02/05/2019


##########################################
Data use policy 

As a condition for use of this data set, users agree:
(1) To notify the lead investigator (Luitgard Schwendenmann, l.schwendenmann@auckland.ac.nz) if the dataset is to be used in any publication;
(2) To provide formal recognition that, at our discretion, may include co-authorship or acknowledgements on publications;
(3) To recognise that we may be using these data for scientific analyses, papers or publications that are currently planned or in preparation, and that such activities have precedence over any that that you might wish to prepare.


##########################################
Citation: 

Luitgard Schwendenmann (2019): Data: H and O isotope signatures of soil and xylem samples, cacao agroforest, Indonesia.

##########################################
Short description:

This dataset contains soil and xylem water delta18O and delta2H values of soil and xylem samples collected from cacao and shade trees (gliricidia) in a cacao agroforest, Marena, Indonesia, from Jan 2007 to April 2008.

The data set includes two files:
Schwendenmann_Marena_metadata.txt
Schwendenmann_Marena_soil and xylem water 2H_18Ovalues.csv


##########################################
Acknowledgement:

This research project was funded by the German Research Foundation (SFB 552). 

##########################################
Site description and methods used:

Site description
The experimental site was located in the vicinity of Marena, a village in the Kulawi Valley, Central Sulawesi, Indonesia (1.552 S, 120.020 E) at 560 m a.s.l. The cacao/Gliricidia agroforest stand was established in December 2000 on former upland rice and maize fields. 


Experimental setup 
To study the impact of drought ecosystem functions in a cacao agroforest a replicated throughfall reduction experiment was conducted over a 13-month period. Samples for stable water isotopes were taken from the control plots (Plot 1, 4 and 5). In each control plot 1 - 3 cacao and gliricidia trees are selected and the same trees were sampled over 1 year (Jan/Feb 2007 to April 2008). A detailed description of the study area and experimental design can be found in Schwendenmann et al. 2010 (https://doi.org/10.1111/j.1365-2486.2009.02034.x)


Sample collection
Suberized twigs (approximately 10 mm in diameter, 50 mm long) were cut from the canopy. Bark was removed to avoid contamination of xylem water with phloem water. Soil samples were taken directly below the canopy of each tree at the following intervals: 0–0.1, 0.1–0.3, 0.3–0.5, 0.5–0.7, and 0.7–1.0 m. Twigs and soil samples were placed into 40 mL glass bottles, closed with a Teflon coated lid, wrapped in Parafilm, and then kept frozen until water extraction. 

Water extraction and isotopic analyses 
Water was extracted from plant and soil samples by cryogenic vacuum extraction (Ehleringer & Osmond, 1989). Hydrogen isotopic composition was measured by injecting the extracted water into a high-temperature elemental analyzer (TC/EA, Thermoelectron cooperation, Breman, Germany) coupled via a ConFlo III interface to a Delta V Plus isotope ratio mass spectrometer (Thermo-Electron Cooperation) (Gehre et al., 2004). Deuterium isotope ratios were expressed in ‰ relative to Vienna Standard Mean Ocean Water. Measurement precision was 2‰. Analyses were carried out at the Center for Stable Isotope Research and Analysis (KOSI, Georg-August-University, Göttingen, Germany).