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Long term effect of land reclamation from lake on chemical composition of soil organic matter and its mineralization.

He D, Ruan H - PLoS ONE (2014)

Bottom Line: It has greatly diminished the lake area, and altered natural ecological succession.However, little is known about its impact on the carbon (C) cycle.The active C pool in EBF at 10-25 cm had longer (62 days) mean residence time (MRT).

View Article: PubMed Central - PubMed

Affiliation: Faculty of Forest Resources and Environmental Science, and Key Laboratory of Forestry and Ecological Engineering of Jiangsu Province, Nanjing Forestry University, Nanjing, Jiangsu, China.

ABSTRACT
Since the late 1950s, land reclamation from lakes has been a common human disturbance to ecosystems in China. It has greatly diminished the lake area, and altered natural ecological succession. However, little is known about its impact on the carbon (C) cycle. We conducted an experiment to examine the variations of chemical properties of dissolved organic matter (DOM) and C mineralization under four land uses, i.e. coniferous forest (CF), evergreen broadleaf forest (EBF), bamboo forest (BF) and cropland (CL) in a reclaimed land area from Taihu Lake. Soils and lake sediments (LS) were incubated for 360 days in the laboratory and the CO2 evolution from each soil during the incubation was fit to a double exponential model. The DOM was analyzed at the beginning and end of the incubation using UV and fluorescence spectroscopy to understand the relationships between DOM chemistry and C mineralization. The C mineralization in our study was influenced by the land use with different vegetation and management. The greatest cumulative CO2-C emission was observed in BF soil at 0-10 cm depth. The active C pool in EBF at 10-25 cm had longer (62 days) mean residence time (MRT). LS showed the highest cumulative CO2-C and shortest MRT comparing with the terrestrial soils. The carbohydrates in DOM were positively correlated with CO2-C evolution and negatively correlated to phenols in the forest soils. Cropland was consistently an outlier in relationships between DOM chemistry and CO2-evolution, highlighting the unique effects that this land use on soil C cycling, which may be attributed the tillage practices. Our results suggest that C mineralization is closely related to the chemical composition of DOM and sensitive to its variation. Conversion of an aquatic ecosystem into a terrestrial ecosystem may alter the chemical structure of DOM, and then influences soil C mineralization.

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Dynamics of C mineralization of soils under different land use types reclaimed from Taihu Lake, China.(a): C mineralization at 0–10 cm depth; (b): C mineralization at 10–25 cm depth. Bars indicate the standard errors (n = 4).
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pone-0099251-g003: Dynamics of C mineralization of soils under different land use types reclaimed from Taihu Lake, China.(a): C mineralization at 0–10 cm depth; (b): C mineralization at 10–25 cm depth. Bars indicate the standard errors (n = 4).

Mentions: The rate of CO2-C evolution from all land use types were highest at the beginning and then decreased progressively with the advancement of time (Fig. 3). The CO2-C evolution patterns in all land uses and lake sediments were best described by the double exponential model, with the model fits resulting in r2 values between 0.96 and 0.99 (Table 3). The size of the labile C pool in different soils was comprised of 0.2%–7.09% with the highest value in LS at 10–25 cm depth. The k1 values (mineralization rate constant) of labile C at 0–10 cm depth ranged from 0.02 to 0.19 with the mean residence time (MRT1) of 21 days (average of all soils), varying from 0.02 to 0.12 at 10–25 cm depth with an average MRT1 of 33 days. Determination of the size and turnover of the stable C pool showed values at 0–10 cm soil depth were larger than those at 10–25 cm soil depth (Table 3). The mineralization rate constants of the stable C pool (k2) were 2–3 orders of magnitude lower than k1, ranging from 0.00022 to 0.00098 in upper soil layer with an average of MRT2 of 9 years and ranging from 0.00011 to 0.00129 in lower soil layer with an average of MRT2 of 12 years. At 0–10 cm soil depth, the mean residence time of active and stable C pools in CL sites was larger than the others, whereas at 10–25 cm soil depth, the largest mean residence time of stable C pools was found in BF. The mean residence time of active and stable C pools in LS was lower than all other land use types.


Long term effect of land reclamation from lake on chemical composition of soil organic matter and its mineralization.

He D, Ruan H - PLoS ONE (2014)

Dynamics of C mineralization of soils under different land use types reclaimed from Taihu Lake, China.(a): C mineralization at 0–10 cm depth; (b): C mineralization at 10–25 cm depth. Bars indicate the standard errors (n = 4).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4048317&req=5

pone-0099251-g003: Dynamics of C mineralization of soils under different land use types reclaimed from Taihu Lake, China.(a): C mineralization at 0–10 cm depth; (b): C mineralization at 10–25 cm depth. Bars indicate the standard errors (n = 4).
Mentions: The rate of CO2-C evolution from all land use types were highest at the beginning and then decreased progressively with the advancement of time (Fig. 3). The CO2-C evolution patterns in all land uses and lake sediments were best described by the double exponential model, with the model fits resulting in r2 values between 0.96 and 0.99 (Table 3). The size of the labile C pool in different soils was comprised of 0.2%–7.09% with the highest value in LS at 10–25 cm depth. The k1 values (mineralization rate constant) of labile C at 0–10 cm depth ranged from 0.02 to 0.19 with the mean residence time (MRT1) of 21 days (average of all soils), varying from 0.02 to 0.12 at 10–25 cm depth with an average MRT1 of 33 days. Determination of the size and turnover of the stable C pool showed values at 0–10 cm soil depth were larger than those at 10–25 cm soil depth (Table 3). The mineralization rate constants of the stable C pool (k2) were 2–3 orders of magnitude lower than k1, ranging from 0.00022 to 0.00098 in upper soil layer with an average of MRT2 of 9 years and ranging from 0.00011 to 0.00129 in lower soil layer with an average of MRT2 of 12 years. At 0–10 cm soil depth, the mean residence time of active and stable C pools in CL sites was larger than the others, whereas at 10–25 cm soil depth, the largest mean residence time of stable C pools was found in BF. The mean residence time of active and stable C pools in LS was lower than all other land use types.

Bottom Line: It has greatly diminished the lake area, and altered natural ecological succession.However, little is known about its impact on the carbon (C) cycle.The active C pool in EBF at 10-25 cm had longer (62 days) mean residence time (MRT).

View Article: PubMed Central - PubMed

Affiliation: Faculty of Forest Resources and Environmental Science, and Key Laboratory of Forestry and Ecological Engineering of Jiangsu Province, Nanjing Forestry University, Nanjing, Jiangsu, China.

ABSTRACT
Since the late 1950s, land reclamation from lakes has been a common human disturbance to ecosystems in China. It has greatly diminished the lake area, and altered natural ecological succession. However, little is known about its impact on the carbon (C) cycle. We conducted an experiment to examine the variations of chemical properties of dissolved organic matter (DOM) and C mineralization under four land uses, i.e. coniferous forest (CF), evergreen broadleaf forest (EBF), bamboo forest (BF) and cropland (CL) in a reclaimed land area from Taihu Lake. Soils and lake sediments (LS) were incubated for 360 days in the laboratory and the CO2 evolution from each soil during the incubation was fit to a double exponential model. The DOM was analyzed at the beginning and end of the incubation using UV and fluorescence spectroscopy to understand the relationships between DOM chemistry and C mineralization. The C mineralization in our study was influenced by the land use with different vegetation and management. The greatest cumulative CO2-C emission was observed in BF soil at 0-10 cm depth. The active C pool in EBF at 10-25 cm had longer (62 days) mean residence time (MRT). LS showed the highest cumulative CO2-C and shortest MRT comparing with the terrestrial soils. The carbohydrates in DOM were positively correlated with CO2-C evolution and negatively correlated to phenols in the forest soils. Cropland was consistently an outlier in relationships between DOM chemistry and CO2-evolution, highlighting the unique effects that this land use on soil C cycling, which may be attributed the tillage practices. Our results suggest that C mineralization is closely related to the chemical composition of DOM and sensitive to its variation. Conversion of an aquatic ecosystem into a terrestrial ecosystem may alter the chemical structure of DOM, and then influences soil C mineralization.

Show MeSH
Related in: MedlinePlus