Comparative gas-exchange in leaves of intact and clipped, natural and planted cherybark 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 inthe field and in a nursery bed. Seedlings inthe field, released frommidstory and understory woody competition, showed significant increases in gas-exchange compared to non-released seedlings due to increases in light levels reaching seedlings. Concurrently, little difference occured in the 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.