Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

Precipitation Mediates Sap Flux Sensitivity to Evaporative Demand in the Neotropics

TitlePrecipitation Mediates Sap Flux Sensitivity to Evaporative Demand in the Neotropics
Publication TypeJournal Article
Year of Publication2019
AuthorsGrossiord, Charlotte, Christoffersen Bradley, Alonso-Rodrígue Aura M., Anderson-Teixeira Kristina, Asbjornsen Heidi, Aparecido Luiza Maria T., Z. Berry Carter, Baraloto Christopher, Bonal Damien, Burban Benoit, Chambers Jeffrey Q., Christianson Danielle S., Detto Matteo, Faybishenko Boris, Fontes Clarissa G., Fortunel Claire, Gimenez Bruno O., Jardine Kolby J., Kueppers Lara, Miller Gretchen R., Moore Georgianne W., Negron-Juarez Robinson, Stahl Clément, Swenson Nathan G., Trotsiuk Volodymyr, Varadharajan Charu, Warren Jeffrey M., Wolfe Brett T., Wei Liang, Wood Tana E., Xu Chonggang, and McDowell Nate G.
JournalOecologia
Volume191
Pages519 - 530
Abstract / Summary

Transpiration in humid tropical forests modulates the global water cycle and is a key driver of climate regulation. Yet, our understanding of how tropical trees regulate sap flux in response to climate variability remains elusive. With a progressively warming climate, atmospheric evaporative demand [i.e., vapor pressure deficit (VPD)] will be increasingly important for plant functioning, becoming the major control of plant water use in the twenty-first century. Using measurements in 34 tree species at seven sites across a precipitation gradient in the neotropics, we determined how the maximum sap flux velocity (vmax) and the VPD threshold at which vmax is reached (VPDmax) vary with precipitation regime [mean annual precipitation (MAP); seasonal drought intensity (PDRY)] and two functional traits related to foliar and wood economics spectra [leaf mass per area (LMA); wood specific gravity (WSG)]. We show that, even though vmax is highly variable within sites, it follows a negative trend in response to increasing MAP and PDRY across sites. LMA and WSG exerted little effect on vmax and VPDmax, suggesting that these widely used functional traits provide limited explanatory power of dynamic plant responses to environmental variation within hyper-diverse forests. This study demonstrates that long-term precipitation plays an important role in the sap flux response of humid tropical forests to VPD. Our findings suggest that under higher evaporative demand, trees growing in wetter environments in humid tropical regions may be subjected to reduced water exchange with the atmosphere relative to trees growing in drier climates.

URLhttp://link.springer.com/content/pdf/10.1007/s00442-019-04513-x.pdfhttp://link.springer.com/content/pdf/10.1007/s00442-019-04513-x.pdfhttp://link.springer.com/article/10.1007/s00442-019-04513-x/fulltext.html
DOI10.1007/s00442-019-04513-x
Journal: Oecologia
Year of Publication: 2019
Volume: 191
Pages: 519 - 530
Publication Date: 09/2019

Transpiration in humid tropical forests modulates the global water cycle and is a key driver of climate regulation. Yet, our understanding of how tropical trees regulate sap flux in response to climate variability remains elusive. With a progressively warming climate, atmospheric evaporative demand [i.e., vapor pressure deficit (VPD)] will be increasingly important for plant functioning, becoming the major control of plant water use in the twenty-first century. Using measurements in 34 tree species at seven sites across a precipitation gradient in the neotropics, we determined how the maximum sap flux velocity (vmax) and the VPD threshold at which vmax is reached (VPDmax) vary with precipitation regime [mean annual precipitation (MAP); seasonal drought intensity (PDRY)] and two functional traits related to foliar and wood economics spectra [leaf mass per area (LMA); wood specific gravity (WSG)]. We show that, even though vmax is highly variable within sites, it follows a negative trend in response to increasing MAP and PDRY across sites. LMA and WSG exerted little effect on vmax and VPDmax, suggesting that these widely used functional traits provide limited explanatory power of dynamic plant responses to environmental variation within hyper-diverse forests. This study demonstrates that long-term precipitation plays an important role in the sap flux response of humid tropical forests to VPD. Our findings suggest that under higher evaporative demand, trees growing in wetter environments in humid tropical regions may be subjected to reduced water exchange with the atmosphere relative to trees growing in drier climates.

DOI: 10.1007/s00442-019-04513-x
Citation:
Grossiord, C, B Christoffersen, AM Alonso-Rodrígue, K Anderson-Teixeira, H Asbjornsen, LM Aparecido, ZC Berry, et al.  2019.  "Precipitation Mediates Sap Flux Sensitivity to Evaporative Demand in the Neotropics."  Oecologia 191: 519 - 530.  https://doi.org/10.1007/s00442-019-04513-x.