Author Topic: Commentary: What ecohydrologic separation is and where we can go with it  (Read 182 times)

Pankaj Dey

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 The “Ecohydrologic separation” hypothesis challenged assumptions of translatory flow through the rooting zone. However, studies claiming to test ecohydrologic separation have largely diverged from testing how water infiltrates and recharges the rooting zone, towards identifying isotopic differences between stream water and plant water. We suggest that differences should exist among the isotopic compositions of water in plants, streams, and other subsurface pools in most scenarios and that ecohydrologic separation is not solely about observing fractionated isotope ratios in plant water. The discussion of ecohydrologic separation should refocus on how heterogeneous infiltration and root uptake processes lead to such differences. More generally, we propose that research objectives should involve interpreting isotope data in the context of processes, rather than settling on describing data patterns that have confounded interpretations (i.e., that plant and stream water isotopically differ). Consequently, we outline areas where plant and soil water stable isotope data can progress us towards improved understanding and representation of soil‐water transport and plant‐water recharge.
  Key points 
  • Isotope ratios of plant water should differ from water flowing in soils to streams and so we need to move beyond confirming this difference
  • To move beyond identifying ecohydrologic separation towards understanding it, we provide a framework for assessing soil water flow processes
  • By focusing on dynamics of how water infiltrates into the subsurface and becomes available to plants we can better interpret past findings