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Physiological coupling mechanisms of carbon and nutrient dynamics underlying the drought-induced decline of Scots pine

English title Physiological coupling mechanisms of carbon and nutrient dynamics underlying the drought-induced decline of Scots pine
Applicant Li Mai-He
Number 157126
Funding scheme Project funding (Div. I-III)
Research institution Swiss Federal Research Inst. WSL Direktion
Institution of higher education Swiss Federal Institute for Forest, Snow and Landscape Research - WSL
Main discipline Agricultural and Forestry Sciences
Start/End 01.03.2015 - 28.02.2019
Approved amount 272'318.00
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All Disciplines (3)

Discipline
Agricultural and Forestry Sciences
Ecology
Environmental Research

Keywords (8)

Drought stress; Long-term field experiment; Carbon dynamics; Carbon stable isotopes; Carbon-nutrient interactions; Laboratory experiment; Pinus sylvestris; Tree ring

Lay Summary (German)

Lead
In den letzten Jahrzehnten verursachte Trockenstress weltweit zunehmend Waldwachstumsverlust und Waldsterben. Auf wissenschaftlicher Ebene wird über die physiologischen Mechanismen dieses Rückgangs der Vitalität von Wäldern intensiv debattiert. Schlussfolgerungen wurden aber noch nicht gezogen. Das vorliegende Projekt hat zum Ziel, Dynamik und Bilanz von Bodennährstoffen und Kohlenhydraten, wie auch das Wachstum von Föhren in Zusammenhang mit der Wasserverfügbarkeit zu untersuchen.
Lay summary

Inhalt und Ziele des Forschungsprojekts

Die aktuelle Debatte zum trockenheitsbedingten Baumsterben konzentriert sich vor allem auf (i) hydraulisches Versagen und (ii) kritische Verluste von Kohlenhydratreserven in trockengestressten Bäumen. Der Einfluss von Trockenheit auf die Aufnahme von Bodennährstoffen wurde dagegen bisher kaum beachtet. Eine Reduktion der Bodennährstoffversorgung unter Trockenstress würde jedoch mittelfristig auch negative Konsequenzen für die photosynthetische Kohlenstoffassimilation mit sich bringen. Das Ziel dieser Studie ist es, die Auswirkungen von Trockenstress auf die Dynamik und Bilanz von Kohlenhydraten in Abhängigkeit von der Nährstoffverfügbarkeit in Föhren zu untersuchen. Dieser Einfluss von Trockenstress auf die Kohlenstoffassimilation und den Transport von Photoassimilaten wird zusätzlich mittels Gaswechselmessungen und Isotopenanalysen quantifiziert.

In einem ersten Versuchsteil (langfristigen Bewässerungsexperiment) untersuchen wir die langfristige Auswirkung der geringen Wasserverfügbarkeit auf die Produktion, das Angebot, und die Speicherung von mobilen Kohlenhydraten in Bezug auf die Verfügbarkeit von Nährstoffen in alten Föhren. In einem zweiten Versuchsteil (vollständig kontrollierten Laborexperiment) werden jungen Föhren in einem faktoriellen Experiment Trockenstress, Düngung, und Entnadelung (Reduktion der Photosynthese) während 3 Jahren ausgesetzt, um die Schlüsselmechanismen der Nährstoff-gekoppelten Assimilation und des Transports von mobilen Kohlenhydraten in Bäumen zu identifizieren.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Die Ergebnisse dieses Projekts sind von unmittelbarem Interesse für das forstwirtschaftliche Waldmanagement in einem zu erwartenden trockenen und heisseren Klima.Darüber hinaus wird dieses Projekt massgeblich zur Klärung der Frage beitragen, ob der aktuell beobachtete Rückgang und die erhöhte Mortalität von Föhren unter Trockenstress durch Kohlenstoffmangel verursacht wird.

Direct link to Lay Summary Last update: 06.10.2014

Responsible applicant and co-applicants

Employees

Publications

Publication
Soil nutrients and lowered source:sink ratio mitigate effects of mild but not of extreme drought in trees
Schönbeck Leonie, Gessler Arthur, Schaub Marcus, Rigling Andreas, Hoch Günter, Kahmen Ansgar, Li Mai-He (2020), Soil nutrients and lowered source:sink ratio mitigate effects of mild but not of extreme drought in trees, in Environmental and Experimental Botany, 169, 103905-103905.
The biogeochemical niche shifts of Pinus sylvestris var. mongolica along an environmental gradient
He Peng, Fontana Simone, Sardans Jordi, Peñuelas Josep, Gessler Arthur, Schaub Marcus, Rigling Andreas, Li Hui, Jiang Yong, Li Mai-He (2019), The biogeochemical niche shifts of Pinus sylvestris var. mongolica along an environmental gradient, in Environmental and Experimental Botany, 167, 103825-103825.
Scale dependent responses of pine reproductive traits to experimental and natural precipitation gradients
He Peng, Fontana Simone, Sui Xin, Gessler Arthur, Schaub Marcus, Rigling Andreas, Jiang Yong, Li Mai-He (2018), Scale dependent responses of pine reproductive traits to experimental and natural precipitation gradients, in Environmental and Experimental Botany, 156, 62-73.
Homeostatic levels of nonstructural carbohydrates after 13 yr of drought and irrigation in Pinus sylvestris
Schönbeck Leonie, Gessler Arthur, Hoch Günter, McDowell Nate G., Rigling Andreas, Schaub Marcus, Li Mai-He (2018), Homeostatic levels of nonstructural carbohydrates after 13 yr of drought and irrigation in Pinus sylvestris, in New Phytologist, 219(4), 1314-1324.

Collaboration

Group / person Country
Types of collaboration
Physiological plant ecology / University of Basel Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Swiss Forestlab Science day Poster Mitigating effects of nutrients on drought stress in Scots pine 22.11.2018 Birmensdorf, Switzerland Gessler Arthur; Rigling Andreas; Li Mai-He; Schoenbeck Leonie;
Gesellschaft für Ökologie meeting Talk given at a conference Nutrients and drought - Allies or opponents to a trees' wellbeing? 03.09.2018 Vienna, Austria Gessler Arthur; Li Mai-He; Rigling Andreas; Schoenbeck Leonie;
International Conference for Ecology Talk given at a conference The winner takes it all? Lont term drought release is beneficial for initially vital trees 22.08.2017 Beijing, China Gessler Arthur; Rigling Andreas; Schoenbeck Leonie; Li Mai-He;
European Geosciences Union meeting Poster Drought stress release increased growth rate but did not affect levels of storage carbohydrates in Scots pine trees 23.04.2017 Vienna, Austria Li Mai-He; Gessler Arthur; Rigling Andreas; Schoenbeck Leonie;


Communication with the public

Communication Title Media Place Year
Video/Film Surviving drought International Western Switzerland German-speaking Switzerland 2018

Abstract

The global climate has changed and is changing (IPCC 2007). In Central Europe, the summer temperature is expected to increase by additional 1.9 - 7.0°C, and the amount of summer precipitation to decrease by 9 - 41% until 2070 (Schär et al. 2004), leading to more frequent drought events. Drought stress considerably affects physiological and biochemical processes of trees (Bray 1997; Körner 2000; Li et al. 2006b; Li et al. 2013), decreases the tree vigor (Martínez-Vilalta and Pinol, 2002) and forest growth and productivity (Bigler et al., 2006; Ciais et al., 2005; Sanchez-Salguero et al., 2012a; Sanchez-Salguero et al., 2012b), increases the tree mortality (Allen et al., 2010; Rebetez and Dobbertin, 2004; Vila-Cabrera et al., 2011), and changes the forest ecosystem functioning. Physiological mechanisms underlying drought-induced growth decline and mortality of forests have been extensively studied (recently reviewed by Allen et al. 2010), and are currently being intensively debated, in particular in respect to hydraulic failure and carbon limitations determining the growth decline and mortality (McDowell et al. 2008; Adams et al. 2009; Leuzinger et al. 2009; Sala 2009; Delzon et al. 2010; McDowell and Sevanto 2010; Sala et al. 2010). This currently active debate indicates that the “physiological mechanisms of drought-induced tree mortality are far from being resolved” (Sala et al. 2010). Except for those two mainly discussed aspects, less attention has been paid to nutrient uptake that is also affected by drought and further influences the process of carbon gain (Gessler et al. 2005; Rennenberg et al. 2006). The interface between water and carbon balance with nutrient relations might, therefore, play a more important role for the impairment of trees under water restriction than previously assumed (Kreuzwieser and Gessler 2010). To discuss the carbon source or sink limitation hypothesis, most previous studies investigated the carbon balance during the growing season only. They, indeed, ignored both the effects of drought-induced changes in nutrient availability on non-structural carbohydrates (NSC) and the NSC dynamics, in particular the winter NSC storage which affects the early spring regrowth. Hence, our proposed study will analyze the growth and dynamics (summer, winter) of carbon and nutrients in Scots pine (Pinus sylvestris L.) growing in a controlled, large-scale (1.2 ha, 800 trees with ~100-yrs-old), long-term (12 years) field irrigation experiment, and in a fully-controlled laboratory experiment with 10-15-yr-old trees (384 trees) treated by water availability (main-plot factor), fertilizer (sub-plot factor) and defoliation (sub-sub-plot factor) in a split-plot design. We aim to answer the questions of: (1) whether (drought-)stressed trees have a mechanism to maintain a minimum level of NSC for their vital functions; (2) whether and to what extent the stored NSC reserve can be remobilized to support growth; and (3) whether the well-documented growth decline of (drought-)stressed trees is mainly resulted from a decline in early spring regrowth caused by a limited NSC storage. The proposed project will significantly contribute (1) to the controversial debate about whether drought may cause acute tree decline and mortality via carbon starvation, (2) to better understanding the long-term effects of low water availability on the supply of the mobile carbohydrates in relation to nutrient availability, (3) to identifying the key mechanisms of nutrient-coupled NSC production and supply underlying the stress-induced growth decline and mortality of trees, and (4) to ecophysiological basis for forest ecosystem management in a changing world.
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