Recovery of trees from drought depends on belowground sink control

作   者：Hagedorn Frank, Joseph Jobin,Peter Martina,Luster Jorg, Pritsch Karin, Geppert Uwe, Kerner Rene, Molinier Virginie, Egli Simon, Schaub Marcus, Liu Jian-Feng, Li Maihe, Sever Krunoslav, Weiler Markus, Siegwolf Rolf T. W., Gessler Arthur, Arend Matthias
期刊名称：Nature Plants
影响因子：11.471
卷 期 号：2
页     码：
关键词：
论文摘要：
Climate projections predict higher precipitation variability with
more frequent dry extremes1. CO2 assimilation of forests
decreases during drought, either by stomatal closure2 or by
direct environmental control of sink tissue activities3.
Ultimately, drought effects on forests depend on the ability of
forests to recover, but the mechanisms controlling ecosystem
resilience are uncertain4. Here, we have investigated the
effects of drought and drought release on the carbon balances
in beech trees by combining CO2 flux measurements, metabolomics
and 13CO2 pulse labelling. During drought, net
photosynthesis (AN), soil respiration (RS) and the allocation of
recent assimilates below ground were reduced. Carbohydrates
accumulated inmetabolically resting roots but not in leaves, indicating
sink control of the tree carbon balance. After drought
release, RS recovered faster than AN and CO2 fluxes exceeded
those in continuously watered trees for months. This stimulation
was related to greater assimilate allocation to and
metabolization in the rhizosphere. These findings show that
trees prioritize the investment of assimilates below ground,
probably to regain root functions after drought. We propose
that root restoration plays a key role in ecosystem resilience
to drought, in that the increased sink activity controls the
recovery of carbon balances.