Impact of temperature and moisture on heterotrophic soil respiration along a moist tropical forest gradient in Australia

Soil Research ◽  
2015 ◽  
Vol 53 (3) ◽  
pp. 286 ◽  
Author(s):  
M. Zimmermann ◽  
K. Davies ◽  
V. T. V. Peña de Zimmermann ◽  
M. I. Bird
Keyword(s):  
Soil Respiration ◽  
Tropical Forest ◽  
Tropical Forests ◽  
Mean Annual Temperature ◽  
Soil Cores ◽  
Site Specific ◽  
Soil C ◽  
Respiration Rates ◽  
C Stocks ◽  
Specific Temperature

Tropical forests represent the largest store of terrestrial carbon (C) and are potentially vulnerable to climatic variations and human impact. However, the combined influence of temperature and precipitation on aboveground and belowground C cycling in tropical ecosystems is not well understood. To simulate the impact of climate (temperature and rainfall) on soil C heterotrophic respiration rates of moist tropical forests, we translocated soil cores among three elevations (100, 700 and 1540 m a.s.l.) representing a range in mean annual temperature of 10.9°C and in rainfall of 6840 mm. Initial soil C stocks in the top 30 cm along the gradient increased linearly with elevation from 6.13 kg C m–2 at 100 m a.s.l. to 10.66 kg C m–2 at 1540 m a.s.l. Respiration rates of translocated soil cores were measured every 3 weeks for 1 year and were fitted to different model functions taking into account soil temperature, soil moisture, mean annual temperature and total annual rainfall. Measured data could be best fitted to the model equation based on temperature alone. Furthermore, Akaike’s information criteria revealed that model functions taking into account the temperature range of the entire translocation gradient led to better estimates of respiration rates than functions solely based on the site-specific temperature range. Soil cores from the highest elevation revealed the largest temperature sensitivity (Q10 = 2.63), whereas these values decreased with decreasing elevation (Q10 = 2.00 at 100 m a.s.l.) or soil C stocks. We therefore conclude that increased temperatures will have the greatest impact on soil C stocks at higher elevations, and that best projections for future soil respiration rates of moist tropical forest soils can be achieved based on temperature alone and large soil cores exposed to temperatures above site-specific temperature regimes.

scholarly journals Controls on heterotrophic soil respiration and carbon cycling in geochemically distinct African tropical forest soils

2021 ◽  
Author(s):  
Benjamin Bukombe ◽  
Peter Fiener ◽  
Alison M. Hoyt ◽  
Sebastian Doetterl
Keyword(s):  
Soil Respiration ◽  
Tropical Forest ◽  
Forest Soils ◽  
Soil Chemistry ◽  
Poor Quality ◽  
Parent Material ◽  
Soil C ◽  
Soil Parent Material ◽  
C Stocks ◽  
Heterotrophic Soil Respiration

Abstract. Heterotrophic soil respiration is an important component of the global terrestrial carbon (C) cycle, driven by environmental factors acting from local to continental scales. For tropical Africa, these factors and their interactions remain largely unknown. Here, using samples collected along strong topographic and geochemical gradients in the East African Rift Valley, we study how soil chemistry and soil fertility, derived from the geochemical composition of soil parent material, can drive soil respiration even after many millennia of weathering and soil development. To address the drivers of soil respiration, we incubated soils from three regions with contrasting geochemistry (mafic, felsic, and mixed sedimentary) sampled along slope gradients. For three soil depths, we measured the potential maximum heterotrophic respiration under stable environmental conditions as well as the radiocarbon content (Δ14C) of the bulk soil and respired CO2. We found that soil microbial communities were able to mineralize C from fossil as well as other poor quality C sources under laboratory conditions representative of tropical topsoils. Furthermore, despite similarities in terms of climate, vegetation, and the size of soil C stocks, soil respiration showed distinct patterns with soil depth and parent material geochemistry. The topographic origin of our samples was not a main determinant of the observed respiration rates and Δ14C. In situ, however, soil hydrological conditions likely influence soil C stability by inhibiting decomposition in valley subsoils. Our study shows that soil fertility conditions are the main determinant of C stability in tropical forest soils. Further, in the presence of organic carbon sources of poor quality or the presence of strong mineral related C stabilization, microorganisms tend to discriminate against these sources in favor of more accessible forms of soil organic matter as energy sources, resulting in a slower rate of C cycling. Our results demonstrate that even in deeply weathered tropical soils, parent material has a long-lasting effect on soil chemistry that can influence and control microbial activity, the size of subsoil C stocks, and the turnover of C in soil. Soil parent material and its lasting control on soil chemistry need to be taken into account to understand and predict C stabilization and rates of C cycling in tropical forest soils.

scholarly journals Heterotrophic soil respiration and carbon cycling in geochemically distinct African tropical forest soils

SOIL ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 639-659
Author(s):  
Benjamin Bukombe ◽  
Peter Fiener ◽  
Alison M. Hoyt ◽  
Laurent K. Kidinda ◽  
Sebastian Doetterl
Keyword(s):  
Soil Respiration ◽  
Tropical Forest ◽  
Forest Soils ◽  
Soil Chemistry ◽  
Parent Material ◽  
Main Determinant ◽  
Soil C ◽  
C Cycling ◽  
C Stocks ◽  
Heterotrophic Soil Respiration

Abstract. Heterotrophic soil respiration is an important component of the global terrestrial carbon (C) cycle, driven by environmental factors acting from local to continental scales. For tropical Africa, these factors and their interactions remain largely unknown. Here, using samples collected along topographic and geochemical gradients in the East African Rift Valley, we study how soil chemistry and fertility drive soil respiration of soils developed from different parent materials even after many millennia of weathering. To address the drivers of soil respiration, we incubated soils from three regions with contrasting geochemistry (mafic, felsic and mixed sediment) sampled along slope gradients. For three soil depths, we measured the potential maximum heterotrophic respiration under stable environmental conditions and the radiocarbon content (Δ14C) of the bulk soil and respired CO2. Our study shows that soil fertility conditions are the main determinant of C stability in tropical forest soils. We found that soil microorganisms were able to mineralize soil C from a variety of sources and with variable C quality under laboratory conditions representative of tropical topsoil. However, in the presence of organic carbon sources of poor quality or the presence of strong mineral-related C stabilization, microorganisms tend to discriminate against these energy sources in favour of more accessible forms of soil organic matter, resulting in a slower rate of C cycling. Furthermore, despite similarities in climate and vegetation, soil respiration showed distinct patterns with soil depth and parent material geochemistry. The topographic origin of our samples was not a main determinant of the observed respiration rates and Δ14C. In situ, however, soil hydrological conditions likely influence soil C stability by inhibiting decomposition in valley subsoils. Our results demonstrate that, even in deeply weathered tropical soils, parent material has a long-lasting effect on soil chemistry that can influence and control microbial activity, the size of subsoil C stocks and the turnover of C in soil. Soil parent material and its control on soil chemistry need to be taken into account to understand and predict C stabilization and rates of C cycling in tropical forest soils.

scholarly journals Carbon release from tropical forest soils informed by soil chemistry, fertility, and carbon quality derived from geochemistry of the parent material 

2021 ◽  
Author(s):  
Benjamin Bukombe ◽  
Peter Fiener ◽  
Alison M. Hoyt ◽  
Sebastian Doetterl
Keyword(s):  
Organic Carbon ◽  
Soil Respiration ◽  
Tropical Forest ◽  
Forest Soils ◽  
Soil Chemistry ◽  
Poor Quality ◽  
Parent Material ◽  
Soil C ◽  
Soil Parent Material ◽  
C Stocks

<p>Tropical forest soils are a vital component of the global carbon (C) cycle and their response to environmental change will determine future atmospheric carbon dioxides (CO<sub>2</sub>). For example, increasing biomass productivity in tropical forests suggests a potential sink for C. However, its storage and stability are driven by factors acting from small to large scale. For tropical Africa, these factors are not well known and documented.  Predicting tropical soil C dynamics ultimately depends on our understanding and the ability to determine the primary environmental controls on soil organic carbon content and respiration.</p><p>Here, using samples collected along strong geochemical gradients in the East African Rift Valley, we demonstrate how soil chemistry and soil fertility, derived from the geochemical composition of soil parent material, can drive soil respiration even in deeply weathered soils. </p><p>To address the drivers of soil respiration, we incubated soils from three regions with contrasting geochemistry (mafic, felsic, and mixed sedimentary). For three soil depths, we measured the potential maximum heterotrophic respiration as well as the radiocarbon isotopic signature (Δ<sup>14</sup>C) of the bulk soil and respired CO<sub>2</sub> under stable environmental conditions. </p><p>We found that soil microbial communities were able to mineralize C from fossil as well as other poor quality C sources under laboratory conditions representative of tropical topsoils. Despite similarities in terms of climate, vegetation, and the size of soil C stocks, soil respiration showed distinct patterns with soil depth and parent material geochemistry. Our study shows that soil fertility conditions are the main determinant of C stability in tropical forest soils. Further, in the presence of organic carbon sources of poor quality or the presence of strong mineral-related C stabilization, microorganisms tend to discriminate against these sources in favor of more accessible forms of soil organic matter as energy sources, resulting in a slower rate of C cycling. </p><p>Our results demonstrate that even in deeply weathered tropical soils, parent material has a long-lasting effect on soil chemistry that can influence and control microbial activity, the size of subsoil C stocks, and the turnover of C in soil. Soil parent material and its lasting control on soil chemistry need to be taken into account to understand and predict C stabilization and rates of C cycling in tropical forest soils. </p>

Carbon stocks in Tasmanian soils

Soil Research ◽  
2012 ◽  
Vol 50 (2) ◽  
pp. 83 ◽  
Author(s):  
W. E. Cotching
Keyword(s):  
Management Practices ◽  
Agricultural Soils ◽  
C Sequestration ◽  
Mean Annual Temperature ◽  
Soil C ◽  
C Stocks ◽  
Initial Soil ◽  
If Current ◽  
Intensive Cropping ◽  
The Difference

Soil carbon (C) stocks were calculated for Tasmanian soil orders to 0.3 and 1.0 m depth from existing datasets. Tasmanian soils have C stocks of 49–117 Mg C/ha in the upper 0.3 m, with Ferrosols having the largest soil C stocks. Mean soil C stocks in agricultural soils were significantly lower under intensive cropping than under irrigated pasture. The range in soil C within soil orders indicates that it is critical to determine initial soil C stocks at individual sites and farms for C accounting and trading purposes, because the initial soil C content will determine if current or changed management practices are likely to result in soil C sequestration or emission. The distribution of C within the profile was significantly different between agricultural and forested land, with agricultural soils having two-thirds of their soil C in the upper 0.3 m, compared with half for forested soils. The difference in this proportion between agricultural and forested land was largest in Dermosols (0.72 v. 0.47). The total amount of soil C in a soil to 1.0 m depth may not change with a change in land use, but the distribution can and any change in soil C deeper in the profile might affect how soil C can be managed for sequestration. Tasmanian soil C stocks are significantly greater than those in mainland states of Australia, reflecting the lower mean annual temperature and higher precipitation in Tasmania, which result in less oxidation of soil organic matter.

Required sample size for estimating soil respiration rates in large areas of two tropical forests and of two types of plantation in Malaysia

2005 ◽  
Vol 210 (1-3) ◽  
pp. 455-459 ◽  
Author(s):  
Minako Adachi ◽  
Yukiko Sakata Bekku ◽  
Akihiro Konuma ◽  
Wan Rasidah Kadir ◽  
Toshinori Okuda ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Sample Size ◽  
Tropical Forests ◽  
Respiration Rates

scholarly journals Beneath the arctic greening: Will soils lose or gain carbon or perhaps a little of both?

2019 ◽  
Author(s):  
Jennifer W. Harden ◽  
Jonathan A. O'Donnell ◽  
Katherine A. Heckman ◽  
Benjamin N. Sulman ◽  
Charles D. Koven ◽  
...  
Keyword(s):  
Steady State ◽  
Forest Soil ◽  
The Arctic ◽  
Mean Annual Temperature ◽  
Spruce Forest ◽  
Organic C ◽  
Soil C ◽  
Community Land Model ◽  
C Stocks ◽  
And Shifts

Abstract. Ecosystem shifts related to climate change are anticipated for the next decades to centuries based on a number of conceptual and experimentally derived models of plant structure and function. Belowground, the potential responses of soil systems are less well known. We used geochemical steady state models, soil density fractionation, and soil radiocarbon data to constrain changes in soil carbon based on measurements from detrital (free light), aggregate-bound (occluded) and complexed or chemically bound (mineral associated) carbon pools and for bulk soil. We explored a space-for-time sequence of soils along a cold-to-warm climatic gradient from Alaskan Black Spruce forest soil with permafrost (Gelisols; 50 cm Mean Annual Temperature −1.5 ºC), Alaskan White Spruce forest soil lacking permafrost (Inceptisols; 50 cm MAT +3 ºC ), and Iowa Grassland soil lacking permafrost (Mollisols; 50 cm MAT +9 ºC) developed on similar geologic substrates (wind-blown loess deposits). These temperature ranges were also representative of temperatures at 50 cm soil depth from model output by the Community Land Model for the years 2014, 2100, and 2300 for Interior Alaska. Fitting an exponential equation to depth trends in soil C down to 2 m depths, we found that depth distributions of organic C were related mainly to depths of rooting and changes in bulk density. Using output from the geochemical steady state model, the direction and magnitude of the C loss or gain upon ecosystem shift was dictated by the C stocks of initial and final ecosystems. Radiocarbon measurements specific to each soil fraction (free light, occluded, and mineral associated) allowed us to constrain the timing of the potential loss or gain of C in each fraction driven by climatic shifts. Thawing from the Gelisol to Inceptisol in loess parent materials from present day to year 2100 resulted in small net gains to soil C, reflecting the net balance between loss of detrital and gain into occluded and mineral associated C. Greater warming and shifts from Inceptisol to Mollisol analogous to predicted warming from circa 2100 to 2300 resulted in net C losses from both occluded and mineral associated C, although small gains to the free light C fraction occurred throughout the depth profile. Gains to occluded and mineral associated C post- thaw likely reflect aggregate formation and physical protection of C as well as formation of organo-mineral compounds that accompany microbial processing. Greater warming and shifts from Inceptisol to Mollisol, which are analogous to predicted warming circa 2100 to 2300, resulted in net C losses from both occluded and mineral associated C resulting from enhanced decomposition, small gains to the free light C fraction occurred throughout the transition to Mollisol reflecting deeper rooting of the tallgrass prairie system.

scholarly journals Soil carbon stocks and their variability across the forests, shrublands and grasslands of peninsular Spain

2013 ◽  
Vol 10 (12) ◽  
pp. 8353-8361 ◽  
Author(s):  
E. Doblas-Miranda ◽  
P. Rovira ◽  
L. Brotons ◽  
J. Martínez-Vilalta ◽  
J. Retana ◽  
...  
Keyword(s):  
Global Change ◽  
Vegetation Cover ◽  
Field Measurements ◽  
Annual Precipitation ◽  
Future Climate Change ◽  
Mean Annual Temperature ◽  
Soil C ◽  
C Stocks ◽  
The Impact ◽  
Peninsular Spain

Abstract. Accurate estimates of C stocks and fluxes of soil organic carbon (SOC) are needed to assess the impact of climate and land use change on soil C uptake and soil C emissions to the atmosphere. Here, we present an assessment of SOC stocks in forests, shrublands and grasslands of peninsular Spain based on field measurements in more than 900 soil profiles. SOC to a depth of 1 m was modelled as a function of vegetation cover, mean annual temperature, total annual precipitation, elevation and the interaction between temperature and elevation, while latitude and longitude were used to model the correlation structure of the errors. The resulting statistical model was used to estimate SOC in the ∼8 million pixels of the Spanish Forest Map (29.3 × 106 ha). We present what we believe is the most reliable estimation of current SOC in forests, shrublands and grasslands of peninsular Spain thus far, based on the use of spatial modelling, the high number of profiles and the validity and refinement of the data layers employed. Mean concentration of SOC was 8.7 kg m−2, ranging from 2.3 kg m−2 in dry Mediterranean areas to 20.4 kg m−2 in wetter northern locations. This value corresponds to a total stock of 2.544 Tg SOC, which is four times the amount of C estimated to be stored in the biomass of Spanish forests. Climate and vegetation cover were the main variables influencing SOC, with important ecological implications for peninsular Spanish ecosystems in the face of global change. The fact that SOC was positively related to annual precipitation and negatively related to mean annual temperature suggests that future climate change predictions of increased temperature and reduced precipitation may strongly reduce the potential of Spanish soils as C sinks. However, this may be mediated by changes in vegetation cover (e.g. by favouring the development of forests associated to higher SOC values) and exacerbated by perturbations such as fire. The estimations presented here provide a baseline to estimate future changes in soil C stocks and to assess their vulnerability to key global change drivers, and should inform future actions aimed at the conservation and management of C stocks.

scholarly journals Evaluating the role soil nutrients play in regulating soil greenhouse gas fluxes from the pristine tropical forests: evidence from a nutrient manipulation experiment in Uganda

2021 ◽  
Author(s):  
Joseph Tamale ◽  
Roman Hüppi ◽  
Marco Griepentrog ◽  
Laban Frank Turyagyenda ◽  
Matti Barthel ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Tropical Forest ◽  
Tropical Forests ◽  
Microbial Respiration ◽  
N Fertilization ◽  
P Fertilization ◽  
Gas Fluxes ◽  
Nutrient Manipulation ◽  
Greenhouse Gas Fluxes ◽  
Manipulation Experiment

<p>The exchange of the climate-relevant greenhouse gases (GHGs) at the soil-atmospheric interface is regulated by both abiotic and biotic controls. However, evidence on nutrient limitations of soil GHG fluxes from African tropical forest ecosystems is still rare. Therefore, an ecosystem-scale nutrient manipulation experiment (NME) consisting of nitrogen (N), phosphorus (P), N + P, and control treatments was set up in a tropical forest in northwestern Uganda. Soil carbon dioxide (CO<sub>2</sub>), methane (CH<sub>4</sub>), and nitrous oxide (N<sub>2</sub>O) fluxes were measured monthly using static vented chambers for 14 months. A root trenching treatment was also done in all the experimental plots in order to disentangle the contribution of root and microbial respiration to total soil CO<sub>2</sub> effluxes. In parallel to soil GHG flux measurements, soil temperature, soil moisture, and mineral N were determined. Lifting the N limitation on the soil nitrifiers and denitrifiers through N fertilization significantly increased N<sub>2</sub>O fluxes in N, and N + P addition plots in the transitory phase (0-28 days after N fertilization, p < 0.01). However, sustained N fertilization did not significantly affect background (measured more than 28 days after fertilization) N<sub>2</sub>O fluxes. Alleviation of the P limitation on soil methanotrophs through P fertilization marginally and significantly increased CH<sub>4</sub> consumption in the transitory (p = 0.052) and background (p = 0.010) phases, respectively. Simultaneous addition of N and P (N + P) significantly affected transitory soil CO<sub>2</sub> effluxes (p = 0.010), suggesting a possible co-limitation of N and P on soil respiration. Microbial CO<sub>2</sub> effluxes were significantly larger than root CO<sub>2</sub> effluxes (p < 0.001) across all treatment plots so was the contribution of microbial respiration to the total soil CO<sub>2</sub> effluxes (about 70 %, p < 0.001). Despite the fact that soil respiration was affected through N + P fertilization, neither heterotrophic nor autotrophic respiration significantly differed in either the N + P or the other treatments. Overall, the study findings suggest that the contribution of tropical forests to the global soil GHG budget could be altered by changes in N and P availability in these biomes.</p><p>Key words: Soil greenhouse gas fluxes, nutrient manipulation experiment, soil nutrient limitation, and Ugandan tropical pristine forest.</p>

scholarly journals Large fluxes and rapid turnover of mineral-associated carbon across topographic gradients in a humid tropical forest: insights from paired <sup>14</sup>C analysis

2015 ◽  
Vol 12 (2) ◽  
pp. 891-932 ◽  
Author(s):  
S. J. Hall ◽  
G. McNicol ◽  
T. Natake ◽  
W. L. Silver
Keyword(s):  
Tropical Forests ◽  
Clay Content ◽  
Multiple Time ◽  
Luquillo Experimental Forest ◽  
Reactive Metal ◽  
Near Surface ◽  
Soil C ◽  
C Stocks ◽  
Pool Model ◽  
Topographic Positions

Abstract. It has been proposed that the large soil carbon (C) stocks of humid tropical forests result predominantly from C stabilization by reactive minerals, whereas oxygen (O2) limitation of decomposition has received much less attention. We examined the importance of these factors in explaining patterns of C stocks and turnover in the Luquillo Experimental Forest, Puerto Rico, using radiocarbon (14C) measurements of contemporary and archived samples. Samples from ridge, slope, and valley positions spanned three soil orders (Ultisol, Oxisol, Inceptisol) representative of humid tropical forests, and differed in texture, reactive metal content, O2 availability, and root biomass. Mineral-associated C comprised the large majority (87 ± 2%, n = 30) of total soil C. Turnover of most mineral-associated C (74 ± 4%) was rapid (9 to 29 years, mean and SE 20 ± 2 years) in 25 of 30 soil samples across surface horizons (0–10 and 10–20 cm depths) and all topographic positions, independent of variation in reactive metal concentrations and clay content. Passive C with centennial – millennial turnover was much less abundant (26%), even at 10–20 cm depths. Carbon turnover times and concentrations significantly increased with concentrations of reduced iron (Fe(II)) across all samples, suggesting that O2 availability may have limited the decomposition of mineral associated C over decadal scales. Steady-state inputs of mineral-associated C were similar among the three topographic positions, and could represent 10–30% of annual litterfall production (estimated by doubling aboveground litterfall). Observed trends in mineral-associated Δ14C over time could not be fit using the single pool model used in many other studies, which generated contradictory relationships between turnover and Δ14C as compared with a more realistic constrained two-pool model. The large C fluxes in surface and near-surface soils implied by our data suggest that other studies using single-pool Δ14C models of mineral-associated C dynamics, unconstrained by multiple time points, may have systematically underestimated C turnover.

scholarly journals Soil carbon stocks and their variability across the woodlands of peninsular Spain

2013 ◽  
Vol 10 (7) ◽  
pp. 10913-10936
Author(s):  
E. Doblas-Miranda ◽  
P. Rovira ◽  
L. Brotons ◽  
J. Martínez-Vilalta ◽  
J. Retana ◽  
...  
Keyword(s):  
Global Change ◽  
Vegetation Cover ◽  
Carbon Stocks ◽  
Annual Precipitation ◽  
Future Climate Change ◽  
Mean Annual Temperature ◽  
Soil C ◽  
C Stocks ◽  
The Impact ◽  
Peninsular Spain

Abstract. Global warming effects in our ecosystems could be offset by reducing carbon emissions and protecting and increasing carbon stocks. Accurate estimates of carbon stocks and fluxes of soil organic carbon (SOC) are thus needed to asses the impact of climate and land-use change on soil C uptake and soil C emissions to the atmosphere. Here, we present an assessment of SOC stocks in woodlands (forest, shrublands and grasslands) of peninsular Spain based on field measurements in more than 900 soil profiles. Estimations of soil C stocks for the 7 796 306 plots of the Spanish Forest Map (24.3 × 106 ha.) were carried out using a statistical model that included, as explanatory variables, vegetation cover, parent material, soil consistency, mean annual temperature, total annual precipitation and elevation, and the influence of spatial correlation. We present what we believe is the most reliable estimation of current SOC in woodlands of peninsular Spain thus far, based on the considered predictors, the high number of profiles and the validity and refinement of the data layers employed. Mean concentration of SOC was 8.8 kg m−2, which is slightly higher than that presented in previous studies. This value corresponds to a total stock of 2574 Tg SOC, which is four times the amount of carbon estimated to be stored in the biomass of Spanish forests. Climate and vegetation cover were the main variables influencing SOC, with important ecological implications for peninsular Spanish ecosystems in the face of global change. The fact that SOC was positively related to annual precipitation and negatively related to mean annual temperature suggests that future climate change may strongly reduce the potential of Spanish soils as carbon sinks. However, this may be mediated by changes in vegetation cover (e.g., by favouring the development of forests associated to higher SOC values) and threatened by perturbations such as fire. The estimations presented here should improve our capacity to respond to global change by carbon stocks conservation and management.

Sign in / Sign up

Export Citation Format

Share Document