Abstract
Line-conditioned excess (lc-excess), the deviation of the relationship between δD and δ18O in soil water from that of precipitation, is often used to indicate soil evaporation loss, but the conditions of using lc-excess under the influences of precipitation infiltration or percolation had not been identified. The interaction effects of climate, soil and vegetation on soil evaporation in forests are not well known. We collected soil water at 0–5, 15–20 and 40–45 cm depths and event-based precipitation from 2011 to 2015 in a subtropical forest plantation and calculated the lc-excess. Precipitation on the sampling day and percolation of upper soil water with low lc-excess affected the capacity of the lc-excess to indicate the soil evaporation fractionation signals. Lc-excess of soil water at 0–5 cm depth indicated a reliable soil evaporation loss estimate over 30 days prior to the sampling day. Soil evaporation loss was dominated by the cumulative soil temperature (Tss) during drought periods and was dominated by the relative soil water content (RSWC) during non-drought periods. High Tss decreased soil evaporation loss by increasing transpiration and relative humidity. Our results emphasize the importance of sampling the upper-most soil layer when there is no rain and vegetation during drought periods in forests when studying soil evaporation loss dynamics.
Highlights
0–5 cm depths when there was no rain on the same day, over different time periods: lc-excess of sampling soil water at 0–5 cm depths when there was no rain on the same day, over different time periods: (a) whole year, (b) non-drought periods and (c) is precipitation; relative humidity (RH)
Our results suggest the lc-excess of soil water at 0–5 cm depth presents a reliable f estimate over 30 days prior to the sampling day and emphasizes, when studying soil evaporation loss dynamics in this area, the importance of sampling shallow soil layers when there was no rain on the same day
Sampling the upper-most soil layer when there was no rain on the same day was important for studying soil evaporation loss dynamics in this forest ecosystem
Summary
Evaporation from the soil surface can increase non-productive soil water loss and adjust the local climate by cooling the surface or increasing the concentrations of atmospheric water vapor [1,2]. The fraction of evaporation loss to total precipitation affects the availability of water in forest ecosystems, determines plant growth and survival and influences the production of food and paper products [3,4]. A reliable assessment of soil evaporation loss is critical for evaluating the forest ecosystem water and energy balance and the associated effects of climate change. The line-conditioned excess (lc-excess; [7]), which is defined as the deviation of the relationship between δD and δ18 O in soil water from that of precipitation, can reflect the integrative soil evaporation loss over a period of time [8,9]. The isotopic enrichment of soil water leads to a deviation of the relationship between δD and δ18 O in soil water from that of precipitation [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
