Computational protocol: Distinguish water utilization strategies of trees growing on earth‐rocky mountainous area with transpiration and water isotopes

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Protocol publication

[…] Regressions between transpiration and environmental factors were plotted and estimates of r 2 and slope p‐values were performed in Sigmaplot 12.5 (SPSS Inc., Chicago, IL, USA).The comparison of δ18O composition between plant tissue samples and soil water yielded information as to which layer was the water source.To discover the possible sources of water uptake by plants, isotopic compositions of plant water samples was first compared with the water sources of soil of different depths (0–10, 10–20, 20–30, 30–40 and 40‐60 cm) and groundwater. According to the principle of isotope mass balance, the isotopic compositions of all potential water sources and plant water were input to IsoSource mixing model (Phillips & Gregg, ) approach to assess the contributions of different water sources used by plants. The fractional increment was set at 1%, and the uncertainty level was set at 0.2‰. Significant differences were determined via independent‐samples t test. This approach analyzed the data more systematically and provided a more quantitative assessment of the estimated range of feasible contributions of potential water sources to total water uptake (Jia, Yu, & Deng, ). It can calculate as many as ten water sources. The IsoSource mixing model was expressed with formula as follows: (7)δY=c1δX1+c2δX2+c3δX3+…+cnδXnc1+c2+c3+…+cn=1where Y is the 18O or D of water in plant, X 1, X 2, X 3…X n are the 18O or D of different water sources, and c 1, c 2, c 3, c n are the contribution rates of different water sources. n is number of water sources and in this study, n is six (soil water: 0–10, 10–20, 20–30, 30–40, and 40–60 cm and groundwater). […]

Pipeline specifications

Software tools SigmaPlot, SPSS
Application Miscellaneous
Organisms Pinus tabuliformis, Quercus variabilis