© 1995 Heron Publishing—Victoria, Canada
Ecophysiological attributes of the native Acer saccharum and the exotic Acer platanoides in urban oak forests in Pennsylvania, USA
Brian D. Kloeppel (1) and Marc D. Abrams (2)
1. Institute of Ecology, University of Georgia, Coweeta Hydrologic Laboratory, 3160 Coweeta Laboratory Road, Otto, NC 28763,
USA / 2. School of Natural Resources, 4 Ferguson Building, Pennsylvania State University, University Park, PA 16802, USA / Received June 22, 1994
Summary
When the exotic Acer platanoides L. (Norway maple) and the native A. saccharum Marsh. (sugar maple) grow together in the understories of urban Quercus forests in the eastern USA, average annual height growth increments are nearly twice as large in A. platanoides as in A. saccharum, 19.26 ± 3.22 versus 10.01 ± 1.69 cm. We examined several ecophysiological mechanisms that might be associated with the superior
invasive ability and growth of A. platanoides in two urban oak forests in Pennsylvania. Leaf longevity was 12 days greater in A. platanoides than in A. saccharum. In addition, leaf mass/leaf area ratio was greater in A. platanoides than in A. saccharum (2.67 ± 0.03 versus 2.32 ± 0.02 mg cm–2); however, leaf thickness was significantly lower in A. platanoides than in A. saccharum suggesting that A. platanoides contains more dense palisade and mesophyll cell layers than A. saccharum. Field net photosynthesis (mass basis) and photosynthetic light response curves (area basis) indicated significantly greater
carbon assimilation, and nitrogen and phosphorus use efficiencies in A. platanoides than in A. saccharum. Acer platanoides also exhibited higher water use efficiency than A. saccharum (0.88 ± 0.12 versus 0.32 ± 0.09 mmol CO2 mol–1 H2O). Acer platanoides exhibited significantly lower osmotic potentials than A. saccharum, but a similar relative water content at zero turgor. We conclude that A. platanoides utilizes light, water and nutrients more efficiently than A. saccharum.
Keywords:
height growth, leaf structure, Norway maple, photosynthesis, sugar maple, water relations.
