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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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Relationships between cumulative C mineralization and DOM chemical properties of the four land use types.0–10 cm soil depth: a–f; 10–25 cm soil depth: g–l. (a and g) between carbohydrate carbon percentages and cumulative CO2-C, (b and h) between phenol carbon percentages and cumulative CO2-C, (c and i) between hydrophilic carbon and cumulative CO2-C, (d and j) between SUVA254 values and cumulative CO2-C, (e and k) between the fluorescence efficiency and cumulative CO2-C, (f and l) between the humification index (emission fluorescence spectra) and cumulative CO2-C. The curves for the figures are generated with the data of the CL samples excluded.
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pone-0099251-g004: Relationships between cumulative C mineralization and DOM chemical properties of the four land use types.0–10 cm soil depth: a–f; 10–25 cm soil depth: g–l. (a and g) between carbohydrate carbon percentages and cumulative CO2-C, (b and h) between phenol carbon percentages and cumulative CO2-C, (c and i) between hydrophilic carbon and cumulative CO2-C, (d and j) between SUVA254 values and cumulative CO2-C, (e and k) between the fluorescence efficiency and cumulative CO2-C, (f and l) between the humification index (emission fluorescence spectra) and cumulative CO2-C. The curves for the figures are generated with the data of the CL samples excluded.

Mentions: C mineralization was significantly correlated with DOM characteristics and its change (the variation of DOM properties between beginning and ending of incubation) under the four land uses (Table 4, Fig. 4). The CO2-C evolution at the 0–10 cm soil depth had a positive correlation with the proportion of CH, variation of the Hi fraction (ΔHi), fluorescence efficiency variation (ΔFE) and HIXem variation (ΔHIXem), while had a negative correlation with initial Phe, Hi, FE and variation of CH (ΔCH), Phe (ΔPhe) and SUVA254 (ΔSUVA254) (Fig. 4). The high proportion of labile C pool (a value of the double exponential model) from upper soil was related to the high proportion of Phe, Hi fraction and high values of FE. In contrast, it was negatively related to most of the parameters including CH fraction, ΔPhe, ΔHi, HIXem, SUVA254, ΔFE, ΔHIXem and ΔSUVA254 (Table 4). The k1 values of upper soils were correlated very well with proportion of Phe and Hi, the values of FE, HIXem, ΔFE and ΔHIXem, whereas the k2 values were only correlated with Phe, ΔCH, ΔPhe and ΔSUVA254 (Table 4).


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)

Relationships between cumulative C mineralization and DOM chemical properties of the four land use types.0–10 cm soil depth: a–f; 10–25 cm soil depth: g–l. (a and g) between carbohydrate carbon percentages and cumulative CO2-C, (b and h) between phenol carbon percentages and cumulative CO2-C, (c and i) between hydrophilic carbon and cumulative CO2-C, (d and j) between SUVA254 values and cumulative CO2-C, (e and k) between the fluorescence efficiency and cumulative CO2-C, (f and l) between the humification index (emission fluorescence spectra) and cumulative CO2-C. The curves for the figures are generated with the data of the CL samples excluded.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0099251-g004: Relationships between cumulative C mineralization and DOM chemical properties of the four land use types.0–10 cm soil depth: a–f; 10–25 cm soil depth: g–l. (a and g) between carbohydrate carbon percentages and cumulative CO2-C, (b and h) between phenol carbon percentages and cumulative CO2-C, (c and i) between hydrophilic carbon and cumulative CO2-C, (d and j) between SUVA254 values and cumulative CO2-C, (e and k) between the fluorescence efficiency and cumulative CO2-C, (f and l) between the humification index (emission fluorescence spectra) and cumulative CO2-C. The curves for the figures are generated with the data of the CL samples excluded.
Mentions: C mineralization was significantly correlated with DOM characteristics and its change (the variation of DOM properties between beginning and ending of incubation) under the four land uses (Table 4, Fig. 4). The CO2-C evolution at the 0–10 cm soil depth had a positive correlation with the proportion of CH, variation of the Hi fraction (ΔHi), fluorescence efficiency variation (ΔFE) and HIXem variation (ΔHIXem), while had a negative correlation with initial Phe, Hi, FE and variation of CH (ΔCH), Phe (ΔPhe) and SUVA254 (ΔSUVA254) (Fig. 4). The high proportion of labile C pool (a value of the double exponential model) from upper soil was related to the high proportion of Phe, Hi fraction and high values of FE. In contrast, it was negatively related to most of the parameters including CH fraction, ΔPhe, ΔHi, HIXem, SUVA254, ΔFE, ΔHIXem and ΔSUVA254 (Table 4). The k1 values of upper soils were correlated very well with proportion of Phe and Hi, the values of FE, HIXem, ΔFE and ΔHIXem, whereas the k2 values were only correlated with Phe, ΔCH, ΔPhe and ΔSUVA254 (Table 4).

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