Water isotope signatures in Swiss forest ecosystems in 2021 and 2022

The isotope composition of different forest water pools was analyzed at 10 sites of the Long-term Forest Ecosystem Research programme in 2021 and 2022. The sampling was done during the vegetation season and included fortnightly xylem water samples taken by stem increment cores and each year 3 bulk soil water sampling campaigns (in April, June, September of 2021 and 2022). Both sample types were cryogenically extracted at WSL and analyzed on a Picarro 2140 with Micro-Combustion-Module. Gravimetric water content in both sample types was computed based on pre-and post-extraction weights. In addition to xylem and bulk soil waters, we analyzed the isotope composition of soil solution from a suction cup lysimeters in three soil depths 0, 15, 50, 80 cm and precipitation from samplers below the canopy and outside of the forest, all collected fortnightly from collection periods of varying length (longest from 2017-2022).
Precipitation samples are further described [here](https://www.doi.org/10.16904/envidat.lwf.15). Lysimeter samples are described further [here](https://www.doi.org/10.16904/envidat.lwf.28).

2021年与2022年，研究团队在长期森林生态系统研究计划的10个样点中，分析了不同森林水体库的同位素组成。本次采样于植被生长季开展，包含每两周采集一次的、通过树干生长芯获取的木质部水样品；此外每年设置3次混合土壤水采样作业，采样时间覆盖2021年与2022年的4月、6月及9月。两类样品均在瑞士联邦森林、雪与景观研究所（WSL）完成低温萃取，并通过搭载微燃烧模块（Micro-Combustion-Module）的Picarro 2140型同位素分析仪完成同位素组成分析。两类样品的重量法含水量均基于萃取前后的称重结果计算得到。
除木质部水与混合土壤水外，本研究还分析了负压式土壤溶液取样器（suction cup lysimeters）在0、15、50、80 cm四个土层采集的土壤溶液同位素组成，以及使用林冠下和林外降水采样器采集的降水样品。所有上述样品均按照不同时长的采样周期每两周采集一次，其中最长采样周期跨度为2017-2022年。
降水样品的详细说明可参见[此处](https://www.doi.org/10.16904/envidat.lwf.15)；渗滤仪采集的土壤溶液样品的详细信息可参见[此处](https://www.doi.org/10.16904/envidat.lwf.28)。