Distribution and mixing of old and new nonstructural carbon in two temperate trees

Richardson, Andrew D.; Carbone, Mariah S.; Huggett, Brett A.; Furze, Morgan E.; Czimczik, C. I.; Walker, Joan; Xu, Xiaomei; Schaberg, Paul G.; Murakami, Paula F.

doi:10.1111/nph.13273

Cited by 132 publications

(109 citation statements)

References 40 publications

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“…, Richardson et al. ), which agrees well with evidence that older NSC may be less available, or even unavailable, to trees compared to more recently fixed carbohydrates (Millard et al. , Sala et al.…”

Section: Discussionsupporting

confidence: 83%

Legacy effects of drought in the southwestern United States: A multi‐species synthesis

Peltier

Fell

Ogle

2016

Ecological Monographs

111

128

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Understanding impacts of drought on tree growth and forest health is of major concern given projected climate change. Droughts may become more common in the Southwest due to extreme temperatures that will drive increased evapotranspiration and lower soil moisture, in combination with uncertain precipitation changes. Utilizing ~1.3 million tree-ring widths from the International Tree Ring Data Bank representing 10 species (8 conifers, 2 oaks) in the Southwest, we evaluated the effects of drought on tree growth. We categorized ring widths by formation year in relation to drought (pre-drought, drought year, and post-drought), and we used a mixed effects model to estimate the effects of current and antecedent precipitation and temperature on tree growth during the post-drought recovery period. This allowed us to assess changes in sensitivity of tree growth to precipitation and temperature at multiple time-scales following multiple droughts, and to evaluate drought resistance and recovery in these species.The effects of precipitation and temperature on ring widths following drought varied among species and time-since-drought. Across species, 16% of the climate effects (i.e., "sensitivities")were significantly different from their pre-drought values. Species differed, with some showing increased sensitivities to precipitation and temperature following drought, and others showing decreased sensitivities. Furthermore, some species (e.g., Abies concolor and Pinus ponderosa)showed low resistance and slow recovery, with changes in growth sensitivities persisting up to 5 years; others (e.g., Juniper spp.) showed high resistance, such that their climatic sensitivities did not change. Among species, the importance of different antecedent climate variables changed with time-since-drought. Though a majority of species responded positively to same-year precipitation pre-drought, all 10 species were positively affected by same-year precipitation the second year after drought. Our results demonstrate tree growth sensitivities vary among species Accepted ArticleThis article is protected by copyright. All rights reserved. and with time-since-drought, raising questions about physiological mechanisms and implications for forest health under future drought.

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Section: Discussionsupporting

confidence: 83%

Legacy effects of drought in the southwestern United States: A multi‐species synthesis

Peltier

Fell

Ogle

2016

Ecological Monographs

111

128

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“…8). This view is supported by several studies showing that starch is more depleted than SS under lethal drought (Adams et al 2013, Mitchell et al 2013, Sevanto et al 2014, Dickman et al 2015, Garcia-Forner et al 2016, and by modeling and empirical results indicating that NSC has two distinct pools with different turnover times (Richardson et al 2013(Richardson et al , 2015. This view is supported by several studies showing that starch is more depleted than SS under lethal drought (Adams et al 2013, Mitchell et al 2013, Sevanto et al 2014, Dickman et al 2015, Garcia-Forner et al 2016, and by modeling and empirical results indicating that NSC has two distinct pools with different turnover times (Richardson et al 2013(Richardson et al , 2015.…”

Section: Hypothesis 4: Plants Rarely Deplete Their Nscmentioning

confidence: 73%

Dynamics of non‐structural carbohydrates in terrestrial plants: a global synthesis

Martínez‐Vilalta

Sala

Asensio

et al. 2016

Ecological Monographs

533

446

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Plants store large amounts of non-structural carbohydrates (NSC). While multiple functions of NSC have long been recognized, the interpretation of NSC seasonal dynamics is often based on the idea that stored NSC is a reservoir of carbon that fluctuates depending on the balance between supply via photosynthesis and demand for growth and respiration (the source-sink dynamics concept). Consequently, relatively high NSC concentrations in some plants have been interpreted to reflect excess supply relative to demand. An alternative view, however, is that NSC accumulation reflects the relatively high NSC levels required for plant survival; an important issue that remains highly controversial. Here, we assembled a new global database to examine broad patterns of seasonal NSC variation across organs (leaves, stems, and belowground), plant functional types (coniferous, drought-deciduous angiosperms, winter deciduous angiosperms, evergreen angiosperms, and herbaceous) and biomes (boreal, temperate, Mediterranean, and tropical). We compiled data from 121 studies, including seasonal measurements for 177 species under natural conditions. Our results showed that, on average, NSC account for ~10% of dry plant biomass and are highest in leaves and lowest in stems, whereas belowground organs show intermediate concentrations. Total NSC, starch, and soluble sugars (SS) varied seasonally, with a strong depletion of starch during the growing season and a general increase during winter months, particularly in boreal and temperate biomes. Across functional types, NSC concentrations were highest and most variable in herbaceous species and in conifer needles. Conifers showed the lowest stem and belowground NSC concentrations. Minimum NSC values were relatively high (46% of seasonal maximums on average for total NSC) and, in contrast to average values, were similar among biomes and functional types. Overall, although starch depletion was relatively common, seasonal depletion of total NSC or SS was rare. These results are consistent with a dual view of NSC function: whereas starch acts mostly as a reservoir for future use, soluble sugars perform immediate functions (e.g., osmoregulation) and are kept above some critical threshold. If confirmed, this dual function of NSC will have important implications for the way we understand and model plant carbon allocation and survival under stress.

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“…Wood, does not necessarily meet the well mixed assumption, so its particles may not have the same probability to leave the compartment at all times. Richardson et al (2015) 20 found a low concentration of old NSC in old rings of stemwood, and a high concentration of old NSC in coarse roots and fine roots of pine. Additionally, they found young and old C in roots.…”

mentioning

confidence: 99%

“…Additionally, they found young and old C in roots. These dynamics were interpreted as poor C mixing and reserves that turn over on different timescales (Richardson et al, 2015), but they may also obey to physiological constraints;…”

mentioning

confidence: 99%

“…for example, the parenchyma in heartwood is thought to be dead, so NSC trapped in there may no longer be accessible to the plant (Richardson et al, 2015), but it has some probability of being respired and lost from the system. So, to study the 25 physiological significance of these findings with models, we might have to include such details regarding tree physiology.…”

mentioning

confidence: 99%

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Ages and transit times as important diagnostics of model performance for predicting carbon dynamics in terrestrial vegetation models

Ceballos-Núñez¹,

Richardson²,

Sierra³

2017

Preprint

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Abstract. The global carbon cycle is strongly controlled by the source/sink strength of vegetation as well as the capacity of terrestrial ecosystems to retain this carbon. These dynamics, as well as processes such as the mixing of old and newly fixed carbon, have been studied using ecosystem models, but different assumptions regarding the carbon allocation strategies and other model structures may result in highly divergent model predictions. We modeled three systems of vegetation compartments and assessed their performance by calculating the age of the carbon in vegetation system and within each compartment, and 5 the overall transit time of C in the system. We used these diagnostics to assess the influence of three different carbon allocation schemes on the rates of C cycling in vegetation. First, we used published measurements of ecosystem C compartments from the Harvard Forest Environmental Measurement Site to find the best set of parameters for the different model structures. Second, we calculated C stocks, release fluxes, radiocarbon values based on the bomb spike, ages, and transit times. We found a good fit of the three model structures to the available data, but the time series of C in foliage and wood need to be complemented 10 with other ecosystem compartments in order to reduce the high parameter collinearity that we observed, and reduce model equifinality. Differences in model structures had a small impact on predicting C stocks in ecosystem compartments, but overall they resulted in very different predictions of age and transit time distributions. In particular, the inclusion of two storage compartments resulted in the prediction of a system mean age that was 10-20 years older than in the models with one or no storage compartments. The age of carbon in the wood compartment of this model was also distributed towards older ages, 15 whereas fast cycling compartments had an age distribution that did not exceed 5 years. As expected, models with C distributed towards older ages also had longer transit times. These results suggest that ages and transit times, which can be indirectly measured using isotope tracers, serve as important diagnostics of model structure and could largely help to reduce uncertainties in model predictions. Furthermore, by considering age and transit times of C in vegetation compartments as distributions, not only their mean values, we obtain additional insights on the temporal dynamics of carbon use, storage, and allocation to plant 20 parts, which not only depends on the rate at which this C is transferred in and out of the compartments, but also on the stochastic nature of the process itself. 1Biogeosciences Discuss., https://doi

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Distribution and mixing of old and new nonstructural carbon in two temperate trees

Cited by 132 publications

References 40 publications

Legacy effects of drought in the southwestern United States: A multi‐species synthesis

Legacy effects of drought in the southwestern United States: A multi‐species synthesis

Dynamics of non‐structural carbohydrates in terrestrial plants: a global synthesis

Ages and transit times as important diagnostics of model performance for predicting carbon dynamics in terrestrial vegetation models

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