|Title||Water relations of Juniperus virginiana and Andropogon gerardii in an unburned tallgrass prairie watershed|
|Publication Type||Journal Article|
|Year of Publication||1993|
|Authors||Axmann, BD, Knapp, AK|
We assessed several factors influencing the success of Juniperus virginiana in unburned tallgrass prairie by mapping the distribution of individuals in a 21-ha watershed on the Konza Prairie Research Natural Area in NE Kansas. We also compared the water relations of this tree with those of the dominant grass Andropogon gerardii. No general relationships were detected between the distribution of J. virginiana and plant water status, plant size, soil type, slope, aspect or elevation. Leaf xylem pressure potential (ψ) in upland trees was significantly lower (0.44 MPa) than in lowland trees, but only during the driest portion of the growing season. In contrast, topographic position influenced ψ more strongly in A. gerardii with ψ in upland plants as much as 1.0 MPa lower than in lowland plants. During wetter periods, photosynthetic rates in A. gerardii were higher than in J. virginiana in uplands, but the reverse occurred during the driest period of the growing season. The ability of J. virginiana to maintain higher ψ and higher photosynthetic rates relative to A. gerardii during periods of water limitation may contribute to its success in tallgrass prairie protected from fire.