Effects of freezing and thawing on soil active organic carbon and enzyme activity in the Sanjiang Plain wetlands

Abstract. Accurate estimation of soil organic carbon (SOC) storage and determination of its pattern controlling factors is critical to understanding the ecosystem carbon cycle and ensuring ecological security. The Sanjiang Plain of China, an important grain production base, is typical of ecosystems, yet the SOC storage and pattern of this region has not been fully investigated because of the deficient soil investigations. In this study, 419 soil samples and a geostatistical method were used to estimate the total SOC storage and density (SOCD) of this region with the former being 2.324 Pg C, and the latter value being higher than the mean value for the whole country. The SOCD was found to have notable changes in spatial and vertical distribution. In addition, the vegetation, climate, and soil texture, as well as the agricultural activities, were demonstrated to have remarkable impacts on the variation of SOCD. Soil texture had stronger impacts on the distribution of SOCD than climate in the Sanjiang Plain. Specifically, the clay content explained the largest proportion of the SOC variation and was thus the most dominant environmental controlling factor. As far as climatic factors are concerned, precipitation exhibited more significant effects on SOCD than temperature. In addition, the effects of both climate and soil texture on SOCD were reduced with increasing soil layer depth. The results from this study provide the most updated knowledge on the storage and pattern of SOC in the Sanjiang Plain, and the analysis conducted here could contribute to the determination of ecosystem carbon budgets and understanding of ecosystem services.

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Response of Soil Active Organic Carbon and Enzyme Activity to Freeze-Thaw Cycle in Wetlands

10.21203/rs.3.rs-1057908/v1 ◽

2021 ◽

Author(s):

Jinqiu Guan ◽

Chunxiang Song ◽

Yude Wu ◽

Xingtian Qi ◽

Rongjun Qu ◽

...

Keyword(s):

Enzyme Activity ◽

Organic Carbon ◽

Enzyme Activities ◽

Soil Depth ◽

Soil Enzyme ◽

Carbon Fractions ◽

Freeze Thaw ◽

Active Organic Carbon ◽

Doc Concentration ◽

Organic Carbon Fractions

Abstract Freeze-thaw cycles (FTCs) are an important element of mid and high latitude ecosystems, and significantly influence soil physicochemical properties and microbial activities in the soil active layers. With the global warming, the effects of FTCs on the dissolved organic carbon (DOC) concentration and soil enzyme activity of different types of soil were still uncertain. In this study, soil of undisturbed Deyeuxia angustifolia wetland (UDAW), disturbed Deyeuxia angustifolia wetland (DDAW) and rice paddy field (RP) from three soil layers of (0–10, 10–20 and 20–30 cm) in Sanjiang Plain, Northeast China, were collected, and then subjected to various FTCs with a large (10 to -10℃) and a small (5 to -5℃) amplitudes, respectively. The results indicated that FTCs increased the soil DOC concentration but reduced the concentration of MBC and activities of cellulase, invertase and catalase. Increase in the freeze-thaw frequency, resulted in the DOC concentration increasing initially and then decreasing, and the MBC concentration and soil enzyme activities were opposite. The DOC concentration increment resulting from the freeze-thaw effects was different across different layers and soil type: as the soil depth increased, the average DOC increments decreased, and the average DOC increments varied across different soil types: UDAW > DDAW > RP. The average MBC concentration and soil enzyme activity decreased from 0-10 cm > 10-20 cm > 20-30 cm soil depth; MBC concentration and soil enzyme activities varied across the different soil types: UDAW > DDAW > RP. The freeze-thaw amplitude and soil moisture content interaction had an effect on soil active organic carbon fractions and enzymatic activity. Small amplitude FTCs and higher water content had the greatest effect on DOC concentration, while larger amplitude and higher water content had the greatest effect on MBC concentration and enzymatic activity. In wetland soil, the significant correlations between active organic carbon fractions and enzyme activities indicate that the increased DOC by FTCs plays an important role in soil microbes and enzyme activities. However, active organic carbon fractions and enzyme activities had little correlation in RP, indicating that FTCs has more influence on wetland than farmland.

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Effects of water gradients on soil enzyme activity and active organic carbon composition under Carex lasiocarpa marsh

Acta Ecologica Sinica ◽

10.1016/s1872-2032(09)60013-5 ◽

2008 ◽

Vol 28 (12) ◽

pp. 5980-5986 ◽

Cited By ~ 15

Author(s):

Wan Zhongmei ◽

Song Changchun ◽

Guo Yuedong ◽

Wang Li ◽

Huang Jingyu

Keyword(s):

Enzyme Activity ◽

Organic Carbon ◽

Soil Enzyme ◽

Soil Enzyme Activity ◽

Carex Lasiocarpa ◽

Active Organic Carbon ◽

Water Gradients ◽

Carbon Composition

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Dissolved organic carbon characteristics in surface ponds from contrasting wetland ecosystems: a case study in the Sanjiang Plain, Northeast China

Hydrology and Earth System Sciences ◽

10.5194/hess-17-371-2013 ◽

2013 ◽

Vol 17 (1) ◽

pp. 371-378 ◽

Cited By ~ 6

Author(s):

L. L. Wang ◽

C. C. Song ◽

G. S. Yang

Keyword(s):

Organic Carbon ◽

Rice Paddy ◽

Sanjiang Plain ◽

Riparian Wetlands ◽

Natural Wetland ◽

The Sanjiang Plain ◽

Wetland Ecosystems ◽

Wetland Site ◽

Doc Concentration ◽

Natural Wetlands

Abstract. Dissolved organic carbon (DOC) is a significant component of carbon and nutrient cycling in fluvial ecosystems. Natural wetlands, as important DOC sources for river and ocean ecosystems, have experienced extensive natural and anthropogenic disturbances such as climate change, hydrological variations and land use change in recent years. The DOC characteristics in surface ponds from contrasting wetlands in the Sanjiang Plain, Northeastern China were investigated. Surface ponds at seven sites (two natural phialiform wetlands, three natural riparian wetlands, one degraded wetland and one artificial wetland, i.e., rice paddy) were monitored during the growing seasons of 2009 and 2010. The results show that the surface ponds at the five natural wetland sites exhibited a wide range of DOC concentrations (10.06–48.73 mg L−1) during the study period. The DOC concentrations showed no annual differences (P > 0.05) at all the wetland sites, except one of the phialiform wetland sites. The two phialiform wetlands exhibited higher DOC concentrations than the three riparian wetlands (P < 0.05). The DOC concentration in the surface pond at the artificial wetland site was relatively low (P < 0.05) compared to that at the degraded wetland site. The C/C ratios (the color per carbon unit ratio, Abs400/DOC concentration) showed inconsistent variations among these seven wetland sites, while the E4/E6 ratio (Abs465/Abs665, fulvic acid/humic acid) from the surface pond in the rice paddy land exerted 42.07–55.36% reductions (P < 0.05), compared to those at the five natural wetland sites. Furthermore, the E4/E6 ratio in the surface pond at the rice paddy site was significantly lower compared to that at the degraded wetland site (P < 0.05), which indicated that disturbance to wetland DOC in surface ponds might be stronger when natural wetlands were converted to rice paddies in comparison with wetland degradation. This study could not only provide insightful points for understanding the aquatic DOC dynamics from different wetland ecosystems, but also support data information for incorporating the aquatic DOC into the model for regional carbon budgets in the future.

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