PMID- 12651508
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20191120
IS  - 1758-4469 (Electronic)
IS  - 0829-318X (Linking)
VI  - 20
IP  - 11
DP  - 2000 Jun
TI  - Responses of trembling aspen and hazelnut to vapor pressure deficit in a boreal 
      deciduous forest.
PG  - 725-734
AB  - The branch bag method was used to monitor photosynthesis and transpiration of 
      trembling aspen (Populus tremuloides Michx.) and hazelnut (Corylus cornuta 
      Marsh.) over a 42-day midsummer period in 1996, as part of the Boreal 
      Ecosystem-Atmosphere Study (BOREAS). During the same period, daytime measurements 
      of stomatal conductance (g(s)) and leaf water potential (Psi(leaf)) were made on 
      these species, and sap flow was monitored in aspen stems by the heat pulse 
      method. Weather conditions during the study period were similar to the long-term 
      average. Despite moist soils, both species showed an inverse relationship between 
      daytime g(s) and vapor pressure deficit (D) when D was > 0.5 kPa. Daytime 
      Psi(leaf) was below -2 MPa in aspen and near -1.5 MPa in hazelnut, except on 
      rainy days. These results are consistent with the hypothesis that stomatal 
      responses are constrained by hydraulic resistance from root to leaf, and by the 
      need to maintain Psi(leaf) above a minimum threshold value. Reductions in g(s) on 
      sunny afternoons with elevated ambient D (maximum 2.3 kPa) were associated with a 
      significant decrease in photosynthetic rates. However, day-to-day variation in 
      mean carbon assimilation rate was small in both species, and appeared to be 
      governed more by solar radiation than D. These results may be generally 
      applicable to healthy aspen stands under normal midsummer conditions in the 
      southern boreal forest. However, strong reductions in carbon uptake may be 
      expected at the more extreme values of D (> 4 kPa) that occur during periods of 
      regional drought, even if soil water is not locally limiting.
FAU - Hogg, E H
AU  - Hogg EH
AD  - Canadian Forest Service, 5320-122 Street, Edmonton, Alberta T6H 3S5, Canada.
FAU - Saugier, B
AU  - Saugier B
FAU - Pontailler, J-Y
AU  - Pontailler JY
FAU - Black, T A
AU  - Black TA
FAU - Chen, W
AU  - Chen W
FAU - Hurdle, P A
AU  - Hurdle PA
FAU - Wu, A
AU  - Wu A
LA  - eng
PT  - Journal Article
PL  - Canada
TA  - Tree Physiol
JT  - Tree physiology
JID - 100955338
EDAT- 2003/03/26 04:00
MHDA- 2003/03/26 04:01
CRDT- 2003/03/26 04:00
PHST- 2003/03/26 04:00 [pubmed]
PHST- 2003/03/26 04:01 [medline]
PHST- 2003/03/26 04:00 [entrez]
AID - 10.1093/treephys/20.11.725 [doi]
PST - ppublish
SO  - Tree Physiol. 2000 Jun;20(11):725-734. doi: 10.1093/treephys/20.11.725.