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Sap-flux-scaled transpiration responses to light, vapor pressure deficit, and leaf area reduction in a flooded Taxodium distichum forest.

Publication ,  Journal Article
Oren, R; Phillips, N; Ewers, BE; Pataki, DE; Megonigal, JP
Published in: Tree physiology
May 1999

We used 20-mm-long, Granier-type sensors to quantify the effects of tree size, azimuth and radial position in the xylem on the spatial variability in xylem sap flux in 64-year-old trees of Taxodium distichum L. Rich. growing in a flooded forest. This information was used to scale flux to the stand level to investigate variations in half-hourly and daily (24-hour) sums of sap flow, transpiration per unit of leaf area, and stand transpiration in relation to vapor pressure deficit (D) and photosynthetically active radiation (Q(o)). Measurements of xylem sap flux density (J(s)) indicated that: (1) J(s) in small diameter trees was 0.70 of that in medium and large diameter trees, but the relationship between stem diameter as a continuous variable and J(s) was not significant; (2) J(s) at 20-40 mm depth in the xylem was 0.40 of that at 0-20 mm depth; and (3) J(s) on the north side of trees was 0.64 of that in directions 120 degrees from the north. Daily transpiration was linearly related to daily daytime mean D, and reached a modest value of 1.3 mm day(-1), reflecting the low leaf area index (LAI = 2.2) of the stand. Because there was no soil water limitation, half-hourly water uptake was nearly linearly related to D at D < 0.6 kPa during both night and day, increasing to saturation during daytime at higher values of D. The positive effect of Q(o) on J(s) was significant, but relatively minor. Thus, a second-order polynomial with D explained 94% of the variation in J(s) and transpiration. An approximately 40% reduction in LAI by a hurricane resulted in decreases of about 18% in J(s) and stand transpiration, indicating partial stomatal compensation.

Duke Scholars

Published In

Tree physiology

DOI

EISSN

1758-4469

ISSN

0829-318X

Publication Date

May 1999

Volume

19

Issue

6

Start / End Page

337 / 347

Related Subject Headings

  • Plant Biology & Botany
  • 4101 Climate change impacts and adaptation
  • 3108 Plant biology
  • 3103 Ecology
  • 0705 Forestry Sciences
  • 0607 Plant Biology
  • 0602 Ecology
 

Citation

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Oren, R., Phillips, N., Ewers, B. E., Pataki, D. E., & Megonigal, J. P. (1999). Sap-flux-scaled transpiration responses to light, vapor pressure deficit, and leaf area reduction in a flooded Taxodium distichum forest. Tree Physiology, 19(6), 337–347. https://doi.org/10.1093/treephys/19.6.337
Oren, R., N. Phillips, B. E. Ewers, D. E. Pataki, and J. P. Megonigal. “Sap-flux-scaled transpiration responses to light, vapor pressure deficit, and leaf area reduction in a flooded Taxodium distichum forest.Tree Physiology 19, no. 6 (May 1999): 337–47. https://doi.org/10.1093/treephys/19.6.337.
Oren R, Phillips N, Ewers BE, Pataki DE, Megonigal JP. Sap-flux-scaled transpiration responses to light, vapor pressure deficit, and leaf area reduction in a flooded Taxodium distichum forest. Tree physiology. 1999 May;19(6):337–47.
Oren, R., et al. “Sap-flux-scaled transpiration responses to light, vapor pressure deficit, and leaf area reduction in a flooded Taxodium distichum forest.Tree Physiology, vol. 19, no. 6, May 1999, pp. 337–47. Epmc, doi:10.1093/treephys/19.6.337.
Oren R, Phillips N, Ewers BE, Pataki DE, Megonigal JP. Sap-flux-scaled transpiration responses to light, vapor pressure deficit, and leaf area reduction in a flooded Taxodium distichum forest. Tree physiology. 1999 May;19(6):337–347.
Journal cover image

Published In

Tree physiology

DOI

EISSN

1758-4469

ISSN

0829-318X

Publication Date

May 1999

Volume

19

Issue

6

Start / End Page

337 / 347

Related Subject Headings

  • Plant Biology & Botany
  • 4101 Climate change impacts and adaptation
  • 3108 Plant biology
  • 3103 Ecology
  • 0705 Forestry Sciences
  • 0607 Plant Biology
  • 0602 Ecology