Homoeostatic maintenance of nonstructural carbohydrates during the 2015–2016 El Niño drought across a tropical forest precipitation gradient

Dickman, L. Turin; McDowell, Nate G.; Grossiord, Charlotte; Collins, Adam; Wolfe, Brett T.; Detto, Matteo; Wright, S. Joseph; Medina‐Vega, José A.; Goodsman, Devin W.; Rogers, Alistair; Serbin, Shawn P.; Wu, Jin; Ely, Kim; Michaletz, Sean T.; Xu, Chonggang; Kueppers, Lara M.; Chambers, Jeffrey Q.

doi:10.1111/pce.13501

Cited by 36 publications

(37 citation statements)

References 65 publications

(91 reference statements)

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“…Additionally, the high axial parenchyma fraction in shade-tolerant understory trees might aid a rapid recovery through effective wound closure (Romero & Bolker, 2008) and vegetative resprouting (Pratt et al, 2007) following mechanical damage induced by falling debris or wind (Van Gelder et al, 2006). Finally, a high axial parenchyma fraction might prevent carbon starvation through the homeostatic maintenance of NSCs, as has been recently observed in tropical wet forest trees (Dickman et al, 2018).…”

Section: What Are the Advantages Of Xylem Volume Allocation To Axiamentioning

confidence: 89%

Wood allocation trade‐offs between fiber wall, fiber lumen, and axial parenchyma drive drought resistance in neotropical trees

Janßen

Hölttä

Fleischer

et al. 2020

Plant Cell & Environment

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Functional relationships between wood density and measures of xylem hydraulic safety and efficiency are ambiguous, especially in wet tropical forests. In this meta‐analysis, we move beyond wood density per se and identify relationships between xylem allocated to fibers, parenchyma, and vessels and measures of hydraulic safety and efficiency. We analyzed published data of xylem traits, hydraulic properties and measures of drought resistance from neotropical tree species retrieved from 346 sources. We found that xylem volume allocation to fiber walls increases embolism resistance, but at the expense of specific conductivity and sapwood capacitance. Xylem volume investment in fiber lumen increases capacitance, while investment in axial parenchyma is associated with higher specific conductivity. Dominant tree taxa from wet forests prioritize xylem allocation to axial parenchyma at the expense of fiber walls, resulting in a low embolism resistance for a given wood density and a high vulnerability to drought‐induced mortality. We conclude that strong trade‐offs between xylem allocation to fiber walls, fiber lumen, and axial parenchyma drive drought resistance in neotropical trees. Moreover, the benefits of xylem allocation to axial parenchyma in wet tropical trees might not outweigh the consequential low embolism resistance under more frequent and severe droughts in a changing climate.

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Section: What Are the Advantages Of Xylem Volume Allocation To Axiamentioning

confidence: 89%

Wood allocation trade‐offs between fiber wall, fiber lumen, and axial parenchyma drive drought resistance in neotropical trees

Janßen

Hölttä

Fleischer

et al. 2020

Plant Cell & Environment

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“…However, the relationship of short‐term to long‐term climate responses is not straightforward, because the importance of particular mechanisms shifts with the timescale. Allocational shifts to/from woody productivity, reproductive output, and carbohydrate stores play a large role in variation over seasonal to annual time scales (Dickman et al, ; Doughty et al, ), but are likely to play little role at decadal and longer time scales. In contrast, shifts in functional composition of the tree community are likely to play a large role in responses to long‐term climate variation (van der Sande et al, ), but very little role in short‐term responses.…”

Section: Discussionmentioning

confidence: 99%

Testing for changes in biomass dynamics in large‐scale forest datasets

Rutishauser

Wright

Condit

et al. 2019

Global Change Biology

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Tropical forest responses to climate and atmospheric change are critical to the future of the global carbon budget. Recent studies have reported increases in estimated above‐ground biomass (EAGB) stocks, productivity, and mortality in old‐growth tropical forests. These increases could reflect a shift in forest functioning due to global change and/or long‐lasting recovery from past disturbance. We introduce a novel approach to disentangle the relative contributions of these mechanisms by decomposing changes in whole‐plot biomass fluxes into contributions from changes in the distribution of gap‐successional stages and changes in fluxes for a given stage. Using 30 years of forest dynamic data at Barro Colorado Island, Panama, we investigated temporal variation in EAGB fluxes as a function of initial EAGB (EAGBi) in 10 × 10 m quadrats. Productivity and mortality fluxes both increased strongly with initial quadrat EAGB. The distribution of EAGB (and thus EAGBi) across quadrats hardly varied over 30 years (and seven censuses). EAGB fluxes as a function of EAGBi varied largely and significantly among census intervals, with notably higher productivity in 1985–1990 associated with recovery from the 1982–1983 El Niño event. Variation in whole‐plot fluxes among census intervals was explained overwhelmingly by variation in fluxes as a function of EAGBi, with essentially no contribution from changes in EAGBi distributions. The high observed temporal variation in productivity and mortality suggests that this forest is very sensitive to climate variability. There was no consistent long‐term trend in productivity, mortality, or biomass in this forest over 30 years, although the temporal variability in productivity and mortality was so strong that it could well mask a substantial trend. Accurate prediction of future tropical forest carbon budgets will require accounting for disturbance‐recovery dynamics and understanding temporal variability in productivity and mortality.

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“…In addition, we used the existing data on stem wood density for our target tree-species collected from the same forests (Wright et al, 2010). Canopy height and diameter at breast height for the target tree-species referred to Dickman et al (2019).…”

Section: Measurement Of the Response Of A To C I Commonly Known Asmentioning

confidence: 99%

The response of stomatal conductance to seasonal drought in tropical forests

Serbin

Ely

et al. 2019

Global Change Biology

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Stomata regulate CO2 uptake for photosynthesis and water loss through transpiration. The approaches used to represent stomatal conductance (gs) in models vary. In particular, current understanding of drivers of the variation in a key parameter in those models, the slope parameter (i.e. a measure of intrinsic plant water‐use‐efficiency), is still limited, particularly in the tropics. Here we collected diurnal measurements of leaf gas exchange and leaf water potential (Ψleaf), and a suite of plant traits from the upper canopy of 15 tropical trees in two contrasting Panamanian forests throughout the dry season of the 2016 El Niño. The plant traits included wood density, leaf‐mass‐per‐area (LMA), leaf carboxylation capacity (Vc,max), leaf water content, the degree of isohydry, and predawn Ψleaf. We first investigated how the choice of four commonly used leaf‐level gs models with and without the inclusion of Ψleaf as an additional predictor variable influence the ability to predict gs, and then explored the abiotic (i.e. month, site‐month interaction) and biotic (i.e. tree‐species‐specific characteristics) drivers of slope parameter variation. Our results show that the inclusion of Ψleaf did not improve model performance and that the models that represent the response of gs to vapor pressure deficit performed better than corresponding models that respond to relative humidity. Within each gs model, we found large variation in the slope parameter, and this variation was attributable to the biotic driver, rather than abiotic drivers. We further investigated potential relationships between the slope parameter and the six available plant traits mentioned above, and found that only one trait, LMA, had a significant correlation with the slope parameter (R2 = 0.66, n = 15), highlighting a potential path towards improved model parameterization. This study advances understanding of gs dynamics over seasonal drought, and identifies a practical, trait‐based approach to improve modeling of carbon and water exchange in tropical forests.

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Homoeostatic maintenance of nonstructural carbohydrates during the 2015–2016 El Niño drought across a tropical forest precipitation gradient

Cited by 36 publications

References 65 publications

Wood allocation trade‐offs between fiber wall, fiber lumen, and axial parenchyma drive drought resistance in neotropical trees

Wood allocation trade‐offs between fiber wall, fiber lumen, and axial parenchyma drive drought resistance in neotropical trees

Testing for changes in biomass dynamics in large‐scale forest datasets

The response of stomatal conductance to seasonal drought in tropical forests

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