Daily water stable isotopes, transpiration, and matrix potential data for an aspen and engelmann stand in the East River Watershed (version 2)

We provide daily stable isotope (2H & 18O) ratios in soil water and xylem (plant stem) water, as well as the sap flow (transpiration) and the soil's matric potential at a forested site near Gothic, Colorado, in the East River catchment. We measured the stable isotopic composition of the transpiration and the daily transpiration flux sum of three aspen and three engelmann spruce. In both forest stands, we installed a soil profile and measured the soil matric potential at 15, 30, and 60 cm depth as well as the stable isotopes of soil pore water at 5, 10, 30, 60, and 90 cm depths. All isotope measurements were done in situ via vapor probes connected to a cavity ring down spectrometer (Picarro L1240i).We further report the daily meteorological data observed at billy barr near our study site. We also provide for each tree the relative share of root water uptake derived from the isotope measurements via a Bayesian mixing model (MixSIAR).The daily data is provided as a time series in "Iso_MP_Sap_DataDaily_ESSDiveUpload.csv" and the units are provided in "dd.csv"; the location of the instrumented trees and soil profiles are given as latitude and longitude coordinates saved as CSV and KMZ files; and a file-level metadata (flmd.csv) file that lists each file contained in the dataset with associated metadata.The data was gathered to investigate the short-term changes of the water sources (i.e., variation of root water uptake from different soil depths) of the studied subalpine trees.Update 07/16/2025: The relative and absolute plant water uptake depths were grouped to ensure that the MixSIAR model was applied with endmembers that differed in their d2H value by at least 3 permill and at least 1 permill for d18O. Whenever the difference between observed d2H values for two or more probes at neighboring depths was less than 3 permill, we used the average value for the source water endmember. For days at which probes that were not next to each other measurements did not differ at least 3 permill, the average of all probes between these two depths was used as the water source endmember representing the depth range between these two probes.

本数据集提供美国科罗拉多州东河流域哥特镇附近森林样地内的土壤水、木质部（植物茎干）水的日稳定同位素（stable isotope）比值数据，同时包含液流（蒸腾作用）与土壤基质势数据。研究团队测定了3棵山杨与3棵恩格尔曼云杉的蒸腾液稳定同位素组成，以及其日蒸腾通量总和。在两个林分中均布设了土壤剖面，分别在15、30、60cm深度测定土壤基质势，在5、10、30、60、90cm深度测定土壤孔隙水的稳定同位素组成。所有同位素测定均通过连接至腔衰荡光谱仪（cavity ring down spectrometer, Picarro L1240i）的蒸汽探针原位完成。此外，本数据集还提供了研究样地附近Billy Barr站点观测的日气象数据；基于同位素测定结果通过贝叶斯混合模型（Bayesian mixing model, MixSIAR）计算得到的每棵树木根系吸水相对占比数据。日数据以时间序列形式存储于"Iso_MP_Sap_DataDaily_ESSDiveUpload.csv"，单位信息存储于"dd.csv"；布设的树木与土壤剖面的位置以经纬度坐标形式保存为CSV与KMZ文件；另有数据集级元数据文件"flmd.csv"，列明数据集内所有文件及其关联元数据。本数据集的采集旨在探究受试亚高山树木水源的短期变化，即不同土壤深度根系吸水占比的变化。2025年7月16日更新说明：对植物吸水的相对与绝对深度进行分组，以确保贝叶斯混合模型（MixSIAR）使用的端元在δ²H值上差异至少为3‰，δ¹⁸O值差异至少为1‰。当相邻深度的两个或多个探针的实测δ²H值差值小于3‰时，采用该组水源端元的平均值；当非相邻深度的探针实测值差值未达到3‰时，采用这两个深度之间所有探针的平均值作为代表该深度区间的水源端元。