|
Linking carbon and water cycling to nitrogen for forests across North America: From the leaf to the ecosystem
Rossella
Guerrieri, University of New Hampshire, rossella.guerrieri@unh.edu
(Presenter)
Lucie
C.
Lepine, University of New Hamphire, lucie.lepine@unh.edu
Heidi
Asbjornsen, University of New Hamphire, heidi.asbjornsen@unh.edu
Jingfeng
Xiao, University of New Hampshire, j.xiao@unh.edu
Scott
Ollinger, University of New Hampshire, scott.ollinger@unh.edu
(Presenter)
Assimilation of atmospheric CO2 by forests through photosynthesis (A) is intrinsically related to the loss of water (H2O) through stomata via transpiration (T), and thus exerts a strong influence on both carbon (C) and H2O exchange in the biosphere. Water use efficiency (WUE; the A/T ratio) is the key physiological parameter that explicitly links H2O and C cycling in forests. Most studies examining the influence of climatic factors on forest WUE have focused on individual sites, most often in water-limited ecosystems. Much less is known about the dynamics of WUE across forest ecosystems that span broad gradients in climate nutrient status, and species diversity. Furthermore, whether observations at the tree level can facilitate a mechanistic understanding of the ecosystem WUE has been poorly investigated. This study explores variation in WUE at eleven forested Ameriflux sites across North America spanning a wide range of forest types and climate conditions. We were interested in answering the following questions: 1) Are patterns of WUE at the leaf/tree level similar to those for whole ecosystems? 2) Is there a consistent relationship between foliar nitrogen (N) and WUE at the two different scales? 3) To what extent does species diversity explain forest ecosystem functioning? We addressed these questions through a combination of techniques applied at both leaf and ecosystem scales, including foliar d13C, d18O and N, eddy covariance and remote sensing data. At each site, we used foliar d13C to infer intrinsic WUE (iWUE=A/gs) for two dominant tree species, and flux data to derive ET and WUEe (i.e., ecosystem WUE= GPP/ET). Variations in iWUE and WUEe in relation to foliar N and climate parameters are considered across sites. Differences in GPP, ET and WUEe are also explored in relation to forest ecosystem type, species richness and Shannon’s diversity index.
Presentation Type: Poster
Session: General Contributions
(Tue 4:35 PM)
Associated Project(s):
- Ollinger, Scott: Exploring Relationships Among Water Use Efficiency, Canopy Nitrogen and Carbon Cycling across North American Ecosystems to Improve Land Surface Models ...details
Poster Location ID: 102
|