LTER Zöbelboden, Austria, Metadata - Sap flow and automated dendrometers

Basic Information
Related Site
LTER Zöbelboden - Austria
Abstract
The LTER site Zöbelboden was equipped with highly modern infrastructure to assess the effects of extreme climate events on the forest ecosystem. The instruments include eddy covariance measurements for CO2 and water vapor fluxes at a tower (900 m a.s.l), and soil respiration auto-chambers, as well as combined sap flow sensors with automated dendrometers in the main footprint area of the eddy tower. This is the so called intensive plot 2 (IP2), which is equipped by a number of different field measurement devices for long-term monitoring (lysimeters water sampling, soil moisture and temperature sensors, manual dendrometers, deposition, litter fall) and supplemented by other monitoring activities (tree inventory, needle and leaf chemistry, soil chemistry). An optical multi-parameter probe for dissolved nitrogen and carbon was installed in the measuring weir of the catchment runoff at 577 m a.s.l. There, weekly water quality, runoff, and meteorology is monitored since many years. The related metadata refer to sap flow measurements and automated dendrometer records. The data can be viewed and downloaded via the link provided using the station names “ZOE_5250B00”, “ZOE_5005B00”, “ZOE_5234B00”, “ZOE_5004B00”, “ZOE_5230B00”, “ZOE_5227B00”, “ZOE_5141B00”, “ZOE_5164B00”, “ZOE_5064B00”, “ZOE_5079B00”, “ZOE_5082B00”, “ZOE_5106B00”.
Keywords
droughts
hydrology
monitoring
sap flow
transpiration
Contact
Gisela Proell
Thomas Dirnboeck
Owner/Creator
Environment Agency Austria (EAA)
Metadata Provider
Gisela Proell
UUID
09d9605f-21eb-4cce-adeb-33f5110f90e9
Dates
Date Range
Post date
Thursday, May 28, 2020 - 15:02
Last modified
Friday, August 4, 2023 - 12:28
Downloads
Online Locator
Distribution Function
Web address (URL)
Distribution URL
LTER-CWN time series management system
Geographic
Show details for observation location(s):
LTER Zöbelboden IP2
Additional information
Method Description
Three clusters of five beech (Fagus sylvatica L.), four spruce (Picea abies (L.) Karst.) and three sycamore (Acer pseudoplatanus L.) trees were randomly selected from the middle to the upper canopy layer (DBH 0.26 – 0.55 m) within the near natural mixed beech forest on Intensive Plot 2. Each tree was equipped with a sap flow sensor SF81 (EMS, Brno, Czech Republic), installed at 1.5 m height on the slope-upward north-facing side of each stem. The measuring principle is based on the tissue heat balance (Cermak et al. 2004). Sap flow rates per tree (Q; kg h−1) are estimated by the power consumption which is required to keep a constant temperature difference (1K) between a defined xylem section (5.5 cm wide) and a reference electrode. Weather protection shields prevented the measuring point from direct solar radiation. The sample trees were subjected to sap flow measurements over the vegetation period (usually from April until October). Every two years, the sensors were reinstalled at the same height nearby the original sensor position. Raw data were stored as 15 minutes average values in a binary format (*.hex) to save storage capacity and to accelerate the data transfer. Data were transferred hourly via GSM signal to a data cloud application. The data download from the cloud application was fully supported by the Mini32 software version 10.2.4.0 (EMS, Brno, Czech Republic) for further processing.
Continuous stem increment was recorded with high-resolution DR26 E dendrometers (EMS Brno, Czech Republic) via stainless tape, which encircles the trunk, and a rotary position sensor. Dendrometers were installed at 1.3 m height on the north side of the stem on the same trees used for sap flow measurements. Additionally, dendrometer readings were used for estimating drought stress of trees by segregating growth rates from physiological processes such as the shrinking and swelling of the bark. Further information on tree height, vitality, diameter at breast height can be downloaded from https://deims.org/dataset/7893ee21-cf83-4b28-8b87-2c305ab4069e.
Sampling Time Unit
minutes
Sampling Time Span
other temporal resolution
Quality Assurance
There is no need for sensor calibration and special maintenance. Weather protection shields were monthly visually checked for symmetrical position around the sensors. Electrodes and thermosensors were cleaned every two years after sensor dismounting. Sensor insulation was renewed if damaged. Shifting of the DRL 26 unit was avoided during the operation. The Mini32 software (EMS, Brno, Czech Republic) supports graphical features to process the data. Fictitious sap flow that represents the heat loss by heat conductivity of the xylem was manually subtracted with the Mini32 software assuming zero or minimum sap flow at 3 a.m.. Additional visual checks were necessary to detect sap flow patterns that interfere with the general measurement theory e.g. night-time sap flow during dry conditions or stem flow under rainy conditions in beech. Hence, baseline subtraction was manually adjusted based on expert knowledge. Unrealistic sap flow values were deleted based on the “operating status”, which indicates any malfunction of the measurement system (dT out of range, resistance too low/high, sensor malfunction, system temporarily off or general system malfunction). In addition, unrealistic values beyond the typical daily variation of sap flow or linear growth rates were visually assessed and deleted based on expert knowledge.
Parameters
ecosystem parameter
water parameter
Spatial Design
representative
Species Groups
Fagus sylvatica
Picea abies
Intellectual Rights
Formal acknowledgement of the dataset providers
Spatial Scale
plot
INSPIRE Data Theme
Environmental monitoring facilities