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.

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

2014 ◽  
Vol 11 (11) ◽  
pp. 15435-15461
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. In contrast, C stocks in organic surface horizons of the soil increase linearly with elevation within the study's elevational range, 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 m−1 increase in elevation), but decreasing with elevation below the forest line (−15 g m−2 m−1 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.

Evaluation of forest management effects on the mineral soil carbon pool of a lowland, mixed-species forest in Maine, USA

2016 ◽  
Vol 96 (2) ◽  
pp. 207-218 ◽  
Author(s):  
Joshua J. Puhlick ◽  
Ivan J. Fernandez ◽  
Aaron R. Weiskittel
Keyword(s):  
Forest Management ◽  
Management Strategies ◽  
Mineral Soil ◽  
Primary Objective ◽  
Significant Treatment ◽  
Soil C ◽  
C Storage ◽  
C Stocks ◽  
C Stock ◽  
Post Hoc

Concerns about climate change have increased interest in ways to maximize carbon (C) storage in forests through the use of alternative forest management strategies. However, the influence of these strategies on soil C pools is unclear. The primary objective of this study was to test for differences in mineral soil C stocks among various silvicultural and harvesting treatments that were initiated in the 1950s and have been maintained since on the Penobscot Experimental Forest in central Maine, USA. Five mineral soil cores below the surface organic horizon to a depth of 1 m were collected from each replicate (n = 2) of selection, shelterwood, and commercial clearcut treatments. For these treatments, the mean mineral soil C stock was 47.7 ± 16.4 Mg ha−1 (mean ± SD). We found no significant differences in average mineral soil C stocks among treatments. However, a post hoc power analysis indicated that the probability of detecting a significant treatment effect was only 6%. We determined that 98 stands per treatment would be required to be 80% certain that the F test would detect a difference in average mineral soil C stocks whenever any pair of treatments had C stocks differing by more than 5 Mg ha−1.

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.

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

The impact of harvesting native forests on vegetation and soil C stocks, and soil CO2, N2O and CH4 fluxes

2011 ◽  
Vol 59 (7) ◽  
pp. 654 ◽  
Author(s):  
K. L. Page ◽  
R. C. Dalal ◽  
R. J. Raison
Keyword(s):  
Primary Production ◽  
Time Course ◽  
Management Practices ◽  
Diverse Range ◽  
Soil C ◽  
C Storage ◽  
Native Forests ◽  
C Stocks ◽  
Ch4 And N2o ◽  
The Impact

Australia’s harvested native forests are extremely diverse in terms of species-mix, disturbance history and ecology, forest productivity and C storage. Our understanding of the effects of harvesting on C storage and greenhouse gas (GHG) emissions from these systems is incomplete, and this paper consolidates current Australian knowledge, places this in a global context, and identifies areas requiring further study. The uptake of CO2 and the re-accumulation of forest C stocks after harvesting or other disturbance is largely dependent on forest primary production. However, in Australian native forests, knowledge of rates of primary production for the diverse range of species and management practices present is poor. Soil respiration rates following harvest have also been largely unquantified for Australian systems. It is essential that both these parameters are quantified if estimates of net ecosystem production (NEP) are to be made. It is generally acknowledged that harvested forests have a negative NEP, and thus are sources of C, immediately following harvest, but attain a positive NEP as the forest regrows and photosynthetic capacity increases. The magnitude and time course of these changes are largely unknown for most Australian forest systems. In addition, little data are available to quantify the effect on soil C storage, and where estimates have been made these are often subject to methodological uncertainty and are thus highly contentious. Following harvest, the changes that occur to soil structure, moisture content, and N cycling may also influence CH4 and N2O flux, although these fluxes also remain largely unquantified in harvested Australian forests. Given the significant changes to NEP, CH4 and N2O fluxes observed after forest harvest in international studies, it is expected that GHG fluxes would typically increase from Australian native forests following harvest, and then slowly decrease over time as biomass accumulates, and N2O and CH4 fluxes return to background levels. However, it is currently difficult to quantify the magnitude and time course of these changes due to a lack of both gas flux and primary production measurements. Clearly, further research effort to quantify these parameters throughout Australia is required in order to obtain a more reliable picture of the effects of harvesting and other disturbances on forest GHG balance.

scholarly journals The carbon cycle in Mexico: past, present and future of C stocks and fluxes

2016 ◽  
Vol 13 (1) ◽  
pp. 223-238 ◽  
Author(s):  
G. Murray-Tortarolo ◽  
P. Friedlingstein ◽  
S. Sitch ◽  
V. J. Jaramillo ◽  
F. Murguía-Flores ◽  
...  
Keyword(s):  
Field Measurements ◽  
Climate Forcing ◽  
Past Century ◽  
Soil C ◽  
C Cycle ◽  
C Stocks ◽  
Fertilization Effect ◽  
C Stock ◽  
Time Frames ◽  
The Impact

Abstract. We modeled the carbon (C) cycle in Mexico with a process-based approach. We used different available products (satellite data, field measurements, models and flux towers) to estimate C stocks and fluxes in the country at three different time frames: present (defined as the period 2000–2005), the past century (1901–2000) and the remainder of this century (2010–2100). Our estimate of the gross primary productivity (GPP) for the country was 2137 ± 1023 TgC yr−1 and a total C stock of 34 506 ± 7483 TgC, with 20 347 ± 4622 TgC in vegetation and 14 159 ± 3861 in the soil.Contrary to other current estimates for recent decades, our results showed that Mexico was a C sink over the period 1990–2009 (+31 TgC yr−1) and that C accumulation over the last century amounted to 1210 ± 1040 TgC. We attributed this sink to the CO2 fertilization effect on GPP, which led to an increase of 3408 ± 1060 TgC, while both climate and land use reduced the country C stocks by −458 ± 1001 and −1740 ± 878 TgC, respectively. Under different future scenarios, the C sink will likely continue over the 21st century, with decreasing C uptake as the climate forcing becomes more extreme. Our work provides valuable insights on relevant driving processes of the C cycle such as the role of drought in drylands (e.g., grasslands and shrublands) and the impact of climate change on the mean residence time of soil C in tropical ecosystems.

scholarly journals Effect of deforestation and subsequent land use management on soil carbon stocks in the South American Chaco

SOIL ◽  
2018 ◽  
Vol 4 (4) ◽  
pp. 251-257 ◽  
Author(s):  
Natalia Andrea Osinaga ◽  
Carina Rosa Álvarez ◽  
Miguel Angel Taboada
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Warm Season ◽  
Continuous Cropping ◽  
Soil Organic C ◽  
Organic C ◽  
Soil C ◽  
C Stocks ◽  
C Stock ◽  
The Impact

Abstract. The subhumid Chaco region of Argentina, originally covered by dry sclerophyll forest, has been subjected to clearing since the end of the 1970s and replacement of the forest by no-till farming. Land use changes produced a decrease in aboveground carbon (C) stored in forests, but little is known about the impact on soil organic C stocks. The aim of this study was to evaluate soil C stocks and C fractions up to 1 m depth in soils under different land use: <10-year continuous cropping, >20-year continuous cropping, warm-season grass pasture and native forest in 32 sites distributed over the Chaco region. The organic C stock content up to 1 m depth expressed as equivalent mass varied as follows: forest (119.3 Mg ha−1) > pasture (87.9 Mg ha−1) > continuous cropping (71.9 and 77.3 Mg ha−1), with no impact of the number of years under cropping. The coarse particle fraction (2000–212 µm) at 0–5 and 5–20 cm depth layers was the most sensitive organic carbon fraction to land use change. Resistant carbon (<53 µm) was the main organic matter fraction in all sample categories except in the forest. Organic C stock, its quality and its distribution in the profile were responsive to land use change. The conversion of the Chaco forest to crops was associated with a decrease of organic C stock up to 1 m depth and with the decrease of the labile fraction. The permanent pastures of warm-season grasses allowed higher C stocks to be sustained than cropping systems and so could be considered a sustainable land use system in terms of soil C preservation. As soil organic C losses were not restricted to the first few centimetres of the soil, the development of models that would allow the estimation of soil organic C changes in depth would be useful to evaluate the impact of land use change on C stocks with greater precision.

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 Effect of deforestation and subsequent land-use management on soil carbon stocks in the South American Chaco

2018 ◽  
Author(s):  
Natalia Andrea Osinaga ◽  
Carina Rosa Álvarez ◽  
Miguel Angel Taboada
Keyword(s):  
Land Use ◽  
Land Use Changes ◽  
Warm Season ◽  
Native Forest ◽  
Continuous Cropping ◽  
Organic C ◽  
Soil C ◽  
C Stocks ◽  
Chaco Region ◽  
The Impact

Abstract. Abstract. The sub-humid Chaco region of Argentina, originally covered by dry sclerophyll forest, has been subjected to clearing since the end of the '70 and replacement of the forest by no till farming. Land use changes produced a decrease in aboveground carbon stored in forests, but little is known about the impact on soil organic C stocks. The aim of this study was to evaluate soil C stocks and C fractions up to 1 m depth in soils under different land use:  20 yr continuous cropping, warm season grass pasture and native forest in 32 sites distributed over the Chaco region. The organic C stock content up to 1 m depth expressed as equivalent mass varied as follows: forest (119.3 Mg ha−1) > pasture (87.9 Mg ha−1) > continuous cropping (71.9 and 77.3 Mg ha−1), with no impact of the number of years under cropping. The most sensitive organic carbon fraction was the coarse particle fraction (2000 μm–212 μm) at 0–5 cm and 5–20 cm depth layers. Resistant carbon (

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.

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