scholarly journals Carbon input control over soil organic matter dynamics in a temperate grassland exposed to elevated CO<sub>2</sub> and warming

2010 ◽  
Vol 7 (2) ◽  
pp. 1575-1602 ◽  
Author(s):  
Y. Carrillo ◽  
E. Pendall ◽  
F. A. Dijkstra ◽  
J. A. Morgan ◽  
J. M. Newcomb
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Elevated Co2 ◽  
Combined Effects ◽  
Organic C ◽  
Soil C ◽  
C Storage ◽  
C Pools ◽  
Labile C ◽  
Semi Arid

Abstract. Elevated CO2 generally increases soil C pools. However, greater available C concentrations can potentially stimulate soil organic matter (SOM) decomposition. The effects of climate warming on C storage can also be positive or negative. There is a high degree of uncertainty on the combined effects of climate warming and atmospheric CO2 increase on SOM dynamics and its potential feedbacks to climate change. Semi-arid systems are predicted to show strong ecosystem responses to both factors. Global change factors can have contrasting effects for different SOM pools, thus, to understand the mechanisms underlying the combined effects of multiple factors on soil C storage, effects on individual C pools and their kinetics should be evaluated. We assessed SOM dynamics by conducting long-term laboratory incubations of soils from PHACE (Prairie Heating and CO2 Enrichment experiment), an elevated CO2 and warming field experiment in semi-arid, native northern mixed grass prairie, Wyoming, USA. We measured total C mineralization and estimated the size of the labile pool and the decomposition rates of the labile and resistant SOM pools. To examine the role of plant inputs on SOM dynamics we measured aboveground biomass, root biomass, and soil dissolved organic C (DOC). Greater aboveground productivity under elevated CO2 translated into enlarged pools of readily available C (measured as total mineralized C, labile C pool and DOC). The effects of warming on the labile C only occurred in the first year of warming suggesting a transient effect of the microbial response to increased temperature. Experimental climate change affected the intrinsic decomposability of both the labile and resistant C pools. Positive relationships of the rate of decomposition of the resistant C with aboveground and belowground biomass and dissolved organic C suggested that plant inputs mediated the response by enhancing the degradability of the resistant C. Our results contribute to a growing body of literature suggesting that priming is a ubiquitous phenomenon that should be included in C cycle models.

scholarly journals Soil management effects on organic carbon in isolated fractions of a Gray Luvisol

2006 ◽  
Vol 86 (1) ◽  
pp. 141-151 ◽  
Author(s):  
A. F. Plante ◽  
C. E. Stewart ◽  
R. T. Conant ◽  
K. Paustian ◽  
J. Six
Keyword(s):  
Organic Matter ◽  
Crop Production ◽  
N Fertilization ◽  
Residue Management ◽  
Soil Organic C ◽  
Organic C ◽  
Straw Management ◽  
Soil C ◽  
C Pools

Agricultural management affects soil organic matter, which is important for sustainable crop production and as a greenhouse gas sink. Our objective was to determine how tillage, residue management and N fertilization affect organic C in unprotected, and physically, chemically and biochemically protected soil C pools. Samples from Breton, Alberta were fractionated and analysed for organic C content. As in previous reports, N fertilization had a positive effect, tillage had a minimal effect, and straw management had no effect on whole-soil organic C. Tillage and straw management did not alter organic C concentrations in the isolated C pools, while N fertilization increased C concentrations in all pools. Compared with a woodlot soil, the cultivated plots had lower total organic C, and the C was redistributed among isolated pools. The free light fraction and coarse particulate organic matter responded positively to C inputs, suggesting that much of the accumulated organic C occurred in an unprotected pool. The easily dispersed silt-sized fraction was the mineral-associated pool most responsive to changes in C inputs, whereas the microaggregate-derived silt-sized fraction best preserved C upon cultivation. These findings suggest that the silt-sized fraction is important for the long-term stabilization of organic matter through both physical occlusion in microaggregates and chemical protection by mineral association. Key words: Soil organic C, tillage, residue management, N fertilization, silt, clay

Assessing biological soil quality with chloroform fumigation-incubation: Why subtract a control?

1999 ◽  
Vol 79 (4) ◽  
pp. 521-528 ◽  
Author(s):  
A. J. Franzluebbers ◽  
R. L. Haney ◽  
F. M. Hons ◽  
D. A. Zuberer
Keyword(s):  
Organic Matter ◽  
Soil Quality ◽  
C Mineralization ◽  
Soil Organic C ◽  
Organic C ◽  
Soil C ◽  
C Pools ◽  
Substrate Induced Respiration ◽  
Chloroform Fumigation ◽  
Fumigation Extraction

Microbial biomass, as part of the active pool of soil organic matter, is critical in decomposition of organic materials, nutrient cycling, and formation of soil structure. We evaluated chloroform fumigation-incubation with subtraction of a control (CFI/F–C) and without subtraction of a control (CFI/F) as methods to assess biological soil quality. Relationships between CFI/F and potential C mineralization, particulate organic C, and soil organic C were stronger (r2 = 0.86 ± 0.07, n = 232) than those between CFI/F–C and the same soil C pools (r2 = 0.25 ± 0.09) in soils from Georgia. From published data, relationships of CFI/F with potential C mineralization and soil organic C were stronger than those of chloroform fumigation-extraction and substrate-induced respiration with these soil C pools. Effects of land management on biological soil quality using CFI/F were consistent with those determined using other soil C pools as response variables. However, land management effects on biological soil quality using CFI/F–C were either contrary to those using other soil C pools or not detectable because of greater inherent variability in CFI/F–C. Chloroform fumigation-incubation without subtraction of a control is a robust and reliable method to assess biological soil quality under a wide range of soil conditions. Key words: Active soil carbon, chloroform fumigation-extraction, microbial biomass, soil organic matter, soil quality, substrate-induced respiration

Post-thinning soil organic matter evolution and soil CO2 effluxes in temperate radiata pine plantations: impacts of moderate thinning regimes on the forest C cycle

2012 ◽  
Vol 42 (11) ◽  
pp. 1953-1964 ◽  
Author(s):  
Irene Fernandez ◽  
Juan Gabriel Álvarez-González ◽  
Beatríz Carrasco ◽  
Ana Daría Ruíz-González ◽  
Ana Cabaneiro
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Radiata Pine ◽  
Soil Samples ◽  
Mitigation Strategies ◽  
Change Scenario ◽  
Soil C ◽  
C Storage ◽  
C Cycle ◽  
C And N

Forest ecosystems can act as C sinks, thus absorbing a high percentage of atmospheric CO2. Appropriate silvicultural regimes can therefore be applied as useful tools in climate change mitigation strategies. The present study analyzed the temporal changes in the effects of thinning on soil organic matter (SOM) dynamics and on soil CO2 emissions in radiata pine ( Pinus radiata D. Don) forests. Soil C effluxes were monitored over a period of 2 years in thinned and unthinned plots. In addition, soil samples from the plots were analyzed by solid-state 13C-NMR to determine the post-thinning SOM composition and fresh soil samples were incubated under laboratory conditions to determine their biodegradability. The results indicate that the potential soil C mineralization largely depends on the proportion of alkyl-C and N-alkyl-C functional groups in the SOM and on the microbial accessibility of the recalcitrant organic pool. Soil CO2 effluxes varied widely between seasons and increased exponentially with soil heating. Thinning led to decreased soil respiration and attenuation of the seasonal fluctuations. These effects were observed for up to 20 months after thinning, although they disappeared thereafter. Thus, moderate thinning caused enduring changes to the SOM composition and appeared to have temporary effects on the C storage capacity of forest soils, which is a critical aspect under the current climatic change scenario.

Comparison of carbon and nitrogen storage in mineral soils of graminoid and shrub tundra sites, western Greenland

2016 ◽  
Vol 2 (4) ◽  
pp. 165-182 ◽  
Author(s):  
Chelsea L. Petrenko ◽  
Julia Bradley-Cook ◽  
Emily M. Lacroix ◽  
Andrew J. Friedland ◽  
Ross A. Virginia
Keyword(s):  
Vegetation Type ◽  
Mineral Soil ◽  
Biotic Interactions ◽  
The Arctic ◽  
Soil C ◽  
N Storage ◽  
C Storage ◽  
Arctic Soils ◽  
C Pools ◽  
C And N

Shrub species are expanding across the Arctic in response to climate change and biotic interactions. Changes in belowground carbon (C) and nitrogen (N) storage are of global importance because Arctic soils store approximately half of global soil C. We collected 10 (60 cm) soil cores each from graminoid- and shrub-dominated soils in western Greenland and determined soil texture, pH, C and N pools, and C:N ratios by depth for the mineral soil. To investigate the relative chemical stability of soil C between vegetation types, we employed a novel sequential extraction method for measuring organo-mineral C pools of increasing bond strength. We found that (i) mineral soil C and N storage was significantly greater under graminoids than shrubs (29.0 ± 1.8 versus 22.5 ± 3.0 kg·C·m−2 and 1.9 ± .12 versus 1.4 ± 1.9 kg·N·m−2), (ii) chemical mechanisms of C storage in the organo-mineral soil fraction did not differ between graminoid and shrub soils, and (iii) weak adsorption to mineral surfaces accounted for 40%–60% of C storage in organo-mineral fractions — a pool that is relatively sensitive to environmental disturbance. Differences in these C pools suggest that rates of C accumulation and retention differ by vegetation type, which could have implications for predicting future soil C pool storage.

Soil carbon sequestration with forest expansion in an arctic forest–tundra landscape

2004 ◽  
Vol 34 (7) ◽  
pp. 1538-1542 ◽  
Author(s):  
Heidi Steltzer
Keyword(s):  
Soil Carbon ◽  
Picea Glauca ◽  
White Spruce ◽  
Tree Age ◽  
Forest Expansion ◽  
Soil C ◽  
C Storage ◽  
C Pools ◽  
Sampling Locations

Soil carbon (C) and nitrogen (N) pools were measured under the canopy of 29 white spruce (Picea glauca (Moench) Voss) trees and in the surrounding tundra 3 and 6 m away from each tree at three sites of recent forest expansion along the Agashashok River in northwestern Alaska. The aim was to characterize the potential for forest expansion to lead to increased soil C pools across diverse tundra types. Soil C beneath the trees correlated positively with tree age, suggesting that tree establishment has led to C storage in the soils under their canopy at a rate of 18.5 ± 4.6 g C·m–2·year–1. Soil C in the surrounding tundra did not differ from those under the trees and showed no relationship to tree age. This characterization of the soil C pools at the 3-m scale strengthens the assertion that the pattern associated with the trees is an effect of the trees, because tree age cannot explain variation among tundra sampling locations at this scale. Potential mechanisms by which these white spruce trees could increase soil C pools include greater production and lower litter quality.

Soil organic carbon stocks under different páramo vegetation covers in Ecuador’s northern Andes

2021 ◽  
Author(s):  
Marlon Calispa ◽  
Raphaël van Ypersele ◽  
Benoît Pereira ◽  
Sebastián Páez-Bimos ◽  
Veerle Vanacker ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Vegetation Type ◽  
Regional Scale ◽  
Soil Samples ◽  
Related Factors ◽  
Organic C ◽  
Soil C ◽  
C Storage ◽  
Soc Stocks ◽  
Volcanic Ash Soils

&lt;p&gt;The Ecuadorian p&amp;#225;ramo, a neotropical ecosystem located in the upper Andes, acts as a constant source of high-quality water. It also stores significant amounts of C at the regional scale. In this region, volcanic ash soils sustain most of the paramo, and C storage results partly from their propensity to accumulate organic matter. Vegetation type is known to influence the balance between plant C inputs and soil C losses, ultimately affecting the soil organic C (SOC) content and stock. Tussock-forming grass (spp. Calamagrostis Intermedia; TU), cushion-like plants (spp. Azorella pedunculata; CU) and shrubs and trees (Polylepis stands) are commonly found in the p&amp;#225;ramo. Our understanding of SOC stocks and dynamics in the p&amp;#225;ramo remains limited, despite mounting concerns that human activities are increasingly affecting vegetation and potentially, the capacity of these ecosystems to store C.&lt;/p&gt;&lt;p&gt;Here, we compare the organic C content and stock in soils under tussock-forming grass (spp. Calamagrostis Intermedia; TU) and soils under cushion-like plants (spp. Azorella pedunculata; CU). The study took place at Jatunhuayco, a watershed on the western slopes of Antisana volcano in the northern Ecuadorian Andes. Two areas of similar size (~0.35 km&lt;sup&gt;2&lt;/sup&gt;) were surveyed. Fourty soil samples were collected randomly in each area to depths varying from 10 to 30 cm (A horizon) and from 30 to 75 cm (2Ab horizon). The soils are Vitric Andosols and the 2Ab horizon corresponds to a soil buried by the tephra fall from the Quilotoa eruption about 800 yr. BP. Sixteen intact soil samples were collected in Kopecky's cylinders for bulk density (BD) determination of each horizon.&lt;/p&gt;&lt;p&gt;The average SOC content in the A horizon of the CU sites (9.4&amp;#177;0.5%) is significantly higher (Mann-Whitney U test, p&lt;0.05) than that of the TU sites (8.0&amp;#177;0.4%), probably reflecting a larger input of root biomass from the cushion-forming plants. The 2Ab horizon contains less organic C (i.e. TU: 4.3&amp;#177;0.3% and CU: 4.0&amp;#177;0.4%) than the A horizon, but the SOC contents are undistinguishable between the two vegetation types. This suggests that the influence of vegetation type on SOC is limited to the A horizon. The average SOC stocks (in the first 30 cm from the soil) for TU and CU are 20.04&amp;#177;1.1 and 18.23&amp;#177;1.0 kg/m&lt;sup&gt;2&lt;/sup&gt;,&lt;sup&gt;&lt;/sup&gt;respectively. These values are almost two times greater than the global average reported for Vitric Andosols (~8.2 kg/m&lt;sup&gt;2&lt;/sup&gt;&amp;#160;), but are lower than the estimates obtained for some wetter Andean p&amp;#225;ramos (22.5&amp;#177;5 kg/m&lt;sup&gt;2&lt;/sup&gt;, 270% higher rainfall) from Ecuador. Our stock values further indicate that vegetation type has a limited effect on C storage in the young volcanic ash soils found at Jatunhuyaco. Despite a higher SOC content, the CU soils store a stock of organic C similar to that estimated for the TU soils. This likely reflects the comparatively lower BD of the former soils (650&amp;#177;100 vs. 840&amp;#177;30 kg/m&lt;sup&gt;3&lt;/sup&gt;). Additional studies are needed in order to establish the vegetation-related factors driving the SOC content and stability in the TU and CU soils.&lt;/p&gt;

Effects of climate change on soil organic matter chemical composition and carbon content in different physical fractions

2021 ◽  
Author(s):  
Moritz Mohrlok ◽  
Victoria Martin ◽  
Alberto Canarini ◽  
Wolfgang Wanek ◽  
Michael Bahn ◽  
...  
Keyword(s):  
Climate Change ◽  
Organic Matter ◽  
Chemical Composition ◽  
Soil Organic Matter ◽  
Soil C ◽  
Size Classes ◽  
Soil Fractions ◽  
Total Soil ◽  
C And N ◽  
Amp Clay

&lt;p&gt;Soil organic matter (SOM) is composed of many pools with different properties (e.g. turnover times) which are generally used in biogeochemical models to predict carbon (C) dynamics. Physical fractionation methods are applied to isolate soil fractions that correspond to these pools. This allows the characterisation of chemical composition and C content of these fractions. There is still a lack of knowledge on how these individual fractions are affected by different climate change drivers, and therefore the fate of SOM remains elusive. We sampled soils from a multifactorial climate change experiment in a managed grassland in Austria four years after starting the experiment to investigate the response of SOM in physical soil fractions to temperature (eT: ambient and elevated by +3&amp;#176;C), atmospheric CO&lt;sub&gt;2&lt;/sub&gt;-concentration (eCO&lt;sub&gt;2&lt;/sub&gt;: ambient and elevated by +300 ppm) and to a future climate treatment (eT x eCO&lt;sub&gt;2&lt;/sub&gt;: +3&amp;#176;C and + 300 ppm). A combination of slaking and wet sieving was used to obtain three size classes: macro-aggregates (maA, &gt; 250 &amp;#181;m), micro-aggregates (miA, 63 &amp;#181;m &amp;#8211; 250 &amp;#181;m) and free silt &amp; clay (sc, &lt; 63 &amp;#181;m). In both maA and miA, four different physical OM fractions were then isolated by density fractionation (using sodium polytungstate of &amp;#961; = 1.6 g*cm&lt;sup&gt;-3&lt;/sup&gt;, ultrasonication and sieving): Free POM (fPOM), intra-aggregate POM (iPOM), silt &amp; clay associated OM (SCaOM) and sand-associated OM (SaOM). We measured C and N contents and isotopic composition by EA-IRMS in all fractions and size classes and used a Pyrolysis-GC/MS approach to assess their chemical composition. For eCO&lt;sub&gt;2&lt;/sub&gt; and eT x eCO&lt;sub&gt;2 &lt;/sub&gt;plots, an isotope mixing-model was used to calculate the proportion of recent C derived from the elevated CO&lt;sub&gt;2 &lt;/sub&gt;treatment. Total soil C and N did not significantly change with treatments.&amp;#160; eCO&lt;sub&gt;2&lt;/sub&gt; decreased the relative proportion of maA-mineral-associated C and increased C in fPOM and iPOM. About 20% of bulk soil C was represented by the recent C derived from the CO&lt;sub&gt;2&lt;/sub&gt; fumigation treatment. This significantly differed between size classes and density fractions (p &lt; 0.001), which indicates inherent differences in OM age and turnover. Warming reduced the amount of new C incorporated into size classes. We found that each size class and fraction possessed a unique chemical fingerprint, but this was not significantly changed by the treatments. Overall, our results show that while climate change effects on total soil C were not significant after 4 years, soil fractions showed specific effects. Chemical composition differed significantly between size classes and fractions but was unaffected by simulated climate change. This highlights the importance to separate SOM into differing pools, while including changes to the molecular composition might not be necessary for improving model predictions.&amp;#160;&amp;#160;&amp;#160;&amp;#160;&lt;/p&gt;

Changes in soil carbon under long-term maize in monoculture and legume-based rotation

2001 ◽  
Vol 81 (1) ◽  
pp. 21-31 ◽  
Author(s):  
E G Gregorich ◽  
C F Drury ◽  
J A Baldock
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Magnetic Resonance ◽  
Soil Carbon ◽  
Crop Residues ◽  
Cropping Systems ◽  
Natural Abundance ◽  
Organic C ◽  
Soil C

Legume-based cropping systems could help to increase crop productivity and soil organic matter levels, thereby enhancing soil quality, as well as having the additional benefit of sequestering atmospheric C. To evaluate the effects of 35 yr of maize monoculture and legume-based cropping on soil C levels and residue retention, we measured organic C and 13C natural abundance in soils under: fertilized and unfertilized maize (Zea mays L.), both in monoculture and legume-based [maize-oat (Avena sativa L.)-alfalfa (Medicago sativa L.)-alfalfa] rotations; fertilized and unfertilized systems of continuous grass (Poa pratensis L.); and under forest. Solid state 13C nuclear magnetic resonance (NMR) was used to chemically characterize the organic matter in plant residues and soils. Soils (70-cm depth) under maize cropping had about 30-40% less C, and those under continuous grass had about 16% less C, than those under adjacent forest. Qualitative differences in crop residues were important in these systems, because quantitative differences in net primary productivity and C inputs in the different agroecosystems did not account for observed differences in total soil C. Cropping sequence (i.e., rotation or monoculture) had a greater effect on soil C levels than application of fertilizer. The difference in soil C levels between rotation and monoculture maize systems was about 20 Mg C ha-1. The effects of fertilization on soil C were small (~6 Mg C ha-1), and differences were observed only in the monoculture system. The NMR results suggest that the chemical composition of organic matter was little affected by the nature of crop residues returned to the soil. The total quantity of maize-derived soil C was different in each system, because the quantity of maize residue returned to the soil was different; hence the maize-derived soil C ranged from 23 Mg ha-1 in the fertilized and 14 Mg ha-1 in the unfertilized monoculture soils (i.e., after 35 maize crops) to 6-7 Mg ha-1 in both the fertilized and unfertilized legume-based rotation soils (i.e., after eight maize crops). The proportion of maize residue C returned to the soil and retained as soil organic C (i.e., Mg maize-derived soil C/Mg maize residue) was about 14% for all maize cropping systems. The quantity of C3-C below the plow layer in legume-based rotation was 40% greater than that in monoculture and about the same as that under either continuous grass or forest. The soil organic matter below the plow layer in soil under the legume-based rotation appeared to be in a more biologically resistant form (i.e., higher aromatic C content) compared with that under monoculture. The retention of maize residue C as soil organic matter was four to five times greater below the plow layer than that within the plow layer. We conclude that residue quality plays a key role in increasing the retention of soil C in agroecosystems and that soils under legume-based rotation tend to be more “preservative” of residue C inputs, particularly from root inputs, than soils under monoculture. Key words: Soil carbon, 13C natural abundance, 13C nuclear magnetic resonance, maize cropping, legumes, root carbon

scholarly journals Biomass and carbon storage in an age-sequence of Acacia mangium plantation forests in Southeastern region, Vietnam

2020 ◽  
Vol 29 (2) ◽  
pp. e009
Author(s):  
Cuong Levan ◽  
Hung Buimanh ◽  
Bolanle-Ojo Oluwasanmi Tope ◽  
Xiaoniu Xu ◽  
Thanh Nguyenminh ◽  
...  
Keyword(s):  
Carbon Storage ◽  
Acacia Mangium ◽  
Understory Vegetation ◽  
Stand Age ◽  
Tree Biomass ◽  
Organic C ◽  
Soil C ◽  
C Storage ◽  
Age Sequence ◽  
Southeastern Region

Aim of the study: The major objective of this study was to estimate the biomass increment and carbon (C) storage of the main ecosystem components in an age-sequence of three Acacia mangium plantation stands.Area of study: Chang Riec Historical - Cultural Forest, Southeastern region, Vietnam.Material and methods: In order to assess the biomass of different tree components, 36 trees with diameter at breast height ranging from 13.38 to 22.87 cm were harvested from the different aged stands. Biomasses of understory (shrubs and herbs), and litter were also determined. Carbon storage in the trees and understory biomass, litter, and mineral soil (0-50 cm) were determined by analyzing the C content of each compartment.Main results: The biomass in trees, understory vegetation, litter, and ecosystem increased with stand age. Soil C represented 61.99% of the total, aboveground tree biomass C made up 26.73%, belowground tree biomass C accounted for 7.01%, and litter comprised 2.96%, whereas only a small amount (1.30%) was associated with understory vegetation. The average C content of total tree (47.97%) was higher than those of understory and litter. Soil organic C stock in the top 50 cm depth in 4-, 7- and 11-year-old stands of A. mangium were 86.86, 126.88 and 140.94 Mg. C ha-1 respectively. Soil C concentration decreased continually with increasing soil depth. Total C storage of three planted forests ranged from 131.36 to 255.86 Mg. C ha-1, of which 56.09 - 67.61% of C storage was in the soil and 26.88 - 40.40% in the trees.Research highlights: These results suggest that A. mangium is a promising afforestation tree species with fast growing, high biomass accumulation and high C sequestration potential.Keywords: Acacia mangium plantations; Biomass; Ecosystem carbon storage; Age-sequence; Vietnam.

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