Water relations of evergreen and drought-deciduous trees along a seasonally dry tropical forest chronosequence

Oecologia. 2010 Dec;164(4):881-90. doi: 10.1007/s00442-010-1725-y. Epub 2010 Jul 24.

Abstract

Seasonally dry tropical forests (SDTF) are characterized by pronounced seasonality in rainfall, and as a result trees in these forests must endure seasonal variation in soil water availability. Furthermore, SDTF on the northern Yucatan Peninsula, Mexico, have a legacy of disturbances, thereby creating a patchy mosaic of different seral stages undergoing secondary succession. We examined the water status of six canopy tree species, representing contrasting leaf phenology (evergreen vs. drought-deciduous) at three seral stages along a fire chronosequence in order to better understand strategies that trees use to overcome seasonal water limitations. The early-seral forest was characterized by high soil water evaporation and low soil moisture, and consequently early-seral trees exhibited lower midday bulk leaf water potentials (Ψ(L)) relative to late-seral trees (-1.01 ± 0.14 and -0.54 ± 0.07 MPa, respectively). Although Ψ(L) did not differ between evergreen and drought-deciduous trees, results from stable isotope analyses indicated different strategies to overcome seasonal water limitations. Differences were especially pronounced in the early-seral stage where evergreen trees had significantly lower xylem water δ(18)O values relative to drought-deciduous trees (-2.6 ± 0.5 and 0.3 ± 0.6‰, respectively), indicating evergreen species used deeper sources of water. In contrast, drought-deciduous trees showed greater enrichment of foliar (18)O (∆(18)O(l)) and (13)C, suggesting lower stomatal conductance and greater water-use efficiency. Thus, the rapid development of deep roots appears to be an important strategy enabling evergreen species to overcome seasonal water limitation, whereas, in addition to losing a portion of their leaves, drought-deciduous trees minimize water loss from remaining leaves during the dry season.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Carbon Isotopes / analysis
  • Carbon Isotopes / metabolism
  • Droughts*
  • Ecosystem*
  • Mexico
  • Oxygen Isotopes / analysis
  • Oxygen Isotopes / metabolism
  • Plant Leaves / growth & development
  • Plant Leaves / metabolism
  • Plant Roots / growth & development
  • Plant Roots / metabolism
  • Seasons
  • Time Factors
  • Trees / classification
  • Trees / growth & development*
  • Trees / metabolism
  • Tropical Climate*
  • Water / metabolism

Substances

  • Carbon Isotopes
  • Oxygen Isotopes
  • Water