occur can have a complex spatial distribution of alluvial sediments due to the meandering and migration of river or stream channels, which may impact the hydrology, nutrient dynamics, and productivity. At Western Kentucky University\u27s Green River Preserve, approximately 9 ha of bottomland hardwood forest were planted in 2006. Although these hardwoods have received equal amounts of sunlight, rainfall, and wind, the productivity of the trees spatially varies. Therefore, the objective of this study was to detect the main components influencing the productivity of the bottomland trees planted at WKU\u27s Green River Preserve. The set of observations for this study included clay, silt, and sand content; electrical conductivity; soil chemical properties (pH and total phosphorus, potassium, calcium, magnesium, and zinc); unmanned aerial vehicle (UAV)-based normalized difference vegetation index (NDVI); and a lidar-based digital elevation model (DEM). Several key factors and their capability of describing the variability in tree productivity were identified using stepwise regression analysis: percentage of san content, elevation, pH, and chemical properties including calcium and magnesium. The low water-holding capacity of the soil due to high percentages of sand, along with depleted nutrients, can cause stress in drought conditions which may lead to decreased productivity or mortality in bottomland hardwood trees