TY - JOUR
T1 - Salinity and light interactively affect neotropical mangrove seedlings at the leaf and whole plant levels
AU - López-Hoffman, Laura
AU - Anten, Niels P.R.
AU - Martínez-Ramos, Miguel
AU - Ackerly, David D.
N1 - Funding Information:
Acknowledgments L.L.H. thanks R. Baskhar, J. DeNoyer, E. Edwards, F. Garcia, A. Loaiza, W. Ludington, I. Monroe, E. Marin-Spiotta, and R. Shaftel. L.L.H especially thanks E. Medina for the introduction to Venezuela’s mangroves and for advice on the study design and F. Barboza and E. Narváez of the In-stituto para la Conservación del Lago de Maracaibo for logistical support. The authors also thank J. Berry and B. Haxo. We appreciate the comments of H. Paz and other reviewers. Funding was provided by a Mellon Foundation grant to Stanford University and Carnegie Institute of Washington, and a N.S.F. dissertation improvement grant (no. 0003023) and Mellon Mays Fellowship to L.L.H.
PY - 2007/1
Y1 - 2007/1
N2 - We have studied the interactive effects of salinity and light on Avicennia germinans mangrove seedlings in greenhouse and field experiments. We hypothesized that net photosynthesis, growth, and survivorship rates should increase more with an increase in light availability for plants growing at low salinity than for those growing at high salinity. This hypothesis was supported by our results for net photosynthesis and growth. Net daily photosynthesis did increase more with increasing light for low-salinity plants than for high-salinity plants. Stomatal conductance, leaf-level transpiration, and internal CO2 concentrations were lower at high than at low salinity. At high light, the ratio of leaf respiration to assimilation was 2.5 times greater at high than at low salinity. Stomatal limitations and increased respiratory costs may explain why, at high salinity, seedlings did not respond to increased light availability with increased net photosynthesis. Seedling mass and growth rates increased more with increasing light availability at low than at high salinity. Ratios of root mass to leaf mass were higher at high salinity, suggesting that either water or nutrient limitations may have limited seedling growth at high salinity in response to increasing light. The interactive effects of salinity and light on seedling size and growth rates observed in the greenhouse were robust in the field, despite the presence of other factors in the field-such as inundation, nutrient gradients, and herbivory. In the field, seedling survivorship was higher at low than at high salinity and increased with light availability. Interestingly, the positive effect of light on seedling survivorship was stronger at high salinity, indicating that growth and survivorship rates are decoupled. In general, this study demonstrates that environmental effects at the leaf-level also influence whole plant growth in mangroves.
AB - We have studied the interactive effects of salinity and light on Avicennia germinans mangrove seedlings in greenhouse and field experiments. We hypothesized that net photosynthesis, growth, and survivorship rates should increase more with an increase in light availability for plants growing at low salinity than for those growing at high salinity. This hypothesis was supported by our results for net photosynthesis and growth. Net daily photosynthesis did increase more with increasing light for low-salinity plants than for high-salinity plants. Stomatal conductance, leaf-level transpiration, and internal CO2 concentrations were lower at high than at low salinity. At high light, the ratio of leaf respiration to assimilation was 2.5 times greater at high than at low salinity. Stomatal limitations and increased respiratory costs may explain why, at high salinity, seedlings did not respond to increased light availability with increased net photosynthesis. Seedling mass and growth rates increased more with increasing light availability at low than at high salinity. Ratios of root mass to leaf mass were higher at high salinity, suggesting that either water or nutrient limitations may have limited seedling growth at high salinity in response to increasing light. The interactive effects of salinity and light on seedling size and growth rates observed in the greenhouse were robust in the field, despite the presence of other factors in the field-such as inundation, nutrient gradients, and herbivory. In the field, seedling survivorship was higher at low than at high salinity and increased with light availability. Interestingly, the positive effect of light on seedling survivorship was stronger at high salinity, indicating that growth and survivorship rates are decoupled. In general, this study demonstrates that environmental effects at the leaf-level also influence whole plant growth in mangroves.
KW - Avicennia germinans
KW - Ecophysiology
KW - Gas exchange
KW - Growth analysis
KW - Venezuela
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UR - http://www.scopus.com/inward/citedby.url?scp=33845777952&partnerID=8YFLogxK
U2 - 10.1007/s00442-006-0563-4
DO - 10.1007/s00442-006-0563-4
M3 - Article
C2 - 17024379
AN - SCOPUS:33845777952
SN - 0029-8549
VL - 150
SP - 545
EP - 556
JO - Oecologia
JF - Oecologia
IS - 4
ER -