Comparative Gas - Exchange in Leaves ofIntact and Clipped , Natural and Planted Cherrybark Oak ( Quercus pagoda Raf . ) Seedlings

Gas-exchange measurements, including CO2-exchange rate (net photosynthesis), stomatal conductance, and transpiration, were conducted on intact and clipped cherrybark oak (Quercus pagoda Raf.) seedlings growing in the field and in a nursery bed. Seedlings inthe field, released from midstory and understory woody competition, showed significant increases in gas-exchange compared to non-released seedlings due to increases in light levels reaching seedlings. Concurrently, littledifference occured inthe CO2-exchange rate between intact and clipped seedlings inthe released treatment although clipped seedlings maintained a consistently greater rate ofstomatal conductance. In order to reduce the high variability of light levels recorded in the field, gas-exchange measurements were conducted on intact and clipped cherrybark oak seedlings growing in a nursery bed under consistent light conditions. Again, no differences were found in the CO2 exchange rate between intact and clipped seedlings. Furthermore, no differences were found instomatal conductance and transpiration between intact and clipped seedlings. However, significant differences in gas-exchange were found between first-flush and second-flush leaves regardless of seedling treatment (intact or a sprout). Greater rates of gas-exchange in second-flush leaves can be attributed to developing third-flush steams and leaves.