Effects of competition control on growth and physiology of two hardwood species

by

Colton L. Eaton, Hal O. Liechty, and Michael A. Blazier

Graduate Research Assistant and Professor, Arkansas Forest Resource Center, School of Forestry and Natural Resources-University of Arkansas at Monticello, 110 University Ct., Monticello, AR 71656; Associate Professor, LSU AgCenter, Hill Farm Research Station, 11959 Hwy 9, Homer, LA. CLE is corresponding author. 870-460-1793; eaton@uamont.edu

Abstract – Thousands of acres of retired agricultural land are annually reforested with hardwood species in the Southern US. One of the primary factors that reduces survival and growth of hardwood seedlings in these projects is a reduction in water availability due to competing vegetation. The objective of this study was to assess the impact of different levels of competition control and moisture availability on green ash (Fraxinus pennsylvanica) and water oak (Quercus nigra) seedling physiological processes and growth. The study utilized two retired sod fields in Central Arkansas. In each field, three different competition control treatments (Low, Moderate, High) were applied. The “Low” treatment had no competition control, the “Moderate” treatment had competition control prior to planting, and the “High” treatment had some level of competition control prior to planting as well as the first and second growing season following planting. Net photosynthesis, stomatal conductance, predawn leaf water potential, soil moisture, seedling height, and seedling basal diameter were monitored on a 3-4 week schedule during the second growing season. Initial results indicated that the green ash had higher photosynthesis rates than water oak, and net photosynthesis, as well as growth, was greatest with the highest level of competition control. During the driest periods of the growing season, soil moisture increased with increased level of competition control. This resulted in a higher leaf water potential of the seedlings in the “High” treatment compared to the other two competition control treatments, at least during a portion of the growing season.