Effects of land use and topography on spatial variety of soil organic carbon density in a hilly, subtropical catchment of China

Soil Research ◽  
2017 ◽  
Vol 55 (2) ◽  
pp. 134 ◽  
Author(s):  
Huanyao Liu ◽  
Jiaogen Zhou ◽  
Qingyu Feng ◽  
Yuyuan Li ◽  
Yong Li ◽  
...  

A good understanding the effects of environmental factors on the spatial variety of soil organic carbon density (SOCD) helps achieve a relatively accurate estimation of the soil organic carbon stock of terrestrial ecosystems. The present study analysed the SOCD of 1033 top soil samples (0–20cm) from the Jinjing catchment located in subtropical China. Spatial variability of SOCD was estimated using a geostatistics method and a geographically weighted regression (GWR) model, and the major environmental factors affecting SOCD were also explored. In the present study, SOCD had a moderate spatial dependence and the best-fitting model was exponential with a nugget-to-sill ratio of 60.72% and a range of 182m. Land use types (woodlands, paddy fields and tea fields) and topography (elevation, slope, topographic wetness index (TWI)) affected the spatial variation of SOCD. Mean SOCD in the paddy fields was higher than in woodland and tea fields (3.50 vs 3.24 and 2.81kgCm–2 respectively; P<0.05). In addition, SOCD was generally higher in the valleys of paddy fields (with low slope and high TWI) and the hills of woodland (with high elevation and increased slope). GWR generated the spatial distribution of SOCD more accurately than ordinary kriging, inverse distance weighted, multiple linear regression model, and linear mixed-effects model. The results of the present study could enhance our understanding of the effects of land use and topography on SOCD, and improve the accuracy in predicting SOCD by GWR in small catchments of complex land use and topography.






2020 ◽  
Vol 12 (22) ◽  
pp. 9330
Author(s):  
Tao Liu ◽  
Huan Zhang ◽  
Tiezhu Shi

Different natural environmental variables affect the spatial distribution of soil organic carbon (SOC), which has strong spatial heterogeneity and non-stationarity. Additionally, the soil organic carbon density (SOCD) has strong spatial varying relationships with the environmental factors, and the residuals should keep independent. This is one hard and challenging study in digital soil mapping. This study was designed to explore the different impacts of natural environmental factors and construct spatial prediction models of SOC in the junction region (with an area of 2130.37 km2) between Enshi City and Yidu City, Hubei Province, China. Multiple spatial interpolation models, such as stepwise linear regression (STR), geographically weighted regression (GWR), regression kriging (RK), and geographically weighted regression kriging (GWRK), were built using different natural environmental variables (e.g., terrain, environmental, and human factors) as auxiliary variables. The goodness of fit (R2), root mean square error, and improving accuracy were used to evaluate the predicted results of the spatial interpolation models. Results from Pearson correlation coefficient analysis and STR showed that SOCD was strongly correlated with elevation, topographic position index (TPI), topographic wetness index (TWI), slope, and normalized difference vegetation index (NDVI). GWRK had the highest simulation accuracy, followed by RK, whereas STR was the weakest. A theoretical scientific basis is, therefore, provided for exploring the relationship between SOCD and the corresponding environmental variables as well as for modeling and estimating the regional soil carbon pool.



CATENA ◽  
2021 ◽  
Vol 201 ◽  
pp. 105187
Author(s):  
Yawen Li ◽  
Xingwu Duan ◽  
Ya Li ◽  
Yuxiang Li ◽  
Lanlan Zhang


2020 ◽  
Vol 12 (5) ◽  
pp. 2094
Author(s):  
Di Zhao ◽  
Junyu Dong ◽  
Shuping Ji ◽  
Miansong Huang ◽  
Quan Quan ◽  
...  

Soil organic carbon (SOC) concentration is closely related to soil quality and climate change. The objectives of this study were to estimate the effects of contemporary land use on SOC concentrations at 0–20 cm depths, and to investigate the dynamics of SOC in paddy-field soil and dry-land soil after their conversion from natural wetlands (20 and 30 years ago). We investigated the dissolved organic carbon (DOC), light fraction organic carbon (LFOC), heavy fraction organic carbon (HFOC), and other soil properties (i.e., moisture content, bulk density, pH, clay, sand, silt, available phosphorous, light fraction nitrogen, and heavy fraction nitrogen) in natural wetlands, constructed wetlands, fishponds, paddy fields, and soybean fields. The results indicated that the content of DOC increased 17% in constructed wetland and decreased 39% in fishponds, and the content of HFOC in constructed wetland and fishponds increased 50% and 8%, respectively, compared with that in natural wetlands at 0–20 cm. After the conversion of a wetland, the content of HFOC increased 72% in the paddy fields and decreased 62% in the dry land, while the content of DOC and LFOC decreased in both types. In the paddy fields, LFOC and HFOC content in the topmost 0.2 m of the soil layer was significantly higher compared to the layer below (from 0.2 to 0.6 m), and there were no significant differences observed in the dry land. The findings suggest that the paddy fields can sequester organic carbon through the accumulation of HFOC. However, the HFOC content decreased 22% after 10 years of cultivation with the decrease of clay content, indicating that paddy fields need to favor clay accumulation for the purpose of enhancing carbon sequestration in the paddy fields.





2012 ◽  
pp. 113-128 ◽  
Author(s):  
Ratko Kadovic ◽  
Snezana Belanovic ◽  
Dragica Obratov-Petkovic ◽  
Ivana Bjedov ◽  
Veljko Perovic ◽  
...  

Soil organic C storage in mountain areas is highly heterogeneous, mainly as a result of local-scale variability in the soil environment and microclimate. The aims of the present study were to estimate soil organic carbon density (SOCD) and stocks in leptosol on morainic deposits of high-altitude grasslands of the Lake Plateau of Mt. Durmitor National Park in Montenegro, and determine the soil variables that can be used as factors to determine the SOCD at 28 soil profiles. Our results indicated that SOC storage in the top 40 cm of the alpine grasslands were estimated at 560 414.86 t C, or 152.66 t?ha-1, with an average density of 15.27 kg?m-2. The soil organic carbon density increased significantly with soil moisture, clay and silt content, but only moderately with mean annual temperature. In conjunction, these variables could explain approximately 51% of the total variation in SOC density.



2015 ◽  
Vol 7 (1) ◽  
pp. 115-145 ◽  
Author(s):  
Y. Mohawesh ◽  
A. Taimeh ◽  
F. Ziadat

Abstract. Land degradation resulting from improper land use and management is a major cause of declined productivity in the arid environment. The objectives of this study were to examine the effects of a sequence of land use changes, soil conservation measures, and the time since their implementation on the degradation of selected soil properties. The climate for the selected 105 km2 watershed varies from semi-arid sub-tropical to Mediterranean sub-humid. Land use changes were detected using aerial photographs acquired in 1953, 1978, and 2008. A total of 218 samples were collected from 40 sites in three different rainfall zones to represent different land use changes and different lengths of time since the construction of stone walls. Analyses of variance were used to test the differences between the sequences of land use changes (interchangeable sequences of forest, orchards, field crops, and range), the time since the implementation of soil conservation measures, and rainfall on the thickness of the A-horizon, soil organic carbon content, and texture. Soil organic carbon reacts actively with different combinations and sequences of land use changes. The time since stone walls were constructed showed significant impacts on soil organic carbon and the thickness of the surface horizon. The effects of changing the land use and whether the changes were associated with the construction of stone walls, varied according to the annual rainfall. The results help in understanding the effects of land use changes on land degradation processes and carbon sequestration potential and in formulating sound soil conservation plans.



2013 ◽  
Vol 316-317 ◽  
pp. 299-306
Author(s):  
Ai Hong Gai ◽  
Ren Zhi Zhang ◽  
Fang Chen ◽  
Xiao Long Wang

The soil organic carbon density and storage of Maiji Area of Tianshui was estmiated, using the data of 6060 soil profile from the second soil survey of China and formulating fertilization for soil conditions in 2008. Integrating the soil map, land use status map and district map of Maiji Area of Tianshui, the index of the characteristic of soil organic distribution in different soil and soil layers were analyzed. Results showed: the soil of Maiji area have low average density, when soil secondary census, depths of 5cm,20cm,1m average density of organic carbon are 0.92kg•m-2,3.31kg•m-2,7.79kg•m-2 respectively, average density of organic carbon at depth of 20cm is 2.43 kg•m-2 in 2008 years, As a standard of Yu Dongsheng’s (2005) estimation of average density of 9.60 kg•m-2 in the depth of 1m all over the China, Maiji area 1m deep soil organic carbon density is lower 1.91kg•m-2 than the average density of whole country; The calculation of the secondary survey, reserves of organic carbon in surface soil (0-5cm) is about 4.83×106t, reserves of organic carbon in fall (0-20cm) is about 12.46×106t, reserves of soil organic carbon in 1m depth is about 45.17×106t, reserves of soil organic carbon in fall (0-20cm) is about 18.55×106t in 2008 years. In a word, the soil organic carbon storage was relatively indigent in Maiji Area of Tianshui.



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