Drought and shade deplete nonstructural carbohydrate reserves in seedlings of five temperate tree species

Abstract

Plants that store nonstructural carbohydrates (NSC) may rely on carbon reserves to survive carbon‐limiting stress, assuming that reserves can be mobilized. We asked whether carbon reserves decrease in resource stressed seedlings, and if NSC allocation is related to species' relative stress tolerances. We tested the effects of stress (shade, drought, and defoliation) on NSC in seedlings of five temperate tree species (Acer rubrum Marsh., Betula papyrifera Marsh., Fraxinus americana L ., Quercus rubra L., and Quercus velutina Lam.). In a greenhouse experiment, seedlings were subjected to combinations of shade, drought, and defoliation. We harvested seedlings over 32–97 days and measured biomass and NSC concentrations in stems and roots to estimate depletion rates. For all species and treatments, except for defoliation, seedling growth and NSC accumulation ceased. Shade and drought combined caused total NSC decreases in all species. For shade or drought alone, only some species experienced decreases. Starch followed similar patterns as total NSC, but soluble sugars increased under drought for drought‐tolerant species. These results provide evidence that species deplete stored carbon in response to carbon limiting stress and that species differences in NSC response may be important for understanding carbon depletion as a buffer against shade‐ and drought‐induced mortality.

Local adaptation mediates floral responses to water limitation in an annual wildflower

“…This is interesting given that nectar is predominantly composed of water and sugar, both of which are likely limited in dry conditions. Furthermore, photosynthetic carbon assimilation can drop due to stomatal closure (Lawlor and Cornic, ) and decrease the availability of nonstructural carbohydrates such as sucrose (Maguire and Kobe, ).…”

Potential of forest thinning to mitigate drought stress: A meta-analysis

“…Trees adapted to drier conditions may invest more in non-structural carbon reserves (Maguire and Kobe, 2015) to maintain growth under adverse conditions, but it may be more difficult for them to replenish these reserves and recover growth subsequently.…”

No role for xylem embolism or carbohydrate shortage in temperate trees during the severe 2015 drought

“…The depletion of nonstructural carbohydrate pools has been suggested to result from the extended closure of stomata during drought leading to reduced photosynthesis and eventually a shortage of carbohydrate metabolites in different tree tissues (Hartmann, ). However, tree carbohydrate reserve pools were often only measured towards the end of drought periods (Adams et al, ; Galiano, Martinez‐Vilalta, & Lloret, ) or observed in seedlings under additional shading treatment (Hartmann, McDowell, & Trumbore, ; Hartmann, Ziegler, & Trumbore, ; Hartmann, Ziegler, Kolle, & Trumbore, ; Maguire & Kobe, ). Hence, most of the information on the vulnerability of temperate trees to xylem embolism and carbohydrate depletion was obtained in experimental work or from very few scattered measurements throughout or at the end of a given period of time.…”