scholarly journals Vertical and seasonal changes in soil carbon pools to vegetation degradation in a wet meadow on the Qinghai-Tibet Plateau

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiangqi Wu ◽  
Haiyan Wang ◽  
Guang Li ◽  
Jianghua Wu ◽  
Weiwei Ma
Keyword(s):  
Organic Carbon ◽  
Soil Carbon ◽  
Seasonal Changes ◽  
Soil Depth ◽  
Plant Litter ◽  
Tibet Plateau ◽  
Wet Meadow ◽  
Wet Meadows ◽  
Vegetation Degradation ◽  
Soc Fractions

AbstractWet meadows provide opportunities to decrease carbon dioxide (CO2) and methane (CH4) released into the atmosphere by increasing the soil organic carbon (SOC) stored in wetland systems. Although wet meadows serve as the most important and stable C sinks, there has been very few investigations on the seasonal distributions of SOC fractions in high-altitude wet meadows. Here, we studied the effects of four vegetation degradation levels, non-degraded (ND), lightly degraded (LD), moderately degraded (MD), and heavily degraded (HD), on the measured vertical and seasonal changes of SOC and its different fractions. Among these vegetation degradation levels, 0–10 and 10–20 cm soil depths in ND plots had significantly higher SOC contents than the other degradation levels had throughout the year. This is attributed to the relatively greater inputs of aboveground plant litter and richer fine-root biomass in ND plots. Particulate organic carbon (POC) and light fraction organic carbon (LFOC) showed similar vertical and seasonal variations in autumn, reaching a minimum. Moreover, microbial biomass (MBC) and easily oxidizable organic carbon (EOC) contents were highest in summer and the smallest in winter, while dissolved organic carbon (DOC) content was highest in spring and lowest in summer, and were mainly concentrated in the 0–20 cm layer. Pearson correlation analysis indicated that soil properties and aboveground biomass were significantly related to different SOC fractions. The results indicate that vegetation degradation reduces the accumulation of total SOC and its different fractions, which may reduce carbon sink capacity and soil quality of alpine wet meadows, and increase atmospheric environmental pressure. In addition, vegetation biomass and soil characteristics play a key role in the formation and transformation of soil carbon. These results strengthen our understanding of soil C dynamics, specifically related to the different C fractions as affected by vegetation degradation levels and soil depth, in wet meadow systems.

scholarly journals Vegetation degradation impacts soil nutrients and enzyme activities in wet meadow on the Qinghai-Tibet Plateau

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jiangqi Wu ◽  
Haiyan Wang ◽  
Guang Li ◽  
Weiwei Ma ◽  
Jianghua Wu ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Soil Nutrients ◽  
Enzyme Activities ◽  
Soil Depth ◽  
Soil Nutrient ◽  
Tibet Plateau ◽  
Wet Meadow ◽  
Vegetation Degradation ◽  
Thaw Cycle ◽  
Qinghai Tibet Plateau

AbstractVegetation degradation, due to climate change and human activities, changes the biomass, vegetation species composition, and soil nutrient input sources and thus affects soil nutrient cycling and enzyme activities. However, few studies have focused on the responses of soil nutrients and enzymes to vegetation degradation in high-altitude wet meadows. In this study, we examined the effects of vegetation degradation on soil nutrients (soil organic carbon, SOC; total nitrogen, TN; total phosphorus, TP) and enzyme activities (i.e., urease, catalase, amylase) in an alpine meadow in the eastern margin of the Qinghai-Tibet Plateau. Four different levels of degradation were defined in terms of vegetation density and composition: primary wet meadow (CK), lightly degraded (LD), moderately degraded (MD), and heavily degraded (HD). Soil samples were collected at depth intervals of 0–10, 10–20, 20–40, 40–60, 60–80, and 80–100 cm to determine soil nutrient levels and enzyme activities. The results showed that SOC, TN, catalase and amylase significantly decreased with degradation level, while TP and urease increased with degradation level (P < 0.05). Soil nutrient and enzyme activity significantly decreased with soil depth (P < 0.05), and the soil nutrient and enzyme activity exhibited obvious "surface aggregation". The activities of soil urease and catalase were strongest in spring and weakest in winter. The content of TN in spring, summer, and autumn was significantly higher than observed in winter (P < 0.05). The soil TP content increased in winter. Soil amylase activity was significantly higher in summerm than in spring, autumn, and winter (P < 0.05). TP was the main limiting factor for plant growth in the Gahai wet meadow. Values of SOC and TN were positively and significantly correlated with amylase and catalase (P < 0.05), but negatively correlated with urease (P < 0.05). These results suggest the significant role that vegetation degradation and seasonal freeze–thaw cycle play in regulating enzyme activities and nutrient availability in wet meadow soil.

scholarly journals Response of soil organic carbon to vegetation degradation along a moisture gradient in a wet meadow on the Qinghai-Tibet Plateau

2018 ◽  
Vol 8 (23) ◽  
pp. 11999-12010 ◽  
Author(s):  
Abdul-Rauf Malimanga Alhassan ◽  
Weiwei Ma ◽  
Guang Li ◽  
Zhirong Jiang ◽  
Jiangqi Wu ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Moisture Gradient ◽  
Tibet Plateau ◽  
Wet Meadow ◽  
Vegetation Degradation ◽  
Qinghai Tibet Plateau

Estimates of soil organic carbon stocks in central Canada using three different approaches

2002 ◽  
Vol 32 (5) ◽  
pp. 805-812 ◽  
Author(s):  
J S Bhatti ◽  
M J Apps ◽  
C Tarnocai
Keyword(s):  
Surface Layer ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Carbon ◽  
Soil Depth ◽  
Peat Soil ◽  
Regression Line ◽  
Organic C ◽  
Soil C ◽  
Total Soil

This study compared three estimates of carbon (C) contained both in the surface layer (0–30 cm) and the total soil pools at polygon and regional scales and the spatial distribution in the three prairie provinces of western Canada (Alberta, Saskatchewan, and Manitoba). The soil C estimates were based on data from (i) analysis of pedon data from both the Boreal Forest Transect Case Study (BFTCS) area and from a national-scale soil profile database; (ii) the Canadian Soil Organic Carbon Database (CSOCD), which uses expert estimation based on soil characteristics; and (iii) model simulations with the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS2). At the polygon scale, good agreement was found between the CSOCD and pedon (the first method) total soil carbon values. Slightly higher total soil carbon values obtained from BFTCS averaged pedon data (the first method), as indicated by the slope of the regression line, may be related to micro- and meso-scale geomorphic and microclimate influences that are not accounted for in the CSOCD. Regional estimates of organic C from these three approaches for upland forest soils ranged from 1.4 to 7.7 kg C·m–2 for the surface layer and 6.2 to 27.4 kg C·m–2 for the total soil. In general, the CBM-CFS2 simulated higher soil C content compared with the field observed and CSOCD soil C estimates, but showed similar patterns in the total soil C content for the different regions. The higher soil C content simulated with CBM-CFS2 arises in part because the modelled results include forest floor detritus pool components (such as coarse woody debris, which account for 4–12% of the total soil pool in the region) that are not included in the other estimates. The comparison between the simulated values (the third method) and the values obtained from the two empirical approaches (the first two methods) provided an independent test of CBM-CFS2 soil simulations for upland forests soils. The CSOCD yielded significantly higher C content for peatland soils than for upland soils, ranging from 14.6 to 28 kg C·m–2 for the surface layer and 60 to 181 kg C·m–2 for the total peat soil depth. All three approaches indicated higher soil carbon content in the boreal zone than in other regions (subarctic, grassland).

scholarly journals Whole-soil warming alters microbial community, but not concentrations of plant-derived soil organic carbon in subsoil

2021 ◽  
Author(s):  
Cyrill Zosso ◽  
Nicholas O.E. Ofiti ◽  
Jennifer L. Soong ◽  
Emily F. Solly ◽  
Margaret S. Torn ◽  
...  
Keyword(s):  
Climate Change ◽  
Microbial Community ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Depth ◽  
Global Climate ◽  
Plant Litter ◽  
Soil Warming ◽  
Four Seasons ◽  
Set Up

&lt;p&gt;Soils will warm in near synchrony with the air over the whole profiles following global climate change. It is largely unknown how subsoil (below 30 cm) microbial communities will respond to this warming and how plant-derived soil organic carbon (SOC) will be affected. Predictions how climate change will affect the large subsoil carbon pool (&gt;50 % of SOC is below 30 cm soil depth) remain uncertain.&lt;/p&gt;&lt;p&gt;At Blodgett forest (California, USA) a field warming experiment was set up in 2013 warming whole soil profiles to 100 cm soil depth by +4&amp;#176;C compared to control plots. We took samples in 2018, after 4.5 years of continuous warming and investigated how warming has affected the abundance and community structure of microoganisms (using phospholipid fatty acids, PLFAs), and plant litter (using cutin and suberin).&lt;/p&gt;&lt;p&gt;The warmed subsoil (below 30 cm) contained significantly less microbial biomass (28%) compared to control plots, whereas the topsoil remained unchanged. Additionally below 50 cm, the microbial community was different in warmed as compared to control plots. Actinobacteria were relatively more abundant and Gram+ bacteria adapted their cell-membrane structure to warming. The decrease in microbial abundance might be related to lower SOC concentrations in warmed compared to control subsoils. In contrast to smaller SOC concentrations and less fine root mass in the warmed plots, the concentrations of the plant polymers suberin and cutin did not change. Overall our results demonstrate that already four seasons of simulated whole-soil warming caused distinct depth-specific responses of soil biogeochemistry: warming altered the subsoil microbial community, but not concentrations of plant-derived soil organic carbon.&lt;/p&gt;

scholarly journals Relative stability of soil carbon revealed by shifts in δ<sup>15</sup>N and C:N ratio

2008 ◽  
Vol 5 (1) ◽  
pp. 123-128 ◽  
Author(s):  
F. Conen ◽  
M. Zimmermann ◽  
J. Leifeld ◽  
B. Seth ◽  
C. Alewell
Keyword(s):  
Organic Carbon ◽  
Soil Carbon ◽  
Vegetation Change ◽  
Soil Depth ◽  
C:N Ratio ◽  
Small Sample ◽  
Swiss Alps ◽  
14C Dating ◽  
High Measurement ◽  
Life On Earth

Abstract. Life on earth drives a continuous exchange of carbon between soils and the atmosphere. Some forms of soil carbon, or organic matter, are more stable and have a longer residence time in soil than others. Relative differences in stability have often been derived from shifts in δ13C (which is bound to a vegetation change from C3 to C4 type) or through 14C-dating (which is bound to small sample numbers because of high measurement costs). Here, we propose a new concept based on the increase in δ15N and the decrease in C:N ratio with increasing stability. We tested the concept on grasslands at different elevations in the Swiss Alps. Depending on elevation and soil depth, it predicted mineral-associated organic carbon to be 3 to 73 times more stable than particulate organic carbon. Analysis of 14C-ages generally endorsed these predictions.

scholarly journals Changes in soil organic carbon and nitrogen capacities of <i>Salix cheilophila</i> Schneid along a revegetation chronosequence in semi-arid degraded sandy land of the Gonghe Basin, Tibet Plateau

2014 ◽  
Vol 6 (2) ◽  
pp. 2371-2399 ◽  
Author(s):  
Y. Yu ◽  
Q. Z. Jia
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Depth ◽  
Tibet Plateau ◽  
Stand Age ◽  
Soil Layers ◽  
N Storage ◽  
C And N ◽  
Gonghe Basin ◽  
Semi Arid

Abstract. The Gonghe Basin is a sandified and desertified region of China, but the distribution of soil organic carbon (SOC) and total nitrogen (TN) along the cultivation chronosequence across this ecologically fragile region is not well understood. This study was carried out to understand the effects of afforestation with Salix cheilophila for different periods of time (6, 11, 16, 21 years) to test whether it enhanced C and N storage. Soil samples, in four replications from seven depth increments (every 10 cm from 0 to 30 cm, every 20 cm from 30 to 50 cm and every 50 cm from 50 to 200 cm), were collected in each stand. Soil bulk density, SOC, TN, aboveground biomass and root biomass were measured. Results indicated that changes occurred in both the upper and deeper soil layers with an increase in revegetation time. The 0–200 cm soil showed that the 6-year stand gained 3.89 Mg C ha−1 and 1.00 Mg N ha−1, which accounted for 40.82% of the original SOC and 11.06% of the TN of the 0-year stand. The 11-year stand gained 7.82 Mg C ha−1 and 1.98 Mg N ha−1 in the 0–200 cm soil layers, accounting for 58.06% of the SOC and 19.80% of the TN of the 0-year stand. The 16-year stand gained 11.32 Mg C ha−1 and 3.30 Mg N ha−1 in the 0–200 cm soil layers, accounting for 66.71% of the SOC and 21.98% of the TN of the 0-year stand. The 21-year stand gained 13.05 Mg C ha−1 and 5.45 Mg N ha−1 from the same soil depth, accounting for 69.79% of the SOC and 40.47% of the TN compared with the 0-year stand. The extent of these changes depended on soil depth and plantation age. The results demonstrated that as stand age increased, the storage of SOC and TN increased. These results further indicated that afforestation with S. cheilophila has positive impacts on the Gonghe Basin and has increased the capacity of SOC sequestration and N storage. Shrub's role as carbon sink is compatible with system's management and persistence. The findings are significant for assessing C and N sequestration accurately in semi-arid degraded high-cold sandy regions in the future.

scholarly journals Relative stability of soil carbon revealed by shifts in δ<sup>15</sup>N and C:N ratio

2007 ◽  
Vol 4 (4) ◽  
pp. 2915-2928 ◽  
Author(s):  
F. Conen ◽  
M. Zimmermann ◽  
J. Leifeld ◽  
B. Seth ◽  
C. Alewell
Keyword(s):  
Organic Carbon ◽  
Soil Carbon ◽  
Vegetation Change ◽  
Soil Depth ◽  
C:N Ratio ◽  
Small Sample ◽  
Swiss Alps ◽  
14C Dating ◽  
High Measurement ◽  
Life On Earth

Abstract. Life on earth drives a continuous exchange of carbon between soils and the atmosphere. Some forms of soil carbon, or organic matter, are more stable and have a longer residence time in soil than others. Relative differences in stability have often been derived from shifts in δ13C (which is bound to a vegetation change from C3 to C4 type) or through 14C-dating (which is bound to small sample numbers because of high measurement costs). Here, we propose a new concept based on the increase in δ15N and the decrease in C:N ratio with increasing stability. We tested the concept on grasslands at different elevations in the Swiss Alps. Depending on elevation and soil depth, it predicted mineral-associated organic carbon to be 3 to 73 times more stable than particulate organic carbon. Analysis of 14C-ages generally endorsed these predictions.

scholarly journals Storage and stability of organic carbon in soils as related to depth, occlusion within aggregates, and attachment to minerals

2013 ◽  
Vol 10 (3) ◽  
pp. 1675-1691 ◽  
Author(s):  
M. Schrumpf ◽  
K. Kaiser ◽  
G. Guggenberger ◽  
T. Persson ◽  
I. Kögel-Knabner ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Soil Depth ◽  
Plant Litter ◽  
Parent Material ◽  
Bulk Soil ◽  
Organic C ◽  
Density Fractions ◽  
Depth Profiles ◽  
Forest Sites

Abstract. Conceptual models suggest that stability of organic carbon (OC) in soil depends on the source of plant litter, occlusion within aggregates, incorporation in organo-mineral complexes, and location within the soil profile. Density fractionation is a useful tool to study the relevance of OC stabilization in aggregates and in association with minerals, but it has rarely been applied to full soil profiles. We aim to determine factors shaping the depth profiles of physically unprotected and mineral associated OC and test their relevance for OC stability across a range of European soils that vary in vegetation, soil types, parent material, and land use. At each of the 12 study sites, 10 soil cores were sampled to 60 cm depth and subjected to density separation. Bulk soil samples and density fractions (free light fractions – fLF, occluded light fractions – oLF, heavy fractions – HF) were analysed for OC, total nitrogen (TN), δ14C, and Δ14C. Bulk samples were also incubated to determine CO2 evolution per g OC in the samples (specific mineralization rates) as an indicator for OC stability. Depth profiles of OC in the light fraction (LF-OC) matched those of roots for undisturbed grassland and forest sites, suggesting that roots are shaping the depth distribution of LF-OC. Organic C in the HF declined less with soil depth than LF-OC and roots, especially at grassland sites. The decrease in Δ14C (increase in age) of HF-OC with soil depth was related to soil pH as well as to dissolved OC fluxes. This indicates that dissolved OC translocation contributes to the formation of subsoil HF-OC and shapes the Δ14C profiles. The LF at three sites were rather depleted in 14C, indicating the presence of fossil material such as coal and lignite, probably inherited from the parent material. At the other sites, modern Δ14C signatures and positive correlations between specific mineralization rates and fLF-OC indicate the fLF is a potentially available energy and nutrient source for subsurface microorganisms throughout the profile. Declining specific mineralization rates with soil depth confirm greater stability of OC in subsoils across sites. The overall importance of OC stabilization by binding to minerals was demonstrated by declining specific mineralization rates with increasing contributions of HF-OC to bulk soil OC, and the low Δ14C values of HF-OC. The stability of HF-OC was greater in subsoils than in topsoils; nevertheless, a portion of HF-OC was active throughout the profile. While quantitatively less important than OC in the HF, consistent older ages of oLF-OC than fLF-OC suggest that occlusion of LF-OC in aggregates also contributes to OC stability in subsoils. Overall, our results indicate that association with minerals is the most important factor in stabilization of OC in soils, irrespective of vegetation, soil type, and land use.

scholarly journals Changes in soil organic carbon and nitrogen capacities of <i>Salix cheilophila</i> Schneid along a revegetation chronosequence in semi-arid degraded sandy land of the Gonghe Basin, Tibet Plateau

Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 1045-1054 ◽  
Author(s):  
Y. Yu ◽  
Z. Q. Jia
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Depth ◽  
Tibet Plateau ◽  
Stand Age ◽  
Soil Layers ◽  
N Storage ◽  
C And N ◽  
Gonghe Basin ◽  
Semi Arid

Abstract. The Gonghe Basin is a sandified and desertified region of China, but the distribution of soil organic carbon (SOC) and total nitrogen (TN) along the cultivation chronosequence across this ecologically fragile region is not well understood. This study was carried out to understand the effects of restoration with Salix cheilophila for different periods of time (6, 11, 16, 21 years) to test whether it enhanced C and N storage. Soil samples, in four replications from seven depth increments (0–10, 10–20, 20–30, 30–50, 50–100, 100–150 and 150–200 cm), were collected in each stand. Soil bulk density, SOC, TN, aboveground biomass and root biomass were measured. Results indicated that changes occurred in both the upper and deeper soil layers with an increase in revegetation time. The 0–200 cm soil showed that the 6-year stand gained 3.89 Mg C ha−1 and 1.00 Mg N ha−1, which accounted for 40.82% of the original SOC and 11.06% of the TN of the 0-year stand. The 11-year stand gained 7.82 Mg C ha−1 and 1.98 Mg N ha−1 in the 0–200 cm soil layers, accounting for 58.06% of the SOC and 19.80% of the TN of the 0-year stand. The 16-year stand gained 11.32 Mg C ha−1 and 3.30 Mg N ha−1 in the 0–200 cm soil layers, accounting for 66.71% of the SOC and 21.98% of the TN of the 0-year stand. The 21-year stand gained 13.05 Mg C ha−1 and 5.45 Mg N ha−1 from the same soil depth, accounting for 69.79% of the SOC and 40.47% of the TN compared with the 0-year stand. The extent of these changes depended on soil depth and plantation age. The results demonstrated that, as stand age increased, the storage of SOC and TN increased. These results further indicated that restoration with S. cheilophila has positive impacts on the Gonghe Basin and has increased the capacity of SOC sequestration and N storage. The shrub's role as carbon sink is compatible with system management and persistence. The findings are significant for assessing C and N sequestration accurately in semi-arid degraded high, cold sandy regions in the future.

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