Limits...
Hydraulic Balance of a Eucalyptus urophylla Plantation in Response to Periodic Drought in Low Subtropical China

View Article: PubMed Central - PubMed

ABSTRACT

A clear understanding of hydraulic regulation in cultivated plants is crucial for addressing challenges to forest water cycling due to climate changes in low subtropical China. Experiments were conducted to determine the hydrologic balance of a Eucalyptus urophylla plantation in response to periodic drought. Trees displayed lower stomatal conductance (GS) and leaf water potentials (ΨL) during the dry periods. A decrease of 22.4% was found for the maximum reference GS (GS at D = 1 kPa; GSref-max). Accordingly, specific hydraulic conductivity (ks) decreased by 45.3 – 65.6% from the wet to the dry season, depending on the tree size. Fairly stable leaf stomatal conductance (gs) with decreasing ΨL (ΨL < -1.6 MPa) contributed to the high water-use efficiency (WUE) of this Eucalyptus species. Additionally, the lower stomatal sensitivity (-m = 0.53) in the dry season might also be responsible for the high WUE, since we found an anisohydric behavior that was associated with photosynthetically active radiation (Q0). Larger trees were found to use water more efficiently than small trees, due to the higher sensitivity of ks to decreasing ΨL. This was also verified by the decreasing leaf carbon isotope discrimination (Δ13C) with increasing tree diameter. However, further studies are needed to determine the universality of these results for other Eucalyptus species in this region.

No MeSH data available.


(A) Limitation of leaf water potential on relative gs during mid-day (at noon, 12:00-13:00) and (B) relationship between tree size and specific hydraulic conductivity ks of 15 sample trees in dry and wet seasons.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5036442&req=5

Figure 7: (A) Limitation of leaf water potential on relative gs during mid-day (at noon, 12:00-13:00) and (B) relationship between tree size and specific hydraulic conductivity ks of 15 sample trees in dry and wet seasons.

Mentions: We also related Ψnoon with the corresponding mid-day gs (Figure 7A) and found a positive relationship between gs and ΨL when light was low. Based on cell turgor theory, the change in ΨL is caused by the Gs-promoted water loss from the leaf (Dow and Bergmann, 2014). However, this value peaked and was maintained from -0.6 to -0.9 MPa before a gradual decrease.


Hydraulic Balance of a Eucalyptus urophylla Plantation in Response to Periodic Drought in Low Subtropical China
(A) Limitation of leaf water potential on relative gs during mid-day (at noon, 12:00-13:00) and (B) relationship between tree size and specific hydraulic conductivity ks of 15 sample trees in dry and wet seasons.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036442&req=5

Figure 7: (A) Limitation of leaf water potential on relative gs during mid-day (at noon, 12:00-13:00) and (B) relationship between tree size and specific hydraulic conductivity ks of 15 sample trees in dry and wet seasons.
Mentions: We also related Ψnoon with the corresponding mid-day gs (Figure 7A) and found a positive relationship between gs and ΨL when light was low. Based on cell turgor theory, the change in ΨL is caused by the Gs-promoted water loss from the leaf (Dow and Bergmann, 2014). However, this value peaked and was maintained from -0.6 to -0.9 MPa before a gradual decrease.

View Article: PubMed Central - PubMed

ABSTRACT

A clear understanding of hydraulic regulation in cultivated plants is crucial for addressing challenges to forest water cycling due to climate changes in low subtropical China. Experiments were conducted to determine the hydrologic balance of a Eucalyptus urophylla plantation in response to periodic drought. Trees displayed lower stomatal conductance (GS) and leaf water potentials (ΨL) during the dry periods. A decrease of 22.4% was found for the maximum reference GS (GS at D = 1 kPa; GSref-max). Accordingly, specific hydraulic conductivity (ks) decreased by 45.3 – 65.6% from the wet to the dry season, depending on the tree size. Fairly stable leaf stomatal conductance (gs) with decreasing ΨL (ΨL < -1.6 MPa) contributed to the high water-use efficiency (WUE) of this Eucalyptus species. Additionally, the lower stomatal sensitivity (-m = 0.53) in the dry season might also be responsible for the high WUE, since we found an anisohydric behavior that was associated with photosynthetically active radiation (Q0). Larger trees were found to use water more efficiently than small trees, due to the higher sensitivity of ks to decreasing ΨL. This was also verified by the decreasing leaf carbon isotope discrimination (Δ13C) with increasing tree diameter. However, further studies are needed to determine the universality of these results for other Eucalyptus species in this region.

No MeSH data available.