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Ecologists conducted a novel study on vegetation transpiration from a global network of 251 sites

Ecologists conducted a novel study on vegetation transpiration from a global network of 251 sites

An ecologist from RUDN University together with colleagues from 14 countries compared three methods for estimating ecosystem transpiration in a study. In the first ever research with such a comprehensive data-set, the team used land-atmosphere water vapor flux data of collected at 251 locations all over the planet, from Australia to Greenland. The outcome of the research help to understand the role of plants in the global water and carbon cycles in the current predicament of global warming.

Plants roots absorb water from the soil and transport through the stems up to their leaves thanks to a gradient of water vapor pressure. Once it reaches the leaves, water evaporates through leaf pores called stomata and gets into the atmosphere. The physical process by which water is released to the atmosphere by plants is called transpiration. Transpiration is a 'meeting point' of carbon, water, and energy cycles in terrestrial ecosystems, since plants need water for fixing atmospheric CO2 by photosynthesis and convert a large fraction of the solar energy input into this process, therefore by improving the modelling of transpiration scientists can analyze the role of vegetation in climate change scenarios. An international group of scientists led by Dr. Jacob Nelson from the Max Planck Institute for Biogeochemistry (Germany) and including an ecologist from RUDN University, compared three methods for estimating ecosystem transpiration based on micrometeorological data from FLUXNET--a global network of stations.

The team used the data collected at 251 FLUXNET sites. Among many environmental physical and chemical parameters, these stations provide continuous flux measurements of water vapor and carbon dioxide between the monitored ecosystems and the atmosphere. To do so, the eddy covariance method is applied, that relies on the three-dimensional monitoring at high frequency of turbulent flows of trace gases. The team chose three methodological approaches to retrieve transpiration from the eddy covariance data and used independent tree sap flow measurements from six test sites to compare the transpiration estimates.

"All three methods are based on the ratio between evapotranspiration and fluxes of carbon uptaken by photosynthesis from the atmosphere, that is termed water use efficiency, and differ by initial assumptions and parameterization. At daily scale, transpiration estimates yielded by the three methods were highly correlated, between 89 and 94%. However, the ratio of transpiration to evapotranspiration differed across models ranging from 45% to 77%." said Dr. Luca Belelli Marchesini researcher at the Agrarian and Technological Institute of RUDN University (Russia) and at the Fondazione Edmund Mach (Italy).

Having further analyzed the results in search of driving factors, the team concluded that the geographic variation in the transpiration to evapotranspiration ratio (T/ET) was mainly controlled by vegetation and soil characteristics rather than by climatic variables such as temperature and precipitation. To explain the relative stability of T/ET among sites, the team suggested two hypotheses. The first consists in a trade-off between the amount of precipitation intercepted by vegetation canopies and soil evaporation: ecosystems with a dense leaf cover, not limited by water availability, would thus intercept more rain and soil evaporation would be reduced. In contrast, water limited ecosystems, characterized by a smaller vegetation cover, would have a larger fraction of water evaporated from the soil. According to the second hypothesis, ecosystems tend to adapt to the available water resources, therefore, for instance, vegetation in dry climates would improve the utilization of the limited precipitation, thus increasing the T/ET ratio.

'The combination of these two hypotheses likely explains the relative stability of the T/ET ratio in different ecosystems. This study represents the first extensive estimate of ecosystem transpiration based on in-situ data and allows shedding new light on the role of plants' water use in the context of the global water and carbon cycles" added Dr. Luca Belelli Marchesini.

The results of the study were published in the December 2020 issue of the journal Global Change Biology.

30 Jan 2018
The conference on international arbitration, where law students from European universities simulate court proceedings and alternately defend the interests of the respondent and the orator.
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International scientific cooperation View all
03 Nov 2017
The main goal of the RUDN University and UNISDR Office for Northeast Asia and Global Education and Training Institute for Disaster Risk Reduction at Incheon (UNISDR ONEA-GETI) cooperation is to obtain knowledge about disaster risk reduction and international experience in this area for creating training courses for basic and additional professional education in RUDN
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30 Dec 2021
Biologists from RUDN University discovered the secret of flaxseed oil with long shelf life

Biologists from RUDN University working together with their colleagues from the Institute of Molecular Biology of the Russian Academy of Sciences and the Institute of Flax studied the genes that determine the fatty acid composition in flaxseed oil and identified polymorphisms in six of them. The team also found out what gene variations could extend the shelf life of flaxseed oil. This data can be used to improve the genetic selection of new flax breeds. The results were published in the BMC Plant Biology journal.

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30 Dec 2021
A Chemist from RUDN University Developed a New Method for Combating Antibiotic Resistance in Microbes

Bacteria in biofilms are 1,000 times more resistant to antibiotics, disinfectants, mechanical treatment, and other types of stress. A chemist from RUDN University suggested a method to prevent the formation of biofilms and reduce the resistance of bacteria to antimicrobial medications. This might help increase the efficiency of antibacterial treatment in the food industry, medicine, and agriculture.

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30 Dec 2021
Chemists from RUDN University used crab shells to improve palladium catalysts

Chemists from RUDN University synthesized soluble biopolymers based on chitin from crab shells. Together with palladium, they form effective catalysts for organic reactions, and their nanoparticles can be re-used over ten times.

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