Mapping seasonal and interannual Non-Structural Carbohydrate variation
to drought-resistance strategies in eastern Amazon tree species
Abstract
Carbon allocation to non-structural carbohydrates (NSC) is essential for
plant metabolism playing an important role in tree responses to drought.
It is still unclear if and how interspecific hydraulic trait variation
modulates NSC concentration dynamics in different plant organs,
particularly in tropical tree species. We investigated whether
drought-resistance strategies (inferred from hydraulic traits) explain
seasonal and interannual NSC dynamics in leaves, branches, trunks, and
roots in seasonal eastern Amazon tree species in Brazil. We measured NSC
concentration in eight abundant species during three years, including
the end of the wet and dry seasons of the typical regular years
(2013-2014) and the extreme drought induced by El Niño–Southern
Oscillation in 2015 (ENSO). Organs have an important contribution to
explain the starch (ST), soluble sugar (SS), and NSC variance among
trees. We showed seasonal and year-to-year homeostasis in ST and SS
concentrations in a majority of organs during 2013 and 2014, but SS
increased in all organs during the extreme ENSO drought, while the ST
concentration did not. The increase in SS concentration was more evident
in woody organs from species with intermediate and tolerant drought
strategies. The drought-tolerant species maintain higher root starch
concentrations and mobilize more SS during extreme drought.