Linking species distributions to tree water relations in a temperate forest in central Pennsylvania

MS in Horticulture (2010)

Collaborators: Kate McCulloh, Rick Meinzer

The hydraulic architecture of a tree could contribute to its ability to tolerate drier
soils by increasing resistance to xylem cavitation and improving the efficiency of water transport. This study examined six co-occurring tree species within three genera (3 congeneric contrasts; Carya glabra and C. tomentosa, Pinus strobus and P. virginiana, Quercus alba and Q. prinus) under naturally occurring soil moisture gradients. Within each genus, species differed significantly in distribution along gradients of soil moisture (P < 0.003), with one species preferentially occupying wetter sites and the other occupying drier sites. I hypothesized that hydraulic architecture might partially explain variation in the distribution of species. I measured a suite of hydraulic architecture parameters including maximum specific hydraulic conductivity (ks max), leaf specific hydraulic conductivity (LSC), and xylem vulnerability at three levels of percent loss of maximum hydraulic conductivity (P20, P50, and P70). For pines, the species associated with drier sites, P. virginiana, was more resistant to cavitation, which was consistent with my hypothesis.


Wubbels, Jane K. 2010. Tree Species Distribution in Relation to Stem Hydraulic Traits and Soil Moisture in a mixed Hardwood Forest in Central Pennsylvania. M.S. Thesis, The Pennsylvania State University, University Park.