The integration of element cycles: contrasting perspectives from natural and managed systems in global change research

Mapping Intimacies ◽

10.5194/egusphere-egu21-14296 ◽

2021 ◽

Author(s):

Kate Buckeridge

Keyword(s):

Global Change ◽

C Sequestration ◽

Process Models ◽

Research Groups ◽

Tight Coupling ◽

Soil C ◽

Natural Systems ◽

Global Change Research ◽

Tightly Coupled ◽

C And N

Despite the ecological connection between natural and managed systems, they are often studied separately, by different research groups. This echoes the focus of this session that, despite the tight coupling of carbon (C) and nitrogen (N), global change investigations of these element cycles may be carried out by different research groups. This talk will address the contrasting approach to integrating element cycles between researchers in natural and managed systems.Global change research in natural systems has focused on predicting the C balance of the system. Integrating research between C and other element cycles makes sense in this situation, because the growth and activity of the research organisms (animals, plants, microorganisms) are limited by other elements. This stoichiometric theory (multiple limitation hypothesis) has been investigated for at least three decades, and although C and other elements are often studied independently, many researchers in natural systems have embraced this elemental integration in their global change research.&#160;Managed systems also have a long history of element limitation research, primarily NPK, with a focus on maximising plant growth and the economy of fertiliser use efficiency. However, natural climate solutions - necessary because mandatory reductions in fossil fuel emissions are insufficient to meet climate targets &#8211; often rely on sequestering C in biomass and soils, changing the focus of managed system research to include C. As we know from our research in natural systems, the process of C sequestration is tightly coupled to N (and other elements). Unfortunately, most soil C process models or earth system models do not include N (or other elements). Very few soil C sequestration predictions include the C-cost of N2O losses - an important trade-off in N-saturated systems - primarily because there has been insufficient research into the microbial interdependency of C and N in managed soils.In this talk I will discuss recent insights into how the integration of C and N (and other elements) in the ecological research of managed systems can improve our ability to mitigate the consequences of global change.

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Manipulation of rhizosphere organisms to enhance glomalin production and C sequestration: Pitfalls and promises

Canadian Journal of Plant Science ◽

10.4141/cjps2013-146 ◽

2014 ◽

Vol 94 (6) ◽

pp. 1025-1032 ◽

Cited By ~ 11

Author(s):

F. L. Walley ◽

A. W. Gillespie ◽

Adekunbi B. Adetona ◽

J. J. Germida ◽

R. E. Farrell

Keyword(s):

Plant Growth ◽

Mycorrhizal Fungi ◽

Plant Growth Promoting Rhizobacteria ◽

C Sequestration ◽

Ionization Mass ◽

Edge Structure ◽

Organic C ◽

Soil C ◽

N Storage ◽

C And N

Walley, F. L., Gillespie, A. W., Adetona, A. B., Germida, J. J. and Farrell, R. E. 2014. Manipulation of rhizosphere organisms to enhance glomalin production and C-sequestration: Pitfalls and promises. Can. J. Plant Sci. 94: 1025–1032. Arbuscular mycorrhizal fungi (AMF) reportedly produce glomalin, a glycoprotein that has the potential to increase soil carbon (C) and nitrogen (N) storage. We hypothesized that interactions between rhizosphere microorganisms, such as plant growth-promoting rhizobacteria (PGPR), and AMF, would influence glomalin production. Our objectives were to determine the effects of AMF/PGPR interactions on plant growth and glomalin production in the rhizosphere of pea (Pisum sativum L.) with the goal of enhancing C and N storage in the rhizosphere. One component of the study focussed on the molecular characterization of glomalin and glomalin-related soil protein (GRSP) using complementary synchrotron-based N and C X-ray absorption near-edge structure (XANES) spectroscopy, pyrolysis field ionization mass spectrometry (Py-FIMS), and proteomics techniques to characterize specific organic C and N fractions associated with glomalin production. Our research ultimately led us to conclude that the proteinaceous material extracted, and characterized in the literature, as GRSP is not exclusively of AMF origin. Our research supports the established concept that GRSP is important to soil quality, and C and N storage, irrespective of origin. However, efforts to manipulate this important soil C pool will remain compromised until we more clearly elucidate the chemical nature and origin of this resource.

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Decoupled Soil Labile Carbon and Nitrogen Dynamics Triggered by Urban Vegetation

10.21203/rs.3.rs-542253/v1 ◽

2021 ◽

Author(s):

Xiaolin Dou ◽

Meng Lu ◽

Liding Chen

Keyword(s):

Land Use ◽

Urban Forest ◽

Urban Ecosystems ◽

Isotopic Analysis ◽

C Sequestration ◽

Bare Soil ◽

N Dynamics ◽

Soil C ◽

Soil C And N ◽

C And N

Abstract Purpose Studies about soil carbon (C) and nitrogen (N) dynamics with land use change are urgently needed for urban ecosystems. We used fractionation of soils combined with stable isotopic analysis to examine soil C and N cycles after decadal forest and lawn planting in the Pearl River Delta, China. Methods Soil samples from bare soil (CK) and four land use treatments (55 and 20 years of forest plantation, F-55 and F-20; 55 and 20 years of lawn plantation, L-55 and L-20) were split into different chemical fractions. Then we analyzed the C and N contents, C/N ratio, δ13C and δ15N, C and N recalcitrant indices (RIC, RIN), and a C pool management index (CPMI).Results Forest vegetation substantially enhanced soil organic carbon (SOC) caused by the recalcitrant (RC) and labile C (LC) pools, while the larger soil organic nitrogen (SON) was ascribed to the increased recalcitrant N (RN). Enhanced LC but minor changes in labile N (LN) suggested a decoupled C and N in labile fractions of the forest soils. In contrast, the larger LN, and the enhanced decomposition of SOC, indicated that the lawns may have inhibited N mineralization of labile pools, also suggesting a decoupled C and N turnover and leading to low RIN values. Conclusions Urban forest and lawn plantations significantly changed the soil C and N dynamics, and emphasized the inconsistency between C and N processes, especially in labile pools, which would eventually lead to minor changes in N and limit the ecosystem C sequestration.

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Management effects on the dynamics and storage rates of organic matter in long-term crop rotations

Canadian Journal of Soil Science ◽

10.4141/s03-022 ◽

2004 ◽

Vol 84 (1) ◽

pp. 49-61 ◽

Cited By ~ 16

Author(s):

E. A. Paul ◽

H. P. Collins ◽

K. Paustian ◽

E. T. Elliott ◽

S. Frey ◽

...

Keyword(s):

Organic Matter ◽

C Sequestration ◽

Organic C ◽

Soil C ◽

Site Analysis ◽

Laboratory Incubation ◽

C And N ◽

A Site ◽

Management Effects

Factors controlling soil organic matter (SOM) dynamics in soil C sequestration and N fertility were determined from multi-site analysis of long-term, crop rotation experiments in Western Canada. Analyses included bulk density, organic and inorganic C and N, particulate organic C (POM-C) and N (POM -N), and CO2-C evolved during laboratory incubation. The POM-C and POM-N contents varied with soil type. Differences in POM-C contents between treatments at a site (δPOM-C) were related (r2= 0.68) to treatment differences in soil C (δSOC). The CO2-C, evolved during laboratory incubation, was the most sensitive indicator of management effects. The Gray Luvisol (Breton, AB) cultivated plots had a fivefold difference in CO2-C release relative to a twofold difference in soil organic carbon (SOC). Soils from cropped, Black Chernozems (Melfort and Indian Head, SK) and Dark Brown Chernozems (Lethbridge, AB) released 50 to 60% as much CO2-C as grassland soils. Differences in CO2 evolution from the treatment with the lowest SOM on a site and that of other treatments (δCO2-C) in the early stages of the incubation were correlated to δPOM-C and this pool reflects short-term SOC storage. Management for soil fertility, such as N release, may differ from management for C sequestration. Key words: Multi-site analysis, soil management, soil C and N, POM-C and N, CO2 evolution

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Soil aggregation according to the dynamics of carbon and nitrogen in soil under different cropping systems

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x2016000900065 ◽

2016 ◽

Vol 51 (9) ◽

pp. 1652-1659 ◽

Cited By ~ 2

Author(s):

Getulio de Freitas Seben Junior ◽

José Eduardo Corá ◽

Rattan Lal

Keyword(s):

Cropping Systems ◽

C Sequestration ◽

Pigeon Pea ◽

Soil Aggregation ◽

Total N ◽

Soil C ◽

Carbon And Nitrogen ◽

Physical Fractionation ◽

C Stock ◽

C And N

Abstract The objective of this work was to evaluate total soil carbon and nitrogen, as well as their contents in particulate and mineral-associated C fractions; to determine C stock and sequestration rates in the soil; and to verify the effect of C and N contents on soil aggregation, using different crop rotations and crop sequences under no-tillage. The study was carried out for nine years in a clayey Oxisol. The treatments consisted of different cropping systems formed by the combination of three summer crops (cropped until March) - corn (Zea mays) monocropping, soybean (Glycine max) monocropping, and soybean/corn rotation - and seven second crops (crop successions). Soil samples were taken at the 0.00-0.10-m layer for physical fractionation of C and N, and to determine soil aggregation by the wet method. Soybean monocropping increased C and N in particulate C fraction, while the crop systems with corn monocropping x pigeon pea (Cajanus cajan), corn monocropping x sun hemp (Crotalaria juncea), and soybean monocropping x corn as a crop succession increased total C in the soil. Greater rates of soil C sequestration were observed with soybean/corn rotation and with soybean monocropping, as well as with sun hemp as a second crop. The increase in total N increases soil C stock. Soil aggregation was most affected at particulate C fraction. Increases in soil N promote C addition to particulate fraction and enhance soil aggregation.

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Total belowground carbon and nitrogen partitioning of mature black spruce displaying genetic × soil moisture interaction in growth

Canadian Journal of Forest Research ◽

10.1139/x2012-145 ◽

2012 ◽

Vol 42 (11) ◽

pp. 1939-1952 ◽

Cited By ~ 10

Author(s):

John E. Major ◽

Kurt H. Johnsen ◽

Debby C. Barsi ◽

Moira Campbell

Keyword(s):

Fine Roots ◽

Root Biomass ◽

Black Spruce ◽

Soil Depth ◽

C Sequestration ◽

Nitrogen Partitioning ◽

Coarse Roots ◽

Soil C ◽

Coarse Root ◽

C And N

Total belowground biomass, soil C, and N mass were measured in plots of 32-year-old black spruce ( Picea mariana (Mill.) Britton, Sterns & Poggenb.) from four full-sib families studied previously for drought tolerance and differential productivity on a dry and a wet site. Stump root biomass was greater on the wet than on the dry site; however, combined fine and coarse root biomass was greater on the dry than on the wet site, resulting in no site root biomass differences. There were no site differences in root distribution by soil depth. Drought-tolerant families had greater stump root biomass and allocated relatively less to combined coarse and fine roots than drought-intolerant families. Fine roots (<2 mm) made up 10.9% and 50.2% of the belowground C and N biomass. Through 50 cm soil depth, mean total belowground C mass was 187.2 Mg·ha–1, of which 8.9%, 3.4%, 0.7%, and 87.0% were from the stump root, combined fine and coarse roots, necromass, and soil, respectively. Here, we show that belowground C sequestration generally mirrors (mostly from stump roots) aboveground growth, and thus, trends in genetic and genetic × environment productivity effects result in similar effects on belowground C sequestration. Thus, tree improvement may well be an important avenue to help stem increases in atmospheric CO2.

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Reflecting on the Anthropocene: The Call for Deeper Transformations

AMBIO ◽

10.1007/s13280-020-01468-9 ◽

2021 ◽

Author(s):

Karen O’Brien

Keyword(s):

Global Change ◽

Environmental Change ◽

Meaning Making ◽

Global Environmental Change ◽

50Th Anniversary ◽

Human Environment ◽

Cultural Narrative ◽

Natural Systems ◽

Global Change Research ◽

Anniversary Issue

AbstractResearch on global environmental change has transformed the way that we think about human-environment relationships and Earth system processes. The four Ambio articles highlighted in this 50th Anniversary Issue have influenced the cultural narrative on environmental change, highlighting concepts such as “resilience,” “coupled human and natural systems”, and the “Anthropocene.” In this peer response, I argue that global change research is still paying insufficient attention to how to deliberately transform systems and cultures to avoid the risks that science itself has warned us about. In particular, global change research has failed to adequately integrate the subjective realm of meaning making into both understanding and action. Although this has been an implicit subtext in global change research, it is time to fully integrate research from the social sciences and environmental humanities.

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Implications of carbon saturation model structures for simulated nitrogen mineralization dynamics

Biogeosciences ◽

10.5194/bg-11-6725-2014 ◽

2014 ◽

Vol 11 (23) ◽

pp. 6725-6738 ◽

Cited By ~ 12

Author(s):

C. M. White ◽

A. R. Kemanian ◽

J. P. Kaye

Keyword(s):

Soil Texture ◽

N Mineralization ◽

Plant Residues ◽

Short Term ◽

Organic C ◽

Soil C ◽

Biogeochemical Models ◽

Tightly Coupled ◽

C And N ◽

Model Structures

Abstract. Carbon (C) saturation theory suggests that soils have a limited capacity to stabilize organic C and that this capacity may be regulated by intrinsic soil properties such as clay concentration and mineralogy. While C saturation theory has advanced our ability to predict soil C stabilization, few biogeochemical ecosystem models have incorporated C saturation mechanisms. In biogeochemical models, C and nitrogen (N) cycling are tightly coupled, with C decomposition and respiration driving N mineralization. Thus, changing model structures from non-saturation to C saturation dynamics can change simulated N dynamics. In this study, we used C saturation models from the literature and of our own design to compare how different methods of modeling C saturation affected simulated N mineralization dynamics. Specifically, we tested (i) how modeling C saturation by regulating either the transfer efficiency (ε, g C retained g−1 C respired) or transfer rate (k) of C to stabilized pools affected N mineralization dynamics, (ii) how inclusion of an explicit microbial pool through which C and N must pass affected N mineralization dynamics, and (iii) whether using ε to implement C saturation in a model results in soil texture controls on N mineralization that are similar to those currently included in widely used non-saturating C and N models. Models were parameterized so that they rendered the same C balance. We found that when C saturation is modeled using ε, the critical C : N ratio for N mineralization from decomposing plant residues (rcr) increases as C saturation of a soil increases. When C saturation is modeled using k, however, rcr is not affected by the C saturation of a soil. Inclusion of an explicit microbial pool in the model structure was necessary to capture short-term N immobilization–mineralization turnover dynamics during decomposition of low N residues. Finally, modeling C saturation by regulating ε led to similar soil texture controls on N mineralization as a widely used non-saturating model, suggesting that C saturation may be a fundamental mechanism that can explain N mineralization patterns across soil texture gradients. These findings indicate that a coupled C and N model that includes saturation can (1) represent short-term N mineralization by including a microbial pool and (2) express the effects of texture on N turnover as an emergent property.

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Role of root inputs from a dinitrogen-fixing tree in soil carbon and nitrogen sequestration in a tropical agroforestry system

Soil Research ◽

10.1071/sr04167 ◽

2005 ◽

Vol 43 (5) ◽

pp. 667 ◽

Cited By ~ 18

Author(s):

Jorge Sierra ◽

Pekka Nygren

Keyword(s):

Root Biomass ◽

Nutrient Recycling ◽

Soil Layer ◽

C Sequestration ◽

Agroforestry System ◽

Tree Roots ◽

Organic C ◽

Soil C ◽

C And N ◽

Soil C Sequestration

Agroforestry is often mentioned as a suitable technology for land rehabilitation in the tropics and for mitigation of climate change because this land-use favours nutrient recycling and C sequestration. The aim of this work was to estimate soil C sequestration in a 12-year-old tropical silvopastoral system composed of a legume tree (Gliricidia sepium) and a C4 fodder grass (Dichanthium aristatum), and to link it with tree root biomass and N status in the soil. The site was under cut-and-carry management, i.e. tree pruning residues and cut grass were removed from the field and fed to stabled animals elsewhere. Thus, main sources for tree C and N inputs were root activity and turnover. Organic C derived from the trees and tree root biomass were determined based on natural 13C abundance. For the 0–0.2 m soil layer, the biomass of tree roots ≤2 mm diameter was 2.4 Mg/ha when the trees were pruned every 6 months (SS6), and 0.6 Mg/ha when pruned every 2 months (SS2). Both C (R2 = 0.39, P < 0.05) and N (R2 = 0.82, P < 0.05) sequestration were correlated with tree root biomass. The trees and grass contributed 18 and 8 Mg C/ha to soil, respectively, over the 12-year experiment in SS6. The net increase of 2.5 Mg N/ha in soil, originating from the trees, contributed to the net soil C sequestration. In SS2, trees contributed 16 Mg C/ha to soil over 12 years, but grass-derived C was reduced by 2 Mg C/ha because of the small amount of grass litter. The increase of 1.7 Mg N/ha in soil, derived from the trees, was not large enough to avoid C loss in this plot. Differences in soil C and N sequestration between plots were due to differences in system management, which affected the amount and the C/N ratio of inputs and outputs.

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