The Photosynthetic Response of Northern Red Oak (Quercus rubra L.) and American Chestnut (Castanea dentata (Marsh.) Borkh) Under Varying Light Intensity and Weed Competition

Although widely distributed across Indiana and the United States Midwest, conifer plantations consist largely of non-native species that are of no value to the state’s forest products industry. This project’s goal is to develop science-based protocols and specific silvicultural prescriptions for successfully converting conifer plantations to higher value native hardwoods. Quantifying photosynthesis rate in a plant is an important tool to help us discern the best methods for implementing conifer conversion. Seedlings from two different native species, northern red oak (Quercus rubra L.) and American chestnut (Castanea dentata (Marsh.) Borkh), were distributed among three different silvicultural cutting treatments (control, thinning and clear cut). Inside each one, two distinct categories of herbaceous control treatments (weed control and no weed control) were installed. Using an AccuPAR LP-80 sensor, canopy PAR (photosynthetically active radiation) interception was measured. Photosynthetic capacity was assessed with a LICOR 6400-XT analyzer to evaluate efficiency in resource use (water, light, gas exchange) and productivity. Among the treatments, clear cut presented maximum PAR intensity, followed by thinning and control, respectively. Both American chestnut and northern red oak seedlings demonstrated the highest photosynthesis rate (Amax) under high light conditions (clear cut), though photosynthesis of chestnut was greater than that of northern red oak. No significant differences were found between species in the weeding treatment for photosynthesis. Results of this study will provide valuable silvicultural prescriptions to Non-Industrial Private Forest (NIPF) landowners, forestry professionals, as well as state and federal agencies in Indiana and other Midwestern states

Characterizing the Late Pleistocene MSA Lithic Technology of Sibudu, KwaZulu-Natal, South Africa

Studies of the African Middle Stone Age (MSA) have become central for defining the cultural adaptations that accompanied the evolution of modern humans. While much of recent research in South Africa has focused on the Still Bay and Howiesons Poort (HP), periods following these technocomplexes were often neglected. Here we examine lithic assemblages from Sibudu that post-date the HP to further the understanding of MSA cultural variability during the Late Pleistocene. Sibudu preserves an exceptionally thick, rich, and high-resolution archaeological sequence that dates to ∼58 ka, which has recently been proposed as type assemblage for the “Sibudan”. This study presents a detailed analysis of the six uppermost lithic assemblages from these deposits (BM-BSP) that we excavated from 2011–2013. We define the key elements of the lithic technology and compare our findings to other assemblages post-dating the HP. The six lithic assemblages provide a distinct and robust cultural signal, closely resembling each other in various technological, techno-functional, techno-economic, and typological characteristics. These results refute assertions that modern humans living after the HP possessed an unstructured and unsophisticated MSA lithic technology. While we observed several parallels with other contemporaneous MSA sites, particularly in the eastern part of southern Africa, the lithic assemblages at Sibudu demonstrate a distinct and so far unique combination of techno-typological traits. Our findings support the use of the Sibudan to help structuring this part of the southern African MSA and emphasize the need for further research to identify the spatial and temporal extent of this proposed cultural unit