Long-term irrigation in a drought-prone pine forest leads to vertical redistribution of C stocks and accelerates C cycling in the soil

2021 ◽  
Author(s):  
Claudia Guidi ◽  
Ivano Brunner ◽  
Josephine Imboden ◽  
Konstantin Gavazov ◽  
Marcus Schaub ◽  
...  
Keyword(s):  
Mineral Soil ◽  
Fine Root Biomass ◽  
Soil Organisms ◽  
Soil C ◽  
Water Limitation ◽  
Organic Layers ◽  
C Storage ◽  
C Cycling ◽  
Soil C Cycling

<p>European forests are facing higher frequencies of extreme droughts, potentially impairing tree growth and ecosystem functioning. Drought limits the metabolic activity of plants and soil organisms, either directly or through reduced belowground carbon (C) allocation of recent assimilates, thus affecting C cycling in the plant-soil system. However, the net effect on belowground soil C storage is still unclear, as drought suppresses both C inputs from plants and outputs from soils. Moreover, understanding the underlying mechanisms is complicated due to long-term acclimation and adaptation of plant and soil organisms to water limitation.</p><p>We investigated the impact of repeated summer droughts in a Scots pine (<em>Pinus sylvestris</em> L.) forest on soil C storage and C cycling, taking advantage of a large-scale irrigation experiment  running since 2003 in a dry inner-Alpine valley in Switzerland (Pfynwald, Valais), which removed the “natural” water limitation. We assessed the responses of soil organic carbon (SOC) stocks and C fluxes by measuring litter fall and decomposition, fine root biomass and production, soil CO<sub>2</sub> effluxes, C-mineralization, and <sup>13</sup>C-labelled glucose utilization by soil microorganisms. </p><p>After 16 years of irrigation, the organic layers lost significant amounts of C (-1000 g m<sup>-2</sup>), despite a 50% increase in litter fall. This C loss was almost compensated by a C gain in the mineral soil (+870 g m<sup>-2</sup>) under irrigation. The decrease in C storage in the organic layers can be related to a three-fold increase in litter decomposition mainly through soil macrofauna as indicated by a litter-bag experiment. In parallel, the C gain in the mineral soil can be attributed mainly to increased incorporation of litter by soil fauna, together with greater C input from the rhizosphere (+70% fine root biomass for Scots pine in mineral soil). Furthermore, irrigation stimulated soil CO<sub>2</sub> efflux as well as microbial C-mineralization of organic and mineral soil, indicating enhanced soil C cycling. Addition of <sup>13</sup>C-enriched glucose to mineral soils revealed a stronger utilization of this easily available C substrate in the drought than in the irrigated soils, together with a negative priming of soil organic matter (SOM) decomposition shortly after substrate addition. These results suggest that the altered quantity and quality of C inputs under irrigation has increased the availability of easily degradable C in soil.</p><p>This study reveals that long-term summer irrigation in a drought-prone pine forest has strong impacts on multiple interlinked processes of the soil C cycle. The removal of water limitation strongly altered vertical soil C distribution, accelerated soil C cycling and altered the substrate use by soil organisms, but had only a small net effect on the whole-profile SOC stocks.</p>

scholarly journals Biochemical proxies indicate differences in soil C cycling induced by long-term tillage and residue management in a tropical agroecosystem

2017 ◽  
Vol 420 (1-2) ◽  
pp. 315-329 ◽  
Author(s):  
Andrew J. Margenot ◽  
Mirjam M. Pulleman ◽  
Rolf Sommer ◽  
Birthe K. Paul ◽  
Sanjai J. Parikh ◽  
...  
Keyword(s):  
Residue Management ◽  
Soil C ◽  
C Cycling ◽  
Soil C Cycling ◽  
Tropical Agroecosystem

The Path From Litter to Soil: Insights Into Soil C Cycling From Long-Term Input Manipulation and High-Resolution Mass Spectrometry

2018 ◽  
Vol 123 (5) ◽  
pp. 1486-1497 ◽  
Author(s):  
Lorien L. Reynolds ◽  
Kate Lajtha ◽  
Richard D. Bowden ◽  
Malak M. Tfaily ◽  
Bart R. Johnson ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
High Resolution Mass Spectrometry ◽  
Soil C ◽  
C Cycling ◽  
High Resolution Mass ◽  
Soil C Cycling ◽  
Resolution Mass

scholarly journals Beyond total carbon: conversion of amazon forest to pasture alters indicators of soil C cycling

2021 ◽  
Author(s):  
Ademir Durrer ◽  
Andrew J. Margenot ◽  
Lucas C. R. Silva ◽  
Brendan J. M. Bohannan ◽  
Klaus Nusslein ◽  
...  
Keyword(s):  
Total Carbon ◽  
Amazon Forest ◽  
Carbon Conversion ◽  
Soil C ◽  
C Cycling ◽  
Soil C Cycling

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.

scholarly journals Reforestation can sequester two petagrams of carbon in US topsoils in a century

2018 ◽  
Vol 115 (11) ◽  
pp. 2776-2781 ◽  
Author(s):  
Lucas E. Nave ◽  
Grant M. Domke ◽  
Kathryn L. Hofmeister ◽  
Umakant Mishra ◽  
Charles H. Perry ◽  
...  
Keyword(s):  
National Level ◽  
Mineral Soil ◽  
C Sequestration ◽  
The United States ◽  
Forest Sector ◽  
Soil C ◽  
C Storage ◽  
C Stocks ◽  
The Us ◽  
Land Use And Management

Soils are Earth’s largest terrestrial carbon (C) pool, and their responsiveness to land use and management make them appealing targets for strategies to enhance C sequestration. Numerous studies have identified practices that increase soil C, but their inferences are often based on limited data extrapolated over large areas. Here, we combine 15,000 observations from two national-level databases with remote sensing information to address the impacts of reforestation on the sequestration of C in topsoils (uppermost mineral soil horizons). We quantify C stocks in cultivated, reforesting, and natural forest topsoils; rates of C accumulation in reforesting topsoils; and their contribution to the US forest C sink. Our results indicate that reforestation increases topsoil C storage, and that reforesting lands, currently occupying >500,000 km2 in the United States, will sequester a cumulative 1.3–2.1 Pg C within a century (13–21 Tg C·y−1). Annually, these C gains constitute 10% of the US forest sector C sink and offset 1% of all US greenhouse gas emissions.

Herbage biomass and its relationship to soil carbon under long-term grazing in northern temperate grasslands

2019 ◽  
Vol 99 (6) ◽  
pp. 905-916
Author(s):  
E.W. Bork ◽  
M.P. Lyseng ◽  
D.B. Hewins ◽  
C.N. Carlyle ◽  
S.X. Chang ◽  
...  
Keyword(s):  
Soil Carbon ◽  
Root Biomass ◽  
Mineral Soil ◽  
Belowground Biomass ◽  
Cattle Grazing ◽  
Shoot Biomass ◽  
Positive Contribution ◽  
Temperate Grasslands ◽  
Soil C

While northern temperate grasslands are important for supporting beef production, it remains unclear how grassland above- and belowground biomass responds to long-term cattle grazing. Here, we use a comprehensive dataset from 73 grasslands distributed across a broad agro-climatic gradient to quantify grassland shoot, litter, and shallow (top 30 cm) root biomass in areas with and without grazing. Additionally, we relate biomass to soil carbon (C) concentrations. Forb biomass was greater (p < 0.05) in grazed areas, particularly those receiving more rainfall. In contrast, grass and total aboveground herbage biomass did not differ with grazing (total: 2320 kg ha−1 for grazed vs. 2210 kg ha−1 for non-grazed; p > 0.05). Forb crude protein concentrations were lower (p < 0.05) in grazed communities compared with those that were non-grazed. Grasslands subjected to grazing had 56% less litter mass. Root biomass down to 30 cm remained similar between areas with (9090 kg ha−1) and without (7130 kg ha−1) grazing (p > 0.05). Surface mineral soil C concentrations were positively related to peak grassland biomass, particularly total (above + belowground) biomass, and with increasing forb biomass in grazed areas. Finally, total aboveground shoot biomass and soil C concentrations in the top 15 cm of soil were both positively related to the proportion of introduced plant diversity in grazed and non-grazed grasslands. Overall, cattle grazing at moderate stocking rates had minimal impact on peak grassland biomass, including above- and belowground, and a positive contribution exists from introduced plant species to maintaining herbage productivity and soil C.

scholarly journals Boreal-forest soil chemistry drives soil organic carbon bioreactivity along a 314-year fire chronosequence

SOIL ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 195-213
Author(s):  
Benjamin Andrieux ◽  
David Paré ◽  
Julien Beguin ◽  
Pierre Grondin ◽  
Yves Bergeron
Keyword(s):  
Organic Carbon ◽  
Indirect Effect ◽  
Soil Chemistry ◽  
Mineral Soil ◽  
Chemical Properties ◽  
Soil C ◽  
C Pools ◽  
Time Since Fire ◽  
C Stock

Abstract. Following a wildfire, organic carbon (C) accumulates in boreal-forest soils. The long-term patterns of accumulation as well as the mechanisms responsible for continuous soil C stabilization or sequestration are poorly known. We evaluated post-fire C stock changes in functional reservoirs (bioreactive and recalcitrant) using the proportion of C mineralized in CO2 by microbes in a long-term lab incubation, as well as the proportion of C resistant to acid hydrolysis. We found that all soil C pools increased linearly with the time since fire. The bioreactive and acid-insoluble soil C pools increased at a rate of 0.02 and 0.12 MgC ha−1 yr−1, respectively, and their proportions relative to total soil C stock remained constant with the time since fire (8 % and 46 %, respectively). We quantified direct and indirect causal relationships among variables and C bioreactivity to disentangle the relative contribution of climate, moss dominance, soil particle size distribution and soil chemical properties (pH, exchangeable manganese and aluminum, and metal oxides) to the variation structure of in vitro soil C bioreactivity. Our analyses showed that the chemical properties of podzolic soils that characterize the study area were the best predictors of soil C bioreactivity. For the O layer, pH and exchangeable manganese were the most important (model-averaged estimator for both of 0.34) factors directly related to soil organic C bioreactivity, followed by the time since fire (0.24), moss dominance (0.08), and climate and texture (0 for both). For the mineral soil, exchangeable aluminum was the most important factor (model-averaged estimator of −0.32), followed by metal oxide (−0.27), pH (−0.25), the time since fire (0.05), climate and texture (∼0 for both). Of the four climate factors examined in this study (i.e., mean annual temperature, growing degree-days above 5 ∘C, mean annual precipitation and water balance) only those related to water availability – and not to temperature – had an indirect effect (O layer) or a marginal indirect effect (mineral soil) on soil C bioreactivity. Given that predictions of the impact of climate change on soil C balance are strongly linked to the size and the bioreactivity of soil C pools, our study stresses the need to include the direct effects of soil chemistry and the indirect effects of climate and soil texture on soil organic matter decomposition in Earth system models to forecast the response of boreal soils to global warming.

scholarly journals Continuous and discontinuous variation in ecosystem carbon stocks with elevation across a treeline ecotone

2015 ◽  
Vol 12 (5) ◽  
pp. 1615-1627 ◽  
Author(s):  
J. D. M. Speed ◽  
V. Martinsen ◽  
A. J. Hester ◽  
Ø. Holand ◽  
J. Mulder ◽  
...  
Keyword(s):  
Large Scale ◽  
Mineral Soil ◽  
Livestock Grazing ◽  
Treeline Ecotone ◽  
Soil C ◽  
C Storage ◽  
C Stocks ◽  
C Stock ◽  
The Impact ◽  
Forest Line

Abstract. Treelines differentiate vastly contrasting ecosystems: open tundra from closed forest. Treeline advance has implications for the climate system due to the impact of the transition from tundra to forest ecosystem on carbon (C) storage and albedo. Treeline advance has been seen to increase above-ground C stocks as low vegetation is replaced with trees but decrease organic soil C stocks as old carbon is decomposed. However, studies comparing across the treeline typically do not account for elevational variation within the ecotone. Here we sample ecosystem C stocks along an elevational gradient (970 to 1300 m), incorporating a large-scale and long-term livestock grazing experiment, in the southern Norwegian mountains. We investigate whether there are continuous or discontinuous changes in C storage across the treeline ecotone, and whether these are modulated by grazing. We find that vegetation C stock decreases with elevation, with a clear breakpoint between the forest line and treeline above which the vegetation C stock is constant. C stocks in organic surface horizons of the soil were higher above the treeline than in the forest, whereas C stocks in mineral soil horizons are unrelated to elevation. Total ecosystem C stocks also showed a discontinuous elevational pattern, increasing with elevation above the treeline (8 g m−2 per metre increase in elevation), but decreasing with elevation below the forest line (−15 g m−2 per metre increase in elevation), such that ecosystem C storage reaches a minimum between the forest line and treeline. We did not find any effect of short-term (12 years) grazing on the elevational patterns. Our findings demonstrate that patterns of C storage across the treeline are complex, and should be taken account of when estimating ecosystem C storage with shifting treelines.

Changes in carbon storage of broadcast burn plantations over 20 years

2007 ◽  
Vol 87 (1) ◽  
pp. 93-102 ◽  
Author(s):  
J M Kranabetter ◽  
A M Macadam
Keyword(s):  
Lodgepole Pine ◽  
Woody Debris ◽  
Mineral Soil ◽  
Biomass Accumulation ◽  
Prescribed Burn ◽  
Soil C ◽  
C Storage ◽  
C Stocks ◽  
Mineral Soils ◽  
Forest Floors

The extent of carbon (C) storage in forests and the change in C stocks after harvesting are important considerations in the management of greenhouse gases. We measured changes in C storage over time (from postharvest, postburn, year 5, year 10 and year 20) in logging slash, forest floors, mineral soils and planted lodgepole pine (Pinus contorta var. latifolia) trees from six prescribed-burn plantations in north central British Columbia. After harvest, site C in these pools averaged 139 Mg ha-1, with approximately equal contributions from mineral soils (0–30 cm), forest floors and logging slash. Together these detrital pools declined by 71 Mg C ha-1, or 51% (28% directly from the broadcast burn, and a further 23% postburn), in the subsequent 20 yr. Postburn decay in logging slash was inferred by reductions in wood density (from 0.40 to 0.34 g cm-3), equal to an average k rate of 0.011 yr-1. Losses in forest floor C, amounting to more than 60% of the initial mass, were immediate and continued to year 5, with no reaccumulation evident by year 20. Mineral soil C concentrations initially fluctuated before declining by 25% through years 10 and 20. Overall, the reductions in C storage were offset by biomass accumulation of lodgepole pine, and we estimate these plantations had become a net sink for C before year 20, although total C storage was still less than postharvest levels. Key words: C sequestration, forest floors; coarse woody debris; soil organic matter

scholarly journals A meta-analysis of soil biodiversity impacts on the carbon cycle

SOIL ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 257-271 ◽  
Author(s):  
M.-A. de Graaff ◽  
J. Adkins ◽  
P. Kardol ◽  
H. L. Throop
Keyword(s):  
Body Size ◽  
Microbial Diversity ◽  
Plant Tissue ◽  
Plant Biomass ◽  
Meta Analysis ◽  
Soil Biodiversity ◽  
Soil C ◽  
C Cycling ◽  
Soil C Cycling ◽  
Group Diversity

Abstract. Loss of biodiversity impacts ecosystem functions, such as carbon (C) cycling. Soils are the largest terrestrial C reservoir, containing more C globally than the biotic and atmospheric pools together. As such, soil C cycling, and the processes controlling it, has the potential to affect atmospheric CO2 concentrations and subsequent climate change. Despite the growing evidence of links between plant diversity and soil C cycling, there is a dearth of information on whether similar relationships exist between soil biodiversity and C cycling. This knowledge gap occurs even though there has been increased recognition that soil communities display high levels of both taxonomic and functional diversity and are key drivers of fluxes of C between the atmosphere and terrestrial ecosystems. Here, we used meta-analysis and regression analysis to quantitatively assess how soil biodiversity affects soil C cycling pools and processes (i.e., soil C respiration, litter decomposition, and plant biomass). We compared the response of process variables to changes in diversity both within and across groups of soil organisms that differed in body size, a grouping that typically correlates with ecological function. When studies that manipulated both within- and across-body size group diversity were included in the meta-analysis, loss of diversity significantly reduced soil C respiration (−27.5%) and plant tissue decomposition (−18%) but did not affect above- or belowground plant biomass. The loss of within-group diversity significantly reduced soil C respiration, while loss of across-group diversity did not. Decomposition was negatively affected both by loss of within-group and across-group diversity. Furthermore, loss of microbial diversity strongly reduced soil C respiration (−41%). In contrast, plant tissue decomposition was negatively affected by loss of soil faunal diversity but was unaffected by loss of microbial diversity. Taken together, our findings show that loss of soil biodiversity strongly impacts on soil C cycling processes, and highlight the importance of diversity across groups of organisms (e.g., primary consumers and secondary decomposers) for maintaining full functionality of C cycle processes. However, our understanding of the complex relationships between soil biodiversity and C cycling processes is currently limited by the sheer number of methodological concerns associated with these studies, which can greatly overestimate or underestimate the impact of soil biodiversity on soil C cycling, challenging extrapolation to natural field settings. Future studies should attempt to further elucidate the relative importance of taxonomic diversity (species numbers) versus functional diversity.

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