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52. Optimal stomatal theory predicts CO2 responses of stomatal conductance in both gymnosperm and angiosperm trees.

Author

Gardner, Anna, Jiang, Mingkai, Ellsworth, David S., MacKenzie, A. Robert, Pritchard, Jeremy, Bader, Martin Karl‐Friedrich, Barton, Craig V. M., Bernacchi, Carl, Calfapietra, Carlo, Crous, Kristine Y., Dusenge, Mirindi Eric, Gimeno, Teresa E., Hall, Marianne, Lamba, Shubhangi, Leuzinger, Sebastian, Uddling, Johan, Warren, Jeffrey, Wallin, Göran, and Medlyn, Belinda E.

Subjects
STOMATA, ATMOSPHERIC carbon dioxide, WATER efficiency, GYMNOSPERMS, WEATHER
Abstract

Summary: Optimal stomatal theory predicts that stomata operate to maximise photosynthesis (Anet) and minimise transpirational water loss to achieve optimal intrinsic water‐use efficiency (iWUE). We tested whether this theory can predict stomatal responses to elevated atmospheric CO2 (eCO2), and whether it can capture differences in responsiveness among woody plant functional types (PFTs).We conducted a meta‐analysis of tree studies of the effect of eCO2 on iWUE and its components Anet and stomatal conductance (gs). We compared three PFTs, using the unified stomatal optimisation (USO) model to account for confounding effects of leaf–air vapour pressure difference (D). We expected smaller gs, but greater Anet, responses to eCO2 in gymnosperms compared with angiosperm PFTs.We found that iWUE increased in proportion to increasing eCO2 in all PFTs, and that increases in Anet had stronger effects than reductions in gs. The USO model correctly captured stomatal behaviour with eCO2 across most datasets. The chief difference among PFTs was a lower stomatal slope parameter (g1) for the gymnosperm, compared with angiosperm, species.Land surface models can use the USO model to describe stomatal behaviour under changing atmospheric CO2 conditions. [ABSTRACT FROM AUTHOR]

Published
2023
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53. The influence of elevated CO2 and soil depth on rhizosphere activity and nutrient availability in a mature Eucalyptus woodland.

Author

Pihlblad, Johanna, Andresen, Louise C., Macdonald, Catriona A., Ellsworth, David S., and Carrillo, Yolima

Subjects
SOIL depth, FOREST biomass, CARBON dioxide, FORESTS & forestry, NUTRIENT cycles, EUCALYPTUS, RHIZOSPHERE, FOREST soils
Abstract

Elevated carbon dioxide (e CO 2) in the atmosphere increases forest biomass productivity but only where soil nutrients, particularly nitrogen (N) and phosphorus (P), are not limiting growth. e CO 2 , in turn, can impact rhizosphere nutrient availability. Our current understanding of nutrient cycling under e CO 2 is mainly derived from surface soil, leaving mechanisms of the impact of e CO 2 on rhizosphere nutrient availability at deeper depths unexplored. To investigate the influence of e CO 2 on nutrient availability in soil at depth, we studied various C, N, and P pools (extractable, microbial biomass, total soil C and N, and mineral-associated P) and nutrient cycling processes (enzyme activity and gross N mineralisation) associated with C, N, and P cycling in both bulk and rhizosphere soil at different depths at the Free Air CO 2 enrichment facility in a native Australian mature Eucalyptus woodland (EucFACE) on a nutrient-poor soil. We found decreasing nutrient availability and gross N mineralisation with depth; however, this depth-associated decrease was reduced under e CO 2 , which we suggest is due to enhanced root influence. Increases in available PO 43- , adsorbed P, and the C : N and C : P ratio of enzyme activity with depth were observed. We conclude that the influences of roots and of e CO 2 can affect available nutrient pools and processes well beyond the surface soil of a mature forest ecosystem. Our findings indicate a faster recycling of nutrients in the rhizosphere, rather than additional nutrients becoming available through soil organic matter (SOM) decomposition. If the plant growth response to e CO 2 is reduced by the constraints of nutrient limitations, then the current results would call to question the potential for mature tree ecosystems to fix more C as biomass in response to e CO 2. Future studies should address how accessible the available nutrients at depth are to deeply rooted plants and if fast recycling of nutrients is a meaningful contribution to biomass production and the accumulation of soil C in response to e CO 2. [ABSTRACT FROM AUTHOR]

Published
2023
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64. Increasing aridity will not offset CO$_{2}$ fertilization in fast-growing eucalypts with access to deep soil water

Author

Nadal-Sala, Daniel, Medlyn, Belinda E., Ruehr, Nadine K., Barton, Craig V. M., Ellsworth, David S., Gracia, Carles, Tissue, David T., Tjoelker, Mark G., and Sabat��, Santi

Subjects
Earth sciences, ddc:550
Abstract

Rising atmospheric [CO$_{2}$] (C$_{a}$) generally enhances tree growth if nutrients are not limiting. However, reduced water availability and elevated evaporative demand may offset such fertilization. Trees with access to deep soil water may be able to mitigate such stresses and respond more positively to C$_{a}$. Here, we sought to evaluate how increased vapor pressure deficit and reduced precipitation are likely to modify the impact of elevated C$_{a}$ (eC$_{a}$) on tree productivity in an Australian Eucalyptus saligna Sm. plantation with access to deep soil water. We parameterized a forest growth simulation model (GOTILWA+) using data from two field experiments on E. saligna: a 2���year whole���tree chamber experiment with factorial C$_{a}$ (ambient =380, elevated =620 ��mol mol$^{-1}$) and watering treatments, and a 10���year stand���scale irrigation experiment. Model evaluation showed that GOTILWA+ can capture the responses of canopy C uptake to (1) rising vapor pressure deficit (D) under both C$_{a}$ treatments; (2) alterations in tree water uptake from shallow and deep soil layers during soil dry���down; and (3) the impact of irrigation on tree growth. Simulations suggest that increasing C$_{a}$ up to 700 ��mol mol$^{-1}$ alone would result in a 33% increase in annual gross primary production (GPP) and a 62% increase in biomass over 10 years. However, a combined 48% increase in D and a 20% reduction in precipitation would halve these values. Our simulations identify high D conditions as a key limiting factor for GPP. They also suggest that rising Ca will compensate for increasing aridity limitations in E. saligna trees with access to deep soil water under non���nutrient limiting conditions, thereby reducing the negative impacts of global warming upon this eucalypt species. Simulation models not accounting for water sources available to deep���rooting trees are likely to overestimate aridity impacts on forest productivity and C stocks.

Published
2021

65. Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO2

Author

Walker, Anthony P., De Kauwe, Martin G., Bastos, Ana, Belmecheri, Soumaya, Georgiou, Katerina, Keeling, Ralph F., McMahon, Sean M., Medlyn, Belinda E., Moore, David J. P., Norby, Richard J., Zaehle, Söenke, Anderson-Teixeira, Kristina J., Battipaglia, Giovanna, Brienen, Roel J. W., Cabugao, Kristine G., Cailleret, Maxime, Campbell, Elliott, Canadell, Josep G., Ciais, Philippe, Craig, Matthew E., Ellsworth, David S., Farquhar, Graham D., Fatichi, Simone, Fisher, Joshua B., Frank, David C., Graven, Heather, Gu, Lianhong, Haverd, Vanessa, Heilman, Kelly, Heimann, Martin, Hungate, Bruce A., Iversen, Colleen M., Joos, Fortunat, Jiang, Mingkai, Keenan, Trevor F., Knauer, Jürgen, Körner, Christian, Leshyk, Victor O., Leuzinger, Sebastian, Liu, Yao, MacBean, Natasha, Malhi, Yadvinder, McVicar, Tim R., Penuelas, Josep, Pongratz, Julia, Powell, A. Shafer, Riutta, Terhi, Sabot, Manon E. B., Schleucher, Jürgen, Sitch, Stephen, Smith, William K., Sulman, Benjamin, Taylor, Benton, Terrer, César, Torn, Margaret S., Treseder, Kathleen K., Trugman, Anna T., Trumbore, Susan E., van Mantgem, Phillip J., Voelker, Steve L., Whelan, Mary E., Zuidema, Pieter A., Walker, Anthony P., De Kauwe, Martin G., Bastos, Ana, Belmecheri, Soumaya, Georgiou, Katerina, Keeling, Ralph F., McMahon, Sean M., Medlyn, Belinda E., Moore, David J. P., Norby, Richard J., Zaehle, Söenke, Anderson-Teixeira, Kristina J., Battipaglia, Giovanna, Brienen, Roel J. W., Cabugao, Kristine G., Cailleret, Maxime, Campbell, Elliott, Canadell, Josep G., Ciais, Philippe, Craig, Matthew E., Ellsworth, David S., Farquhar, Graham D., Fatichi, Simone, Fisher, Joshua B., Frank, David C., Graven, Heather, Gu, Lianhong, Haverd, Vanessa, Heilman, Kelly, Heimann, Martin, Hungate, Bruce A., Iversen, Colleen M., Joos, Fortunat, Jiang, Mingkai, Keenan, Trevor F., Knauer, Jürgen, Körner, Christian, Leshyk, Victor O., Leuzinger, Sebastian, Liu, Yao, MacBean, Natasha, Malhi, Yadvinder, McVicar, Tim R., Penuelas, Josep, Pongratz, Julia, Powell, A. Shafer, Riutta, Terhi, Sabot, Manon E. B., Schleucher, Jürgen, Sitch, Stephen, Smith, William K., Sulman, Benjamin, Taylor, Benton, Terrer, César, Torn, Margaret S., Treseder, Kathleen K., Trugman, Anna T., Trumbore, Susan E., van Mantgem, Phillip J., Voelker, Steve L., Whelan, Mary E., and Zuidema, Pieter A.

Abstract

Atmospheric carbon dioxide concentration ([CO2]) is increasing, which increases leaf‐scale photosynthesis and intrinsic water‐use efficiency. These direct responses have the potential to increase plant growth, vegetation biomass, and soil organic matter; transferring carbon from the atmosphere into terrestrial ecosystems (a carbon sink). A substantial global terrestrial carbon sink would slow the rate of [CO2] increase and thus climate change. However, ecosystem CO2 responses are complex or confounded by concurrent changes in multiple agents of global change and evidence for a [CO2]‐driven terrestrial carbon sink can appear contradictory. Here we synthesize theory and broad, multidisciplinary evidence for the effects of increasing [CO2] (iCO2) on the global terrestrial carbon sink. Evidence suggests a substantial increase in global photosynthesis since pre‐industrial times. Established theory, supported by experiments, indicates that iCO2 is likely responsible for about half of the increase. Global carbon budgeting, atmospheric data, and forest inventories indicate a historical carbon sink, and these apparent iCO2 responses are high in comparison to experiments and predictions from theory. Plant mortality and soil carbon iCO2 responses are highly uncertain. In conclusion, a range of evidence supports a positive terrestrial carbon sink in response to iCO2, albeit with uncertain magnitude and strong suggestion of a role for additional agents of global change.

Published
2021
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66. A reporting format for leaf-level gas exchange data and metadata

Author

Ely, Kim S., Rogers, Alistair, Agarwal, Deborah A., Ainsworth, Elizabeth A., Albert, Loren P., Ali, Ashehad, Anderson, Jeremiah, Aspinwall, Michael J., Bellasio, Chandra, Bernacchi, Carl, Bonnage, Steve, Buckley, Thomas N., Bunce, James, Burnett, Angela C., Busch, Florian A., Cavanagh, Amanda, Cernusak, Lucas A., Crystal-Ornelas, Robert, Damerow, Joan, Davidson, Kenneth J., De Kauwe, Martin G., Dietze, Michael C., Domingues, Tomas F., Dusenge, Mirindi Eric, Ellsworth, David S., Evans, John R., Gauthier, Paul P.G., Gimenez, Bruno O., Gordon, Elizabeth P., Gough, Christopher M., Halbritter, Aud H., Hanson, David T., Heskel, Mary, Hogan, J. Aaron, Hupp, Jason R., Jardine, Kolby, Kattge, Jens, Keenan, Trevor, Kromdijk, Johannes, Kumarathunge, Dushan P., Ely, Kim S., Rogers, Alistair, Agarwal, Deborah A., Ainsworth, Elizabeth A., Albert, Loren P., Ali, Ashehad, Anderson, Jeremiah, Aspinwall, Michael J., Bellasio, Chandra, Bernacchi, Carl, Bonnage, Steve, Buckley, Thomas N., Bunce, James, Burnett, Angela C., Busch, Florian A., Cavanagh, Amanda, Cernusak, Lucas A., Crystal-Ornelas, Robert, Damerow, Joan, Davidson, Kenneth J., De Kauwe, Martin G., Dietze, Michael C., Domingues, Tomas F., Dusenge, Mirindi Eric, Ellsworth, David S., Evans, John R., Gauthier, Paul P.G., Gimenez, Bruno O., Gordon, Elizabeth P., Gough, Christopher M., Halbritter, Aud H., Hanson, David T., Heskel, Mary, Hogan, J. Aaron, Hupp, Jason R., Jardine, Kolby, Kattge, Jens, Keenan, Trevor, Kromdijk, Johannes, and Kumarathunge, Dushan P.

Abstract

Leaf-level gas exchange data support the mechanistic understanding of plant fluxes of carbon and water. These fluxes inform our understanding of ecosystem function, are an important constraint on parameterization of terrestrial biosphere models, are necessary to understand the response of plants to global environmental change, and are integral to efforts to improve crop production. Collection of these data using gas analyzers can be both technically challenging and time consuming, and individual studies generally focus on a small range of species, restricted time periods, or limited geographic regions. The high value of these data is exemplified by the many publications that reuse and synthesize gas exchange data, however the lack of metadata and data reporting conventions make full and efficient use of these data difficult. Here we propose a reporting format for leaf-level gas exchange data and metadata to provide guidance to data contributors on how to store data in repositories to maximize their discoverability, facilitate their efficient reuse, and add value to individual datasets. For data users, the reporting format will better allow data repositories to optimize data search and extraction, and more readily integrate similar data into harmonized synthesis products. The reporting format specifies data table variable naming and unit conventions, as well as metadata characterizing experimental conditions and protocols. For common data types that were the focus of this initial version of the reporting format, i.e., survey measurements, dark respiration, carbon dioxide and light response curves, and parameters derived from those measurements, we took a further step of defining required additional data and metadata that would maximize the potential reuse of those data types. To aid data contributors and the development of data ingest tools by data repositories we provided a translation table comparing the outputs of common gas exchange instruments. Extensive consult

Published
2021

67. How Nitrogen and Phosphorus Availability Change Water Use Efficiency in a Mediterranean Savanna Ecosystem

Author

El‐Madany, Tarek S., primary, Reichstein, Markus, additional, Carrara, Arnaud, additional, Martín, M. Pilar, additional, Moreno, Gerardo, additional, Gonzalez‐Cascon, Rosario, additional, Peñuelas, Josep, additional, Ellsworth, David S., additional, Burchard‐Levine, Vicente, additional, Hammer, Tiana W., additional, Knauer, Jürgen, additional, Kolle, Olaf, additional, Luo, Yunpeng, additional, Pacheco‐Labrador, Javier, additional, Nelson, Jacob A., additional, Perez‐Priego, Oscar, additional, Rolo, Victor, additional, Wutzler, Thomas, additional, and Migliavacca, Mirco, additional

Published
2021
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68. The influence of elevated CO2 and soil depth on rhizosphere activity and nutrient availability in a mature Eucalyptus woodland.

Author

Pihlblad, Johanna, Andresen, Louise C., Macdonald, Cartriona A., Ellsworth, David S., and Carrillo, Yolima

Subjects
SOIL depth, EUCALYPTUS, FOREST biomass, FORESTS & forestry, RHIZOSPHERE, NUTRIENT cycles, BIOMASS production
Abstract

Elevated carbon dioxide (eCO2) in the atmosphere increases forest biomass productivity, but only where soil nutrients, particularly nitrogen (N) and phosphorus (P) are not limiting growth. eCO2, in turn, can impact rhizosphere nutrient availability. Our current understanding of nutrient cycling under eCO2 is mainly derived from surface soil, leaving mechanisms of the impact of eCO2 on rhizosphere nutrient availability at deeper depths unexplored. To investigate the influence of eCO2 on nutrient availability in soil at depth, we studied various C, N and P pools (extractable, microbial biomass, total soil C and N, and mineral associated P) and nutrient cycling processes (enzyme activity and gross N mineralization) associated with C, N, and P cycling in both bulk and rhizosphere soil at different depths at the Free Air CO2 enrichment facility in a native Australian mature Eucalyptus woodland (EucFACE) on a nutrient-poor soil. We found that the depth-induced decrease in nutrient availability, gross N mineralization was counteracted by the root influence and by eCO2. Increases in available PO43-, adsorbed P and the C : N and C : P ratio of enzyme activity with depth were observed. We conclude that the influences of roots and of eCO2 can affect available-nutrient pools and processes well beyond the surface soil of a mature forest ecosystem. Our findings indicate a faster recycling of nutrients in the rhizosphere, rather than additional nutrients becoming available through SOM decomposition. If the plant growth response to eCO2 is reduced by the constraints of nutrient limitations, then the current results would call to question the potential for mature tree ecosystems to fix more C as biomass in response to eCO2. Future studies should address how accessible the available nutrients at depth are to deeply rooted plants, and if fast recycling of nutrients is a meaningful contribution to biomass production and the accumulation of soil C in response to eCO2. [ABSTRACT FROM AUTHOR]

Published
2022
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71. A reporting format for leaf-level gas exchange data and metadata

Author

Ely, Kim S., primary, Rogers, Alistair, additional, Agarwal, Deborah A., additional, Ainsworth, Elizabeth A., additional, Albert, Loren P., additional, Ali, Ashehad, additional, Anderson, Jeremiah, additional, Aspinwall, Michael J., additional, Bellasio, Chandra, additional, Bernacchi, Carl, additional, Bonnage, Steve, additional, Buckley, Thomas N., additional, Bunce, James, additional, Burnett, Angela C., additional, Busch, Florian A., additional, Cavanagh, Amanda, additional, Cernusak, Lucas A., additional, Crystal-Ornelas, Robert, additional, Damerow, Joan, additional, Davidson, Kenneth J., additional, De Kauwe, Martin G., additional, Dietze, Michael C., additional, Domingues, Tomas F., additional, Dusenge, Mirindi Eric, additional, Ellsworth, David S., additional, Evans, John R., additional, Gauthier, Paul P.G., additional, Gimenez, Bruno O., additional, Gordon, Elizabeth P., additional, Gough, Christopher M., additional, Halbritter, Aud H., additional, Hanson, David T., additional, Heskel, Mary, additional, Hogan, J. Aaron, additional, Hupp, Jason R., additional, Jardine, Kolby, additional, Kattge, Jens, additional, Keenan, Trevor, additional, Kromdijk, Johannes, additional, Kumarathunge, Dushan P., additional, Lamour, Julien, additional, Leakey, Andrew D.B., additional, LeBauer, David S., additional, Li, Qianyu, additional, Lundgren, Marjorie R., additional, McDowell, Nate, additional, Meacham-Hensold, Katherine, additional, Medlyn, Belinda E., additional, Moore, David J.P., additional, Negrón-Juárez, Robinson, additional, Niinemets, Ülo, additional, Osborne, Colin P., additional, Pivovaroff, Alexandria L., additional, Poorter, Hendrik, additional, Reed, Sasha C., additional, Ryu, Youngryel, additional, Sanz-Saez, Alvaro, additional, Schmiege, Stephanie C., additional, Serbin, Shawn P., additional, Sharkey, Thomas D., additional, Slot, Martijn, additional, Smith, Nicholas G., additional, Sonawane, Balasaheb V., additional, South, Paul F., additional, Souza, Daisy C., additional, Stinziano, Joseph Ronald, additional, Stuart-Haëntjens, Ellen, additional, Taylor, Samuel H., additional, Tejera, Mauricio D., additional, Uddling, Johan, additional, Vandvik, Vigdis, additional, Varadharajan, Charuleka, additional, Walker, Anthony P., additional, Walker, Berkley J., additional, Warren, Jeffrey M., additional, Way, Danielle A., additional, Wolfe, Brett T., additional, Wu, Jin, additional, Wullschleger, Stan D., additional, Xu, Chonggang, additional, Yan, Zhengbing, additional, and Yang, Dedi, additional

Published
2021
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72. Low sensitivity of gross primary production to elevated CO2 in a mature eucalypt woodland

Author

Yang, Jinyan, Medlyn, Belinda E., Kauwe, Martin G., Duursma, Remko A., Jiang, Mingkai, Kumarathunge, Dushan, Crous, Kristine Y., Gimeno, Teresa E., Wujeska-Klause, Agnieszka, and Ellsworth, David S.

Abstract

The response of mature forest ecosystems to a rising atmospheric carbon dioxide concentration (span classCombining double low line"inline-formula"iC/ia/span) is a major uncertainty in projecting the future trajectory of the Earth's climate. Although leaf-level net photosynthesis is typically stimulated by exposure to elevated span classCombining double low line"inline-formula"iC/ia/span (espan classCombining double low line"inline-formula"iC/ia/span), it is unclear how this stimulation translates into carbon cycle responses at the ecosystem scale. Here we estimate a key component of the carbon cycle, the gross primary productivity (GPP), of a mature native eucalypt forest exposed to free-air span classCombining double low line"inline-formula"CO2/span enrichment (the EucFACE experiment). In this experiment, light-saturated leaf photosynthesis increased by 19 % in response to a 38 % increase in span classCombining double low line"inline-formula"iC/ia/span. We used the process-based forest canopy model, MAESPA, to upscale these leaf-level measurements of photosynthesis with canopy structure to estimate the GPP and its response to espan classCombining double low line"inline-formula"iC/ia/span. We assessed the direct impact of espan classCombining double low line"inline-formula"iC/ia/span, as well as the indirect effect of photosynthetic acclimation to espan classCombining double low line"inline-formula"iC/ia/span and variability among treatment plots using different model scenarios./p At the canopy scale, MAESPA estimated a GPP of 1574 g C mspan classCombining double low line"inline-formula"-2/span yrspan classCombining double low line"inline-formula"-1/span under ambient conditions across 4 years and a direct increase in the GPP of span classCombining double low line"inline-formula"+/span11 % in response to espan classCombining double low line"inline-formula"iC/ia/span. The smaller canopy-scale response simulated by the model, as compared with the leaf-level response, could be attributed to the prevalence of RuBP regeneration limitation of leaf photosynthesis within the canopy. Photosynthetic acclimation reduced this estimated response to 10 %. After taking the baseline variability in the leaf area index across plots in account, we estimated a field GPP response to espan classCombining double low line"inline-formula"iC/ia/span of 6 % with a 95 % confidence interval (span classCombining double low line"inline-formula"-/span2 %, 14 %). These findings highlight that the GPP response of mature forests to espan classCombining double low line"inline-formula"iC/ia/span is likely to be considerably lower than the response of light-saturated leaf photosynthesis. Our results provide an important context for interpreting the espan classCombining double low line"inline-formula"iC/ia/span responses of other components of the ecosystem carbon cycle.

Published
2020

73. Growing-season temperature and precipitation are independent drivers of global variation in xylem hydraulic conductivity

Author

He, Pengcheng, Gleason, Sean M., Wright, Ian J., Weng, Ensheng, Liu, Hui, Zhu, Shidan, Lu, Mingzhen, Luo, Qi, Li, Ronghua, Wu, Guilin, Yan, Enrong, Song, Yanjun, Mi, Xiangcheng, Reich, Peter B., Wang, Yingping, Ellsworth, David S., and Ye, Qing

Subjects
Vegetation and climate, Botany, Biotic communities, Hydrology, Stems (Botany)
Abstract

Stem xylem-specific hydraulic conductivity (KS) represents the potential for plant water transport normalized by xylem cross section, length, and driving force. Variation in KS has implications for plant transpiration and photosynthesis, growth and survival, and also the geographic distribution of species. Clarifying the global- scale patterns of KS and its major drivers is needed to achieve a better understanding of how plants adapt to different environmental conditions, particularly under climate change scenarios. Here, we compiled a xylem hydraulics dataset with 1,186 species- at-site combinations (975 woody species representing 146 families, from 199 sites worldwide), and investigated how KS varied with climatic variables, plant functional types, and biomes. Growing-season temperature and growing-season precipitation drove global variation in KS independently. Both the mean and the variation in KS were highest in the warm and wet tropical regions, and lower in cold and dry regions, such as tundra and desert biomes. Our results suggest that future warming and redistribution of seasonal precipitation may have a significant impact on species functional diversity, and is likely to be particularly important in regions becoming warmer or drier, such as high latitudes. This highlights an important role for KS in predicting shifts in community composition in the face of climate change.

Published
2020
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74. Can light‐saturated photosynthesis in lowland tropical forests be estimated by one light level?

Author

Verryckt, Lore T., Ellsworth, David S., Vicca, Sara, Van Langenhove, Leandro, Peñuelas, Josep, Ciais, Philippe, Posada, Juan M., Stahl, Clément, Coste, Sabrina, Courtois, Elodie A., Obersteiner, Michael, Chave, Jérôme, Janssens, Ivan A., Verryckt, Lore T., Ellsworth, David S., Vicca, Sara, Van Langenhove, Leandro, Peñuelas, Josep, Ciais, Philippe, Posada, Juan M., Stahl, Clément, Coste, Sabrina, Courtois, Elodie A., Obersteiner, Michael, Chave, Jérôme, and Janssens, Ivan A.

Abstract

Leaf‐level net photosynthesis (A n) estimates and associated photosynthetic parameters are crucial for accurately parameterizing photosynthesis models. For tropical forests, such data are poorly available and collected at variable light conditions. To avoid over‐ or underestimation of modeled photosynthesis, it is critical to know at which photosynthetic photon flux density (PPFD) photosynthesis becomes light‐saturated. We studied the dependence of A n on PPFD in two tropical forests in French Guiana. We estimated the light saturation range, including the lowest PPFD level at which A sat (A n at light saturation) is reached, as well as the PPFD range at which A sat remained unaltered. The light saturation range was derived from photosynthetic light‐response curves, and within‐canopy and interspecific differences were studied. We observed wide light saturation ranges of A n. Light saturation ranges differed among canopy heights, but a PPFD level of 1,000 µmol m−2 s−1 was common across all heights, except for pioneer trees species that did not reach light saturation below 2,000 µmol m−2 s−1. A light intensity of 1,000 µmol m−2 s−1 sufficed for measuring A sat of climax species at our study sites, independent of the species or the canopy height. Because of the wide light saturation ranges, results from studies measuring A sat at higher PPFD levels (for upper canopy leaves up to 1,600 µmol m−2 s−1) are comparable with studies measuring at 1,000 µmol m−2 s−1.

Published
2020
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75. Coping with branch excision when measuring leaf net photosynthetic rates in a lowland tropical forest

Author

Verryckt, Lore T., Van Langenhove, Leandro, Ciais, Philippe, Courtois, Elodie A., Vicca, Sara, Peñuelas, Josep, Stahl, Clément, Coste, Sabrina, Ellsworth, David S., Posada, Juan M., Obersteiner, Michael, Chave, Jérôme, Janssens, Ivan A., Verryckt, Lore T., Van Langenhove, Leandro, Ciais, Philippe, Courtois, Elodie A., Vicca, Sara, Peñuelas, Josep, Stahl, Clément, Coste, Sabrina, Ellsworth, David S., Posada, Juan M., Obersteiner, Michael, Chave, Jérôme, and Janssens, Ivan A.

Abstract

Measuring leaf gas exchange from canopy leaves is fundamental for our understanding of photosynthesis and for a realistic representation of carbon uptake in vegetation models. Since canopy leaves are often difficult to reach, especially in tropical forests with emergent trees up to 60 m at remote places, canopy access techniques such as canopy cranes or towers have facilitated photosynthetic measurements. These structures are expensive and therefore not very common. As an alternative, branches are often cut to enable leaf gas exchange measurements. The effect of branch excision on leaf gas exchange rates should be minimized and quantified to evaluate possible bias. We compared light‐saturated leaf net photosynthetic rates measured on excised and intact branches. We selected branches positioned at three canopy positions, estimated relative to the top of the canopy: upper sunlit foliage, middle canopy foliage, and lower canopy foliage. We studied the variation of the effects of branch excision and transport among branches at these different heights in the canopy. After excision and transport, light‐saturated leaf net photosynthetic rates were close to zero for most leaves due to stomatal closure. However, when the branch had acclimated to its new environmental conditions—which took on average 20 min—light‐saturated leaf net photosynthetic rates did not significantly differ between the excised and intact branches. We therefore conclude that branch excision does not affect the measurement of light‐saturated leaf net photosynthesis, provided that the branch is recut under water and is allowed sufficient time to acclimate to its new environmental conditions.

Published
2020
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76. Nitrogen limitation constrains sustainability of ecosystem response to CO2

Author

Reich, Peter B., Hobbie, Sarah E., Lee, Tali, Ellsworth, David S., West, Jason B., Tilman, David, Knops, Johannes M. H., Naeem, Shahid, and Trost, Jared

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Peter B. Reich (corresponding author) [1]; Sarah E. Hobbie [2]; Tali Lee [1, 3]; David S. Ellsworth [4]; Jason B. West [2]; David Tilman [2]; Johannes M. H. Knops [...]

Published
2006
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81. Soil fertility limits carbon sequestration by forest ecosystems in a CO2-enriched atmosphere

Author

Oren, Ram, Ellsworth, David S., Johnsen, Kurt H., Phillips, Nathan, Ewers, Brent E., Maier, Chris, Schafer, Karina V.R., McCarthy, Heather, Hendrey, George, McNulty, Steven G., and Katul, Gabriel G.

Subjects
Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): Ram Oren (corresponding author) [1]; David S. Ellsworth [2, 3]; Kurt H. Johnsen [4]; Nathan Phillips [5]; Brent E. Ewers [1]; Chris Maier [4]; Karina V.R. Schäfer [1]; Heather [...]

Published
2001
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84. Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO2

Author

Walker, Anthony P., primary, De Kauwe, Martin G., additional, Bastos, Ana, additional, Belmecheri, Soumaya, additional, Georgiou, Katerina, additional, Keeling, Ralph F., additional, McMahon, Sean M., additional, Medlyn, Belinda E., additional, Moore, David J. P., additional, Norby, Richard J., additional, Zaehle, Sönke, additional, Anderson‐Teixeira, Kristina J., additional, Battipaglia, Giovanna, additional, Brienen, Roel J. W., additional, Cabugao, Kristine G., additional, Cailleret, Maxime, additional, Campbell, Elliott, additional, Canadell, Josep G., additional, Ciais, Philippe, additional, Craig, Matthew E., additional, Ellsworth, David S., additional, Farquhar, Graham D., additional, Fatichi, Simone, additional, Fisher, Joshua B., additional, Frank, David C., additional, Graven, Heather, additional, Gu, Lianhong, additional, Haverd, Vanessa, additional, Heilman, Kelly, additional, Heimann, Martin, additional, Hungate, Bruce A., additional, Iversen, Colleen M., additional, Joos, Fortunat, additional, Jiang, Mingkai, additional, Keenan, Trevor F., additional, Knauer, Jürgen, additional, Körner, Christian, additional, Leshyk, Victor O., additional, Leuzinger, Sebastian, additional, Liu, Yao, additional, MacBean, Natasha, additional, Malhi, Yadvinder, additional, McVicar, Tim R., additional, Penuelas, Josep, additional, Pongratz, Julia, additional, Powell, A. Shafer, additional, Riutta, Terhi, additional, Sabot, Manon E. B., additional, Schleucher, Juergen, additional, Sitch, Stephen, additional, Smith, William K., additional, Sulman, Benjamin, additional, Taylor, Benton, additional, Terrer, César, additional, Torn, Margaret S., additional, Treseder, Kathleen K., additional, Trugman, Anna T., additional, Trumbore, Susan E., additional, van Mantgem, Phillip J., additional, Voelker, Steve L., additional, Whelan, Mary E., additional, and Zuidema, Pieter A., additional

Published
2020
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85. Low phosphorus supply constrains plant responses to elevated CO 2 : A meta‐analysis

Author

Jiang, Mingkai, primary, Caldararu, Silvia, additional, Zhang, Haiyang, additional, Fleischer, Katrin, additional, Crous, Kristine Y., additional, Yang, Jinyan, additional, De Kauwe, Martin G., additional, Ellsworth, David S., additional, Reich, Peter B., additional, Tissue, David T., additional, Zaehle, Sönke, additional, and Medlyn, Belinda E., additional

Published
2020
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88. Can light‐saturated photosynthesis in lowland tropical forests be estimated by one light level?

Author

Verryckt, Lore T., primary, Ellsworth, David S., additional, Vicca, Sara, additional, Van Langenhove, Leandro, additional, Peñuelas, Josep, additional, Ciais, Philippe, additional, Posada, Juan M., additional, Stahl, Clément, additional, Coste, Sabrina, additional, Courtois, Elodie A., additional, Obersteiner, Michael, additional, Chave, Jérôme, additional, and Janssens, Ivan A., additional

Published
2020
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91. Coping with branch excision when measuring leaf net photosynthetic rates in a lowland tropical forest

Author

Verryckt, Lore T., primary, Van Langenhove, Leandro, additional, Ciais, Philippe, additional, Courtois, Elodie A., additional, Vicca, Sara, additional, Peñuelas, Josep, additional, Stahl, Clément, additional, Coste, Sabrina, additional, Ellsworth, David S., additional, Posada, Juan M., additional, Obersteiner, Michael, additional, Chave, Jérôme, additional, and Janssens, Ivan A., additional

Published
2020
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94. Growing‐season temperature and precipitation are independent drivers of global variation in xylem hydraulic conductivity

Author

He, Pengcheng, primary, Gleason, Sean M., additional, Wright, Ian J., additional, Weng, Ensheng, additional, Liu, Hui, additional, Zhu, Shidan, additional, Lu, Mingzhen, additional, Luo, Qi, additional, Li, Ronghua, additional, Wu, Guilin, additional, Yan, Enrong, additional, Song, Yanjun, additional, Mi, Xiangcheng, additional, Hao, Guangyou, additional, Reich, Peter B., additional, Wang, Yingping, additional, Ellsworth, David S., additional, and Ye, Qing, additional

Published
2019
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96. Leaf inclination angle and foliage clumping in an evergreen broadleaf Eucalyptus forest under elevated atmospheric CO2.

Author

Pisek, Jan, Řezníčková, Ladislava, Adamson, Kairi, and Ellsworth, David S.

Abstract

How leaves are presented affects interaction of atmospheric CO2, energy (light), and plant physiology. Plant productivity is primarily determined by the amount of leaf area, leaf orientation and distribution in space. Not much attention has been paid to possible changes in leaf orientation and distribution with elevated CO2, but its effect on plant growth could alter the proportions of sunlit and shaded leaf areas and feedback on carbohydrate available for further growth. We report on first measurements of leaf inclination angle distribution and foliage clumping in a native evergreen Eucalyptus woodland in ambient CO2 and under +150 ppm elevated CO2. We found that a spherical leaf angle distribution was not an appropriate supposition for present species (Eucalyptus tereticornis Sm.) at this site. Our measurements of leaf inclination angles from imagery indicated an erectophile, highly skewed unimodal leaf inclination angle distribution function. We conclude that despite the measured steeper angles under elevated CO2 concentrations, the leaf angle change is not significant and falls within the expected natural variability and uncertainties connected with the measurement method. The lack of a clear response of leaf orientation and foliage clumping to elevated CO2 concentration indicates that the previously produced datasets of leaf inclination angles and foliage clumping maps with Earth observation data may be suitable while modelling carbon and water cycles under climate change. How leaves are presented affects interaction of atmospheric CO2, energy (light), and plant physiology. Not much attention has been paid to possible changes in leaf orientation and distribution with elevated CO2, but its effect on plant growth could alter the proportions of sunlit and shaded leaf areas and feedback on carbohydrate available for further growth. We report on first measurements of leaf inclination angle distribution and foliage clumping in a native evergreen Eucalyptus woodland in ambient CO2 and under +150 ppm elevated CO2. [ABSTRACT FROM AUTHOR]

Published
2021
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98. Leaf to Landscape

Author

Williams, Mathew, primary, Woodward, F. Ian, additional, Baldocchi, Dennis D., additional, and Ellsworth, David S., additional

Published
2004
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99. The quasi-equilibrium framework re-visited: analyzing long-term CO2 enrichment responses in plant-soil models

Author

Jiang, Mingkai, Zaehle, Sönke, Kauwe, Martin G., Walker, Anthony P., Caldararu, Silvia, Ellsworth, David S., and Medlyn, Belinda E.

Abstract

Elevated carbon dioxide (CO2) can increase plant growth, but the magnitude of this CO2 fertilization effect is modified by soil nutrient availability. Predicting how nutrient availability affects plant responses to elevated CO2 is a key consideration for ecosystem models, and many modelling groups have moved to, or are moving towards, incorporating nutrient limitation in their models. The choice of assumptions to represent nutrient cycling processes has a major impact on model predictions, but it can be difficult to attribute outcomes to specific assumptions in complex ecosystem simulation models. Here we revisit the quasi-equilibrium (QE) analytical framework introduced by Comins & McMurtrie (1993) and explore the consequences of specific model assumptions for ecosystem net primary productivity. We review the literature applying this framework to plant-soil models, and then examine the effect of several new assumptions on predicted plant responses to elevated CO2. Examination of alternative assumptions for plant nitrogen uptake showed that a linear function of the mineral nitrogen pool or a saturating function of root biomass yield similar CO2 responses over time. In contrast, a saturating function of the mineral nitrogen pool yields no soil nutrient feedback at the very long-term, near-equilibrium timescale, meaning that a full CO2 fertilization effect on production is realized. We show that incorporating a priming effect on slow soil organic matter decomposition attenuates the nutrient feedback effect on production, leading to a strong medium-term CO2 response. Finally, we demonstrate that using a “potential NPP” approach to represent nutrient limitation of growth yields a relatively small CO2 fertilization effect across all timescales. Our results highlight that the QE analytical framework is effective for evaluating both the consequence and the mechanism through which different model assumptions affect predictions. To help constrain predictions of the future terrestrial carbon sink, we recommend use of this framework to analyze likely outcomes of new model assumptions before introducing them to complex model structures.

Published
2018

100. Acclimation and adaptation components of the temperature dependence of plant photosynthesis at the global scale

Author

Kumarathunge, Dushan P., Medlyn, Belinda E., Drake, John E., Tjoelker, Mark G., Aspinwall, Michael J., Battaglia, Michael, Cano, Francisco J., Carter, Kelsey R., Cavaleri, Molly A., Cernusak, Lucas A., Chambers, Jeffrey Q., Crous, Kristine Y., De Kauwe, Martin G., Dillaway, Dylan N., Dreyer, Erwin, Ellsworth, David S., Ghannoum, Oula, Han, Qingmin, Hikosaka, Kouki, Jensen, Anna M., Kelly, Jeff W.G., Kruger, Eric L., Mercado, Lina M., Onoda, Yusuke, Reich, Peter B., Rogers, Alistair, Slot, Martijn, Smith, Nicholas G., Tarvainen, Lasse, Tissue, David T., Togashi, Henrique F., Tribuzy, Edgard S., Uddling, Johan, Vårhammar, Angelica, Wallin, Göran, Warren, Jeffrey M., Way, Danielle A., Kumarathunge, Dushan P., Medlyn, Belinda E., Drake, John E., Tjoelker, Mark G., Aspinwall, Michael J., Battaglia, Michael, Cano, Francisco J., Carter, Kelsey R., Cavaleri, Molly A., Cernusak, Lucas A., Chambers, Jeffrey Q., Crous, Kristine Y., De Kauwe, Martin G., Dillaway, Dylan N., Dreyer, Erwin, Ellsworth, David S., Ghannoum, Oula, Han, Qingmin, Hikosaka, Kouki, Jensen, Anna M., Kelly, Jeff W.G., Kruger, Eric L., Mercado, Lina M., Onoda, Yusuke, Reich, Peter B., Rogers, Alistair, Slot, Martijn, Smith, Nicholas G., Tarvainen, Lasse, Tissue, David T., Togashi, Henrique F., Tribuzy, Edgard S., Uddling, Johan, Vårhammar, Angelica, Wallin, Göran, Warren, Jeffrey M., and Way, Danielle A.

Abstract

• The temperature response of photosynthesis is one of the key factors determining predicted responses to warming in global vegetation models (GVMs). The response may vary geographically, owing to genetic adaptation to climate, and temporally, as a result of acclimation to changes in ambient temperature. Our goal was to develop a robust quantitative global model representing acclimation and adaptation of photosynthetic temperature responses. • We quantified and modelled key mechanisms responsible for photosynthetic temperature acclimation and adaptation using a global dataset of photosynthetic CO2 response curves, including data from 141 C3 species from tropical rainforest to Arctic tundra. We separated temperature acclimation and adaptation processes by considering seasonal and common‐garden datasets, respectively. • The observed global variation in the temperature optimum of photosynthesis was primarily explained by biochemical limitations to photosynthesis, rather than stomatal conductance or respiration. We found acclimation to growth temperature to be a stronger driver of this variation than adaptation to temperature at climate of origin. • We developed a summary model to represent photosynthetic temperature responses and showed that it predicted the observed global variation in optimal temperatures with high accuracy. This novel algorithm should enable improved prediction of the function of global ecosystems in a warming climate.

Published
2019

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