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| Titel |
Transpiration and Groundwater Uptake Dynamics of Pinus Brutia on a Fractured Mediterranean Mountain Slope during Two Hydrologically Contrasting Years |
| VerfasserIn |
Marinos Eliades, Adriana Bruggeman, Maciek Lubczynski, Andreas Christou, Corrado Camera, Hakan Djuma |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250138464
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| Publikation (Nr.) |
 EGU/EGU2017-1491.pdf |
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| Zusammenfassung |
| Semi-arid environments tend to have extreme temporal variability in rainfall, resulting in
extended periods with little to no precipitation. The mountainous topography is characterized
by steep slopes, often leading to shallow soil layers with limited water storage capacity. Tree
species survive in these environments by developing various adaptation mechanisms to access
water. The main objective of this study is to examine the differences of two hydrologically
contrasting years on the transpiration and groundwater uptake dynamics of Pinus brutia
trees.
We selected four trees for sap flow monitoring in an 8966-m2 fenced area of Pinus brutia
forest. The site is located at 620 m elevation, on the northern foothills of the Troodos
mountains in Cyprus. The slope of the site ranges between 0 and 82%. The average daily
minimum temperature is 5 0C in January and the average daily maximum temperature is 35
oC in August. The mean annual rainfall is 425 mm. Monitoring started on 1 January 2015 and
is ongoing.
We measured soil depth in a 1-m grid around each of the selected trees for
monitoring. We processed soil depths in ArcGIS software (ESRI) to create a soil
depth map. We used a Total Station and a differential GPS for the creation of a high
resolution DEM of the area covering the selected trees. We installed seventeen soil
moisture sensors at 12-cm depth and two at 30-cm depth, where the soil was deeper
than 24 cm. We randomly installed 28 metric manual rain gauges under the trees’
canopy to measure throughfall. For stemflow we installed a plastic tube around
each tree trunk and connected it to a manual rain gauge. We used sap flow heat
ratio method (HRM) instruments to determine sap flow rates of the Pinus brutia.
Hourly meteorological conditions were observed by an automatic meteorological
station.
Here we present the results of the January to October periods, in order to have
comparable results for the two contrasting years. During the wet year of 2015, we measured
439 mm rainfall and an average transpiration of 225 mm. During the dry year of 2016,
rainfall was 188 mm while the average transpiration was 96 mm. Both during the
wet and dry years, the transpiration was 51% of the total rainfall. The average soil
moisture content during these two periods was 15% in 2015 and 13% in 2016; and was
not enough for the transpiration needs. The water balance of the trees revealed
that most of the water needed for transpiration is provided by groundwater uptake
from bedrock fractures (about 80%). Reverse sap flow rates were measured during
negative temperatures, indicating that Pinus brutia trees release water to avoid
freezing. Pinus brutia was found to adapt to the annual and seasonal variations in
climatic conditions by regulating their transpiration rates according to the water
availability.
This research is supported by the European Union’s H2020 BINGO project. |
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