Robert Ficklin

Alteration of the fire regime in upland oak–hickory (Quercus L. spp.–Carya Nutt. spp.) forests of the Central Hardwood Region is a major factor for the current shifts in species’ composition and oak recruitment and regeneration failures. The reintroduction of fire into these ecosystems requires a better understanding of fire effects on oak and co-occurring competitors. First-order (i.e., during and immediately after) fire effects on oak and red maple (Acer rubrum L.) topkill and resprouting at neighborhood scales were evaluated in frequently burned upland oak–hickory forests. A groundline threshold of 5 cm provided oaks with high (60%) survival probability (p < 0.001). White (Quercus alba L.) and post (Quercus stellata Wangenh.) oak survival odds were 21 and 14 times higher than that of red maple (p = 0.01 and 0.03), respectively. Three and twelve months after burn, oaks had three to six times more sprouts per clump than red maple. Frequent fires may continue to topkill the maples, while maintaining oak dominance in the reproduction pool and, thus, providing higher recruitment potential into the overstory. Burns with fire behavior that is very low to low in these frequently burned systems may provide greater control in favoring oaks and selecting against red maple, especially if groundline diameter thresholds are considered.

Knowledge of physical and chemical properties of soil is relevant for landowners, researchers, and foresters, so that appropriate crop species and management practices to maximize site productivity can be selected. In addition to issues of plant productivity, the need for assessing soil properties has been expanded due to public interest in determining the consequences of management practices on soil quality relative to sustainability of crop ecosystem functions. The USDA-Natural Resources Conservation Service (NRCS) delineated soil mapping units to provide information about physical and chemical properties of soil in each soil series. However, soil mapping units do not provide details about the variability of soil properties within a single soil series. To determine the variability of physical and chemical properties within Amy soil series, 200 soil samples were collected to a depth of 0–15cm and 15–30cm from soil individuals mapped as the Amy silt loam soils in five different locations in southeastern Arkansas. Comparisons of soil texture, bulk density, carbon, nitrogen, Mehlich III extractable macronutrients, and micronutrients revealed significant differences among soil individuals/ locations for both depth increments. Additionally, all nutrients except potassium, magnesium, and copper differed between the two soil depths. The results suggest inherent variation in biogeochemical and geochemical cycling in the surface horizons of soils mapped as the Amy series.

A mixture of cherrybark oak (Quercus pagoda Raf.), white oak (Q. alba L.), persimmon (Diospyros virginiana L.), and sweetgum (Liquidambar styraciflua L.) seedlings was grown in shadehouses to simulate light conditions beneath a canopy. After the first growing season, two release treatments were implemented (released and not released), and treatments were conducted during two seasons (winter and spring). All seedlings were clipped at 2.5 em from the groundline in height when treatments were imposed. Survival of persimmon and sweetgum was 100% following clipping. There appeared to be a weak seasonal effect on oak survival, especially for white oak; survival was 100% for winter clipping and 93% for spring clipping. The oaks were considerably smaller in height, diameter, and above-ground biomass than their competitors, and the competitors also produced more stems per rootstock than the oaks. Cherrybark oak was more productive than white oak especially in the released treatment. The oaks tended to have a higher percentage of their total biomass in foliage when compared with their competitors. Stem wood density of the oaks was considerably greater than that of their competitors. Leaf characteristics of all species were very responsive to the treatments; specific leaf area was consistently greater for the no-release treatment for all species. Results of this study suggest that for oak sprouts to grow faster than their competitors they must begin with an initial size advantage.

Methodologies for determining soil chemical properties have evolved dramatically during the past century. Early geochemical analyses were conducted exclusively through the use of wet chemistry techniques that were relatively reliable but painstaking and subject to errors at various stages of analysis. Near infrared reflectance spectroscopy (NIRS) has emerged as a new approach for rapidly analyzing a variety of materials including soils. In this study soil samples were taken from eight study areas across the Ozark Highlands of Arkansas, and NIRS calibration models were developed to determine the accuracy of using NIRS to analyze soils compared with standard soil chemical analysis protocols. Multivariate regression models were highly effective for analyzing several important elements. C and N models explained 92% and 88% of their variation, respectively, and Ca, Mg, P, and Mn models explained 72-88% of the variability in these elements. Models for C:N and pH explained 82% and 86% of their variability, respectively. Models for micronutrients Cu and Zn did not fit as well with 22% and 40% of their variability explained, respectively. Our findings suggest that additional NIRS calibration and modeling is promising for rapidly analyzing the chemical composition of soils, and it is desirable to develop model libraries that are calibrated for the soils of a given region.