Ecophysiological responses in mesic versus xeric hardwood species to an early-season drought in central Pennsylvania

Examined net photosynthesis and plant and tissue water relations in saplings of co-occurring xeric (Quercus prinus and Q. ilicifolia) verus mesic (Q. rubra and Castanea dentata) hardwood species during a droughty summer. Mean daily net photosynthesis, leaf conductance, leaf water potential, and water use efficiency were reduced in all 4 species during the peak drought period. Throughout the study, net photosynthesis and leaf conductance were on average high in Q. ilicifolia and Q. prinus, intermediate in Q. rubra, and low in C. dentata. Leaf water potential was generally highest in C. dentata and not significantly different among the oaks. There were few consistent patterns in the tissue water relations data, despite relatively high gas exchange in those plants. -Authors