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Harvard Forest REU Symposium Abstract 2006

  • Title: Developmental plasticity in the hydraulic properties of Quercus rubra leaves
  • Author: ()
  • Abstract:

    Water transport systems form a major component of a plantís carbon allocation, indicating that water supply occurs at a substantial resource cost. This raises the possibility that plants may modify their hydraulic investments based on their water status during development. Although a hydraulic system tailored to the specific environmental conditions experienced during a given growing season is beneficial if these conditions persist, too much sensitivity to current water availability puts plants at risk to changing conditions later in the year. Taking advantage of a particularly wet growing season, we compared Quercus rubraís response to water stress in 2006 with data collected in 2003. We focused on the hydraulic properties of leaves because they form the key interface between liquid- and vapor-phase transport and thus play a critical role in linking stomatal and xylem function. We studied leavesí abilities to retain their hydraulic conductance at negative water potentials, as such resilience allows plants to photosynthesize efficiently in conditions with limited water availability and indicates how effectively they are able to function during drought. We calculated leaf hydraulic conductance (Kleaf) based on the speed with which leaves rehydrate, an approach that allowed us to estimate Kleaf across a broad range of leaf water potentials. We found that leaves in 2006 cavitated at less negative water potentials than those from 2003, suggesting that leaves respond to abundant water during development by investing fewer resources in their hydraulic systems. This relatively high degree of plasticity suggests that the cost of building a resilient hydraulic system may outweigh the risks associated with potential losses in carbon uptake should drought subsequently occur.

  • Research Category: Physiological Ecology, Population Dynamics, and Species Interactions