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Tuesday, April 10 • 10:45am - 11:00am
BELOWGROUND PROCESSES: Changing Patterns of Soil Water and Plant Water Isotopes in Response to a Rainfall Event in a Peri-Urban Zone with Shallow Soils

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AUTHORS: Long Sun*, Lei Yang, Liding Chen, Fangkai Zhao, Shoujuan Li – Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences

ABSTRACT: Identifying the changing patterns of soil water and related plant water isotopes in response to a rainfall event will benefit both water management and plant water-use efficiency. This study presented results at multi-day timescales. Two crop sites and four wood sites (including 2 forest sites and 2 orchard sites) were selected in a typical peri-urban area in eastern China. Water for dD and d18O analysis was collected from rainfall, branch xylem, and soil (three soil layers). Basic topographic features and soil properties were measured. Soil water recharge processes were varied in different land uses. The extents of isotopes depletion in topsoil (0–10 cm) were along the sequence of forest (9.90%) < orchard (10.86%) < cropland (13.70%), in contrast to the reduction of soil water content (17.46% in cropland, 32.06% in forest, and 41.78% in orchard). Trees in forest lands had larger variability in stem water dD compared with trees in orchards (peach and tea). Opposite changing patterns of stem water dD were found between the orchards and forest lands. Although the soil water in bottom soil layer was mainly used by trees, the stem water dD had limited correlation with soil water dD due to the influence of rainwater mixing. Eight factors, including altitude, capillary porosity, porosity, slope gradient, pH, total phosphorous, available nitrogen, soil bulk density, were mainly responsible for shaping changing patterns of stem water dD. Accompanied another 4 factors (clay, sand, soil organic matter, and antecedent soil moisture), all the 12 factors explained 97.4% of the total variability in stem water dD for the five samplings. This study emphasized importance to characterize the changing patterns of soil water and related plant water dD in tiny timescale, which may be helpful for water management and increasing plant water-use efficiency.

Tuesday April 10, 2018 10:45am - 11:00am CDT
LaSalle 2 (7th Floor)

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