BG3.2 | Carbon allocation in plants and ecosystems: mechanisms, responses and biogeochemical implications
Carbon allocation in plants and ecosystems: mechanisms, responses and biogeochemical implications
Convener: Michael Bahn | Co-conveners: Henrik Hartmann, Mariah Carbone, Daniel Epron, Andrew Richardson
Orals
| Wed, 26 Apr, 14:00–15:45 (CEST)
 
Room C
Posters on site
| Attendance Wed, 26 Apr, 16:15–18:00 (CEST)
 
Hall A
Posters virtual
| Attendance Wed, 26 Apr, 16:15–18:00 (CEST)
 
vHall BG
Orals |
Wed, 14:00
Wed, 16:15
Wed, 16:15
Carbon allocation is a key process in ecosystems: it is coupled with plant growth, fuels metabolism and plays a crucial role for carbon sequestration in standing biomass and soil organic matter. While the importance of carbon allocation for plant and ecosystem functioning and the carbon balance is widely recognized, we still lack a comprehensive understanding of the underlying mechanisms, responses to global changes and wider biogeochemical implications. Open questions include: 1) what drives carbon allocation in plants and ecosystems?; 2) what is the fate of newly assimilated carbon?; 3) what determines the allocation of nonstructural carbon to growth, metabolism and storage?, 4) how does carbon allocation affect nutrient and water relations in plants and ecosystems?; and 5) how do allocation patterns change under changing environmental conditions and what are the consequences for biogeochemical cycles? This session invites contributions from observational, experimental and modelling studies.

Orals: Wed, 26 Apr | Room C

Chairpersons: Michael Bahn, Henrik Hartmann
14:00–14:05
14:05–14:15
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EGU23-2971
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BG3.2
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ECS
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solicited
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Highlight
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Virtual presentation
Anna Trugman and Gregory Quetin

The extent to which future climate change will increase forest stress and the amount to which species and forest ecosystems can acclimate or adapt to increased stress is a major unknown. We used high resolution maps of hydraulic traits representing the diversity in tree drought tolerance across the United States combined with a hydraulically-enabled tree model to quantify the ability for within-species changes in allocation and between-species range shifts to mediate climate stress. We found that forests are likely to experience increases in chronic hydraulic stress with climate change, even with expected increases in atmospheric CO2. Based on current species distributions, regional hydraulic trait diversity was sufficient to buffer against increased stress in 86% of forested areas. Importantly, changes in leaf allocation have the potential to substantially decrease stress, reducing the need for biogeographic shifts in species distributions. However, observed trait velocities are not keeping up with the rate required to ameliorate projected future stress.

How to cite: Trugman, A. and Quetin, G.: Allocation mediates plant drought stress and productivity in a changing climate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2971, https://doi.org/10.5194/egusphere-egu23-2971, 2023.

14:15–14:25
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EGU23-5745
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BG3.2
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ECS
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On-site presentation
Ido Rog, Boaz Hilman, Hagar Fox, Shifra Avital, and Tamir Klein

Climate change is expected to increase the frequency and severity of droughts in Mediterranean forests. Tree survival and storage of atmospheric CO2 in these forests depend on how individual tree species allocate their carbon (C). Here, we measured a complete set of above- and belowground C pools and fluxes in five coniferous and broadleaf species co-existing in a mature evergreen forest. Our study period included a drought year, followed by an above-average wet year, and the seasonal long dry period characterizes Mediterranean climate. To quantify the exact timing and spatial distribution of belowground C allocation, we additionally applied 13CO2 pulse labelling of one of the tree species (Quercus calliprinos). We found that during the dry versus wet year, photosynthetic C uptake decreased, C use in the C sinks remained unchanged and C allocation to belowground sinks increased. Among the five major C sinks, respiration was the main flux (~64%), while smaller fluxes like exudation (~9%) and reproduction (~1%) were those which increased the most in the dry year. To cope with seasonal drought, most trees relied on starch to maintain the C supply, but between years we found no significant differences in starch and sugars in aboveground tissues. Relative to the C storage dynamics, higher water use efficiency was found in conifers, while species-specific differences between dry and wet years were found among the broadleaves. Interestingly, in the wet season, after pulse labelling, C was allocated from the labeled leaves to the roots in two main time-lags: first after 3-5 days and second after 15-20 days. Labeled C reached fine roots at a distance of 0-6 m from the labeled tree. These detailed tree-level observations expose inter-annual and interspecific differences in C allocation among fluxes and tissues, specifically in response to varying water availability.

How to cite: Rog, I., Hilman, B., Fox, H., Avital, S., and Klein, T.: Increased belowground tree carbon allocation in a mature mixed forest in a dry vs. a wet year, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5745, https://doi.org/10.5194/egusphere-egu23-5745, 2023.

14:25–14:35
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EGU23-4097
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BG3.2
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On-site presentation
Xuhui Zhou, Zheng Jiang, and Yuling Fu

Root exudates are an important pathway for plant-microbial interactions and are highly sensitive to climate change. However, how extreme drought affects root exudate and its components, as well as species-specific difference in response magnitude and direction, are poorly understood. In this study, root exudation rates of total carbon (C) and its components (e.g., sugar, organic acid, and amino acid) were measured under the control and drought treatments (i.e., 70% throughfall reduction) by in situ collection of four tree species with different growth rates in a subtropical forest. We also quantified soil properties, root morphological traits, and mycorrhizal infection rates to examine the driving factors underlying variations in root exudation. Our results showed that drought significantly decreased root exudation rates of total C, sugar, and amino acid by 17.8%, 30.8%, and 35.0%, respectively, but increased root exudation rate of organic acid by 38.6%. These changes were largely associated with drought-induced changes in tree growth rates, root morphological traits, and mycorrhizal infection rates. Specifically, trees with relatively high growth rates were more responsive to drought for root exudation rates compared to those with relatively low growth rates, which were closely related to root morphological traits and mycorrhizal infection rates. These findings highlight the importance of plant growth strategy in mediating drought-induced changes in root exudation rates. The trade-offs between root exudation rates, root morphological traits, and mycorrhizal symbioses in response to drought could be incorporated into land surface models to improve the prediction of climate change impacts on rhizosphere C dynamics in forest ecosystems. 

How to cite: Zhou, X., Jiang, Z., and Fu, Y.: Plant growth strategy determines the magnitude and direction of drought-induced changes in root exudates in subtropical forests, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4097, https://doi.org/10.5194/egusphere-egu23-4097, 2023.

14:35–14:45
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EGU23-8002
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BG3.2
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ECS
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On-site presentation
Benjamin D. Hafner, Melanie Brunn, Marie J. Zwetsloot, Kyohsuke Hikino, Fabian Weikl, Karin Pritsch, Emma J. Sayer, Nadine K. Ruehr, and Taryn L. Bauerle

In recent years, important processes controlling ecosystem carbon dynamics have been connected to fine-root exudation of soluble carbon compounds. Root exudation patterns may change depending on plant interactions and plant susceptibility to and recovery from drought. Recent investigations suggest that root exudation tends to increase with stress events, but quantification of the amount of carbon released from roots across soil depths with differing water availability and species interactions are missing.

We tested if root exudation rates were negatively correlated with soil water content across soil depths during and after drought. We further tested if species in mixture, often considered to be less stressed under drought, exuded less carbon than species in monospecific environments. Exudates were sampled in a mature Fagus sylvatica L. and Picea abies (L.) Karst. forest at the end of a five-year throughfall exclusion period and again one year after the drought ended. We quantified root exudates and their variation with soil depth for both tree species in monospecific and mixed species zones.

Carbon exudation significantly increased in fine roots exposed to dry soils (< c. 10vol-% SWC), with fine roots growing in driest surface soils exuding the most. Under drought, the proportion of net assimilated carbon allocated to exudates doubled for F. sylvatica and tripled for P. abies, respectively. One year after drought release, carbon allocation to exudates was not different for F. sylvatica between previously drought stressed and control trees, while the proportion was still significantly increased in previously drought stressed P. abies compared to control trees. This indicates long-term disruptions in carbon allocation patterns even after the end of a drought period in evergreen vs. broadleaved temperate tree species. Both species exuded significantly more carbon when in monoculture than when in a mixed zone, especially in the surface soil layer.

Our results demonstrate that carbon is released preferentially in the surface soil layers exposed to more variable soil water contents and exudation amounts are maintained by allocating bigger proportions of net-assimilated carbon into exudates even among variable carbon assimilation rates throughout periods of drought and re-wetting. In addition, plant interactions significantly influenced root exudation patterns. Further studies are planned to understand if differences in exudate quantity correlate to differences in functioning of released exudates in monospecific and mixed environments by analyzing the chemical profile of the exudate metabolome.

How to cite: Hafner, B. D., Brunn, M., Zwetsloot, M. J., Hikino, K., Weikl, F., Pritsch, K., Sayer, E. J., Ruehr, N. K., and Bauerle, T. L.: Carbon allocation to root exudates in a mature mixed F. sylvatica – P. abies forest under drought and one year after drought release., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8002, https://doi.org/10.5194/egusphere-egu23-8002, 2023.

14:45–14:55
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EGU23-5188
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BG3.2
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ECS
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On-site presentation
Emily Solly, Astrid Jaeger, Matti Barthel, Roland Werner, Alois Zürcher, Frank Hagedorn, Johan Six, and Martin Hartmann

Climate change is causing negative effects on forests and their functioning through more frequent and intense periods of drought. Repeated conditions of water limitation not only affect the growth and vitality of trees but also feed back on the cycling of carbon (C) at the plant-soil interface. However, the impact of the intensity of drought on the transfer of assimilated C belowground remains quantitatively unresolved. We assessed how increasing levels of soil water limitation affect the growth of Scots pine (Pinus sylvestris L.) saplings and performed a 13C-CO2 pulse labelling experiment to trace the pathway of newly-assimilated C into needles, fine roots, soil pore CO2, and phospholipid fatty acids of soil microbial groups. We hypothesized that increased water stress would reduce tree C uptake, and the magnitude and velocity at which newly-assimilated C is allocated belowground and further metabolized. Moreover, we expected that severe levels of soil water deficit would lead to a build-up of newly-assimilated C in fine roots. Our data indicated that with more intense water limitation, trees reduced their growth despite initially partitioning more biomass to belowground tissues under severe water stress. Moderate levels of water limitation barely affected the uptake of 13C label and the magnitude and transit times of C being allocated from needles to the rhizosphere. In contrast, severe water limitation increased the fraction of 13C label allocated to roots and soil fungi while a lower fraction of 13CO2 was respired from the soil. We conclude that when soil water becomes largely unavailable, C cycling within trees becomes slower, and a major fraction of C allocated belowground is accumulated in roots or transferred to the soil and associated microorganisms without being metabolically used. Our experiment overall demonstrates the relevance of quantifying the level of water limitation at which C allocation dynamics within trees and soils are altered to inform about the trajectory of forests to the environmental pressures they face.

How to cite: Solly, E., Jaeger, A., Barthel, M., Werner, R., Zürcher, A., Hagedorn, F., Six, J., and Hartmann, M.: Drought intensity controls carbon allocation dynamics within experimental Scots pine-soil systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5188, https://doi.org/10.5194/egusphere-egu23-5188, 2023.

14:55–15:05
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EGU23-13571
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BG3.2
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ECS
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On-site presentation
Mathilde Vantyghem, Eline Beelen, Rebecca Hood-Nowotny, Roel Merckx, and Gerd Dercon

Banana is a perennial crop that propagates vegetatively through the formation of so-called suckers. Suckers are photosynthetically active, but remain connected to the mother plant. Their initial formation is driven by a carbon flux from the mother plant, but it is not known to which extent this flux persists once the sucker develops further. Drought stress is one of the most important limitations to banana production. Nonetheless, the effect of drought stress on the integrated system of mother plant and suckers remains unknown. In a greenhouse experiment, we aimed to quantify carbon fluxes in banana plants and assess the effects of drought stress and suckers on carbon allocation. We labeled banana mother plants with and without suckers with 13CO2, while the suckers were sealed gas tight. An optimal and suboptimal watering treatment were applied. The label was then traced in the phloem sap, in the leaves of mother plant and sucker and in the underground corm for a period of two weeks. Most of the label was either lost through respiration (37.5 ± 3.0 %) or allocated to the mother plant leaves (35.6 ± 2.2 %). Plants without suckers did not invest more in the growing mother plant, but instead, had higher respiratory losses. In plants with suckers, 3.1 ± 0.7 % of 13C assimilated by the mother plant was translocated to the sucker. Drought stress reduced the allocation to the sucker. On average, 5.8 ± 0.4 % of the label ended up in the corm, which connects all leaves and plant parts but also serves as a storage organ, by accumulating starch. Both drought stress and sucker presence increased overall translocation to the corm. Starch accumulation also increased under drought stress or in the presence of a sucker. However, when drought stress and a sucker were both present, starch accumulation was severely reduced. Finally, 17.2 ± 1.1 % of the label ended up in the wrapped leaf sheaths of the mother plant, that form the structurally important pseudostem. The pseudostem as well serves as a source of carbohydrates for future fruit and sucker development. Sucker presence increased carbon allocation to the pseudostem. In conclusion, it seems that suckers and drought stress affected carbon dynamics in banana plants similarly, namely by increasing carbon allocation to storage tissues. Their combination, however, resulted in an imbalance between carbon supply and demand and hence the plants’ investment in sucker growth, as well as in long-term storage were reduced.

How to cite: Vantyghem, M., Beelen, E., Hood-Nowotny, R., Merckx, R., and Dercon, G.: Carbon allocation in banana plants – the effects of drought stress and suckers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13571, https://doi.org/10.5194/egusphere-egu23-13571, 2023.

15:05–15:15
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EGU23-5410
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BG3.2
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On-site presentation
Boaz Hilman, Emily Solly, Ivano Brunner, Susan Trumbore, and Frank Hagedorn

The formation of high elevation treelines is thought to result from direct low-temperature growth limitation, but the in-direct role of nitrogen (N) in modifying growth has rarely been evaluated. Slow N mineralization rates in cold soils may push trees to rely more on N supplied by symbiotic mycorrhizal fungi. Here, we investigated the carbon (C) and N exchange between trees and mycorrhizal fungi along an Alpine treeline ecotone using bomb 14C and natural abundance isotopes (13C and 15N). We collected fine roots, branches, and needles from two tree species (Larix decidua L. and Pinus mugo spp. uncinata Ramond) and sporocarps of mycorrhizal and free-living (saprotrophic) fungal genera. 14C measurements demonstrated that mycorrhizal fungi rely on new photo-assimilates derived from fine roots, while saprotrophic fungi feed on several years old C (4-10 yr). The C transfer root-fungi seems to have isotopic fractionation that enriches the fungi with 13C in 1-5‰. Mycorrhizal fungi had higher δ15N values and C:N ratio than saprotrophic fungi. Assuming that the two fungi types share the same N source in the soil, the 15N enrichment and the lower N concentration of the mycorrhizal fungi could be explained through preferential transfer of 14N to the hosting trees. The δ15N in the trees generally decreased with increasing elevation, suggesting a greater reliance on N supplied by mycorrhizal fungi in colder soils. However, abrupt increase in the Larix δ15N at the treeline suggests opening of the N cycle for this deciduous tree species, either by a decreasing N demand of slow-growing trees or a reduced competition for N with other plants. Overall, our results indicate that in cold treeline ecotones the sources and availabilities of soil N have a key influence on determing the N uptake pathways of trees and consequently plant growth.

How to cite: Hilman, B., Solly, E., Brunner, I., Trumbore, S., and Hagedorn, F.: Carbon and nitrogen exchange between trees and mycorrhizal fungi at treeline ecotone, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5410, https://doi.org/10.5194/egusphere-egu23-5410, 2023.

15:15–15:25
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EGU23-1232
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BG3.2
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Highlight
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On-site presentation
Guenter Hoch, Raphael Weber, Cedric Zahnd, and Ansgar Kahmen

Most of the carbon (C) reserves in trees are stored in the living parenchyma of stems and roots and exhibit characteristic variations with phenology, growth and environmental stress. Up to date, it is only partially understood how the formation and re-mobilization of stored C in sapwood is regulated and synchronized over tissues and long distances. Mechanistic concepts of C storage therefore often assume simple bucket-models, where the amount of stored C equals the net-balance between C assimilation and the sum of all C sink activities (e.g., respiration and growth).

Here, we summarize results from previous experimental and observational studies in our group, that tested the reaction of non-structural carbohydrate reserve pools in trees to situations of limited photosynthetic C supply. Overall, these studies suggested that C reserve concentrations in sapwood follow abrupt changes of the net C-source-sink balance in the short-term and at severe C starvation, but they consistently reach homeostatic levels that are very similar across different C-source-sink conditions over longer time periods. According to our findings, we propose that C reserve pool sizes in tree are determined and closely controlled rather than the simple net-result of C source vs. -sink activities. With respect to mechanistic C models of trees, this suggests that C reserves should be rather treated as a fixed C-sink than a variable parameter.

How to cite: Hoch, G., Weber, R., Zahnd, C., and Kahmen, A.: Carbon storage pools of trees: fixed or flexible?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1232, https://doi.org/10.5194/egusphere-egu23-1232, 2023.

15:25–15:35
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EGU23-13912
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BG3.2
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ECS
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On-site presentation
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Jan De Pue, José Miguel Barrios, Alirio Arboleda, Rafiq Hamdi, Manuela Balzarolo, Fabienne Maignan, Christine Delire, Ivan Janssens, and Françoise Gellens-Meulenberghs

Within land surface models (LSM), the biomass allocation scheme (BAS) allows to simulate the dynamics of vegetation growth in response to climatic variation and other drivers. It distributes the assimilated carbon across different biomass pools, and consequently determines the spatio-temporal variability of the leaf area index (LAI).

In many LSM, large uncertainties are associated with the BAS, which propagate via the prognostic LAI to the surface fluxes. Here, we propose a revision to the BAS of the ISBA land surface model, by incorporating the dynamics of non-structural carbohydrates (NSC) explicitly. The target of the proposed BAS is the reproduction of LAI as observed with remote sensing, coupled to the modelled surface fluxes. Using in situ eddy covariance observations of the carbon fluxes, and remote sensing observations of the leaf biomass, estimates can be made of the biomass allocation and NSC dynamics. By combining this dataset with other (climatological) variables, a machine-learning based BAS is developed.

The simulated evolution of the biomass pools is evaluated using in situ observations of leaf turnover and remote sensing observations of leaf biomass. The proposed model is compared to the standard photosynthesis-driven BAS of ISBA and the more advanced BAS in ORCHIDEE.

How to cite: De Pue, J., Barrios, J. M., Arboleda, A., Hamdi, R., Balzarolo, M., Maignan, F., Delire, C., Janssens, I., and Gellens-Meulenberghs, F.: Incorporating nonstructural carbohydrate dynamics in the ISBA biomass allocation scheme, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13912, https://doi.org/10.5194/egusphere-egu23-13912, 2023.

15:35–15:45
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EGU23-11113
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BG3.2
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ECS
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Highlight
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On-site presentation
Holger Metzler, Samuli Launiainen, and Giulia Vico

Boreal forests have enormous potential to mitigate climate change by taking up and holding back carbon (C) from the atmosphere, but often they are managed to maximize wood productivity. To achieve regional and global climate goals, boreal forest management must consider trade-offs between wood productivity and potential climate change mitigation. Quantifying forests' climate change mitigation potentials requires knowledge of both the amount of C fixed from the atmosphere and how long trees and subsequently soil and wood products withhold it from the atmosphere (C transit time). Despite its importance for climate change mitigation, transit time is often overlooked when focusing on climate change mitigation potential.

We developed a novel mass-balanced and process-based compartmental forest management model comprising trees of different ages and species in a single stand. The model follows the C path from photosynthetical fixation to return to the atmosphere by autotrophic or heterotrophic respiration or by wood-product burning. The fixed C is allocated to different tree organs according to dynamically changing allometries derived from site- and species-specific forest inventory data and affected by the tree's physiological state (healthy or stressed). The compartmental model structure and its mathematical description as a system of ordinary differential equations enable computing stored nonstructural C age as well as age and provenance of C used for tissue growth and respiration. Furthermore, the dynamical implementation of nonstructural C provides a measure of the forest stands' resilience to stressors and a mechanism for tree mortality .

We apply the model to even-aged pure Scots pine and Norway spruce stands as well as to an even-aged mixed-species stand and to a mixed-aged pine stand, under conditions for southern Finland. We compute: 1) wood productivity as the amount of C in harvested wood products, 2) the net balance of C in trees, soil, and wood products, and 3) the amount of fixed C together with its transit time - a key metric to assess climate change mitigation potential. Different metrics entail different conclusions regarding the most beneficial stand structure and management strategy. Even-aged stand management strategies provide more long-lasting wood products than the mixed-aged stand, and the same amount of short-lasting and long-lasting wood products combined. Furthermore, they have substantially better net C balance afters an 80-years rotation. However, it takes them about 40 years to regain the C lost at initial clear cut. Considering also the transit time of C, the even-aged strategies need almost the entire rotation to offset early clear-cut related C losses. While C sequestration assessed by the net C balance evaluates even-aged strategies as beneficial, a trade-off emerges between considering long-lasting wood products and climate change mitigation potential when taking the C transit time into account.

These results show the importance of considering the transit time in the assessment of forest management strategies and highlight that clear-cut based, even-aged management strategies on stand level undermine climate goals on regional and global scale.

How to cite: Metzler, H., Launiainen, S., and Vico, G.: A novel mechanistic boreal forest model with dynamical carbon allocation to quantify climate mitigation potential of management scenarios, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11113, https://doi.org/10.5194/egusphere-egu23-11113, 2023.

Posters on site: Wed, 26 Apr, 16:15–18:00 | Hall A

Chairpersons: Michael Bahn, Henrik Hartmann
A.244
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EGU23-8562
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BG3.2
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ECS
Mukund Palat Rao, Arturo Pacheco-Solana, Kevin Griffin, Johanna Elizabeth Jensen, Neil Pederson, Bar Oryan, Troy Nixon, Milagros Rocio Rodriguez Caton, Laia Andreu Hayles, Jeremy Hise, Josep Peñuelas, and Troy Magney

The ‘growing season’ of trees is often assumed to be coupled with climatology (e.g., summer vs winter) and visual canopy phenology cues (e.g., leaf emergence in spring and senescence in autumn). However, green leaves are not always photosynthetically active and actual tree radial growth via cambial cell division is ‘invisible’ since it is hard to see and occurs at micrometer resolution. Therefore, despite the presence of apparently green vegetation, trees may not be assimilating carbon or growing. Here, we study photosynthesis and tree-growth at near-instantaneous timescales using in-situ and satellite remote sensing, point dendrometers, quantitative wood anatomy, and Pulse Amplitude Modulated chlorophyll fluorescence. Tree and leaf-level measurements are being made on eight oak (Quercus spp.) trees in a temperate forest in southern New York, USA. We find that oak trees commence radial growth in the first week of April approximately one-month prior to canopy development that is not completed until the first week of May. Additionally, the development of foliar photosynthetic capacity lags leaf expansion by nearly two weeks. Further, we find that oak growth for the season is completed by late July while photosynthetic activity is maintained for three additional months until early November. Finally, we examine the growth climate sensitivity across a network of 16 oak tree-ring width chronologies distributed across the northeastern US. These relationships suggest that oak earlywood growth relies on carbon assimilated in prior year autumn while oak latewood relies on current year assimilated carbon. Therefore, photosynthesis and tree-growth in Northeastern US oaks occurs asynchronously, since trees don’t reach peak photosynthetic performance the moment leaves emerge or grow through the ‘growing season’.

How to cite: Rao, M. P., Pacheco-Solana, A., Griffin, K., Jensen, J. E., Pederson, N., Oryan, B., Nixon, T., Rodriguez Caton, M. R., Andreu Hayles, L., Hise, J., Peñuelas, J., and Magney, T.: Temporal decoupling between carbon assimilation and tree growth in temperate oaks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8562, https://doi.org/10.5194/egusphere-egu23-8562, 2023.

A.245
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EGU23-4386
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BG3.2
Simon M. Landhäusser, Coral Fermaniuk, Killian G. Fleurial, and Erin Wiley

Assimilated non-structural carbohydrates (NSC) can be stored as reserves in plants and remobilized during periods of asynchrony between carbon acquisition and carbon demand to fuel essential metabolic functions and growth. However, the framework of NSC allocation to reserves and their remobilization remains unclear, especially for mature trees which potentially can store large quantities of reserves. Here, we explore the role of stem reserves and potential constraints in their remobilization in large Betula papyrifera trees. To explore reserve remobilizations between organs, we use different patterns of phloem girdling to induce carbon stress and to isolate crown, stem, and root NSC storage pools.  Our results suggest that NSC reserves in the stem tissues may not be easily remobilized to other, more distant, organ sinks. However, we also found that some root reserves may be allocated toward the lowermost stem/root collar position, indicating that under carbon limiting conditions the roots might not be the strongest sink for NSC reserves. We suggest this response represents an adaptive recovery strategy for a collar-sprouting species like B. papyrifera, which occupies areas prone to aboveground disturbance. We also found that storage capacity of tissues (here stem wood and crown) can far exceed the concentrations that are normally stored in these trees.  Additionally, we found stem NSC concentrations positively correlated with disease resistance and branch water content.  These relationships suggest that a maintenance of greater stem reserves may be required to support other important roles directly or indirectly, such as defense or spring leaf flush, respectively.  Overall, it appears that the remobilization of different organ reserve storage pools is regulated somewhat autonomously, which, particularly under carbon limiting conditions, could potentially limit the sharing of reserves within a large tree.

How to cite: Landhäusser, S. M., Fermaniuk, C., Fleurial, K. G., and Wiley, E.: The role of the bole: constraints in the remobilization of stem reserves under experimental carbon limitation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4386, https://doi.org/10.5194/egusphere-egu23-4386, 2023.

A.246
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EGU23-7551
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BG3.2
Erin Wiley, Ashley Hart, and Simon Landhäusser

Woody plants rely on the remobilization of carbon (C) and nitrogen (N) reserves to support growth and survival when resource demand exceeds supply at seasonally predictable times like spring leaf flush and following unpredictable disturbances like defoliation. Despite their importance, we still have a poor understanding of how reserve remobilization is regulated and whether remobilization and the allocation of mobilized reserves is constrained by distance between source and sink tissues. This leads to uncertainty in which reserves—and how much—are actually available to support plant functions like leaf growth during spring flush or following defoliation. To better understand the source of remobilized reserves and constraints on their allocation, we used stable isotopes (13C,15N) to label C and N reserve pools in aspen (Populus tremuloides Michx.) saplings, and then grafted unlabeled and labelled stems to labelled and unlabeled root stocks, to create organ-specific labelled reserves.  We then tested for differences in reliance on reserves from different organs between 1) upper and lower leaves 2) early and late leaves and 3) early flush and reflush leaves produced after defoliation.  During spring flush, both C and N reserves were preferentially allocated to sinks nearer the reserve source (i.e the roots), but reliance on C reserves was reduced over time.  Additionally, N appeared to be preferentially remobilized from sources closer to the developing leaves.  However, following defoliation, we found that reflush leaves imported the same proportion of N from the roots as spring flush leaves, but that a lower proportion of C was imported from root reserves. The lower import of reserve C suggests reflush leaves must rely more on their own photosynthetic gains to fuel leaf growth, which may explain the reduced total leaf mass of reflush canopies (31% of initial mass).  The reduced import of reserves occurred even though roots retained significant starch reserves (~5% dry wt), suggesting aspen prioritizes the maintenance of root C reserves at the expense of fast canopy recovery.

How to cite: Wiley, E., Hart, A., and Landhäusser, S.: Tracing the origin of imported carbon and nitrogen reserves: remobilization during spring leaf expansion and recovery following defoliation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7551, https://doi.org/10.5194/egusphere-egu23-7551, 2023.

A.247
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EGU23-13892
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BG3.2
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ECS
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Highlight
Jianbei Huang, Nemiah Ladd, Laura Meredith, Christiane Werner, and Marco Lehmann and the the coauthors

Nonstructural carbohydrates (NSCs) play a crucial role in plant functioning and survival. Nonetheless, substantial knowledge gaps remain regarding NSC mobilization and transport in forests experiencing more frequent extreme droughts. We combined drought manipulation and 13CO2 pulse-labeling in an enclosed rainforest, and assessed changes in tissue NSC content and allocation of recent photosynthates in eight species that represent ecosystem biomass and cover different positions and hydraulic strategies. Drought reduced starch in leaves but not in stem phloem and roots across species. However, soluble sugars remained constant or increased in understory plants and anisohydric trees, and decreased only in leaves of isohydric trees with relatively constant leaf water potential and sap flow. Drought slowed export and transport of recent photosynthates, not only for anisohydric species with a strong decrease in leaf water potential and sap flow but also for isohydric species with a strong decrease in photosynthetic supply and carbohydrate levels.  We provide evidence that tropical plants under drought mobilize starch to buffer carbon deficiency, while regulating local utilization, export and transport of soluble sugars depending on position and isohydricity. We highlight the importance of plant functional types for understanding NSC dynamics and their role in determining forest carbon balance under drought. 

How to cite: Huang, J., Ladd, N., Meredith, L., Werner, C., and Lehmann, M. and the the coauthors: Plant water use strategies drive the fate of newly fixed carbon in an experimental rainforest under drought, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13892, https://doi.org/10.5194/egusphere-egu23-13892, 2023.

A.248
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EGU23-6985
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BG3.2
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ECS
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Ruth Adamczewski, Qiong Liu, Johanna Pausch, and Mohsen Zarebanadkouki

Modeling and quantification of carbon (C) allocation through the soil-plant-atmosphere continuum (SPAC) has received increasing attention in recent years. Although advanced imaging and numerical methods have boosted our knowledge, we still lack an experimental and mechanistic understanding of C flux and its partitioning across the SPAC. Here we combined a 13C pulse labeling technique with modeling of C transport across the SPAC to describe the flow of newly assimilated C from shoots to roots, to soils and then respired back to the atmosphere. To do so, different plants - maize (Zea mays L.), soybean (Glycine max (L.) merr. cv. sohae), and wheat (Triticum aestivum L.) - were exposed to a 13CO2 pulse for 2 hoursduring daytime. A CO2 Isotope Analyzer (CCIA-38d-EP, Los Gatos Research) was used to continuously monitor 13CO2 flux from the soils. Subsequently, after harvest the respective 13C contents of shoot and root biomass and of the soil was quantified.

To model the C fluxes, we developed a simple multi-compartment domain, representing the SPAC. The SPAC was envisioned as four interconnected horizontal compartments namely atmosphere, shoots, roots, and soil compartment. The shoots and roots compartment were further simplified in three vertical compartments (phloem, storage, and structural pool). The C transport between these pools was represented by constant rates. These rates were inversely estimated by adjusting the model parameters to best reproduce the measured C flux and C contents in the various compartments.   

Our model described the allocation and transport of 13C within the shoots, roots, and soil well. The best-fitted coefficients of the model were reproducible among different replications of the same plant species. We also checked the sensitivity of our model to its parameters and observed a good sensitivity to most of the model parameters. In particular, our model was very sensitive to C loading and unloading in the phloem and also root exudation rates. The results of our study show that the combination of tracing 13C and modeling of 13C transport across SPAC is a promising tool to study C flux and its partitioning across SPAC.

How to cite: Adamczewski, R., Liu, Q., Pausch, J., and Zarebanadkouki, M.: Modeling the partitioning of assimilated C along the soil-plant-atmosphere continuum based on a 13C labeling experiment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6985, https://doi.org/10.5194/egusphere-egu23-6985, 2023.

A.249
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EGU23-5105
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BG3.2
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ECS
Baptiste Hulin and Samuel Abiven

Plants allocate carbon to roots, shoots, respiration and rhizodeposition. The quantitative partitioning depends on genetic and environmental factors, as well as on the plant’s phenology. The first two or three pools represent most of the carbon input to the soil, depending on the ecosystem considered. Quantifying this partitioning is of major importance as roots, shoots, and rhizodeposition are constituted of several organic compounds differing in residence time. Moreover, besides being carbon inputs, these compounds modify in different ways their surroundings and might slow down or accelerate the cycling of carbon and nutrients.

One frequently used method to quantify this partitioning is the 13C labelling of atmospheric CO2, which allows to trace organic carbon in the soil-plant system. 13C labelling of CO2 can be either continuous, or as single or multiple pulses. It can be combined with gas measurements that estimate the priming effect induced by the plant inputs. This poster aims at synthesizing the literature about experimental quantification of carbon allocation to different plant pools, and comparing the methods used. It allows to identify the plant traits that predict this allocation. Moreover, we show the preliminary results of a continuous 13C labelling experiment that compares plant traits with carbon content variations in soil columns.

Whereas shoots and roots are relatively simple to quantify, rhizodeposition is not. It therefore represents a major incertitude when considering the carbon inputs to soil. Moreover, labile exudates represent an important part of rhizodeposition that induce an increase of older soil carbon mineralisation. Several experiments show that the loss of carbon induced by rhizodeposition priming effect is bigger than the input. These results are often associated to plants with high photosynthetic activity.

A trade-off is to be found when considering 13C labelling. Continuous labelling allows a quantification of net rhizodeposition which is independent of the phenology and that integrates the whole plant growth. On the other side, pulse labelling is easier and less expensive. Regarding priming effect quantification, gas flux measurements are precise but do not integrate the whole plant growth. Mass quantification through carbon content change do, but it requires very accurate estimations of these changes.

How to cite: Hulin, B. and Abiven, S.: Implication of carbon allocation in plants for soil organic matter cycling., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5105, https://doi.org/10.5194/egusphere-egu23-5105, 2023.

A.250
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EGU23-6348
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BG3.2
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Richard Nair, Martin Strube, Marion Schrumpf, and Mirco Migliavacca

Roots are difficult to measure at high temporal resolution but are important as belowground sinks and sources of CO2. Even in an age of automated and remote estimation of many ecosystem properties, belowground plant biomass is opaque at all but the coarsest timescales. Further, root dynamics are not fully predictable from aerial biomass change. Many uncertainties in predicting whole ecosystem function derive from this lack of data belowground.

Using automated minirhizotrons, we captured images of root dynamics four times a day from February to October in a permanent temperate grassland in Germany. We processed all images collected using a trained neural network model and image analysis scripts to extract morphological traits from segmented images. We found root growth occurring continuously, even at sub-zero aboveground air temperatures. As a whole population, most of the root growth was in spring, although turnover and replacement happened at all times. Root length density and extractable root surface area increased through spring but decreased through a dry summer into autumn. Mean rooting depth increased until summer but did not decrease during the study period. Mean root diameter only increased once the dry period began.

We also examined the patterns of growth between day and night. Early in the year roots grew in both day and night time periods, but after initial rapid biomass growth, root growth was at night. We examine the  reasons for this switch relating to source and sink control of plant growth. We also consider implications for an accurate partitioning of carbon budgets in terrestrial ecosystems.

 

How to cite: Nair, R., Strube, M., Schrumpf, M., and Migliavacca, M.: Day-night root dynamics change through the growing season, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6348, https://doi.org/10.5194/egusphere-egu23-6348, 2023.

A.251
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EGU23-5112
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BG3.2
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ECS
Andrea Cecere and Mathieu Javaux

In a context of global change, it is crucial to understand the factors and processes by which plants respond to drought and by which crops may limit the development of their aboveground biomass.

Experimental studies have showed that soil water status, soil structure and soil texture impact carbon allocation within plant and in particular the root:shoot ratio. We used a conceptual soil-plant hydraulic model to analyze the results of a meta-analysis gathering literature data of root:shoot ratio measured in controlled conditions. For each paper, information on soil water status, soil and plant traits and abiotic factors were collected. Soil hydraulic conductivity was estimated based on pedotransfer functions, when unavailable.

The results feature that the root:shoot ratio is an adaptation strategy that depends on the soil conductance in order to balance the water availability with the transpiration demand. The partitioning response varies between plant types. This study gives an explanation to current observations and shows the necessity to collect accurate soil measurements and information for further experiments.  

How to cite: Cecere, A. and Javaux, M.: Experimental investigation of the relationship between root:shoot ratio and soil-plant hydraulics., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5112, https://doi.org/10.5194/egusphere-egu23-5112, 2023.

A.252
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EGU23-1764
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BG3.2
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ECS
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Huiying Xu, Han Wang, I. Colin Prentice, Sandy P. Harrison, Lucy Rowland, Maurizio Mencuccini, Pablo Sanchez-Martinez, Pengcheng He, Ian J. Wright, Stephen Sitch, and Qing Ye

The sapwood area supporting a given leaf area (vH) reflects a coordinated coupling between carbon uptake, water transport and loss at a whole plant level. Worldwide variation in vH reflects diverse plants strategies adapt to prevailing environments, and impact the evolution of global carbon and water cycles. Why such a variation has not been convincingly explained yet, thus hinder its representation in Earth System Models. Here we hypothese that optimal vH tends to mediate between sapwood conductance and climates so that leaf water loss matches both sapwood hydraulics and leaf photosynthesis. By compiling and testing against two extensive datasets, we show that our hypothesis explains nearly 60% of vH variation responding to light, vapor pressure deficit, temperature, and sapwood conductance in a quantitively predictable manner. Sapwood conductance or warming-enhanced hydraulic efficiency reduces the demand on sapwood area for a given total leaf area and, whereas brightening and air dryness enhance photosynthetic capacities consequently increasing the demand. This knowledge can enrich Earth System Models where carbon allocation and water hydraulics play key roles in predicting future climate-carbon feedback.

How to cite: Xu, H., Wang, H., Prentice, I. C., Harrison, S. P., Rowland, L., Mencuccini, M., Sanchez-Martinez, P., He, P., Wright, I. J., Sitch, S., and Ye, Q.: Global variation in the ratio of sapwood to leaf area explained by optimality principles, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1764, https://doi.org/10.5194/egusphere-egu23-1764, 2023.

A.253
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EGU23-8387
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BG3.2
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ECS
Nora Linscheid, Miguel D. Mahecha, Anja Rammig, Ana Bastos, Jacob A. Nelson, and Markus Reichstein

 

Vegetation carbon uptake is a major sink for anthropogenic greenhouse gas emissions, yet inferring longer-term behaviour of ecosystems as carbon sinks or sources is still difficult. Here, using a time series decomposition technique and eddy covariance data, we show that while at subseasonal scales net ecosystem CO2 uptake (NEP) is closely related to photosynthetic uptake, there is an increased importance of ecosystem respiration for determining NEP on longer time scales. 

 

The interannual evolution of net ecosystem CO2 uptake (NEP) is insufficiently understood and often not well captured in state-of-the-art vegetation models and data products. This lack of understanding may in part be due to different drivers between interannual and seasonal scales affecting the two terms balancing NEP - photosynthetic uptake of CO2 (GPP) and ecosystem respiration (Reco).

Here, we extract timescale specific carbon flux dynamics at 20 long-running FLUXNET eddy covariance sites (>13 years) using time series decomposition to relate variability in GPP and Reco to NEP at subseasonal to interannual timescales. The results indicate that relations between NEP and GPP or Reco, respectively, are not constant across different timescales, but that GPP and Reco exert differential control on NEP between sub-seasonal, seasonal, and longer timescales.

  • Overall, the fraction of variance in NEP explained by GPP variance is decreased at longer timescales, while the fraction of NEP variance explained by Reco variance and by the covariance of GPP and Reco generally increases at longer timescales.

  • Regarding GPP, we find that the slopes between NEP and GPP, which could be interpreted as scale specific apparent carbon use efficiencies (NEP/GPP) are highest and most consistent at subseasonal scales, while generally smaller in magnitude and less constrained at interannual scales. This indicates that GPP and NEP are generally more strongly and directly linked at the subseasonalscale.

  • Regarding Reco, we find a positive relationship between NEP and Reco at the seasonal scale. This is counterintuitive given NEP = GPP – Reco, but similar to spatial relations in other studies and likely related to GPP seasonality as a common driver. In contrast, the subseasonal and interannual NEP-Reco relations are mostly negative, as would be expected since higher respiratory loss would generally indicate lower ecosystem carbon retention, i.e. lower NEP. 

The timescale specific relations extracted here based on direct ecosystem CO2 exchange measurements suggest an increased importance of ecosystem respiration for long-term carbon source or sink behavior for some ecosystems. These results give insight into ecosystem functioning, as well as demonstrate the utility of time series decomposition as a diagnostic of ecosystem dynamics at different timescales. Such information may eventually serve as a basis to infer turnover times of ecosystem carbon pools and better characterize interannual ecosystem carbon dynamics.

 

How to cite: Linscheid, N., Mahecha, M. D., Rammig, A., Bastos, A., Nelson, J. A., and Reichstein, M.: Increasing importance of ecosystem respiration for ecosystem carbon exchange dynamics from weekly to interannual timescales, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8387, https://doi.org/10.5194/egusphere-egu23-8387, 2023.

A.254
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EGU23-13662
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BG3.2
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ECS
Giulia De Luca, Marianna Papp, Szilvia Fóti, Krisztina Pintér, Ádám Mészáros, Zoltán Nagy, and János Balogh

Soil respiration is a highly complex process including a wide range of soil biota (autotrophic and heterotrophic functioning) and different pathways of carbon cycling (decomposition, arbon allocation), all being under the control of environmental and biotic drivers. The most important biotic driver is the photosynthetic activity of the vegetation providing supply mainly for the autotrophic component of soil respiration: plant roots and their symbiotic partners - such as arbuscular mycorrhizal fungi (AMF). By acting as a source of CO2 and a pathway of carbon to the SOM, the role of AMF in carbon balance is unquestionable, not to mention that mycorrhizal C allocation could determine the long-term C storage potential of an ecosystem.

The objective of this study was to describe the time-lagged relationship between gross primary production (GPP) and the mycorrhizal soil respiration component, so to determine the amount of carbon derived from GPP appearing as mycorrhizal mycelial respiration. Measurements of CO2 efflux were conducted in three different treatments – i) undisturbed, root and AMF-included (Rs), ii) root-excluded (Rbasal + myc) and iii) root- and AMF-excluded (Rbasal) plots – for three consecutive years in a Central-Hungarian dry sandy grassland between July 2011 and May 2014. GPP data were derived from eddy-covariance (EC) measurements, while an automated soil respiration system (SRS) consisting of ten chambers was used for continuous and long-term measurement of soil CO2 efflux. We analysed the relationship between mycorrhizal mycelial respiration and GPP by using cross-correlation and GAMs (generalized additive models). Besides, we used sine wave models to describe the diel pattern of basal and mycorrhizal fungi respiration in the soil together with the diel patterns of soil temperature and GPP.

Considering the whole dataset correlation between GPP and mycorrhizal fungi respiration was highest at 13.5 hours time lag, while the average difference between peak timing of mycorrhizal fungi respiration and peak timing of GPP was 15 hours. However, the time lag and the peak timing difference varied from 10-24 hours. According to the results, carbon allocation to mycorrhizal fungi is a fast process in dry grasslands and the main driver of this respiration component is the GPP.

How to cite: De Luca, G., Papp, M., Fóti, S., Pintér, K., Mészáros, Á., Nagy, Z., and Balogh, J.: Dynamics of mycorrhizal respiration in relation to GPP in a Central-Hungarian dry grassland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13662, https://doi.org/10.5194/egusphere-egu23-13662, 2023.

A.255
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EGU23-12082
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BG3.2
János Balogh, Szilvia Fóti, Giulia de Luca, Ádám Mészáros, Krisztina Pintér, and Zoltán Nagy

Soil respiration of grasslands is highly variable both in time and space reflecting the topographic characteristics, the changing environmental constrains and biological activity of the vegetation. The aim of this study was to describe the effect of gross primary productivity (GPP) and soil organic carbon content (SOC) on soil respiration under varying environmental conditions in a dry grassland site in Hungary. We made spatially explicit measurements of variables including soil respiration, aboveground biomass, green vegetation index, soil water content, and soil temperature during an 8-year study in the vegetation periods. Sampling was conducted 23 times in 80 x 60 m grids of 10 m resolution with 78 sampling points. Altitude, slope, and soil organic carbon were used as background factors at each sampling position. Site-level GPP data were derived from eddy-covariance measurements and used for the estimation of GPP at every sampling position as a weighted metric on the basis of the biomass and green vegetation index of the positions. Data were analyzed using generalized additive models (GAM). Spatially, soil respiration had negative correlation with soil temperature, altitude and slope, while it was positively correlated with soil water content, aboveground biomass, green vegetation index and SOC. Soil respiration was significantly different between SOC groups (low-medium-high carbon content), mean soil respiration increased with soil carbon content. According to the GAM analysis, the shape of the GPP response was almost linear in each SOC groups and GPP had a strong influence on soil respiration in all of the groups besides temperature and soil water content. The results suggest that GPP and the resulting belowground carbon allocation affecting mainly the autotrophic components of soil respiration have similar influence on soil respiration as the main environmental variables.

How to cite: Balogh, J., Fóti, S., de Luca, G., Mészáros, Á., Pintér, K., and Nagy, Z.: Influence of gross primary productivity and soil carbon content on soil CO2 efflux in dry grasslands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12082, https://doi.org/10.5194/egusphere-egu23-12082, 2023.

A.256
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EGU23-11020
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BG3.2
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ECS
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Torben Oliver Callesen, Leonardo Montagnani, Carina Verónica Gonzales, Flávio Bastos Campos, Massimo Tagliavini, and Damiano Zanotelli

Vineyards have the potential to act as potential carbon sinks due to various characteristics such as low soil disturbance, high biodiversity and long-term carbon reservoirs. In mountainous regions where soil stability and erosion are priorities, grassed alleys are essential to vineyard management. Cover cropping is also frequently employed to improve soil quality and provide various ecosystem services. Among them, these practices are generally considered to have a positive impact on carbon sequestration, although there is still debate over the extent of this. Disentangling the carbon fluxes of grapevines and resident herbaceous vegetation as well as the in-plant allocation is essential for understanding the effects of management decisions and environmental conditions on the fate of sequestered carbon.

To this end, we conducted continuous carbon flux measurements over the growing season of 2021 (15 April – 15 November) using an eddy covariance tower mounted in a grassed and irrigated hillside vineyard in Alto Adige, Italy. The cultivars present were Chardonnay and Sauvingon blanc on SO4 rootstock (average density: 6500 vines ha -1) and the vines were trained in a vertical shoot position manner with Guyot pruning. Eddy covariance measurements were complemented with surveys using soil respiration chambers and biometric measurements of net primary production (NPP).

Results showed that the seasonal gross primary production (GPP) of the vineyard was very high (2409 ± 35 g C m-2) relative to other studies, but was closely matched by the carbon lost as respiration (Reco; 2163 ± 88 g C m-2), of which the majority originated from the soil. The resulting carbon accumulation during the season (NEP, net ecosystem production; 246 ± 54 g C m-2) was moderate, and a large portion was accounted for by the berries exported after harvest. The grassed alleys played an important role carbon assimilation, accounting for roughly half of the above-ground vegetative growth for the season. 25% of the final carbon storage was attributed to the growth of permanent grapevine organs. Periods of summer heat in combination with relatively long absences of rain occurred, during which the NEP decreased and drought stress was observed in the grass cover but not the grapevines.

In comparison with other studies reported in literature, the patterns of observed ecosystem fluxes of our site more closely resembled managed grasslands in the area than forests or other vineyards, possibly due to the open structure of the canopy, which may differ between vineyard training systems. However, literature suggests that the biomass produced by the grasses is more easily decomposed than the grapevine leaf litter and pruning material, so although the ground cover accounts for a large portion of the carbon accumulated, we speculate that it contributes proportionally less to long-term storage by increasing soil organic carbon. Therefore, while changing climate conditions may adversely affect the short-term carbon sequestration of vineyards, they are likely to have less of an impact on long-term accumulation attributable to grapevines.

How to cite: Callesen, T. O., Montagnani, L., Gonzales, C. V., Bastos Campos, F., Tagliavini, M., and Zanotelli, D.: The relative importance of grassed alleys in C dynamics of open-canopy vineyards, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11020, https://doi.org/10.5194/egusphere-egu23-11020, 2023.

A.257
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EGU23-10322
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BG3.2
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ECS
Lydia O'Halloran

Herbaceous dominated ecosystems are found throughout the world representing a wide variety of locations that differ in their mean annual precipitation, annual temperature ranges, light availability, and soil nutrient concentrations. This is reflected in a wide range of annual above- and belowground biomass production, plant diversity and canopy density between these ecosystems worldwide. Our study aims to understand how nutrient availability and disturbance impact species relative abundance, diversity, and annual aboveground production. Here, we present background data on herbaceous dominated ecosystems found in coastal South Carolina, USA that are part of a global network (DragNet) of herbaceous dominated ecosystem study sites distributed across the world. Dominated by both grass species and forbs, we found that within a site, there is variation in the relationship between species diversity and biomass production. Aboveground biomass and accumulated litter are not correlated suggesting that the drivers for carbon assimilation and decomposition are different. This research will serve as the foundation for future research on how nutrients and soil disturbance interact with the amount of carbon assimilation and if some species show trait variation in response to these treatments in different regions of the world.

How to cite: O'Halloran, L.: Aboveground biomass production and litter accumulation in coastal grassland ecosystems: the basis of a global study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10322, https://doi.org/10.5194/egusphere-egu23-10322, 2023.

Posters virtual: Wed, 26 Apr, 16:15–18:00 | vHall BG

Chairpersons: Andrew Richardson, Mariah Carbone, Michael Bahn
vBG.2
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EGU23-13157
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BG3.2
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ECS
Return on carbon investment for plant water transport tissues: functional life span matters
(withdrawn)
Louis Krieger and Stanislaus Schymanski
vBG.3
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EGU23-3944
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BG3.2
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ECS
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Subashree Kothandaraman, Javid Dar, Somaiah Sundarapandian, and Mohammed Khan

A major global challenge is the urgent need to bend the curve of rising atmospheric carbon dioxide (CO2) concentration. Carbon (C) pools in forests play an important role in regulating the regional and global C cycles. In this study, C stocks of all the pools {live biomass (trees and non-tree vegetation), detritus (deadwood and forest floor litter), and soil} were assessed from six vegetation types {3 natural forests (tropical dry deciduous, semi-evergreen and evergreen) and 3 plantations (teak, rubber and areca nut)} in Kanyakumari Wildlife Sanctuary, Western Ghats, India. The total ecosystem C stock averaged 262.7 ± 56 Mg C ha-1 and ranged between 94.7 and 506.8 56 Mg C ha-1. Soil was the major C pool in tropical dry deciduous forest and areca nut plantation, whereas biomass was the largest pool in other vegetation types. The C stocks of teak and rubber plantations were comparable with those of dry deciduous and semi-evergreen forest types respectively. The C stocks were significantly positively correlated with stand density, basal area and mean annual precipitation, and negatively correlated with mean annual temperature. The present study would improve our understanding on C allocation patterns at ecosystem-level in different vegetation types of Western Ghats, and can be used for ecosystem restoration and forest management programmes to enhance C sequestration.

How to cite: Kothandaraman, S., Dar, J., Sundarapandian, S., and Khan, M.: Variation in ecosystem carbon allocation patterns among different vegetation types in Western Ghats, India, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3944, https://doi.org/10.5194/egusphere-egu23-3944, 2023.